diff --git a/.travis.yml b/.travis.yml
index b41a0f5..ed2d4bf 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -1,6 +1,6 @@
 language: cpp
 
-dist: trusty
+dist: xenial
 sudo: required
 group: edge
 
@@ -51,7 +51,7 @@ matrix:
       - TEST_LANGUAGE_STANDARD=14
     addons:
       apt:
-        sources: ['ubuntu-toolchain-r-test', 'llvm-toolchain-trusty-5.0']
+        sources: ['ubuntu-toolchain-r-test', 'llvm-toolchain-xenial-5.0']
         packages: ['g++-7', 'clang-5.0', 'ninja-build']
 
   - os: linux
@@ -61,9 +61,30 @@ matrix:
       - TEST_LANGUAGE_STANDARD=17
     addons:
       apt:
-        sources: ['ubuntu-toolchain-r-test', 'llvm-toolchain-trusty-6.0']
+        sources: ['ubuntu-toolchain-r-test', 'llvm-toolchain-xenial-6.0']
         packages: ['g++-7', 'clang-6.0', 'ninja-build']
 
+  - os: linux
+    compiler: clang
+    env:
+      - COMPILER=clang++-7
+      - TEST_LANGUAGE_STANDARD=17
+    addons:
+      apt:
+        sources: ['ubuntu-toolchain-r-test', 'llvm-toolchain-xenial-7']
+        packages: ['g++-8', 'clang-7', 'ninja-build']
+
+  - os: linux
+    compiler: clang
+    env:
+      - COMPILER=clang++-8
+      - TEST_LANGUAGE_STANDARD=17
+    addons:
+      apt:
+        sources: ['ubuntu-toolchain-r-test', 'llvm-toolchain-xenial-8']
+        packages: ['g++-8', 'clang-8', 'ninja-build']
+
+
 ################
 # build script #
 ################
diff --git a/README.md b/README.md
index dc3759a..b7fa19f 100644
--- a/README.md
+++ b/README.md
@@ -91,7 +91,7 @@ See the DirectX 12 enabled [viewer](examples/viewer) example for a demonstration
 | ------------| -------------------------- |
 | .gltf files w/external resources  | 100% complete and passing  |
 | .gltf files w/embedded resources  | 100% complete and passing (2 models excluded due to out-of-spec mimetypes)  |
-| .gltf files w/pbrSpecularGlossiness extension | 100% complete and passing  |
+| .gltf files w/Draco extension     | 100% complete and passing  |
 | .glb files                        | 100% complete and passing  |
 
 * Safety
diff --git a/examples/thirdparty/CLI11/CLI11.hpp b/examples/thirdparty/CLI11/CLI11.hpp
index bf3f813..ae58c81 100644
--- a/examples/thirdparty/CLI11/CLI11.hpp
+++ b/examples/thirdparty/CLI11/CLI11.hpp
@@ -1,15 +1,15 @@
 #pragma once
 
-// CLI11: Version 1.6.1
+// CLI11: Version 1.7.1
 // Originally designed by Henry Schreiner
 // https://github.com/CLIUtils/CLI11
 //
 // This is a standalone header file generated by MakeSingleHeader.py in CLI11/scripts
-// from: v1.6.1
+// from: v1.7.1
 //
 // From LICENSE:
 //
-// CLI11 1.6 Copyright (c) 2017-2018 University of Cincinnati, developed by Henry
+// CLI11 1.7 Copyright (c) 2017-2019 University of Cincinnati, developed by Henry
 // Schreiner under NSF AWARD 1414736. All rights reserved.
 // 
 // Redistribution and use in source and binary forms of CLI11, with or without
@@ -67,9 +67,9 @@
 
 
 #define CLI11_VERSION_MAJOR 1
-#define CLI11_VERSION_MINOR 6
+#define CLI11_VERSION_MINOR 7
 #define CLI11_VERSION_PATCH 1
-#define CLI11_VERSION "1.6.1"
+#define CLI11_VERSION "1.7.1"
 
 
 
@@ -117,14 +117,21 @@
 
 #ifdef __has_include
 
+// You can explicitly enable or disable support
+// by defining these to 1 or 0.
 #if defined(CLI11_CPP17) && __has_include(<optional>) && \
      !defined(CLI11_STD_OPTIONAL)
 #define CLI11_STD_OPTIONAL 1
+#elif !defined(CLI11_STD_OPTIONAL)
+#define CLI11_STD_OPTIONAL 0
 #endif
 
 #if defined(CLI11_CPP14) && __has_include(<experimental/optional>) && \
-    !defined(CLI11_EXPERIMENTAL_OPTIONAL)
+    !defined(CLI11_EXPERIMENTAL_OPTIONAL) \
+    && (!defined(CLI11_STD_OPTIONAL) || CLI11_STD_OPTIONAL == 0)
 #define CLI11_EXPERIMENTAL_OPTIONAL 1
+#elif !defined(CLI11_EXPERIMENTAL_OPTIONAL)
+#define CLI11_EXPERIMENTAL_OPTIONAL 0
 #endif
 
 #if __has_include(<boost/optional.hpp>) && !defined(CLI11_BOOST_OPTIONAL)
@@ -132,6 +139,8 @@
 #if BOOST_VERSION >= 105800
 #define CLI11_BOOST_OPTIONAL 1
 #endif
+#elif !defined(CLI11_BOOST_OPTIONAL)
+#define CLI11_BOOST_OPTIONAL 0
 #endif
 
 #endif
@@ -335,27 +344,54 @@ inline std::string to_lower(std::string str) {
     return str;
 }
 
+/// remove underscores from a string
+inline std::string remove_underscore(std::string str) {
+    str.erase(std::remove(std::begin(str), std::end(str), '_'), std::end(str));
+    return str;
+}
+
+/// Find and replace a substring with another substring
+inline std::string find_and_replace(std::string str, std::string from, std::string to) {
+
+    size_t start_pos = 0;
+
+    while((start_pos = str.find(from, start_pos)) != std::string::npos) {
+        str.replace(start_pos, from.length(), to);
+        start_pos += to.length();
+    }
+
+    return str;
+}
+
+/// Find a trigger string and call a modify callable function that takes the current string and starting position of the
+/// trigger and returns the position in the string to search for the next trigger string
+template <typename Callable> inline std::string find_and_modify(std::string str, std::string trigger, Callable modify) {
+    size_t start_pos = 0;
+    while((start_pos = str.find(trigger, start_pos)) != std::string::npos) {
+        start_pos = modify(str, start_pos);
+    }
+    return str;
+}
+
 /// Split a string '"one two" "three"' into 'one two', 'three'
+/// Quote characters can be ` ' or "
 inline std::vector<std::string> split_up(std::string str) {
 
-    std::vector<char> delims = {'\'', '\"'};
+    const std::string delims("\'\"`");
     auto find_ws = [](char ch) { return std::isspace<char>(ch, std::locale()); };
     trim(str);
 
     std::vector<std::string> output;
-
+    bool embeddedQuote = false;
+    char keyChar = ' ';
     while(!str.empty()) {
-        if(str[0] == '\'') {
-            auto end = str.find('\'', 1);
-            if(end != std::string::npos) {
-                output.push_back(str.substr(1, end - 1));
-                str = str.substr(end + 1);
-            } else {
-                output.push_back(str.substr(1));
-                str = "";
+        if(delims.find_first_of(str[0]) != std::string::npos) {
+            keyChar = str[0];
+            auto end = str.find_first_of(keyChar, 1);
+            while((end != std::string::npos) && (str[end - 1] == '\\')) { // deal with escaped quotes
+                end = str.find_first_of(keyChar, end + 1);
+                embeddedQuote = true;
             }
-        } else if(str[0] == '\"') {
-            auto end = str.find('\"', 1);
             if(end != std::string::npos) {
                 output.push_back(str.substr(1, end - 1));
                 str = str.substr(end + 1);
@@ -363,7 +399,6 @@ inline std::vector<std::string> split_up(std::string str) {
                 output.push_back(str.substr(1));
                 str = "";
             }
-
         } else {
             auto it = std::find_if(std::begin(str), std::end(str), find_ws);
             if(it != std::end(str)) {
@@ -375,9 +410,13 @@ inline std::vector<std::string> split_up(std::string str) {
                 str = "";
             }
         }
+        // transform any embedded quotes into the regular character
+        if(embeddedQuote) {
+            output.back() = find_and_replace(output.back(), std::string("\\") + keyChar, std::string(1, keyChar));
+            embeddedQuote = false;
+        }
         trim(str);
     }
-
     return output;
 }
 
@@ -397,6 +436,34 @@ inline std::string fix_newlines(std::string leader, std::string input) {
     return input;
 }
 
+/// This function detects an equal or colon followed by an escaped quote after an argument
+/// then modifies the string to replace the equality with a space.  This is needed
+/// to allow the split up function to work properly and is intended to be used with the find_and_modify function
+/// the return value is the offset+1 which is required by the find_and_modify function.
+inline size_t escape_detect(std::string &str, size_t offset) {
+    auto next = str[offset + 1];
+    if((next == '\"') || (next == '\'') || (next == '`')) {
+        auto astart = str.find_last_of("-/ \"\'`", offset - 1);
+        if(astart != std::string::npos) {
+            if(str[astart] == ((str[offset] == '=') ? '-' : '/'))
+                str[offset] = ' '; // interpret this as a space so the split_up works properly
+        }
+    }
+    return offset + 1;
+}
+
+/// Add quotes if the string contains spaces
+inline std::string &add_quotes_if_needed(std::string &str) {
+    if((str.front() != '"' && str.front() != '\'') || str.front() != str.back()) {
+        char quote = str.find('"') < str.find('\'') ? '\'' : '"';
+        if(str.find(' ') != std::string::npos) {
+            str.insert(0, 1, quote);
+            str.append(1, quote);
+        }
+    }
+    return str;
+}
+
 } // namespace detail
 } // namespace CLI
 
@@ -408,9 +475,9 @@ namespace CLI {
 // These are temporary and are undef'd at the end of this file.
 #define CLI11_ERROR_DEF(parent, name)                                                                                  \
   protected:                                                                                                           \
-    name(std::string name, std::string msg, int exit_code) : parent(std::move(name), std::move(msg), exit_code) {}     \
-    name(std::string name, std::string msg, ExitCodes exit_code)                                                       \
-        : parent(std::move(name), std::move(msg), exit_code) {}                                                        \
+    name(std::string ename, std::string msg, int exit_code) : parent(std::move(ename), std::move(msg), exit_code) {}   \
+    name(std::string ename, std::string msg, ExitCodes exit_code)                                                      \
+        : parent(std::move(ename), std::move(msg), exit_code) {}                                                       \
                                                                                                                        \
   public:                                                                                                              \
     name(std::string msg, ExitCodes exit_code) : parent(#name, std::move(msg), exit_code) {}                           \
@@ -452,16 +519,16 @@ enum class ExitCodes {
 
 /// All errors derive from this one
 class Error : public std::runtime_error {
-    int exit_code;
-    std::string name{"Error"};
+    int actual_exit_code;
+    std::string error_name{"Error"};
 
   public:
-    int get_exit_code() const { return exit_code; }
+    int get_exit_code() const { return actual_exit_code; }
 
-    std::string get_name() const { return name; }
+    std::string get_name() const { return error_name; }
 
     Error(std::string name, std::string msg, int exit_code = static_cast<int>(ExitCodes::BaseClass))
-        : runtime_error(msg), exit_code(exit_code), name(std::move(name)) {}
+        : runtime_error(msg), actual_exit_code(exit_code), error_name(std::move(name)) {}
 
     Error(std::string name, std::string msg, ExitCodes exit_code) : Error(name, msg, static_cast<int>(exit_code)) {}
 };
@@ -549,7 +616,7 @@ class CallForHelp : public ParseError {
     CallForHelp() : CallForHelp("This should be caught in your main function, see examples", ExitCodes::Success) {}
 };
 
-/// Usually somethign like --help-all on command line
+/// Usually something like --help-all on command line
 class CallForAllHelp : public ParseError {
     CLI11_ERROR_DEF(ParseError, CallForAllHelp)
     CallForAllHelp()
@@ -853,7 +920,7 @@ inline bool split_short(const std::string &current, std::string &name, std::stri
 // Returns false if not a long option. Otherwise, sets opt name and other side of = and returns true
 inline bool split_long(const std::string &current, std::string &name, std::string &value) {
     if(current.size() > 2 && current.substr(0, 2) == "--" && valid_first_char(current[2])) {
-        auto loc = current.find("=");
+        auto loc = current.find_first_of('=');
         if(loc != std::string::npos) {
             name = current.substr(2, loc - 2);
             value = current.substr(loc + 1);
@@ -866,6 +933,22 @@ inline bool split_long(const std::string &current, std::string &name, std::strin
         return false;
 }
 
+// Returns false if not a windows style option. Otherwise, sets opt name and value and returns true
+inline bool split_windows(const std::string &current, std::string &name, std::string &value) {
+    if(current.size() > 1 && current[0] == '/' && valid_first_char(current[1])) {
+        auto loc = current.find_first_of(':');
+        if(loc != std::string::npos) {
+            name = current.substr(1, loc - 1);
+            value = current.substr(loc + 1);
+        } else {
+            name = current.substr(1);
+            value = "";
+        }
+        return true;
+    } else
+        return false;
+}
+
 // Splits a string into multiple long and short names
 inline std::vector<std::string> split_names(std::string current) {
     std::vector<std::string> output;
@@ -1025,7 +1108,7 @@ class ConfigINI : public Config {
         std::vector<ConfigItem> output;
 
         while(getline(input, line)) {
-            std::vector<std::string> items;
+            std::vector<std::string> items_buffer;
 
             detail::trim(line);
             size_t len = line.length();
@@ -1040,10 +1123,10 @@ class ConfigINI : public Config {
                 if(pos != std::string::npos) {
                     out.name = detail::trim_copy(line.substr(0, pos));
                     std::string item = detail::trim_copy(line.substr(pos + 1));
-                    items = detail::split_up(item);
+                    items_buffer = detail::split_up(item);
                 } else {
                     out.name = detail::trim_copy(line);
-                    items = {"ON"};
+                    items_buffer = {"ON"};
                 }
 
                 if(detail::to_lower(section) != "default") {
@@ -1057,7 +1140,7 @@ class ConfigINI : public Config {
                     out.parents.insert(out.parents.end(), plist.begin(), plist.end());
                 }
 
-                out.inputs.insert(std::end(out.inputs), std::begin(items), std::end(items));
+                out.inputs.insert(std::end(out.inputs), std::begin(items_buffer), std::end(items_buffer));
             }
         }
         return output;
@@ -1244,6 +1327,33 @@ struct Range : public Validator {
     template <typename T> explicit Range(T max) : Range(static_cast<T>(0), max) {}
 };
 
+namespace detail {
+/// split a string into a program name and command line arguments
+/// the string is assumed to contain a file name followed by other arguments
+/// the return value contains is a pair with the first argument containing the program name and the second everything
+/// else
+inline std::pair<std::string, std::string> split_program_name(std::string commandline) {
+    // try to determine the programName
+    std::pair<std::string, std::string> vals;
+    trim(commandline);
+    auto esp = commandline.find_first_of(' ', 1);
+    while(!ExistingFile(commandline.substr(0, esp)).empty()) {
+        esp = commandline.find_first_of(' ', esp + 1);
+        if(esp == std::string::npos) {
+            // if we have reached the end and haven't found a valid file just assume the first argument is the
+            // program name
+            esp = commandline.find_first_of(' ', 1);
+            break;
+        }
+    }
+    vals.first = commandline.substr(0, esp);
+    rtrim(vals.first);
+    // strip the program name
+    vals.second = (esp != std::string::npos) ? commandline.substr(esp + 1) : std::string{};
+    ltrim(vals.second);
+    return vals;
+}
+} // namespace detail
 /// @}
 
 } // namespace CLI
@@ -1440,6 +1550,9 @@ template <typename CRTP> class OptionBase {
     /// Ignore the case when matching (option, not value)
     bool ignore_case_{false};
 
+    /// Ignore underscores when matching (option, not value)
+    bool ignore_underscore_{false};
+
     /// Allow this option to be given in a configuration file
     bool configurable_{true};
 
@@ -1451,6 +1564,7 @@ template <typename CRTP> class OptionBase {
         other->group(group_);
         other->required(required_);
         other->ignore_case(ignore_case_);
+        other->ignore_underscore(ignore_underscore_);
         other->configurable(configurable_);
         other->multi_option_policy(multi_option_policy_);
     }
@@ -1485,6 +1599,9 @@ template <typename CRTP> class OptionBase {
     /// The status of ignore case
     bool get_ignore_case() const { return ignore_case_; }
 
+    /// The status of ignore_underscore
+    bool get_ignore_underscore() const { return ignore_underscore_; }
+
     /// The status of configurable
     bool get_configurable() const { return configurable_; }
 
@@ -1540,6 +1657,12 @@ class OptionDefaults : public OptionBase<OptionDefaults> {
         ignore_case_ = value;
         return this;
     }
+
+    /// Ignore underscores in the option name
+    OptionDefaults *ignore_underscore(bool value = true) {
+        ignore_underscore_ = value;
+        return this;
+    }
 };
 
 class Option : public OptionBase<Option> {
@@ -1595,7 +1718,7 @@ class Option : public OptionBase<Option> {
     std::vector<std::function<std::string(std::string &)>> validators_;
 
     /// A list of options that are required with this option
-    std::set<Option *> requires_;
+    std::set<Option *> needs_;
 
     /// A list of options that are excluded with this option
     std::set<Option *> excludes_;
@@ -1610,9 +1733,6 @@ class Option : public OptionBase<Option> {
     /// Options store a callback to do all the work
     callback_t callback_;
 
-    /// Options can short-circuit for help options or similar (called before parsing is validated)
-    bool short_circuit_{false};
-
     ///@}
     /// @name Parsing results
     ///@{
@@ -1626,11 +1746,14 @@ class Option : public OptionBase<Option> {
     ///@}
 
     /// Making an option by hand is not defined, it must be made by the App class
-    Option(
-        std::string name, std::string description, std::function<bool(results_t)> callback, bool defaulted, App *parent)
+    Option(std::string option_name,
+           std::string description,
+           std::function<bool(results_t)> callback,
+           bool defaulted,
+           App *parent)
         : description_(std::move(description)), default_(defaulted), parent_(parent),
           callback_(callback ? std::move(callback) : [](results_t) { return true; }) {
-        std::tie(snames_, lnames_, pname_) = detail::get_names(detail::split_names(name));
+        std::tie(snames_, lnames_, pname_) = detail::get_names(detail::split_names(option_name));
     }
 
   public:
@@ -1717,7 +1840,7 @@ class Option : public OptionBase<Option> {
 
     /// Sets required options
     Option *needs(Option *opt) {
-        auto tup = requires_.insert(opt);
+        auto tup = needs_.insert(opt);
         if(!tup.second)
             throw OptionAlreadyAdded::Requires(get_name(), opt->get_name());
         return this;
@@ -1737,6 +1860,18 @@ class Option : public OptionBase<Option> {
         return needs(opt1, args...);
     }
 
+    /// Remove needs link from an option. Returns true if the option really was in the needs list.
+    bool remove_needs(Option *opt) {
+        auto iterator = std::find(std::begin(needs_), std::end(needs_), opt);
+
+        if(iterator != std::end(needs_)) {
+            needs_.erase(iterator);
+            return true;
+        } else {
+            return false;
+        }
+    }
+
     /// Sets excluded options
     Option *excludes(Option *opt) {
         excludes_.insert(opt);
@@ -1764,6 +1899,18 @@ class Option : public OptionBase<Option> {
         return excludes(opt1, args...);
     }
 
+    /// Remove needs link from an option. Returns true if the option really was in the needs list.
+    bool remove_excludes(Option *opt) {
+        auto iterator = std::find(std::begin(excludes_), std::end(excludes_), opt);
+
+        if(iterator != std::end(excludes_)) {
+            excludes_.erase(iterator);
+            return true;
+        } else {
+            return false;
+        }
+    }
+
     /// Sets environment variable to read if no option given
     Option *envname(std::string name) {
         envname_ = name;
@@ -1785,6 +1932,20 @@ class Option : public OptionBase<Option> {
         return this;
     }
 
+    /// Ignore underscores in the option names
+    ///
+    /// The template hides the fact that we don't have the definition of App yet.
+    /// You are never expected to add an argument to the template here.
+    template <typename T = App> Option *ignore_underscore(bool value = true) {
+        ignore_underscore_ = value;
+        auto *parent = dynamic_cast<T *>(parent_);
+        for(const Option_p &opt : parent->options_)
+            if(opt.get() != this && *opt == *this)
+                throw OptionAlreadyAdded(opt->get_name(true, true));
+
+        return this;
+    }
+
     /// Take the last argument if given multiple times (or another policy)
     Option *multi_option_policy(MultiOptionPolicy value = MultiOptionPolicy::Throw) {
 
@@ -1794,14 +1955,6 @@ class Option : public OptionBase<Option> {
         return this;
     }
 
-    /// Options with a short circuit set will run this function before parsing is finished.
-    ///
-    /// This is set on help functions, for example, to escape the normal validation.
-    Option *short_circuit(bool value = true) {
-        short_circuit_ = value;
-        return this;
-    }
-
     ///@}
     /// @name Accessors
     ///@{
@@ -1813,7 +1966,7 @@ class Option : public OptionBase<Option> {
     std::string get_envname() const { return envname_; }
 
     /// The set of options needed
-    std::set<Option *> get_needs() const { return requires_; }
+    std::set<Option *> get_needs() const { return needs_; }
 
     /// The set of options excluded
     std::set<Option *> get_excludes() const { return excludes_; }
@@ -1821,9 +1974,6 @@ class Option : public OptionBase<Option> {
     /// The default value (for help printing)
     std::string get_defaultval() const { return defaultval_; }
 
-    /// See if this is supposed to short circuit (skip validation, INI, etc) (Used for help flags)
-    bool get_short_circuit() const { return short_circuit_; }
-
     /// Get the callback function
     callback_t get_callback() const { return callback_; }
 
@@ -1837,7 +1987,7 @@ class Option : public OptionBase<Option> {
     int get_expected() const { return expected_; }
 
     /// \brief The total number of expected values (including the type)
-    /// This is positive if exactly this number is expected, and negitive for at least N values
+    /// This is positive if exactly this number is expected, and negative for at least N values
     ///
     /// v = fabs(size_type*expected)
     /// !MultiOptionPolicy::Throw
@@ -1872,11 +2022,17 @@ class Option : public OptionBase<Option> {
     /// Get the description
     const std::string &get_description() const { return description_; }
 
+    /// Set the description
+    Option *description(const std::string &description) {
+        description_ = description;
+        return this;
+    }
+
     ///@}
     /// @name Help tools
     ///@{
 
-    /// \brief Gets a comma seperated list of names.
+    /// \brief Gets a comma separated list of names.
     /// Will include / prefer the positional name if positional is true.
     /// If all_options is false, pick just the most descriptive name to show.
     /// Use `get_name(true)` to get the positional name (replaces `get_pname`)
@@ -1888,7 +2044,7 @@ class Option : public OptionBase<Option> {
 
             std::vector<std::string> name_list;
 
-            /// The all list wil never include a positional unless asked or that's the only name.
+            /// The all list will never include a positional unless asked or that's the only name.
             if((positional && pname_.length()) || (snames_.empty() && lnames_.empty()))
                 name_list.push_back(pname_);
 
@@ -1927,6 +2083,8 @@ class Option : public OptionBase<Option> {
     /// Process the callback
     void run_callback() {
 
+        callback_run_ = true;
+
         // Run the validators (can change the string)
         if(!validators_.empty()) {
             for(std::string &result : results_)
@@ -1985,7 +2143,7 @@ class Option : public OptionBase<Option> {
         for(const std::string &lname : lnames_)
             if(other.check_lname(lname))
                 return true;
-        // We need to do the inverse, just in case we are ignore_case
+        // We need to do the inverse, just in case we are ignore_case or ignore underscore
         for(const std::string &sname : other.snames_)
             if(check_sname(sname))
                 return true;
@@ -2008,13 +2166,17 @@ class Option : public OptionBase<Option> {
                 local_pname = detail::to_lower(local_pname);
                 name = detail::to_lower(name);
             }
+            if(ignore_underscore_) {
+                local_pname = detail::remove_underscore(local_pname);
+                name = detail::remove_underscore(name);
+            }
             return name == local_pname;
         }
     }
 
     /// Requires "-" to be removed from string
     bool check_sname(std::string name) const {
-        if(ignore_case_) {
+        if(ignore_case_) { // there can be no extra underscores in check_sname
             name = detail::to_lower(name);
             return std::find_if(std::begin(snames_), std::end(snames_), [&name](std::string local_sname) {
                        return detail::to_lower(local_sname) == name;
@@ -2026,9 +2188,22 @@ class Option : public OptionBase<Option> {
     /// Requires "--" to be removed from string
     bool check_lname(std::string name) const {
         if(ignore_case_) {
-            name = detail::to_lower(name);
+            if(ignore_underscore_) {
+                name = detail::to_lower(detail::remove_underscore(name));
+                return std::find_if(std::begin(lnames_), std::end(lnames_), [&name](std::string local_sname) {
+                           return detail::to_lower(detail::remove_underscore(local_sname)) == name;
+                       }) != std::end(lnames_);
+            } else {
+                name = detail::to_lower(name);
+                return std::find_if(std::begin(lnames_), std::end(lnames_), [&name](std::string local_sname) {
+                           return detail::to_lower(local_sname) == name;
+                       }) != std::end(lnames_);
+            }
+
+        } else if(ignore_underscore_) {
+            name = detail::remove_underscore(name);
             return std::find_if(std::begin(lnames_), std::end(lnames_), [&name](std::string local_sname) {
-                       return detail::to_lower(local_sname) == name;
+                       return detail::remove_underscore(local_sname) == name;
                    }) != std::end(lnames_);
         } else
             return std::find(std::begin(lnames_), std::end(lnames_), name) != std::end(lnames_);
@@ -2042,8 +2217,8 @@ class Option : public OptionBase<Option> {
     }
 
     /// Set the results vector all at once
-    Option *set_results(std::vector<std::string> results) {
-        results_ = results;
+    Option *set_results(std::vector<std::string> result_vector) {
+        results_ = std::move(result_vector);
         callback_run_ = false;
         return this;
     }
@@ -2070,16 +2245,12 @@ class Option : public OptionBase<Option> {
         return this;
     }
 
-    /// Provided for backward compatibility \deprecated
-    CLI11_DEPRECATED("Please use type_name instead")
-    Option *set_type_name(std::string typeval) { return type_name(typeval); }
-
     /// Set a custom option size
-    Option *type_size(int type_size) {
-        type_size_ = type_size;
+    Option *type_size(int option_type_size) {
+        type_size_ = option_type_size;
         if(type_size_ == 0)
             required_ = false;
-        if(type_size < 0)
+        if(option_type_size < 0)
             expected_ = -1;
         return this;
     }
@@ -2120,7 +2291,7 @@ namespace CLI {
 #endif
 
 namespace detail {
-enum class Classifer { NONE, POSITIONAL_MARK, SHORT, LONG, SUBCOMMAND };
+enum class Classifier { NONE, POSITIONAL_MARK, SHORT, LONG, WINDOWS, SUBCOMMAND };
 struct AppFriend;
 } // namespace detail
 
@@ -2198,7 +2369,7 @@ class App {
     /// @name Parsing
     ///@{
 
-    using missing_t = std::vector<std::pair<detail::Classifer, std::string>>;
+    using missing_t = std::vector<std::pair<detail::Classifier, std::string>>;
 
     /// Pair of classifier, string for missing options. (extra detail is removed on returning from parse)
     ///
@@ -2221,14 +2392,26 @@ class App {
     /// If true, the program name is not case sensitive INHERITABLE
     bool ignore_case_{false};
 
+    /// If true, the program should ignore underscores INHERITABLE
+    bool ignore_underscore_{false};
+
     /// Allow subcommand fallthrough, so that parent commands can collect commands after subcommand.  INHERITABLE
     bool fallthrough_{false};
 
+    /// Allow '/' for options for Windows like options. Defaults to true on Windows, false otherwise. INHERITABLE
+    bool allow_windows_style_options_{
+#ifdef _WIN32
+        true
+#else
+        false
+#endif
+    };
+
     /// A pointer to the parent if this is a subcommand
     App *parent_{nullptr};
 
-    /// True if this command/subcommand was parsed
-    bool parsed_{false};
+    /// Counts the number of times this command/subcommand was parsed
+    size_t parsed_ = 0;
 
     /// Minimum required subcommands (not inheritable!)
     size_t require_subcommand_min_ = 0;
@@ -2258,8 +2441,8 @@ class App {
     ///@}
 
     /// Special private constructor for subcommand
-    App(std::string description_, std::string name, App *parent)
-        : name_(std::move(name)), description_(std::move(description_)), parent_(parent) {
+    App(std::string description, std::string app_name, App *parent)
+        : name_(std::move(app_name)), description_(std::move(description)), parent_(parent) {
         // Inherit if not from a nullptr
         if(parent_ != nullptr) {
             if(parent_->help_ptr_ != nullptr)
@@ -2277,7 +2460,9 @@ class App {
             allow_config_extras_ = parent_->allow_config_extras_;
             prefix_command_ = parent_->prefix_command_;
             ignore_case_ = parent_->ignore_case_;
+            ignore_underscore_ = parent_->ignore_underscore_;
             fallthrough_ = parent_->fallthrough_;
+            allow_windows_style_options_ = parent_->allow_windows_style_options_;
             group_ = parent_->group_;
             footer_ = parent_->footer_;
             formatter_ = parent_->formatter_;
@@ -2291,7 +2476,7 @@ class App {
     ///@{
 
     /// Create a new program. Pass in the same arguments as main(), along with a help string.
-    explicit App(std::string description_ = "", std::string name = "") : App(description_, name, nullptr) {
+    explicit App(std::string description = "", std::string app_name = "") : App(description, app_name, nullptr) {
         set_help_flag("-h,--help", "Print this help message and exit");
     }
 
@@ -2304,14 +2489,14 @@ class App {
     /// it is not possible to overload on std::function (fixed in c++14
     /// and backported to c++11 on newer compilers). Use capture by reference
     /// to get a pointer to App if needed.
-    App *callback(std::function<void()> callback) {
-        callback_ = callback;
+    App *callback(std::function<void()> app_callback) {
+        callback_ = std::move(app_callback);
         return this;
     }
 
     /// Set a name for the app (empty will use parser to set the name)
-    App *name(std::string name = "") {
-        name_ = name;
+    App *name(std::string app_name = "") {
+        name_ = app_name;
         return this;
     }
 
@@ -2329,13 +2514,13 @@ class App {
         return this;
     }
 
-    /// Do not parse anything after the first unrecognised option and return
+    /// Do not parse anything after the first unrecognized option and return
     App *prefix_command(bool allow = true) {
         prefix_command_ = allow;
         return this;
     }
 
-    /// Ignore case. Subcommand inherit value.
+    /// Ignore case. Subcommands inherit value.
     App *ignore_case(bool value = true) {
         ignore_case_ = value;
         if(parent_ != nullptr) {
@@ -2347,6 +2532,24 @@ class App {
         return this;
     }
 
+    /// Allow windows style options, such as `/opt`. First matching short or long name used. Subcommands inherit value.
+    App *allow_windows_style_options(bool value = true) {
+        allow_windows_style_options_ = value;
+        return this;
+    }
+
+    /// Ignore underscore. Subcommands inherit value.
+    App *ignore_underscore(bool value = true) {
+        ignore_underscore_ = value;
+        if(parent_ != nullptr) {
+            for(const auto &subc : parent_->subcommands_) {
+                if(subc.get() != this && (this->check_name(subc->name_) || subc->check_name(this->name_)))
+                    throw OptionAlreadyAdded(subc->name_);
+            }
+        }
+        return this;
+    }
+
     /// Set the help formatter
     App *formatter(std::shared_ptr<FormatterBase> fmt) {
         formatter_ = fmt;
@@ -2366,7 +2569,7 @@ class App {
     }
 
     /// Check to see if this subcommand was parsed, true only if received on command line.
-    bool parsed() const { return parsed_; }
+    bool parsed() const { return parsed_ > 0; }
 
     /// Get the OptionDefault object, to set option defaults
     OptionDefaults *option_defaults() { return &option_defaults_; }
@@ -2389,15 +2592,18 @@ class App {
     ///     std::string filename;
     ///     program.add_option("filename", filename, "description of filename");
     ///
-    Option *add_option(std::string name, callback_t callback, std::string description = "", bool defaulted = false) {
-        Option myopt{name, description, callback, defaulted, this};
+    Option *add_option(std::string option_name,
+                       callback_t option_callback,
+                       std::string description = "",
+                       bool defaulted = false) {
+        Option myopt{option_name, description, option_callback, defaulted, this};
 
         if(std::find_if(std::begin(options_), std::end(options_), [&myopt](const Option_p &v) {
                return *v == myopt;
            }) == std::end(options_)) {
             options_.emplace_back();
             Option_p &option = options_.back();
-            option.reset(new Option(name, description, callback, defaulted, this));
+            option.reset(new Option(option_name, description, option_callback, defaulted, this));
             option_defaults_.copy_to(option.get());
             return option.get();
         } else
@@ -2406,27 +2612,27 @@ class App {
 
     /// Add option for non-vectors (duplicate copy needed without defaulted to avoid `iostream << value`)
     template <typename T, enable_if_t<!is_vector<T>::value, detail::enabler> = detail::dummy>
-    Option *add_option(std::string name,
+    Option *add_option(std::string option_name,
                        T &variable, ///< The variable to set
                        std::string description = "") {
 
         CLI::callback_t fun = [&variable](CLI::results_t res) { return detail::lexical_cast(res[0], variable); };
 
-        Option *opt = add_option(name, fun, description, false);
+        Option *opt = add_option(option_name, fun, description, false);
         opt->type_name(detail::type_name<T>());
         return opt;
     }
 
     /// Add option for non-vectors with a default print
     template <typename T, enable_if_t<!is_vector<T>::value, detail::enabler> = detail::dummy>
-    Option *add_option(std::string name,
+    Option *add_option(std::string option_name,
                        T &variable, ///< The variable to set
                        std::string description,
                        bool defaulted) {
 
         CLI::callback_t fun = [&variable](CLI::results_t res) { return detail::lexical_cast(res[0], variable); };
 
-        Option *opt = add_option(name, fun, description, defaulted);
+        Option *opt = add_option(option_name, fun, description, defaulted);
         opt->type_name(detail::type_name<T>());
         if(defaulted) {
             std::stringstream out;
@@ -2438,7 +2644,7 @@ class App {
 
     /// Add option for vectors (no default)
     template <typename T>
-    Option *add_option(std::string name,
+    Option *add_option(std::string option_name,
                        std::vector<T> &variable, ///< The variable vector to set
                        std::string description = "") {
 
@@ -2452,14 +2658,14 @@ class App {
             return (!variable.empty()) && retval;
         };
 
-        Option *opt = add_option(name, fun, description, false);
+        Option *opt = add_option(option_name, fun, description, false);
         opt->type_name(detail::type_name<T>())->type_size(-1);
         return opt;
     }
 
     /// Add option for vectors
     template <typename T>
-    Option *add_option(std::string name,
+    Option *add_option(std::string option_name,
                        std::vector<T> &variable, ///< The variable vector to set
                        std::string description,
                        bool defaulted) {
@@ -2474,7 +2680,7 @@ class App {
             return (!variable.empty()) && retval;
         };
 
-        Option *opt = add_option(name, fun, description, defaulted);
+        Option *opt = add_option(option_name, fun, description, defaulted);
         opt->type_name(detail::type_name<T>())->type_size(-1);
         if(defaulted)
             opt->default_str("[" + detail::join(variable) + "]");
@@ -2482,16 +2688,15 @@ class App {
     }
 
     /// Set a help flag, replace the existing one if present
-    Option *set_help_flag(std::string name = "", std::string description = "") {
+    Option *set_help_flag(std::string flag_name = "", std::string description = "") {
         if(help_ptr_ != nullptr) {
             remove_option(help_ptr_);
             help_ptr_ = nullptr;
         }
 
         // Empty name will simply remove the help flag
-        if(!name.empty()) {
-            help_ptr_ = add_flag_function(name, [](size_t) -> void { throw CallForHelp(); }, description);
-            help_ptr_->short_circuit(true);
+        if(!flag_name.empty()) {
+            help_ptr_ = add_flag(flag_name, description);
             help_ptr_->configurable(false);
         }
 
@@ -2499,16 +2704,15 @@ class App {
     }
 
     /// Set a help all flag, replaced the existing one if present
-    Option *set_help_all_flag(std::string name = "", std::string description = "") {
+    Option *set_help_all_flag(std::string help_name = "", std::string description = "") {
         if(help_all_ptr_ != nullptr) {
             remove_option(help_all_ptr_);
             help_all_ptr_ = nullptr;
         }
 
         // Empty name will simply remove the help all flag
-        if(!name.empty()) {
-            help_all_ptr_ = add_flag_function(name, [](size_t) -> void { throw CallForAllHelp(); }, description);
-            help_all_ptr_->short_circuit(true);
+        if(!help_name.empty()) {
+            help_all_ptr_ = add_flag(help_name, description);
             help_all_ptr_->configurable(false);
         }
 
@@ -2516,12 +2720,12 @@ class App {
     }
 
     /// Add option for flag
-    Option *add_flag(std::string name, std::string description = "") {
+    Option *add_flag(std::string flag_name, std::string description = "") {
         CLI::callback_t fun = [](CLI::results_t) { return true; };
 
-        Option *opt = add_option(name, fun, description, false);
+        Option *opt = add_option(flag_name, fun, description, false);
         if(opt->get_positional())
-            throw IncorrectConstruction::PositionalFlag(name);
+            throw IncorrectConstruction::PositionalFlag(flag_name);
         opt->type_size(0);
         return opt;
     }
@@ -2529,19 +2733,19 @@ class App {
     /// Add option for flag integer
     template <typename T,
               enable_if_t<std::is_integral<T>::value && !is_bool<T>::value, detail::enabler> = detail::dummy>
-    Option *add_flag(std::string name,
-                     T &count, ///< A variable holding the count
+    Option *add_flag(std::string flag_name,
+                     T &flag_count, ///< A variable holding the count
                      std::string description = "") {
 
-        count = 0;
-        CLI::callback_t fun = [&count](CLI::results_t res) {
-            count = static_cast<T>(res.size());
+        flag_count = 0;
+        CLI::callback_t fun = [&flag_count](CLI::results_t res) {
+            flag_count = static_cast<T>(res.size());
             return true;
         };
 
-        Option *opt = add_option(name, fun, description, false);
+        Option *opt = add_option(flag_name, fun, description, false);
         if(opt->get_positional())
-            throw IncorrectConstruction::PositionalFlag(name);
+            throw IncorrectConstruction::PositionalFlag(flag_name);
         opt->type_size(0);
         return opt;
     }
@@ -2549,59 +2753,58 @@ class App {
     /// Bool version - defaults to allowing multiple passings, but can be forced to one if
     /// `multi_option_policy(CLI::MultiOptionPolicy::Throw)` is used.
     template <typename T, enable_if_t<is_bool<T>::value, detail::enabler> = detail::dummy>
-    Option *add_flag(std::string name,
-                     T &count, ///< A variable holding true if passed
+    Option *add_flag(std::string flag_name,
+                     T &flag_count, ///< A variable holding true if passed
                      std::string description = "") {
 
-        count = false;
-        CLI::callback_t fun = [&count](CLI::results_t res) {
-            count = true;
+        flag_count = false;
+        CLI::callback_t fun = [&flag_count](CLI::results_t res) {
+            flag_count = true;
             return res.size() == 1;
         };
 
-        Option *opt = add_option(name, fun, description, false);
+        Option *opt = add_option(flag_name, fun, description, false);
         if(opt->get_positional())
-            throw IncorrectConstruction::PositionalFlag(name);
+            throw IncorrectConstruction::PositionalFlag(flag_name);
         opt->type_size(0);
         opt->multi_option_policy(CLI::MultiOptionPolicy::TakeLast);
         return opt;
     }
 
     /// Add option for callback
-    Option *add_flag_function(std::string name,
+    Option *add_flag_function(std::string flag_name,
                               std::function<void(size_t)> function, ///< A function to call, void(size_t)
                               std::string description = "") {
 
         CLI::callback_t fun = [function](CLI::results_t res) {
-            auto count = static_cast<size_t>(res.size());
-            function(count);
+            function(res.size());
             return true;
         };
 
-        Option *opt = add_option(name, fun, description, false);
+        Option *opt = add_option(flag_name, fun, description, false);
         if(opt->get_positional())
-            throw IncorrectConstruction::PositionalFlag(name);
+            throw IncorrectConstruction::PositionalFlag(flag_name);
         opt->type_size(0);
         return opt;
     }
 
 #ifdef CLI11_CPP14
     /// Add option for callback (C++14 or better only)
-    Option *add_flag(std::string name,
+    Option *add_flag(std::string flag_name,
                      std::function<void(size_t)> function, ///< A function to call, void(size_t)
                      std::string description = "") {
-        return add_flag_function(name, function, description);
+        return add_flag_function(flag_name, std::move(function), description);
     }
 #endif
 
-    /// Add set of options (No default, temp refernce, such as an inline set)
+    /// Add set of options (No default, temp reference, such as an inline set)
     template <typename T>
-    Option *add_set(std::string name,
-                    T &member,                   ///< The selected member of the set
-                    const std::set<T> &&options, ///< The set of possibilities
+    Option *add_set(std::string option_name,
+                    T &member,           ///< The selected member of the set
+                    std::set<T> options, ///< The set of possibilities
                     std::string description = "") {
 
-        std::string simple_name = CLI::detail::split(name, ',').at(0);
+        std::string simple_name = CLI::detail::split(option_name, ',').at(0);
         CLI::callback_t fun = [&member, options, simple_name](CLI::results_t res) {
             bool retval = detail::lexical_cast(res[0], member);
             if(!retval)
@@ -2609,21 +2812,21 @@ class App {
             return std::find(std::begin(options), std::end(options), member) != std::end(options);
         };
 
-        Option *opt = add_option(name, fun, description, false);
+        Option *opt = add_option(option_name, fun, description, false);
         std::string typeval = detail::type_name<T>();
         typeval += " in {" + detail::join(options) + "}";
         opt->type_name(typeval);
         return opt;
     }
 
-    /// Add set of options (No default, non-temp refernce, such as an existing set)
+    /// Add set of options (No default, set can be changed afterwords - do not destroy the set)
     template <typename T>
-    Option *add_set(std::string name,
-                    T &member,                  ///< The selected member of the set
-                    const std::set<T> &options, ///< The set of possibilities
-                    std::string description = "") {
+    Option *add_mutable_set(std::string option_name,
+                            T &member,                  ///< The selected member of the set
+                            const std::set<T> &options, ///< The set of possibilities
+                            std::string description = "") {
 
-        std::string simple_name = CLI::detail::split(name, ',').at(0);
+        std::string simple_name = CLI::detail::split(option_name, ',').at(0);
         CLI::callback_t fun = [&member, &options, simple_name](CLI::results_t res) {
             bool retval = detail::lexical_cast(res[0], member);
             if(!retval)
@@ -2631,22 +2834,22 @@ class App {
             return std::find(std::begin(options), std::end(options), member) != std::end(options);
         };
 
-        Option *opt = add_option(name, fun, description, false);
+        Option *opt = add_option(option_name, fun, description, false);
         opt->type_name_fn(
             [&options]() { return std::string(detail::type_name<T>()) + " in {" + detail::join(options) + "}"; });
 
         return opt;
     }
 
-    /// Add set of options (with default, R value, such as an inline set)
+    /// Add set of options (with default, static set, such as an inline set)
     template <typename T>
-    Option *add_set(std::string name,
-                    T &member,                   ///< The selected member of the set
-                    const std::set<T> &&options, ///< The set of posibilities
+    Option *add_set(std::string option_name,
+                    T &member,           ///< The selected member of the set
+                    std::set<T> options, ///< The set of possibilities
                     std::string description,
                     bool defaulted) {
 
-        std::string simple_name = CLI::detail::split(name, ',').at(0);
+        std::string simple_name = CLI::detail::split(option_name, ',').at(0);
         CLI::callback_t fun = [&member, options, simple_name](CLI::results_t res) {
             bool retval = detail::lexical_cast(res[0], member);
             if(!retval)
@@ -2654,7 +2857,7 @@ class App {
             return std::find(std::begin(options), std::end(options), member) != std::end(options);
         };
 
-        Option *opt = add_option(name, fun, description, defaulted);
+        Option *opt = add_option(option_name, fun, description, defaulted);
         std::string typeval = detail::type_name<T>();
         typeval += " in {" + detail::join(options) + "}";
         opt->type_name(typeval);
@@ -2666,15 +2869,15 @@ class App {
         return opt;
     }
 
-    /// Add set of options (with default, L value refernce, such as an existing set)
+    /// Add set of options (with default, set can be changed afterwards - do not destroy the set)
     template <typename T>
-    Option *add_set(std::string name,
-                    T &member,                  ///< The selected member of the set
-                    const std::set<T> &options, ///< The set of posibilities
-                    std::string description,
-                    bool defaulted) {
+    Option *add_mutable_set(std::string option_name,
+                            T &member,                  ///< The selected member of the set
+                            const std::set<T> &options, ///< The set of possibilities
+                            std::string description,
+                            bool defaulted) {
 
-        std::string simple_name = CLI::detail::split(name, ',').at(0);
+        std::string simple_name = CLI::detail::split(option_name, ',').at(0);
         CLI::callback_t fun = [&member, &options, simple_name](CLI::results_t res) {
             bool retval = detail::lexical_cast(res[0], member);
             if(!retval)
@@ -2682,7 +2885,7 @@ class App {
             return std::find(std::begin(options), std::end(options), member) != std::end(options);
         };
 
-        Option *opt = add_option(name, fun, description, defaulted);
+        Option *opt = add_option(option_name, fun, description, defaulted);
         opt->type_name_fn(
             [&options]() { return std::string(detail::type_name<T>()) + " in {" + detail::join(options) + "}"; });
         if(defaulted) {
@@ -2693,13 +2896,13 @@ class App {
         return opt;
     }
 
-    /// Add set of options, string only, ignore case (no default, R value)
-    Option *add_set_ignore_case(std::string name,
-                                std::string &member,                   ///< The selected member of the set
-                                const std::set<std::string> &&options, ///< The set of possibilities
+    /// Add set of options, string only, ignore case (no default, static set)
+    Option *add_set_ignore_case(std::string option_name,
+                                std::string &member,           ///< The selected member of the set
+                                std::set<std::string> options, ///< The set of possibilities
                                 std::string description = "") {
 
-        std::string simple_name = CLI::detail::split(name, ',').at(0);
+        std::string simple_name = CLI::detail::split(option_name, ',').at(0);
         CLI::callback_t fun = [&member, options, simple_name](CLI::results_t res) {
             member = detail::to_lower(res[0]);
             auto iter = std::find_if(std::begin(options), std::end(options), [&member](std::string val) {
@@ -2713,7 +2916,7 @@ class App {
             }
         };
 
-        Option *opt = add_option(name, fun, description, false);
+        Option *opt = add_option(option_name, fun, description, false);
         std::string typeval = detail::type_name<std::string>();
         typeval += " in {" + detail::join(options) + "}";
         opt->type_name(typeval);
@@ -2721,13 +2924,14 @@ class App {
         return opt;
     }
 
-    /// Add set of options, string only, ignore case (no default, L value)
-    Option *add_set_ignore_case(std::string name,
-                                std::string &member,                  ///< The selected member of the set
-                                const std::set<std::string> &options, ///< The set of possibilities
-                                std::string description = "") {
+    /// Add set of options, string only, ignore case (no default, set can be changed afterwards - do not destroy the
+    /// set)
+    Option *add_mutable_set_ignore_case(std::string option_name,
+                                        std::string &member,                  ///< The selected member of the set
+                                        const std::set<std::string> &options, ///< The set of possibilities
+                                        std::string description = "") {
 
-        std::string simple_name = CLI::detail::split(name, ',').at(0);
+        std::string simple_name = CLI::detail::split(option_name, ',').at(0);
         CLI::callback_t fun = [&member, &options, simple_name](CLI::results_t res) {
             member = detail::to_lower(res[0]);
             auto iter = std::find_if(std::begin(options), std::end(options), [&member](std::string val) {
@@ -2741,7 +2945,7 @@ class App {
             }
         };
 
-        Option *opt = add_option(name, fun, description, false);
+        Option *opt = add_option(option_name, fun, description, false);
         opt->type_name_fn([&options]() {
             return std::string(detail::type_name<std::string>()) + " in {" + detail::join(options) + "}";
         });
@@ -2749,14 +2953,14 @@ class App {
         return opt;
     }
 
-    /// Add set of options, string only, ignore case (default, R value)
-    Option *add_set_ignore_case(std::string name,
-                                std::string &member,                   ///< The selected member of the set
-                                const std::set<std::string> &&options, ///< The set of posibilities
+    /// Add set of options, string only, ignore case (default, static set)
+    Option *add_set_ignore_case(std::string option_name,
+                                std::string &member,           ///< The selected member of the set
+                                std::set<std::string> options, ///< The set of possibilities
                                 std::string description,
                                 bool defaulted) {
 
-        std::string simple_name = CLI::detail::split(name, ',').at(0);
+        std::string simple_name = CLI::detail::split(option_name, ',').at(0);
         CLI::callback_t fun = [&member, options, simple_name](CLI::results_t res) {
             member = detail::to_lower(res[0]);
             auto iter = std::find_if(std::begin(options), std::end(options), [&member](std::string val) {
@@ -2770,7 +2974,7 @@ class App {
             }
         };
 
-        Option *opt = add_option(name, fun, description, defaulted);
+        Option *opt = add_option(option_name, fun, description, defaulted);
         std::string typeval = detail::type_name<std::string>();
         typeval += " in {" + detail::join(options) + "}";
         opt->type_name(typeval);
@@ -2780,14 +2984,14 @@ class App {
         return opt;
     }
 
-    /// Add set of options, string only, ignore case (default, L value)
-    Option *add_set_ignore_case(std::string name,
-                                std::string &member,                  ///< The selected member of the set
-                                const std::set<std::string> &options, ///< The set of posibilities
-                                std::string description,
-                                bool defaulted) {
+    /// Add set of options, string only, ignore case (default, set can be changed afterwards - do not destroy the set)
+    Option *add_mutable_set_ignore_case(std::string option_name,
+                                        std::string &member,                  ///< The selected member of the set
+                                        const std::set<std::string> &options, ///< The set of possibilities
+                                        std::string description,
+                                        bool defaulted) {
 
-        std::string simple_name = CLI::detail::split(name, ',').at(0);
+        std::string simple_name = CLI::detail::split(option_name, ',').at(0);
         CLI::callback_t fun = [&member, &options, simple_name](CLI::results_t res) {
             member = detail::to_lower(res[0]);
             auto iter = std::find_if(std::begin(options), std::end(options), [&member](std::string val) {
@@ -2801,7 +3005,247 @@ class App {
             }
         };
 
-        Option *opt = add_option(name, fun, description, defaulted);
+        Option *opt = add_option(option_name, fun, description, defaulted);
+        opt->type_name_fn([&options]() {
+            return std::string(detail::type_name<std::string>()) + " in {" + detail::join(options) + "}";
+        });
+        if(defaulted) {
+            opt->default_str(member);
+        }
+        return opt;
+    }
+
+    /// Add set of options, string only, ignore underscore (no default, static set)
+    Option *add_set_ignore_underscore(std::string option_name,
+                                      std::string &member,           ///< The selected member of the set
+                                      std::set<std::string> options, ///< The set of possibilities
+                                      std::string description = "") {
+
+        std::string simple_name = CLI::detail::split(option_name, ',').at(0);
+        CLI::callback_t fun = [&member, options, simple_name](CLI::results_t res) {
+            member = detail::remove_underscore(res[0]);
+            auto iter = std::find_if(std::begin(options), std::end(options), [&member](std::string val) {
+                return detail::remove_underscore(val) == member;
+            });
+            if(iter == std::end(options))
+                throw ConversionError(member, simple_name);
+            else {
+                member = *iter;
+                return true;
+            }
+        };
+
+        Option *opt = add_option(option_name, fun, description, false);
+        std::string typeval = detail::type_name<std::string>();
+        typeval += " in {" + detail::join(options) + "}";
+        opt->type_name(typeval);
+
+        return opt;
+    }
+
+    /// Add set of options, string only, ignore underscore (no default, set can be changed afterwards - do not destroy
+    /// the set)
+    Option *add_mutable_set_ignore_underscore(std::string option_name,
+                                              std::string &member,                  ///< The selected member of the set
+                                              const std::set<std::string> &options, ///< The set of possibilities
+                                              std::string description = "") {
+
+        std::string simple_name = CLI::detail::split(option_name, ',').at(0);
+        CLI::callback_t fun = [&member, &options, simple_name](CLI::results_t res) {
+            member = detail::remove_underscore(res[0]);
+            auto iter = std::find_if(std::begin(options), std::end(options), [&member](std::string val) {
+                return detail::remove_underscore(val) == member;
+            });
+            if(iter == std::end(options))
+                throw ConversionError(member, simple_name);
+            else {
+                member = *iter;
+                return true;
+            }
+        };
+
+        Option *opt = add_option(option_name, fun, description, false);
+        opt->type_name_fn([&options]() {
+            return std::string(detail::type_name<std::string>()) + " in {" + detail::join(options) + "}";
+        });
+
+        return opt;
+    }
+
+    /// Add set of options, string only, ignore underscore (default, static set)
+    Option *add_set_ignore_underscore(std::string option_name,
+                                      std::string &member,           ///< The selected member of the set
+                                      std::set<std::string> options, ///< The set of possibilities
+                                      std::string description,
+                                      bool defaulted) {
+
+        std::string simple_name = CLI::detail::split(option_name, ',').at(0);
+        CLI::callback_t fun = [&member, options, simple_name](CLI::results_t res) {
+            member = detail::remove_underscore(res[0]);
+            auto iter = std::find_if(std::begin(options), std::end(options), [&member](std::string val) {
+                return detail::remove_underscore(val) == member;
+            });
+            if(iter == std::end(options))
+                throw ConversionError(member, simple_name);
+            else {
+                member = *iter;
+                return true;
+            }
+        };
+
+        Option *opt = add_option(option_name, fun, description, defaulted);
+        std::string typeval = detail::type_name<std::string>();
+        typeval += " in {" + detail::join(options) + "}";
+        opt->type_name(typeval);
+        if(defaulted) {
+            opt->default_str(member);
+        }
+        return opt;
+    }
+
+    /// Add set of options, string only, ignore underscore (default, set can be changed afterwards - do not destroy the
+    /// set)
+    Option *add_mutable_set_ignore_underscore(std::string option_name,
+                                              std::string &member,                  ///< The selected member of the set
+                                              const std::set<std::string> &options, ///< The set of possibilities
+                                              std::string description,
+                                              bool defaulted) {
+
+        std::string simple_name = CLI::detail::split(option_name, ',').at(0);
+        CLI::callback_t fun = [&member, &options, simple_name](CLI::results_t res) {
+            member = detail::remove_underscore(res[0]);
+            auto iter = std::find_if(std::begin(options), std::end(options), [&member](std::string val) {
+                return detail::remove_underscore(val) == member;
+            });
+            if(iter == std::end(options))
+                throw ConversionError(member, simple_name);
+            else {
+                member = *iter;
+                return true;
+            }
+        };
+
+        Option *opt = add_option(option_name, fun, description, defaulted);
+        opt->type_name_fn([&options]() {
+            return std::string(detail::type_name<std::string>()) + " in {" + detail::join(options) + "}";
+        });
+        if(defaulted) {
+            opt->default_str(member);
+        }
+        return opt;
+    }
+
+    /// Add set of options, string only, ignore underscore and case (no default, static set)
+    Option *add_set_ignore_case_underscore(std::string option_name,
+                                           std::string &member,           ///< The selected member of the set
+                                           std::set<std::string> options, ///< The set of possibilities
+                                           std::string description = "") {
+
+        std::string simple_name = CLI::detail::split(option_name, ',').at(0);
+        CLI::callback_t fun = [&member, options, simple_name](CLI::results_t res) {
+            member = detail::to_lower(detail::remove_underscore(res[0]));
+            auto iter = std::find_if(std::begin(options), std::end(options), [&member](std::string val) {
+                return detail::to_lower(detail::remove_underscore(val)) == member;
+            });
+            if(iter == std::end(options))
+                throw ConversionError(member, simple_name);
+            else {
+                member = *iter;
+                return true;
+            }
+        };
+
+        Option *opt = add_option(option_name, fun, description, false);
+        std::string typeval = detail::type_name<std::string>();
+        typeval += " in {" + detail::join(options) + "}";
+        opt->type_name(typeval);
+
+        return opt;
+    }
+
+    /// Add set of options, string only, ignore underscore and case (no default, set can be changed afterwards - do not
+    /// destroy the set)
+    Option *add_mutable_set_ignore_case_underscore(std::string option_name,
+                                                   std::string &member, ///< The selected member of the set
+                                                   const std::set<std::string> &options, ///< The set of possibilities
+                                                   std::string description = "") {
+
+        std::string simple_name = CLI::detail::split(option_name, ',').at(0);
+        CLI::callback_t fun = [&member, &options, simple_name](CLI::results_t res) {
+            member = detail::to_lower(detail::remove_underscore(res[0]));
+            auto iter = std::find_if(std::begin(options), std::end(options), [&member](std::string val) {
+                return detail::to_lower(detail::remove_underscore(val)) == member;
+            });
+            if(iter == std::end(options))
+                throw ConversionError(member, simple_name);
+            else {
+                member = *iter;
+                return true;
+            }
+        };
+
+        Option *opt = add_option(option_name, fun, description, false);
+        opt->type_name_fn([&options]() {
+            return std::string(detail::type_name<std::string>()) + " in {" + detail::join(options) + "}";
+        });
+
+        return opt;
+    }
+
+    /// Add set of options, string only, ignore underscore and case (default, static set)
+    Option *add_set_ignore_case_underscore(std::string option_name,
+                                           std::string &member,           ///< The selected member of the set
+                                           std::set<std::string> options, ///< The set of possibilities
+                                           std::string description,
+                                           bool defaulted) {
+
+        std::string simple_name = CLI::detail::split(option_name, ',').at(0);
+        CLI::callback_t fun = [&member, options, simple_name](CLI::results_t res) {
+            member = detail::to_lower(detail::remove_underscore(res[0]));
+            auto iter = std::find_if(std::begin(options), std::end(options), [&member](std::string val) {
+                return detail::to_lower(detail::remove_underscore(val)) == member;
+            });
+            if(iter == std::end(options))
+                throw ConversionError(member, simple_name);
+            else {
+                member = *iter;
+                return true;
+            }
+        };
+
+        Option *opt = add_option(option_name, fun, description, defaulted);
+        std::string typeval = detail::type_name<std::string>();
+        typeval += " in {" + detail::join(options) + "}";
+        opt->type_name(typeval);
+        if(defaulted) {
+            opt->default_str(member);
+        }
+        return opt;
+    }
+
+    /// Add set of options, string only, ignore underscore and case (default, set can be changed afterwards - do not
+    /// destroy the set)
+    Option *add_mutable_set_ignore_case_underscore(std::string option_name,
+                                                   std::string &member, ///< The selected member of the set
+                                                   const std::set<std::string> &options, ///< The set of possibilities
+                                                   std::string description,
+                                                   bool defaulted) {
+
+        std::string simple_name = CLI::detail::split(option_name, ',').at(0);
+        CLI::callback_t fun = [&member, &options, simple_name](CLI::results_t res) {
+            member = detail::to_lower(detail::remove_underscore(res[0]));
+            auto iter = std::find_if(std::begin(options), std::end(options), [&member](std::string val) {
+                return detail::to_lower(detail::remove_underscore(val)) == member;
+            });
+            if(iter == std::end(options))
+                throw ConversionError(member, simple_name);
+            else {
+                member = *iter;
+                return true;
+            }
+        };
+
+        Option *opt = add_option(option_name, fun, description, defaulted);
         opt->type_name_fn([&options]() {
             return std::string(detail::type_name<std::string>()) + " in {" + detail::join(options) + "}";
         });
@@ -2813,13 +3257,13 @@ class App {
 
     /// Add a complex number
     template <typename T>
-    Option *add_complex(std::string name,
+    Option *add_complex(std::string option_name,
                         T &variable,
                         std::string description = "",
                         bool defaulted = false,
                         std::string label = "COMPLEX") {
 
-        std::string simple_name = CLI::detail::split(name, ',').at(0);
+        std::string simple_name = CLI::detail::split(option_name, ',').at(0);
         CLI::callback_t fun = [&variable, simple_name, label](results_t res) {
             if(res[1].back() == 'i')
                 res[1].pop_back();
@@ -2830,7 +3274,7 @@ class App {
             return worked;
         };
 
-        CLI::Option *opt = add_option(name, fun, description, defaulted);
+        CLI::Option *opt = add_option(option_name, fun, description, defaulted);
         opt->type_name(label)->type_size(2);
         if(defaulted) {
             std::stringstream out;
@@ -2841,9 +3285,9 @@ class App {
     }
 
     /// Set a configuration ini file option, or clear it if no name passed
-    Option *set_config(std::string name = "",
+    Option *set_config(std::string option_name = "",
                        std::string default_filename = "",
-                       std::string help = "Read an ini file",
+                       std::string help_message = "Read an ini file",
                        bool required = false) {
 
         // Remove existing config if present
@@ -2851,10 +3295,10 @@ class App {
             remove_option(config_ptr_);
 
         // Only add config if option passed
-        if(!name.empty()) {
+        if(!option_name.empty()) {
             config_name_ = default_filename;
             config_required_ = required;
-            config_ptr_ = add_option(name, config_name_, help, !default_filename.empty());
+            config_ptr_ = add_option(option_name, config_name_, help_message, !default_filename.empty());
             config_ptr_->configurable(false);
         }
 
@@ -2863,6 +3307,17 @@ class App {
 
     /// Removes an option from the App. Takes an option pointer. Returns true if found and removed.
     bool remove_option(Option *opt) {
+        // Make sure no links exist
+        for(Option_p &op : options_) {
+            op->remove_needs(opt);
+            op->remove_excludes(opt);
+        }
+
+        if(help_ptr_ == opt)
+            help_ptr_ = nullptr;
+        if(help_all_ptr_ == opt)
+            help_all_ptr_ = nullptr;
+
         auto iterator =
             std::find_if(std::begin(options_), std::end(options_), [opt](const Option_p &v) { return v.get() == opt; });
         if(iterator != std::end(options_)) {
@@ -2877,12 +3332,12 @@ class App {
     ///@{
 
     /// Add a subcommand. Inherits INHERITABLE and OptionDefaults, and help flag
-    App *add_subcommand(std::string name, std::string description = "") {
-        subcommands_.emplace_back(new App(description, name, this));
+    App *add_subcommand(std::string subcommand_name, std::string description = "") {
+        CLI::App_p subcom(new App(description, subcommand_name, this));
         for(const auto &subc : subcommands_)
-            if(subc.get() != subcommands_.back().get())
-                if(subc->check_name(subcommands_.back()->name_) || subcommands_.back()->check_name(subc->name_))
-                    throw OptionAlreadyAdded(subc->name_);
+            if(subc->check_name(subcommand_name) || subcom->check_name(subc->name_))
+                throw OptionAlreadyAdded(subc->name_);
+        subcommands_.push_back(std::move(subcom));
         return subcommands_.back().get();
     }
 
@@ -2902,9 +3357,13 @@ class App {
         throw OptionNotFound(subcom);
     }
 
+    /// No argument version of count counts the number of times this subcommand was
+    /// passed in. The main app will return 1.
+    size_t count() const { return parsed_; }
+
     /// Changes the group membership
-    App *group(std::string name) {
-        group_ = name;
+    App *group(std::string group_name) {
+        group_ = group_name;
         return this;
     }
 
@@ -2946,7 +3405,7 @@ class App {
 
     /// Check to see if this subcommand was parsed, true only if received on command line.
     /// This allows the subcommand to be directly checked.
-    operator bool() const { return parsed_; }
+    operator bool() const { return parsed_ > 0; }
 
     ///@}
     /// @name Extras for subclassing
@@ -2976,7 +3435,7 @@ class App {
         }
     }
 
-    /// Parses the command line - throws errors
+    /// Parses the command line - throws errors.
     /// This must be called after the options are in but before the rest of the program.
     void parse(int argc, const char *const *argv) {
         // If the name is not set, read from command line
@@ -2989,19 +3448,49 @@ class App {
         parse(args);
     }
 
+    /// Parse a single string as if it contained command line arguments.
+    /// This function splits the string into arguments then calls parse(std::vector<std::string> &)
+    /// the function takes an optional boolean argument specifying if the programName is included in the string to
+    /// process
+    void parse(std::string commandline, bool program_name_included = false) {
+
+        if(program_name_included) {
+            auto nstr = detail::split_program_name(commandline);
+            if(name_.empty()) {
+                name_ = nstr.first;
+            }
+            commandline = std::move(nstr.second);
+        } else
+            detail::trim(commandline);
+        // the next section of code is to deal with quoted arguments after an '=' or ':' for windows like operations
+        if(!commandline.empty()) {
+            commandline = detail::find_and_modify(commandline, "=", detail::escape_detect);
+            if(allow_windows_style_options_)
+                commandline = detail::find_and_modify(commandline, ":", detail::escape_detect);
+        }
+
+        auto args = detail::split_up(std::move(commandline));
+        // remove all empty strings
+        args.erase(std::remove(args.begin(), args.end(), std::string()), args.end());
+        std::reverse(args.begin(), args.end());
+
+        parse(args);
+    }
+
     /// The real work is done here. Expects a reversed vector.
     /// Changes the vector to the remaining options.
     void parse(std::vector<std::string> &args) {
         // Clear if parsed
-        if(parsed_)
+        if(parsed_ > 0)
             clear();
 
-        // Redundant (set by _parse on commands/subcommands)
+        // _parse is incremented in commands/subcommands,
         // but placed here to make sure this is cleared when
         // running parse after an error is thrown, even by _validate.
-        parsed_ = true;
-
+        parsed_ = 1;
         _validate();
+        parsed_ = 0;
+
         _parse(args);
         run_callback();
     }
@@ -3041,13 +3530,13 @@ class App {
     ///@{
 
     /// Counts the number of times the given option was passed.
-    size_t count(std::string name) const {
+    size_t count(std::string option_name) const {
         for(const Option_p &opt : options_) {
-            if(opt->check_name(name)) {
+            if(opt->check_name(option_name)) {
                 return opt->count();
             }
         }
-        throw OptionNotFound(name);
+        throw OptionNotFound(option_name);
     }
 
     /// Get a subcommand pointer list to the currently selected subcommands (after parsing by by default, in command
@@ -3092,24 +3581,24 @@ class App {
     /// Check to see if given subcommand was selected
     bool got_subcommand(App *subcom) const {
         // get subcom needed to verify that this was a real subcommand
-        return get_subcommand(subcom)->parsed_;
+        return get_subcommand(subcom)->parsed_ > 0;
     }
 
     /// Check with name instead of pointer to see if subcommand was selected
-    bool got_subcommand(std::string name) const { return get_subcommand(name)->parsed_; }
+    bool got_subcommand(std::string subcommand_name) const { return get_subcommand(subcommand_name)->parsed_ > 0; }
 
     ///@}
     /// @name Help
     ///@{
 
     /// Set footer.
-    App *footer(std::string footer) {
-        footer_ = footer;
+    App *footer(std::string footer_string) {
+        footer_ = std::move(footer_string);
         return this;
     }
 
-    /// Produce a string that could be read in as a config of the current values of the App. Set default_also to include
-    /// default arguments. Prefix will add a string to the beginning of each option.
+    /// Produce a string that could be read in as a config of the current values of the App. Set default_also to
+    /// include default arguments. Prefix will add a string to the beginning of each option.
     std::string config_to_str(bool default_also = false, bool write_description = false) const {
         return config_formatter_->to_config(this, default_also, write_description, "");
     }
@@ -3125,23 +3614,11 @@ class App {
         // Delegate to subcommand if needed
         auto selected_subcommands = get_subcommands();
         if(!selected_subcommands.empty())
-            return selected_subcommands.at(0)->help(prev);
+            return selected_subcommands.at(0)->help(prev, mode);
         else
             return formatter_->make_help(this, prev, mode);
     }
 
-    /// Provided for backwards compatibility \deprecated
-    CLI11_DEPRECATED("Please use footer instead")
-    App *set_footer(std::string msg) { return footer(msg); }
-
-    /// Provided for backwards compatibility \deprecated
-    CLI11_DEPRECATED("Please use name instead")
-    App *set_name(std::string msg) { return name(msg); }
-
-    /// Provided for backwards compatibility \deprecated
-    CLI11_DEPRECATED("Please use callback instead")
-    App *set_callback(std::function<void()> fn) { return callback(fn); }
-
     ///@}
     /// @name Getters
     ///@{
@@ -3155,6 +3632,12 @@ class App {
     /// Get the app or subcommand description
     std::string get_description() const { return description_; }
 
+    /// Set the description
+    App *description(const std::string &description) {
+        description_ = description;
+        return this;
+    }
+
     /// Get the list of options (user facing function, so returns raw pointers), has optional filter function
     std::vector<const Option *> get_options(const std::function<bool(const Option *)> filter = {}) const {
         std::vector<const Option *> options(options_.size());
@@ -3173,31 +3656,37 @@ class App {
     }
 
     /// Get an option by name
-    const Option *get_option(std::string name) const {
+    const Option *get_option(std::string option_name) const {
         for(const Option_p &opt : options_) {
-            if(opt->check_name(name)) {
+            if(opt->check_name(option_name)) {
                 return opt.get();
             }
         }
-        throw OptionNotFound(name);
+        throw OptionNotFound(option_name);
     }
 
     /// Get an option by name (non-const version)
-    Option *get_option(std::string name) {
+    Option *get_option(std::string option_name) {
         for(Option_p &opt : options_) {
-            if(opt->check_name(name)) {
+            if(opt->check_name(option_name)) {
                 return opt.get();
             }
         }
-        throw OptionNotFound(name);
+        throw OptionNotFound(option_name);
     }
 
     /// Check the status of ignore_case
     bool get_ignore_case() const { return ignore_case_; }
 
+    /// Check the status of ignore_underscore
+    bool get_ignore_underscore() const { return ignore_underscore_; }
+
     /// Check the status of fallthrough
     bool get_fallthrough() const { return fallthrough_; }
 
+    /// Check the status of the allow windows style options
+    bool get_allow_windows_style_options() const { return allow_windows_style_options_; }
+
     /// Get the group of this subcommand
     const std::string &get_group() const { return group_; }
 
@@ -3243,9 +3732,13 @@ class App {
     /// Get the name of the current app
     std::string get_name() const { return name_; }
 
-    /// Check the name, case insensitive if set
+    /// Check the name, case insensitive and underscore insensitive if set
     bool check_name(std::string name_to_check) const {
         std::string local_name = name_;
+        if(ignore_underscore_) {
+            local_name = detail::remove_underscore(name_);
+            name_to_check = detail::remove_underscore(name_to_check);
+        }
         if(ignore_case_) {
             local_name = detail::to_lower(name_);
             name_to_check = detail::to_lower(name_to_check);
@@ -3274,7 +3767,7 @@ class App {
     /// This returns the missing options from the current subcommand
     std::vector<std::string> remaining(bool recurse = false) const {
         std::vector<std::string> miss_list;
-        for(const std::pair<detail::Classifer, std::string> &miss : missing_) {
+        for(const std::pair<detail::Classifier, std::string> &miss : missing_) {
             miss_list.push_back(std::get<1>(miss));
         }
 
@@ -3288,18 +3781,18 @@ class App {
         return miss_list;
     }
 
-    /// This returns the number of remaining options, minus the -- seperator
+    /// This returns the number of remaining options, minus the -- separator
     size_t remaining_size(bool recurse = false) const {
-        auto count = static_cast<size_t>(std::count_if(
-            std::begin(missing_), std::end(missing_), [](const std::pair<detail::Classifer, std::string> &val) {
-                return val.first != detail::Classifer::POSITIONAL_MARK;
+        auto remaining_options = static_cast<size_t>(std::count_if(
+            std::begin(missing_), std::end(missing_), [](const std::pair<detail::Classifier, std::string> &val) {
+                return val.first != detail::Classifier::POSITIONAL_MARK;
             }));
         if(recurse) {
             for(const App_p &sub : subcommands_) {
-                count += sub->remaining_size(recurse);
+                remaining_options += sub->remaining_size(recurse);
             }
         }
-        return count;
+        return remaining_options;
     }
 
     ///@}
@@ -3309,10 +3802,10 @@ class App {
     ///
     /// Currently checks to see if multiple positionals exist with -1 args
     void _validate() const {
-        auto count = std::count_if(std::begin(options_), std::end(options_), [](const Option_p &opt) {
+        auto pcount = std::count_if(std::begin(options_), std::end(options_), [](const Option_p &opt) {
             return opt->get_items_expected() < 0 && opt->get_positional();
         });
-        if(count > 1)
+        if(pcount > 1)
             throw InvalidError(name_);
         for(const App_p &app : subcommands_)
             app->_validate();
@@ -3344,33 +3837,26 @@ class App {
     }
 
     /// Selects a Classifier enum based on the type of the current argument
-    detail::Classifer _recognize(const std::string &current) const {
+    detail::Classifier _recognize(const std::string &current) const {
         std::string dummy1, dummy2;
 
         if(current == "--")
-            return detail::Classifer::POSITIONAL_MARK;
+            return detail::Classifier::POSITIONAL_MARK;
         if(_valid_subcommand(current))
-            return detail::Classifer::SUBCOMMAND;
+            return detail::Classifier::SUBCOMMAND;
         if(detail::split_long(current, dummy1, dummy2))
-            return detail::Classifer::LONG;
+            return detail::Classifier::LONG;
         if(detail::split_short(current, dummy1, dummy2))
-            return detail::Classifer::SHORT;
-        return detail::Classifer::NONE;
+            return detail::Classifier::SHORT;
+        if((allow_windows_style_options_) && (detail::split_windows(current, dummy1, dummy2)))
+            return detail::Classifier::WINDOWS;
+        return detail::Classifier::NONE;
     }
 
-    /// Internal parse function
-    void _parse(std::vector<std::string> &args) {
-        parsed_ = true;
-        bool positional_only = false;
-
-        while(!args.empty()) {
-            _parse_single(args, positional_only);
-        }
-
-        for(const Option_p &opt : options_)
-            if(opt->get_short_circuit() && opt->count() > 0)
-                opt->run_callback();
+    // The parse function is now broken into several parts, and part of process
 
+    /// Read and process an ini file (main app only)
+    void _process_ini() {
         // Process an INI file
         if(config_ptr_ != nullptr) {
             if(*config_ptr_) {
@@ -3387,8 +3873,10 @@ class App {
                 }
             }
         }
+    }
 
-        // Get envname options if not yet passed
+    /// Get envname options if not yet passed. Runs on *all* subcommands.
+    void _process_env() {
         for(const Option_p &opt : options_) {
             if(opt->count() == 0 && !opt->envname_.empty()) {
                 char *buffer = nullptr;
@@ -3414,15 +3902,53 @@ class App {
             }
         }
 
-        // Process callbacks
+        for(App_p &sub : subcommands_) {
+            sub->_process_env();
+        }
+    }
+
+    /// Process callbacks. Runs on *all* subcommands.
+    void _process_callbacks() {
         for(const Option_p &opt : options_) {
             if(opt->count() > 0 && !opt->get_callback_run()) {
                 opt->run_callback();
             }
         }
 
-        // Verify required options
+        for(App_p &sub : subcommands_) {
+            sub->_process_callbacks();
+        }
+    }
+
+    /// Run help flag processing if any are found.
+    ///
+    /// The flags allow recursive calls to remember if there was a help flag on a parent.
+    void _process_help_flags(bool trigger_help = false, bool trigger_all_help = false) const {
+        const Option *help_ptr = get_help_ptr();
+        const Option *help_all_ptr = get_help_all_ptr();
+
+        if(help_ptr != nullptr && help_ptr->count() > 0)
+            trigger_help = true;
+        if(help_all_ptr != nullptr && help_all_ptr->count() > 0)
+            trigger_all_help = true;
+
+        // If there were parsed subcommands, call those. First subcommand wins if there are multiple ones.
+        if(!parsed_subcommands_.empty()) {
+            for(const App *sub : parsed_subcommands_)
+                sub->_process_help_flags(trigger_help, trigger_all_help);
+
+            // Only the final subcommand should call for help. All help wins over help.
+        } else if(trigger_all_help) {
+            throw CallForAllHelp();
+        } else if(trigger_help) {
+            throw CallForHelp();
+        }
+    }
+
+    /// Verify required options and cross requirements. Subcommands too (only if selected).
+    void _process_requirements() {
         for(const Option_p &opt : options_) {
+
             // Required or partially filled
             if(opt->get_required() || opt->count() != 0) {
                 // Make sure enough -N arguments parsed (+N is already handled in parsing function)
@@ -3434,7 +3960,7 @@ class App {
                     throw RequiredError(opt->get_name());
             }
             // Requires
-            for(const Option *opt_req : opt->requires_)
+            for(const Option *opt_req : opt->needs_)
                 if(opt->count() > 0 && opt_req->count() == 0)
                     throw RequiresError(opt->get_name(), opt_req->get_name());
             // Excludes
@@ -3447,7 +3973,26 @@ class App {
         if(require_subcommand_min_ > selected_subcommands.size())
             throw RequiredError::Subcommand(require_subcommand_min_);
 
-        // Convert missing (pairs) to extras (string only)
+        // Max error cannot occur, the extra subcommand will parse as an ExtrasError or a remaining item.
+
+        for(App_p &sub : subcommands_) {
+            if(sub->count() > 0)
+                sub->_process_requirements();
+        }
+    }
+
+    /// Process callbacks and such.
+    void _process() {
+        _process_ini();
+        _process_env();
+        _process_callbacks();
+        _process_help_flags();
+        _process_requirements();
+    }
+
+    /// Throw an error if anything is left over and should not be.
+    /// Modifies the args to fill in the missing items before throwing.
+    void _process_extras(std::vector<std::string> &args) {
         if(!(allow_extras_ || prefix_command_)) {
             size_t num_left_over = remaining_size();
             if(num_left_over > 0) {
@@ -3456,7 +4001,28 @@ class App {
             }
         }
 
+        for(App_p &sub : subcommands_) {
+            if(sub->count() > 0)
+                sub->_process_extras(args);
+        }
+    }
+
+    /// Internal parse function
+    void _parse(std::vector<std::string> &args) {
+        parsed_++;
+        bool positional_only = false;
+
+        while(!args.empty()) {
+            _parse_single(args, positional_only);
+        }
+
         if(parent_ == nullptr) {
+            _process();
+
+            // Throw error if any items are left over (depending on settings)
+            _process_extras(args);
+
+            // Convert missing (pairs) to extras (string only)
             args = remaining(false);
         }
     }
@@ -3477,7 +4043,6 @@ class App {
         if(level < item.parents.size()) {
             App *subcom;
             try {
-                std::cout << item.parents.at(level) << std::endl;
                 subcom = get_subcommand(item.parents.at(level));
             } catch(const OptionNotFound &) {
                 return false;
@@ -3492,7 +4057,7 @@ class App {
             // If the option was not present
             if(get_allow_config_extras())
                 // Should we worry about classifying the extras properly?
-                missing_.emplace_back(detail::Classifer::NONE, item.fullname());
+                missing_.emplace_back(detail::Classifier::NONE, item.fullname());
             return false;
         }
 
@@ -3512,29 +4077,27 @@ class App {
         return true;
     }
 
-    /// Parse "one" argument (some may eat more than one), delegate to parent if fails, add to missing if missing from
-    /// master
+    /// Parse "one" argument (some may eat more than one), delegate to parent if fails, add to missing if missing
+    /// from master
     void _parse_single(std::vector<std::string> &args, bool &positional_only) {
 
-        detail::Classifer classifer = positional_only ? detail::Classifer::NONE : _recognize(args.back());
-        switch(classifer) {
-        case detail::Classifer::POSITIONAL_MARK:
-            missing_.emplace_back(classifer, args.back());
+        detail::Classifier classifier = positional_only ? detail::Classifier::NONE : _recognize(args.back());
+        switch(classifier) {
+        case detail::Classifier::POSITIONAL_MARK:
+            missing_.emplace_back(classifier, args.back());
             args.pop_back();
             positional_only = true;
             break;
-        case detail::Classifer::SUBCOMMAND:
+        case detail::Classifier::SUBCOMMAND:
             _parse_subcommand(args);
             break;
-        case detail::Classifer::LONG:
+        case detail::Classifier::LONG:
+        case detail::Classifier::SHORT:
+        case detail::Classifier::WINDOWS:
             // If already parsed a subcommand, don't accept options_
-            _parse_arg(args, true);
+            _parse_arg(args, classifier);
             break;
-        case detail::Classifer::SHORT:
-            // If already parsed a subcommand, don't accept options_
-            _parse_arg(args, false);
-            break;
-        case detail::Classifer::NONE:
+        case detail::Classifier::NONE:
             // Probably a positional or something for a parent (sub)command
             _parse_positional(args);
         }
@@ -3571,11 +4134,11 @@ class App {
             return parent_->_parse_positional(args);
         else {
             args.pop_back();
-            missing_.emplace_back(detail::Classifer::NONE, positional);
+            missing_.emplace_back(detail::Classifier::NONE, positional);
 
             if(prefix_command_) {
                 while(!args.empty()) {
-                    missing_.emplace_back(detail::Classifer::NONE, args.back());
+                    missing_.emplace_back(detail::Classifier::NONE, args.back());
                     args.pop_back();
                 }
             }
@@ -3605,33 +4168,46 @@ class App {
     }
 
     /// Parse a short (false) or long (true) argument, must be at the top of the list
-    void _parse_arg(std::vector<std::string> &args, bool second_dash) {
-
-        detail::Classifer current_type = second_dash ? detail::Classifer::LONG : detail::Classifer::SHORT;
+    void _parse_arg(std::vector<std::string> &args, detail::Classifier current_type) {
 
         std::string current = args.back();
 
-        std::string name;
+        std::string arg_name;
         std::string value;
         std::string rest;
 
-        if(second_dash) {
-            if(!detail::split_long(current, name, value))
+        switch(current_type) {
+        case detail::Classifier::LONG:
+            if(!detail::split_long(current, arg_name, value))
                 throw HorribleError("Long parsed but missing (you should not see this):" + args.back());
-        } else {
-            if(!detail::split_short(current, name, rest))
+            break;
+        case detail::Classifier::SHORT:
+            if(!detail::split_short(current, arg_name, rest))
                 throw HorribleError("Short parsed but missing! You should not see this");
+            break;
+        case detail::Classifier::WINDOWS:
+            if(!detail::split_windows(current, arg_name, value))
+                throw HorribleError("windows option parsed but missing! You should not see this");
+            break;
+        default:
+            throw HorribleError("parsing got called with invalid option! You should not see this");
         }
 
-        auto op_ptr = std::find_if(std::begin(options_), std::end(options_), [name, second_dash](const Option_p &opt) {
-            return second_dash ? opt->check_lname(name) : opt->check_sname(name);
-        });
+        auto op_ptr =
+            std::find_if(std::begin(options_), std::end(options_), [arg_name, current_type](const Option_p &opt) {
+                if(current_type == detail::Classifier::LONG)
+                    return opt->check_lname(arg_name);
+                if(current_type == detail::Classifier::SHORT)
+                    return opt->check_sname(arg_name);
+                // this will only get called for detail::Classifier::WINDOWS
+                return opt->check_lname(arg_name) || opt->check_sname(arg_name);
+            });
 
         // Option not found
         if(op_ptr == std::end(options_)) {
             // If a subcommand, try the master command
             if(parent_ != nullptr && fallthrough_)
-                return parent_->_parse_arg(args, second_dash);
+                return parent_->_parse_arg(args, current_type);
             // Otherwise, add to missing
             else {
                 args.pop_back();
@@ -3673,7 +4249,7 @@ class App {
 
         // Unlimited vector parser
         if(num < 0) {
-            while(!args.empty() && _recognize(args.back()) == detail::Classifer::NONE) {
+            while(!args.empty() && _recognize(args.back()) == detail::Classifier::NONE) {
                 if(collected >= -num) {
                     // We could break here for allow extras, but we don't
 
@@ -3688,7 +4264,7 @@ class App {
             }
 
             // Allow -- to end an unlimited list and "eat" it
-            if(!args.empty() && _recognize(args.back()) == detail::Classifer::POSITIONAL_MARK)
+            if(!args.empty() && _recognize(args.back()) == detail::Classifier::POSITIONAL_MARK)
                 args.pop_back();
 
         } else {
@@ -3717,8 +4293,19 @@ namespace FailureMessage {
 /// Printout a clean, simple message on error (the default in CLI11 1.5+)
 inline std::string simple(const App *app, const Error &e) {
     std::string header = std::string(e.what()) + "\n";
+    std::vector<std::string> names;
+
+    // Collect names
     if(app->get_help_ptr() != nullptr)
-        header += "Run with " + app->get_help_ptr()->get_name() + " for more information.\n";
+        names.push_back(app->get_help_ptr()->get_name());
+
+    if(app->get_help_all_ptr() != nullptr)
+        names.push_back(app->get_help_all_ptr()->get_name());
+
+    // If any names found, suggest those
+    if(!names.empty())
+        header += "Run with " + detail::join(names, " or ") + " for more information.\n";
+
     return header;
 }
 
@@ -3797,7 +4384,12 @@ ConfigINI::to_config(const App *app, bool default_also, bool write_description,
                     }
                     out << "; " << detail::fix_newlines("; ", opt->get_description()) << std::endl;
                 }
-                out << name << "=" << value << std::endl;
+
+                // Don't try to quote anything that is not size 1
+                if(opt->get_items_expected() != 1)
+                    out << name << "=" << value << std::endl;
+                else
+                    out << name << "=" << detail::add_quotes_if_needed(value) << std::endl;
             }
         }
     }
@@ -3919,7 +4511,7 @@ inline std::string Formatter::make_footer(const App *app) const {
 
 inline std::string Formatter::make_help(const App *app, std::string name, AppFormatMode mode) const {
 
-    // This immediatly forwards to the make_expanded method. This is done this way so that subcommands can
+    // This immediately forwards to the make_expanded method. This is done this way so that subcommands can
     // have overridden formatters
     if(mode == AppFormatMode::Sub)
         return make_expanded(app);
@@ -3956,14 +4548,13 @@ inline std::string Formatter::make_subcommands(const App *app, AppFormatMode mod
     for(const std::string &group : subcmd_groups_seen) {
         out << "\n" << group << ":\n";
         std::vector<const App *> subcommands_group = app->get_subcommands(
-            [&group](const App *app) { return detail::to_lower(app->get_group()) == detail::to_lower(group); });
+            [&group](const App *sub_app) { return detail::to_lower(sub_app->get_group()) == detail::to_lower(group); });
         for(const App *new_com : subcommands_group) {
             if(mode != AppFormatMode::All) {
                 out << make_subcommand(new_com);
             } else {
                 out << new_com->help(new_com->get_name(), AppFormatMode::Sub);
-                if(new_com != subcommands_group.back())
-                    out << "\n";
+                out << "\n";
             }
         }
     }
@@ -3979,12 +4570,19 @@ inline std::string Formatter::make_subcommand(const App *sub) const {
 
 inline std::string Formatter::make_expanded(const App *sub) const {
     std::stringstream out;
-    if(sub->get_description().empty())
-        out << sub->get_name();
-    else
-        out << sub->get_name() << " -> " << sub->get_description();
+    out << sub->get_name() << "\n";
+
+    out << make_description(sub);
+    out << make_positionals(sub);
     out << make_groups(sub, AppFormatMode::Sub);
-    return out.str();
+    out << make_subcommands(sub, AppFormatMode::Sub);
+
+    // Drop blank spaces
+    std::string tmp = detail::find_and_replace(out.str(), "\n\n", "\n");
+    tmp = tmp.substr(0, tmp.size() - 1); // Remove the final '\n'
+
+    // Indent all but the first line (the name)
+    return detail::find_and_replace(tmp, "\n", "\n  ") + "\n";
 }
 
 inline std::string Formatter::make_option_name(const Option *opt, bool is_positional) const {
diff --git a/examples/viewer/DirectX/d3dx12.h b/examples/viewer/DirectX/d3dx12.h
index 06390f2..ff07b49 100644
--- a/examples/viewer/DirectX/d3dx12.h
+++ b/examples/viewer/DirectX/d3dx12.h
@@ -48,7 +48,6 @@ struct CD3DX12_RECT : public D3D12_RECT
         right = Right;
         bottom = Bottom;
     }
-    ~CD3DX12_RECT() {}
 };
 
 //------------------------------------------------------------------------------------------------
@@ -81,7 +80,7 @@ struct CD3DX12_VIEWPORT : public D3D12_VIEWPORT
         FLOAT minDepth = D3D12_MIN_DEPTH,
         FLOAT maxDepth = D3D12_MAX_DEPTH )
     {
-        D3D12_RESOURCE_DESC Desc = pResource->GetDesc();
+        auto Desc = pResource->GetDesc();
         const UINT64 SubresourceWidth = Desc.Width >> mipSlice;
         const UINT64 SubresourceHeight = Desc.Height >> mipSlice;
         switch (Desc.Dimension)
@@ -111,7 +110,6 @@ struct CD3DX12_VIEWPORT : public D3D12_VIEWPORT
         MinDepth = minDepth;
         MaxDepth = maxDepth;
     }
-    ~CD3DX12_VIEWPORT() {}
 };
 
 //------------------------------------------------------------------------------------------------
@@ -160,7 +158,6 @@ struct CD3DX12_BOX : public D3D12_BOX
         bottom = Bottom;
         back = Back;
     }
-    ~CD3DX12_BOX() {}
 };
 inline bool operator==( const D3D12_BOX& l, const D3D12_BOX& r )
 {
@@ -221,7 +218,6 @@ struct CD3DX12_DEPTH_STENCIL_DESC : public D3D12_DEPTH_STENCIL_DESC
         BackFace.StencilPassOp = backStencilPassOp;
         BackFace.StencilFunc = backStencilFunc;
     }
-    ~CD3DX12_DEPTH_STENCIL_DESC() {}
 };
 
 //------------------------------------------------------------------------------------------------
@@ -296,7 +292,6 @@ struct CD3DX12_DEPTH_STENCIL_DESC1 : public D3D12_DEPTH_STENCIL_DESC1
         BackFace.StencilFunc = backStencilFunc;
         DepthBoundsTestEnable = depthBoundsTestEnable;
     }
-    ~CD3DX12_DEPTH_STENCIL_DESC1() {}
     operator D3D12_DEPTH_STENCIL_DESC() const
     {
         D3D12_DEPTH_STENCIL_DESC D;
@@ -340,7 +335,6 @@ struct CD3DX12_BLEND_DESC : public D3D12_BLEND_DESC
         for (UINT i = 0; i < D3D12_SIMULTANEOUS_RENDER_TARGET_COUNT; ++i)
             RenderTarget[ i ] = defaultRenderTargetBlendDesc;
     }
-    ~CD3DX12_BLEND_DESC() {}
 };
 
 //------------------------------------------------------------------------------------------------
@@ -389,7 +383,6 @@ struct CD3DX12_RASTERIZER_DESC : public D3D12_RASTERIZER_DESC
         ForcedSampleCount = forcedSampleCount;
         ConservativeRaster = conservativeRaster;
     }
-    ~CD3DX12_RASTERIZER_DESC() {}
 };
 
 //------------------------------------------------------------------------------------------------
@@ -738,8 +731,7 @@ struct CD3DX12_RESOURCE_BARRIER : public D3D12_RESOURCE_BARRIER
         UINT subresource = D3D12_RESOURCE_BARRIER_ALL_SUBRESOURCES,
         D3D12_RESOURCE_BARRIER_FLAGS flags = D3D12_RESOURCE_BARRIER_FLAG_NONE)
     {
-        CD3DX12_RESOURCE_BARRIER result;
-        ZeroMemory(&result, sizeof(result));
+        CD3DX12_RESOURCE_BARRIER result = {};
         D3D12_RESOURCE_BARRIER &barrier = result;
         result.Type = D3D12_RESOURCE_BARRIER_TYPE_TRANSITION;
         result.Flags = flags;
@@ -753,8 +745,7 @@ struct CD3DX12_RESOURCE_BARRIER : public D3D12_RESOURCE_BARRIER
         _In_ ID3D12Resource* pResourceBefore,
         _In_ ID3D12Resource* pResourceAfter)
     {
-        CD3DX12_RESOURCE_BARRIER result;
-        ZeroMemory(&result, sizeof(result));
+        CD3DX12_RESOURCE_BARRIER result = {};
         D3D12_RESOURCE_BARRIER &barrier = result;
         result.Type = D3D12_RESOURCE_BARRIER_TYPE_ALIASING;
         barrier.Aliasing.pResourceBefore = pResourceBefore;
@@ -764,8 +755,7 @@ struct CD3DX12_RESOURCE_BARRIER : public D3D12_RESOURCE_BARRIER
     static inline CD3DX12_RESOURCE_BARRIER UAV(
         _In_ ID3D12Resource* pResource)
     {
-        CD3DX12_RESOURCE_BARRIER result;
-        ZeroMemory(&result, sizeof(result));
+        CD3DX12_RESOURCE_BARRIER result = {};
         D3D12_RESOURCE_BARRIER &barrier = result;
         result.Type = D3D12_RESOURCE_BARRIER_TYPE_UAV;
         barrier.UAV.pResource = pResource;
@@ -832,14 +822,19 @@ struct CD3DX12_TEXTURE_COPY_LOCATION : public D3D12_TEXTURE_COPY_LOCATION
     explicit CD3DX12_TEXTURE_COPY_LOCATION(const D3D12_TEXTURE_COPY_LOCATION &o) :
         D3D12_TEXTURE_COPY_LOCATION(o)
     {}
-    CD3DX12_TEXTURE_COPY_LOCATION(ID3D12Resource* pRes) { pResource = pRes; }
-    CD3DX12_TEXTURE_COPY_LOCATION(ID3D12Resource* pRes, D3D12_PLACED_SUBRESOURCE_FOOTPRINT const& Footprint)
+    CD3DX12_TEXTURE_COPY_LOCATION(_In_ ID3D12Resource* pRes)
+    {
+        pResource = pRes;
+        Type = D3D12_TEXTURE_COPY_TYPE_SUBRESOURCE_INDEX;
+        PlacedFootprint = {};
+    }
+    CD3DX12_TEXTURE_COPY_LOCATION(_In_ ID3D12Resource* pRes, D3D12_PLACED_SUBRESOURCE_FOOTPRINT const& Footprint)
     {
         pResource = pRes;
         Type = D3D12_TEXTURE_COPY_TYPE_PLACED_FOOTPRINT;
         PlacedFootprint = Footprint;
     }
-    CD3DX12_TEXTURE_COPY_LOCATION(ID3D12Resource* pRes, UINT Sub)
+    CD3DX12_TEXTURE_COPY_LOCATION(_In_ ID3D12Resource* pRes, UINT Sub)
     {
         pResource = pRes;
         Type = D3D12_TEXTURE_COPY_TYPE_SUBRESOURCE_INDEX;
@@ -1206,21 +1201,21 @@ struct CD3DX12_ROOT_SIGNATURE_DESC : public D3D12_ROOT_SIGNATURE_DESC
         UINT numParameters,
         _In_reads_opt_(numParameters) const D3D12_ROOT_PARAMETER* _pParameters,
         UINT numStaticSamplers = 0,
-        _In_reads_opt_(numStaticSamplers) const D3D12_STATIC_SAMPLER_DESC* _pStaticSamplers = NULL,
+        _In_reads_opt_(numStaticSamplers) const D3D12_STATIC_SAMPLER_DESC* _pStaticSamplers = nullptr,
         D3D12_ROOT_SIGNATURE_FLAGS flags = D3D12_ROOT_SIGNATURE_FLAG_NONE)
     {
         Init(numParameters, _pParameters, numStaticSamplers, _pStaticSamplers, flags);
     }
     CD3DX12_ROOT_SIGNATURE_DESC(CD3DX12_DEFAULT)
     {
-        Init(0, NULL, 0, NULL, D3D12_ROOT_SIGNATURE_FLAG_NONE);
+        Init(0, nullptr, 0, nullptr, D3D12_ROOT_SIGNATURE_FLAG_NONE);
     }
     
     inline void Init(
         UINT numParameters,
         _In_reads_opt_(numParameters) const D3D12_ROOT_PARAMETER* _pParameters,
         UINT numStaticSamplers = 0,
-        _In_reads_opt_(numStaticSamplers) const D3D12_STATIC_SAMPLER_DESC* _pStaticSamplers = NULL,
+        _In_reads_opt_(numStaticSamplers) const D3D12_STATIC_SAMPLER_DESC* _pStaticSamplers = nullptr,
         D3D12_ROOT_SIGNATURE_FLAGS flags = D3D12_ROOT_SIGNATURE_FLAG_NONE)
     {
         Init(*this, numParameters, _pParameters, numStaticSamplers, _pStaticSamplers, flags);
@@ -1231,7 +1226,7 @@ struct CD3DX12_ROOT_SIGNATURE_DESC : public D3D12_ROOT_SIGNATURE_DESC
         UINT numParameters,
         _In_reads_opt_(numParameters) const D3D12_ROOT_PARAMETER* _pParameters,
         UINT numStaticSamplers = 0,
-        _In_reads_opt_(numStaticSamplers) const D3D12_STATIC_SAMPLER_DESC* _pStaticSamplers = NULL,
+        _In_reads_opt_(numStaticSamplers) const D3D12_STATIC_SAMPLER_DESC* _pStaticSamplers = nullptr,
         D3D12_ROOT_SIGNATURE_FLAGS flags = D3D12_ROOT_SIGNATURE_FLAG_NONE)
     {
         desc.NumParameters = numParameters;
@@ -1491,7 +1486,7 @@ struct CD3DX12_VERSIONED_ROOT_SIGNATURE_DESC : public D3D12_VERSIONED_ROOT_SIGNA
         UINT numParameters,
         _In_reads_opt_(numParameters) const D3D12_ROOT_PARAMETER* _pParameters,
         UINT numStaticSamplers = 0,
-        _In_reads_opt_(numStaticSamplers) const D3D12_STATIC_SAMPLER_DESC* _pStaticSamplers = NULL,
+        _In_reads_opt_(numStaticSamplers) const D3D12_STATIC_SAMPLER_DESC* _pStaticSamplers = nullptr,
         D3D12_ROOT_SIGNATURE_FLAGS flags = D3D12_ROOT_SIGNATURE_FLAG_NONE)
     {
         Init_1_0(numParameters, _pParameters, numStaticSamplers, _pStaticSamplers, flags);
@@ -1500,21 +1495,21 @@ struct CD3DX12_VERSIONED_ROOT_SIGNATURE_DESC : public D3D12_VERSIONED_ROOT_SIGNA
         UINT numParameters,
         _In_reads_opt_(numParameters) const D3D12_ROOT_PARAMETER1* _pParameters,
         UINT numStaticSamplers = 0,
-        _In_reads_opt_(numStaticSamplers) const D3D12_STATIC_SAMPLER_DESC* _pStaticSamplers = NULL,
+        _In_reads_opt_(numStaticSamplers) const D3D12_STATIC_SAMPLER_DESC* _pStaticSamplers = nullptr,
         D3D12_ROOT_SIGNATURE_FLAGS flags = D3D12_ROOT_SIGNATURE_FLAG_NONE)
     {
         Init_1_1(numParameters, _pParameters, numStaticSamplers, _pStaticSamplers, flags);
     }
     CD3DX12_VERSIONED_ROOT_SIGNATURE_DESC(CD3DX12_DEFAULT)
     {
-        Init_1_1(0, NULL, 0, NULL, D3D12_ROOT_SIGNATURE_FLAG_NONE);
+        Init_1_1(0, nullptr, 0, nullptr, D3D12_ROOT_SIGNATURE_FLAG_NONE);
     }
     
     inline void Init_1_0(
         UINT numParameters,
         _In_reads_opt_(numParameters) const D3D12_ROOT_PARAMETER* _pParameters,
         UINT numStaticSamplers = 0,
-        _In_reads_opt_(numStaticSamplers) const D3D12_STATIC_SAMPLER_DESC* _pStaticSamplers = NULL,
+        _In_reads_opt_(numStaticSamplers) const D3D12_STATIC_SAMPLER_DESC* _pStaticSamplers = nullptr,
         D3D12_ROOT_SIGNATURE_FLAGS flags = D3D12_ROOT_SIGNATURE_FLAG_NONE)
     {
         Init_1_0(*this, numParameters, _pParameters, numStaticSamplers, _pStaticSamplers, flags);
@@ -1525,7 +1520,7 @@ struct CD3DX12_VERSIONED_ROOT_SIGNATURE_DESC : public D3D12_VERSIONED_ROOT_SIGNA
         UINT numParameters,
         _In_reads_opt_(numParameters) const D3D12_ROOT_PARAMETER* _pParameters,
         UINT numStaticSamplers = 0,
-        _In_reads_opt_(numStaticSamplers) const D3D12_STATIC_SAMPLER_DESC* _pStaticSamplers = NULL,
+        _In_reads_opt_(numStaticSamplers) const D3D12_STATIC_SAMPLER_DESC* _pStaticSamplers = nullptr,
         D3D12_ROOT_SIGNATURE_FLAGS flags = D3D12_ROOT_SIGNATURE_FLAG_NONE)
     {
         desc.Version = D3D_ROOT_SIGNATURE_VERSION_1_0;
@@ -1540,7 +1535,7 @@ struct CD3DX12_VERSIONED_ROOT_SIGNATURE_DESC : public D3D12_VERSIONED_ROOT_SIGNA
         UINT numParameters,
         _In_reads_opt_(numParameters) const D3D12_ROOT_PARAMETER1* _pParameters,
         UINT numStaticSamplers = 0,
-        _In_reads_opt_(numStaticSamplers) const D3D12_STATIC_SAMPLER_DESC* _pStaticSamplers = NULL,
+        _In_reads_opt_(numStaticSamplers) const D3D12_STATIC_SAMPLER_DESC* _pStaticSamplers = nullptr,
         D3D12_ROOT_SIGNATURE_FLAGS flags = D3D12_ROOT_SIGNATURE_FLAG_NONE)
     {
         Init_1_1(*this, numParameters, _pParameters, numStaticSamplers, _pStaticSamplers, flags);
@@ -1551,7 +1546,7 @@ struct CD3DX12_VERSIONED_ROOT_SIGNATURE_DESC : public D3D12_VERSIONED_ROOT_SIGNA
         UINT numParameters,
         _In_reads_opt_(numParameters) const D3D12_ROOT_PARAMETER1* _pParameters,
         UINT numStaticSamplers = 0,
-        _In_reads_opt_(numStaticSamplers) const D3D12_STATIC_SAMPLER_DESC* _pStaticSamplers = NULL,
+        _In_reads_opt_(numStaticSamplers) const D3D12_STATIC_SAMPLER_DESC* _pStaticSamplers = nullptr,
         D3D12_ROOT_SIGNATURE_FLAGS flags = D3D12_ROOT_SIGNATURE_FLAG_NONE)
     {
         desc.Version = D3D_ROOT_SIGNATURE_VERSION_1_1;
@@ -1620,7 +1615,7 @@ struct CD3DX12_CPU_DESCRIPTOR_HANDLE : public D3D12_CPU_DESCRIPTOR_HANDLE
     
     static inline void InitOffsetted(_Out_ D3D12_CPU_DESCRIPTOR_HANDLE &handle, _In_ const D3D12_CPU_DESCRIPTOR_HANDLE &base, INT offsetInDescriptors, UINT descriptorIncrementSize)
     {
-        handle.ptr = base.ptr + INT64(offsetInDescriptors) * UINT64(descriptorIncrementSize);
+        handle.ptr = static_cast<SIZE_T>(base.ptr + INT64(offsetInDescriptors) * UINT64(descriptorIncrementSize));
     }
 };
 
@@ -1681,7 +1676,7 @@ struct CD3DX12_GPU_DESCRIPTOR_HANDLE : public D3D12_GPU_DESCRIPTOR_HANDLE
     
     static inline void InitOffsetted(_Out_ D3D12_GPU_DESCRIPTOR_HANDLE &handle, _In_ const D3D12_GPU_DESCRIPTOR_HANDLE &base, INT offsetInDescriptors, UINT descriptorIncrementSize)
     {
-        handle.ptr = base.ptr + INT64(offsetInDescriptors) * UINT64(descriptorIncrementSize);
+        handle.ptr = static_cast<UINT64>(base.ptr + INT64(offsetInDescriptors) * UINT64(descriptorIncrementSize));
     }
 };
 
@@ -1706,7 +1701,7 @@ inline UINT8 D3D12GetFormatPlaneCount(
     DXGI_FORMAT Format
     )
 {
-    D3D12_FEATURE_DATA_FORMAT_INFO formatInfo = {Format};
+    D3D12_FEATURE_DATA_FORMAT_INFO formatInfo = { Format, 0 };
     if (FAILED(pDevice->CheckFeatureSupport(D3D12_FEATURE_FORMAT_INFO, &formatInfo, sizeof(formatInfo))))
     {
         return 0;
@@ -1851,7 +1846,6 @@ struct CD3DX12_VIEW_INSTANCING_DESC : public D3D12_VIEW_INSTANCING_DESC
         pViewInstanceLocations = InViewInstanceLocations;
         Flags = InFlags;
     }
-    ~CD3DX12_VIEW_INSTANCING_DESC() {}
 };
 
 //------------------------------------------------------------------------------------------------
@@ -1883,10 +1877,10 @@ inline UINT64 GetRequiredIntermediateSize(
     _In_range_(0,D3D12_REQ_SUBRESOURCES) UINT FirstSubresource,
     _In_range_(0,D3D12_REQ_SUBRESOURCES-FirstSubresource) UINT NumSubresources)
 {
-    D3D12_RESOURCE_DESC Desc = pDestinationResource->GetDesc();
+    auto Desc = pDestinationResource->GetDesc();
     UINT64 RequiredSize = 0;
     
-    ID3D12Device* pDevice;
+    ID3D12Device* pDevice = nullptr;
     pDestinationResource->GetDevice(__uuidof(*pDevice), reinterpret_cast<void**>(&pDevice));
     pDevice->GetCopyableFootprints(&Desc, FirstSubresource, NumSubresources, 0, nullptr, nullptr, nullptr, &RequiredSize);
     pDevice->Release();
@@ -1909,11 +1903,11 @@ inline UINT64 UpdateSubresources(
     _In_reads_(NumSubresources) const D3D12_SUBRESOURCE_DATA* pSrcData)
 {
     // Minor validation
-    D3D12_RESOURCE_DESC IntermediateDesc = pIntermediate->GetDesc();
-    D3D12_RESOURCE_DESC DestinationDesc = pDestinationResource->GetDesc();
+    auto IntermediateDesc = pIntermediate->GetDesc();
+    auto DestinationDesc = pDestinationResource->GetDesc();
     if (IntermediateDesc.Dimension != D3D12_RESOURCE_DIMENSION_BUFFER || 
         IntermediateDesc.Width < RequiredSize + pLayouts[0].Offset || 
-        RequiredSize > (SIZE_T)-1 || 
+        RequiredSize > SIZE_T(-1) || 
         (DestinationDesc.Dimension == D3D12_RESOURCE_DIMENSION_BUFFER && 
             (FirstSubresource != 0 || NumSubresources != 1)))
     {
@@ -1921,7 +1915,7 @@ inline UINT64 UpdateSubresources(
     }
     
     BYTE* pData;
-    HRESULT hr = pIntermediate->Map(0, NULL, reinterpret_cast<void**>(&pData));
+    HRESULT hr = pIntermediate->Map(0, nullptr, reinterpret_cast<void**>(&pData));
     if (FAILED(hr))
     {
         return 0;
@@ -1929,11 +1923,11 @@ inline UINT64 UpdateSubresources(
     
     for (UINT i = 0; i < NumSubresources; ++i)
     {
-        if (pRowSizesInBytes[i] > (SIZE_T)-1) return 0;
+        if (pRowSizesInBytes[i] > SIZE_T(-1)) return 0;
         D3D12_MEMCPY_DEST DestData = { pData + pLayouts[i].Offset, pLayouts[i].Footprint.RowPitch, SIZE_T(pLayouts[i].Footprint.RowPitch) * SIZE_T(pNumRows[i]) };
-        MemcpySubresource(&DestData, &pSrcData[i], (SIZE_T)pRowSizesInBytes[i], pNumRows[i], pLayouts[i].Footprint.Depth);
+        MemcpySubresource(&DestData, &pSrcData[i], static_cast<SIZE_T>(pRowSizesInBytes[i]), pNumRows[i], pLayouts[i].Footprint.Depth);
     }
-    pIntermediate->Unmap(0, NULL);
+    pIntermediate->Unmap(0, nullptr);
     
     if (DestinationDesc.Dimension == D3D12_RESOURCE_DIMENSION_BUFFER)
     {
@@ -1970,16 +1964,16 @@ inline UINT64 UpdateSubresources(
        return 0;
     }
     void* pMem = HeapAlloc(GetProcessHeap(), 0, static_cast<SIZE_T>(MemToAlloc));
-    if (pMem == NULL)
+    if (pMem == nullptr)
     {
        return 0;
     }
-    D3D12_PLACED_SUBRESOURCE_FOOTPRINT* pLayouts = reinterpret_cast<D3D12_PLACED_SUBRESOURCE_FOOTPRINT*>(pMem);
+    auto pLayouts = reinterpret_cast<D3D12_PLACED_SUBRESOURCE_FOOTPRINT*>(pMem);
     UINT64* pRowSizesInBytes = reinterpret_cast<UINT64*>(pLayouts + NumSubresources);
     UINT* pNumRows = reinterpret_cast<UINT*>(pRowSizesInBytes + NumSubresources);
     
-    D3D12_RESOURCE_DESC Desc = pDestinationResource->GetDesc();
-    ID3D12Device* pDevice;
+    auto Desc = pDestinationResource->GetDesc();
+    ID3D12Device* pDevice = nullptr;
     pDestinationResource->GetDevice(__uuidof(*pDevice), reinterpret_cast<void**>(&pDevice));
     pDevice->GetCopyableFootprints(&Desc, FirstSubresource, NumSubresources, IntermediateOffset, pLayouts, pNumRows, pRowSizesInBytes, &RequiredSize);
     pDevice->Release();
@@ -2006,8 +2000,8 @@ inline UINT64 UpdateSubresources(
     UINT NumRows[MaxSubresources];
     UINT64 RowSizesInBytes[MaxSubresources];
     
-    D3D12_RESOURCE_DESC Desc = pDestinationResource->GetDesc();
-    ID3D12Device* pDevice;
+    auto Desc = pDestinationResource->GetDesc();
+    ID3D12Device* pDevice = nullptr;
     pDestinationResource->GetDevice(__uuidof(*pDevice), reinterpret_cast<void**>(&pDevice));
     pDevice->GetCopyableFootprints(&Desc, FirstSubresource, NumSubresources, IntermediateOffset, Layouts, NumRows, RowSizesInBytes, &RequiredSize);
     pDevice->Release();
@@ -2041,9 +2035,9 @@ inline HRESULT D3DX12SerializeVersionedRootSignature(
     _Outptr_ ID3DBlob** ppBlob,
     _Always_(_Outptr_opt_result_maybenull_) ID3DBlob** ppErrorBlob)
 {
-    if (ppErrorBlob != NULL)
+    if (ppErrorBlob != nullptr)
     {
-        *ppErrorBlob = NULL;
+        *ppErrorBlob = nullptr;
     }
 
     switch (MaxVersion)
@@ -2060,12 +2054,12 @@ inline HRESULT D3DX12SerializeVersionedRootSignature(
                     const D3D12_ROOT_SIGNATURE_DESC1& desc_1_1 = pRootSignatureDesc->Desc_1_1;
 
                     const SIZE_T ParametersSize = sizeof(D3D12_ROOT_PARAMETER) * desc_1_1.NumParameters;
-                    void* pParameters = (ParametersSize > 0) ? HeapAlloc(GetProcessHeap(), 0, ParametersSize) : NULL;
-                    if (ParametersSize > 0 && pParameters == NULL)
+                    void* pParameters = (ParametersSize > 0) ? HeapAlloc(GetProcessHeap(), 0, ParametersSize) : nullptr;
+                    if (ParametersSize > 0 && pParameters == nullptr)
                     {
                         hr = E_OUTOFMEMORY;
                     }
-                    D3D12_ROOT_PARAMETER* pParameters_1_0 = reinterpret_cast<D3D12_ROOT_PARAMETER*>(pParameters);
+                    auto pParameters_1_0 = reinterpret_cast<D3D12_ROOT_PARAMETER*>(pParameters);
 
                     if (SUCCEEDED(hr))
                     {
@@ -2094,12 +2088,12 @@ inline HRESULT D3DX12SerializeVersionedRootSignature(
                                 const D3D12_ROOT_DESCRIPTOR_TABLE1& table_1_1 = desc_1_1.pParameters[n].DescriptorTable;
 
                                 const SIZE_T DescriptorRangesSize = sizeof(D3D12_DESCRIPTOR_RANGE) * table_1_1.NumDescriptorRanges;
-                                void* pDescriptorRanges = (DescriptorRangesSize > 0 && SUCCEEDED(hr)) ? HeapAlloc(GetProcessHeap(), 0, DescriptorRangesSize) : NULL;
-                                if (DescriptorRangesSize > 0 && pDescriptorRanges == NULL)
+                                void* pDescriptorRanges = (DescriptorRangesSize > 0 && SUCCEEDED(hr)) ? HeapAlloc(GetProcessHeap(), 0, DescriptorRangesSize) : nullptr;
+                                if (DescriptorRangesSize > 0 && pDescriptorRanges == nullptr)
                                 {
                                     hr = E_OUTOFMEMORY;
                                 }
-                                D3D12_DESCRIPTOR_RANGE* pDescriptorRanges_1_0 = reinterpret_cast<D3D12_DESCRIPTOR_RANGE*>(pDescriptorRanges);
+                                auto pDescriptorRanges_1_0 = reinterpret_cast<D3D12_DESCRIPTOR_RANGE*>(pDescriptorRanges);
 
                                 if (SUCCEEDED(hr))
                                 {
@@ -2157,7 +2151,7 @@ struct CD3DX12_RT_FORMAT_ARRAY : public D3D12_RT_FORMAT_ARRAY
     explicit CD3DX12_RT_FORMAT_ARRAY(const D3D12_RT_FORMAT_ARRAY& o)
         : D3D12_RT_FORMAT_ARRAY(o)
     {}
-    explicit CD3DX12_RT_FORMAT_ARRAY(const DXGI_FORMAT* pFormats, UINT NumFormats)
+    explicit CD3DX12_RT_FORMAT_ARRAY(_In_reads_(NumFormats) const DXGI_FORMAT* pFormats, UINT NumFormats)
     {
         NumRenderTargets = NumFormats;
         memcpy(RTFormats, pFormats, sizeof(RTFormats));
@@ -2175,6 +2169,8 @@ struct CD3DX12_RT_FORMAT_ARRAY : public D3D12_RT_FORMAT_ARRAY
 struct DefaultSampleMask { operator UINT() { return UINT_MAX; } };
 struct DefaultSampleDesc { operator DXGI_SAMPLE_DESC() { return DXGI_SAMPLE_DESC{1, 0}; } };
 
+#pragma warning(push)
+#pragma warning(disable : 4324)
 template <typename InnerStructType, D3D12_PIPELINE_STATE_SUBOBJECT_TYPE Type, typename DefaultArg = InnerStructType>
 class alignas(void*) CD3DX12_PIPELINE_STATE_STREAM_SUBOBJECT
 {
@@ -2188,6 +2184,7 @@ class alignas(void*) CD3DX12_PIPELINE_STATE_STREAM_SUBOBJECT
     operator InnerStructType() const { return _Inner; }
     operator InnerStructType&() { return _Inner; }
 };
+#pragma warning(pop)
 typedef CD3DX12_PIPELINE_STATE_STREAM_SUBOBJECT< D3D12_PIPELINE_STATE_FLAGS,         D3D12_PIPELINE_STATE_SUBOBJECT_TYPE_FLAGS>                             CD3DX12_PIPELINE_STATE_STREAM_FLAGS;
 typedef CD3DX12_PIPELINE_STATE_STREAM_SUBOBJECT< UINT,                               D3D12_PIPELINE_STATE_SUBOBJECT_TYPE_NODE_MASK>                         CD3DX12_PIPELINE_STATE_STREAM_NODE_MASK;
 typedef CD3DX12_PIPELINE_STATE_STREAM_SUBOBJECT< ID3D12RootSignature*,               D3D12_PIPELINE_STATE_SUBOBJECT_TYPE_ROOT_SIGNATURE>                    CD3DX12_PIPELINE_STATE_STREAM_ROOT_SIGNATURE;
@@ -2247,6 +2244,7 @@ struct ID3DX12PipelineParserCallbacks
     virtual void ErrorDuplicateSubobject(D3D12_PIPELINE_STATE_SUBOBJECT_TYPE /*DuplicateType*/) {}
     virtual void ErrorUnknownSubobject(UINT /*UnknownTypeValue*/) {}
 
+    virtual ~ID3DX12PipelineParserCallbacks() = default;
 };
 
 // CD3DX12_PIPELINE_STATE_STREAM1 Works on RS3+ (where there is a new view instancing subobject).  
@@ -2451,34 +2449,33 @@ struct CD3DX12_PIPELINE_STATE_STREAM_PARSE_HELPER : public ID3DX12PipelineParser
         // Depth disabled if no DSV format specified.
         static_cast<D3D12_DEPTH_STENCIL_DESC1&>(PipelineStream.DepthStencilState).DepthEnable = false;
     }
-    virtual ~CD3DX12_PIPELINE_STATE_STREAM_PARSE_HELPER() {}
 
     // ID3DX12PipelineParserCallbacks
-    void FlagsCb(D3D12_PIPELINE_STATE_FLAGS Flags) {PipelineStream.Flags = Flags;}
-    void NodeMaskCb(UINT NodeMask) {PipelineStream.NodeMask = NodeMask;}
-    void RootSignatureCb(ID3D12RootSignature* pRootSignature) {PipelineStream.pRootSignature = pRootSignature;}
-    void InputLayoutCb(const D3D12_INPUT_LAYOUT_DESC& InputLayout) {PipelineStream.InputLayout = InputLayout;}
-    void IBStripCutValueCb(D3D12_INDEX_BUFFER_STRIP_CUT_VALUE IBStripCutValue) {PipelineStream.IBStripCutValue = IBStripCutValue;}
-    void PrimitiveTopologyTypeCb(D3D12_PRIMITIVE_TOPOLOGY_TYPE PrimitiveTopologyType) {PipelineStream.PrimitiveTopologyType = PrimitiveTopologyType;}
-    void VSCb(const D3D12_SHADER_BYTECODE& VS) {PipelineStream.VS = VS;}
-    void GSCb(const D3D12_SHADER_BYTECODE& GS) {PipelineStream.GS = GS;}
-    void StreamOutputCb(const D3D12_STREAM_OUTPUT_DESC& StreamOutput) {PipelineStream.StreamOutput = StreamOutput;}
-    void HSCb(const D3D12_SHADER_BYTECODE& HS) {PipelineStream.HS = HS;}
-    void DSCb(const D3D12_SHADER_BYTECODE& DS) {PipelineStream.DS = DS;}
-    void PSCb(const D3D12_SHADER_BYTECODE& PS) {PipelineStream.PS = PS;}
-    void CSCb(const D3D12_SHADER_BYTECODE& CS) {PipelineStream.CS = CS;}
-    void BlendStateCb(const D3D12_BLEND_DESC& BlendState) {PipelineStream.BlendState = CD3DX12_BLEND_DESC(BlendState);}
-    void DepthStencilStateCb(const D3D12_DEPTH_STENCIL_DESC& DepthStencilState)
+    void FlagsCb(D3D12_PIPELINE_STATE_FLAGS Flags) override {PipelineStream.Flags = Flags;}
+    void NodeMaskCb(UINT NodeMask) override {PipelineStream.NodeMask = NodeMask;}
+    void RootSignatureCb(ID3D12RootSignature* pRootSignature) override {PipelineStream.pRootSignature = pRootSignature;}
+    void InputLayoutCb(const D3D12_INPUT_LAYOUT_DESC& InputLayout) override {PipelineStream.InputLayout = InputLayout;}
+    void IBStripCutValueCb(D3D12_INDEX_BUFFER_STRIP_CUT_VALUE IBStripCutValue) override {PipelineStream.IBStripCutValue = IBStripCutValue;}
+    void PrimitiveTopologyTypeCb(D3D12_PRIMITIVE_TOPOLOGY_TYPE PrimitiveTopologyType) override {PipelineStream.PrimitiveTopologyType = PrimitiveTopologyType;}
+    void VSCb(const D3D12_SHADER_BYTECODE& VS) override {PipelineStream.VS = VS;}
+    void GSCb(const D3D12_SHADER_BYTECODE& GS) override {PipelineStream.GS = GS;}
+    void StreamOutputCb(const D3D12_STREAM_OUTPUT_DESC& StreamOutput) override {PipelineStream.StreamOutput = StreamOutput;}
+    void HSCb(const D3D12_SHADER_BYTECODE& HS) override {PipelineStream.HS = HS;}
+    void DSCb(const D3D12_SHADER_BYTECODE& DS) override {PipelineStream.DS = DS;}
+    void PSCb(const D3D12_SHADER_BYTECODE& PS) override {PipelineStream.PS = PS;}
+    void CSCb(const D3D12_SHADER_BYTECODE& CS) override {PipelineStream.CS = CS;}
+    void BlendStateCb(const D3D12_BLEND_DESC& BlendState) override {PipelineStream.BlendState = CD3DX12_BLEND_DESC(BlendState);}
+    void DepthStencilStateCb(const D3D12_DEPTH_STENCIL_DESC& DepthStencilState) override
     {
         PipelineStream.DepthStencilState = CD3DX12_DEPTH_STENCIL_DESC1(DepthStencilState);
         SeenDSS = true;
     }
-    void DepthStencilState1Cb(const D3D12_DEPTH_STENCIL_DESC1& DepthStencilState)
+    void DepthStencilState1Cb(const D3D12_DEPTH_STENCIL_DESC1& DepthStencilState) override
     {
         PipelineStream.DepthStencilState = CD3DX12_DEPTH_STENCIL_DESC1(DepthStencilState);
         SeenDSS = true;
     }
-    void DSVFormatCb(DXGI_FORMAT DSVFormat)
+    void DSVFormatCb(DXGI_FORMAT DSVFormat) override
     {
         PipelineStream.DSVFormat = DSVFormat;
         if (!SeenDSS && DSVFormat != DXGI_FORMAT_UNKNOWN)
@@ -2487,15 +2484,12 @@ struct CD3DX12_PIPELINE_STATE_STREAM_PARSE_HELPER : public ID3DX12PipelineParser
             static_cast<D3D12_DEPTH_STENCIL_DESC1&>(PipelineStream.DepthStencilState).DepthEnable = true;
         }
     }
-    void RasterizerStateCb(const D3D12_RASTERIZER_DESC& RasterizerState) {PipelineStream.RasterizerState = CD3DX12_RASTERIZER_DESC(RasterizerState);}
-    void RTVFormatsCb(const D3D12_RT_FORMAT_ARRAY& RTVFormats) {PipelineStream.RTVFormats = RTVFormats;}
-    void SampleDescCb(const DXGI_SAMPLE_DESC& SampleDesc) {PipelineStream.SampleDesc = SampleDesc;}
-    void SampleMaskCb(UINT SampleMask) {PipelineStream.SampleMask = SampleMask;}
-    void ViewInstancingCb(const D3D12_VIEW_INSTANCING_DESC& ViewInstancingDesc) {PipelineStream.ViewInstancingDesc = CD3DX12_VIEW_INSTANCING_DESC(ViewInstancingDesc);}
-    void CachedPSOCb(const D3D12_CACHED_PIPELINE_STATE& CachedPSO) {PipelineStream.CachedPSO = CachedPSO;}
-    void ErrorBadInputParameter(UINT) {}
-    void ErrorDuplicateSubobject(D3D12_PIPELINE_STATE_SUBOBJECT_TYPE) {}
-    void ErrorUnknownSubobject(UINT) {}
+    void RasterizerStateCb(const D3D12_RASTERIZER_DESC& RasterizerState) override {PipelineStream.RasterizerState = CD3DX12_RASTERIZER_DESC(RasterizerState);}
+    void RTVFormatsCb(const D3D12_RT_FORMAT_ARRAY& RTVFormats) override {PipelineStream.RTVFormats = RTVFormats;}
+    void SampleDescCb(const DXGI_SAMPLE_DESC& SampleDesc) override {PipelineStream.SampleDesc = SampleDesc;}
+    void SampleMaskCb(UINT SampleMask) override {PipelineStream.SampleMask = SampleMask;}
+    void ViewInstancingCb(const D3D12_VIEW_INSTANCING_DESC& ViewInstancingDesc) override {PipelineStream.ViewInstancingDesc = CD3DX12_VIEW_INSTANCING_DESC(ViewInstancingDesc);}
+    void CachedPSOCb(const D3D12_CACHED_PIPELINE_STATE& CachedPSO) override {PipelineStream.CachedPSO = CachedPSO;}
 
 private:
     bool SeenDSS;
@@ -2530,11 +2524,11 @@ inline HRESULT D3DX12ParsePipelineStream(const D3D12_PIPELINE_STATE_STREAM_DESC&
     {
         BYTE* pStream = static_cast<BYTE*>(Desc.pPipelineStateSubobjectStream)+CurOffset;
         auto SubobjectType = *reinterpret_cast<D3D12_PIPELINE_STATE_SUBOBJECT_TYPE*>(pStream);
-        if (SubobjectType >= D3D12_PIPELINE_STATE_SUBOBJECT_TYPE_MAX_VALID)
+        if (SubobjectType < 0 || SubobjectType >= D3D12_PIPELINE_STATE_SUBOBJECT_TYPE_MAX_VALID)
         {
             pCallbacks->ErrorUnknownSubobject(SubobjectType);
             return E_INVALIDARG;
-        }
+        } 
         if (SubobjectSeen[D3DX12GetBaseSubobjectType(SubobjectType)])
         {
             pCallbacks->ErrorDuplicateSubobject(SubobjectType);
@@ -2645,10 +2639,800 @@ inline HRESULT D3DX12ParsePipelineStream(const D3D12_PIPELINE_STATE_STREAM_DESC&
     return S_OK;
 }
 
+//------------------------------------------------------------------------------------------------
+inline bool operator==( const D3D12_CLEAR_VALUE &a, const D3D12_CLEAR_VALUE &b)
+{
+    if (a.Format != b.Format) return false;
+    if (a.Format == DXGI_FORMAT_D24_UNORM_S8_UINT
+     || a.Format == DXGI_FORMAT_D16_UNORM
+     || a.Format == DXGI_FORMAT_D32_FLOAT
+     || a.Format == DXGI_FORMAT_D32_FLOAT_S8X24_UINT)
+    {
+        return (a.DepthStencil.Depth == b.DepthStencil.Depth) && 
+          (a.DepthStencil.Stencil == b.DepthStencil.Stencil);
+    } else {
+        return (a.Color[0] == b.Color[0]) && 
+               (a.Color[1] == b.Color[1]) && 
+               (a.Color[2] == b.Color[2]) && 
+               (a.Color[3] == b.Color[3]);
+    }
+}
+inline bool operator==( const D3D12_RENDER_PASS_BEGINNING_ACCESS_CLEAR_PARAMETERS &a, const D3D12_RENDER_PASS_BEGINNING_ACCESS_CLEAR_PARAMETERS &b)
+{
+    return a.ClearValue == b.ClearValue;
+}
+inline bool operator==( const D3D12_RENDER_PASS_ENDING_ACCESS_RESOLVE_PARAMETERS &a, const D3D12_RENDER_PASS_ENDING_ACCESS_RESOLVE_PARAMETERS &b)
+{
+    if (a.pSrcResource != b.pSrcResource) return false;
+    if (a.pDstResource != b.pDstResource) return false;
+    if (a.SubresourceCount != b.SubresourceCount) return false;
+    if (a.Format != b.Format) return false;
+    if (a.ResolveMode != b.ResolveMode) return false; 
+    if (a.PreserveResolveSource != b.PreserveResolveSource) return false; 
+    return true;
+}
+inline bool operator==( const D3D12_RENDER_PASS_BEGINNING_ACCESS &a, const D3D12_RENDER_PASS_BEGINNING_ACCESS &b)
+{
+    if (a.Type != b.Type) return false;
+    if (a.Type == D3D12_RENDER_PASS_BEGINNING_ACCESS_TYPE_CLEAR && !(a.Clear == b.Clear)) return false; 
+    return true;
+}
+inline bool operator==( const D3D12_RENDER_PASS_ENDING_ACCESS &a, const D3D12_RENDER_PASS_ENDING_ACCESS &b)
+{
+    if (a.Type != b.Type) return false;
+    if (a.Type == D3D12_RENDER_PASS_ENDING_ACCESS_TYPE_RESOLVE && !(a.Resolve == b.Resolve)) return false; 
+    return true;
+}
+inline bool operator==( const D3D12_RENDER_PASS_RENDER_TARGET_DESC &a, const D3D12_RENDER_PASS_RENDER_TARGET_DESC &b)
+{
+    if (a.cpuDescriptor.ptr != b.cpuDescriptor.ptr) return false;
+    if (!(a.BeginningAccess == b.BeginningAccess)) return false;
+    if (!(a.EndingAccess == b.EndingAccess)) return false;
+    return true;
+}
+inline bool operator==( const D3D12_RENDER_PASS_DEPTH_STENCIL_DESC &a, const D3D12_RENDER_PASS_DEPTH_STENCIL_DESC &b)
+{
+    if (a.cpuDescriptor.ptr != b.cpuDescriptor.ptr) return false;
+    if (!(a.DepthBeginningAccess == b.DepthBeginningAccess)) return false;
+    if (!(a.StencilBeginningAccess == b.StencilBeginningAccess)) return false;
+    if (!(a.DepthEndingAccess == b.DepthEndingAccess)) return false;
+    if (!(a.StencilEndingAccess == b.StencilEndingAccess)) return false;
+    return true;
+}
+
+
+#ifndef D3DX12_NO_STATE_OBJECT_HELPERS
+
+//================================================================================================
+// D3DX12 State Object Creation Helpers
+// 
+// Helper classes for creating new style state objects out of an arbitrary set of subobjects.
+// Uses STL
+//
+// Start by instantiating CD3DX12_STATE_OBJECT_DESC (see it's public methods).
+// One of its methods is CreateSubobject(), which has a comment showing a couple of options for
+// defining subobjects using the helper classes for each subobject (CD3DX12_DXIL_LIBRARY_SUBOBJECT 
+// etc.). The subobject helpers each have methods specific to the subobject for configuring it's 
+// contents.
+// 
+//================================================================================================
+#include <list>
+#include <vector>
+#include <string>
+#include <memory>
+#include <wrl/client.h>
+
+//------------------------------------------------------------------------------------------------
+class CD3DX12_STATE_OBJECT_DESC
+{
+public:
+    CD3DX12_STATE_OBJECT_DESC()
+    {
+        Init(D3D12_STATE_OBJECT_TYPE_COLLECTION);
+    }
+    CD3DX12_STATE_OBJECT_DESC(D3D12_STATE_OBJECT_TYPE Type)
+    {
+        Init(Type);
+    }
+    void SetStateObjectType(D3D12_STATE_OBJECT_TYPE Type) { m_Desc.Type = Type; }
+    operator const D3D12_STATE_OBJECT_DESC&()
+    {
+        // Do final preparation work
+        m_RepointedAssociations.clear();
+        m_SubobjectArray.clear();
+        m_SubobjectArray.reserve(m_Desc.NumSubobjects);
+        // Flatten subobjects into an array (each flattened subobject still has a 
+        // member that's a pointer to it's desc that's not flattened)
+        for (auto Iter = m_SubobjectList.begin();
+            Iter != m_SubobjectList.end(); Iter++)
+        {
+            m_SubobjectArray.push_back(*Iter);
+            // Store new location in array so we can redirect pointers contained in subobjects 
+            Iter->pSubobjectArrayLocation = &m_SubobjectArray.back(); 
+        }
+        // For subobjects with pointer fields, create a new copy of those subobject definitions
+        // with fixed pointers
+        for (UINT i = 0; i < m_Desc.NumSubobjects; i++)
+        {
+            if (m_SubobjectArray[i].Type == D3D12_STATE_SUBOBJECT_TYPE_SUBOBJECT_TO_EXPORTS_ASSOCIATION)
+            {
+                auto pOriginalSubobjectAssociation = 
+                    reinterpret_cast<const D3D12_SUBOBJECT_TO_EXPORTS_ASSOCIATION*>(m_SubobjectArray[i].pDesc);
+                D3D12_SUBOBJECT_TO_EXPORTS_ASSOCIATION Repointed = *pOriginalSubobjectAssociation;
+                auto pWrapper = 
+                    static_cast<const SUBOBJECT_WRAPPER*>(pOriginalSubobjectAssociation->pSubobjectToAssociate);
+                Repointed.pSubobjectToAssociate = pWrapper->pSubobjectArrayLocation;
+                m_RepointedAssociations.push_back(Repointed);
+                m_SubobjectArray[i].pDesc = &m_RepointedAssociations.back();
+            }
+        }
+        // Below: using ugly way to get pointer in case .data() is not defined
+        m_Desc.pSubobjects = m_Desc.NumSubobjects ? &m_SubobjectArray[0] : nullptr; 
+        return m_Desc;
+    }
+    operator const D3D12_STATE_OBJECT_DESC*()
+    {
+        // Cast calls the above final preparation work
+        return &static_cast<const D3D12_STATE_OBJECT_DESC&>(*this);
+    }
+
+    // CreateSubobject creates a sububject helper (e.g. CD3DX12_HIT_GROUP_SUBOBJECT) 
+    // whose lifetime is owned by this class.
+    // e.g. 
+    // 
+    //    CD3DX12_STATE_OBJECT_DESC Collection1(D3D12_STATE_OBJECT_TYPE_COLLECTION);
+    //    auto Lib0 = Collection1.CreateSubobject<CD3DX12_DXIL_LIBRARY_SUBOBJECT>();
+    //    Lib0->SetDXILLibrary(&pMyAppDxilLibs[0]);
+    //    Lib0->DefineExport(L"rayGenShader0"); // in practice these export listings might be 
+    //                                          // data/engine driven
+    //    etc.
+    //
+    // Alternatively, users can instantiate sububject helpers explicitly, such as via local 
+    // variables instead, passing the state object desc that should point to it into the helper 
+    // constructor (or call mySubobjectHelper.AddToStateObject(Collection1)).  
+    // In this alternative scenario, the user must keep the subobject alive as long as the state 
+    // object it is associated with is alive, else it's pointer references will be stale.
+    // e.g.
+    //
+    //    CD3DX12_STATE_OBJECT_DESC RaytracingState2(D3D12_STATE_OBJECT_TYPE_RAYTRACING_PIPELINE);
+    //    CD3DX12_DXIL_LIBRARY_SUBOBJECT LibA(RaytracingState2);
+    //    LibA.SetDXILLibrary(&pMyAppDxilLibs[4]); // not manually specifying exports 
+    //                                             // - meaning all exports in the libraries 
+    //                                             // are exported
+    //    etc.
+
+    template<typename T>
+    T* CreateSubobject()
+    {
+        T* pSubobject = new T(*this);
+        m_OwnedSubobjectHelpers.emplace_back(pSubobject);
+        return pSubobject;
+    }
+
+private:
+    D3D12_STATE_SUBOBJECT* TrackSubobject(D3D12_STATE_SUBOBJECT_TYPE Type, void* pDesc)
+    {
+        SUBOBJECT_WRAPPER Subobject;
+        Subobject.pSubobjectArrayLocation = nullptr;
+        Subobject.Type = Type;
+        Subobject.pDesc = pDesc;
+        m_SubobjectList.push_back(Subobject);
+        m_Desc.NumSubobjects++;
+        return &m_SubobjectList.back();
+    }
+    void Init(D3D12_STATE_OBJECT_TYPE Type)
+    {
+        SetStateObjectType(Type);
+        m_Desc.pSubobjects = nullptr;
+        m_Desc.NumSubobjects = 0;
+        m_SubobjectList.clear();
+        m_SubobjectArray.clear();
+        m_RepointedAssociations.clear();
+    }
+    typedef struct SUBOBJECT_WRAPPER : public D3D12_STATE_SUBOBJECT
+    {
+        D3D12_STATE_SUBOBJECT* pSubobjectArrayLocation; // new location when flattened into array 
+                                                        // for repointing pointers in subobjects
+    } SUBOBJECT_WRAPPER;
+    D3D12_STATE_OBJECT_DESC m_Desc;
+    std::list<SUBOBJECT_WRAPPER>   m_SubobjectList; // Pointers to list nodes handed out so 
+                                                    // these can be edited live
+    std::vector<D3D12_STATE_SUBOBJECT> m_SubobjectArray; // Built at the end, copying list contents
+
+    std::list<D3D12_SUBOBJECT_TO_EXPORTS_ASSOCIATION> 
+            m_RepointedAssociations; // subobject type that contains pointers to other subobjects, 
+                                     // repointed to flattened array
+
+    class StringContainer
+    {
+    public:
+        LPCWSTR LocalCopy(LPCWSTR string, bool bSingleString = false)
+        {
+            if (string)
+            {
+                if (bSingleString)
+                {
+                    m_Strings.clear();
+                    m_Strings.push_back(string);
+                }
+                else
+                {
+                    m_Strings.push_back(string);
+                }
+                return m_Strings.back().c_str();
+            }
+            else
+            {
+                return nullptr;
+            }
+        }
+        void clear() { m_Strings.clear(); }
+    private:
+        std::list<std::wstring> m_Strings;
+    };
+
+    class SUBOBJECT_HELPER_BASE
+    {
+    public:
+        SUBOBJECT_HELPER_BASE() { Init(); };
+        virtual ~SUBOBJECT_HELPER_BASE() {};
+        virtual D3D12_STATE_SUBOBJECT_TYPE Type() const = 0;
+        void AddToStateObject(CD3DX12_STATE_OBJECT_DESC& ContainingStateObject)
+        {
+            m_pSubobject = ContainingStateObject.TrackSubobject(Type(), Data());
+        }
+    protected:
+        virtual void* Data() = 0;
+        void Init() { m_pSubobject = nullptr; }
+        D3D12_STATE_SUBOBJECT* m_pSubobject;
+    };
+
+#if(__cplusplus >= 201103L)
+    std::list<std::unique_ptr<const SUBOBJECT_HELPER_BASE>> m_OwnedSubobjectHelpers;
+#else
+    class OWNED_HELPER
+    {
+    public:
+        OWNED_HELPER(const SUBOBJECT_HELPER_BASE* pHelper) { m_pHelper = pHelper; }
+        ~OWNED_HELPER() { delete m_pHelper; }
+        const SUBOBJECT_HELPER_BASE* m_pHelper;
+    };
+
+    std::list<OWNED_HELPER> m_OwnedSubobjectHelpers;
+#endif
+
+    friend class CD3DX12_DXIL_LIBRARY_SUBOBJECT;
+    friend class CD3DX12_EXISTING_COLLECTION_SUBOBJECT;
+    friend class CD3DX12_SUBOBJECT_TO_EXPORTS_ASSOCIATION_SUBOBJECT;
+    friend class CD3DX12_DXIL_SUBOBJECT_TO_EXPORTS_ASSOCIATION;
+    friend class CD3DX12_HIT_GROUP_SUBOBJECT;
+    friend class CD3DX12_RAYTRACING_SHADER_CONFIG_SUBOBJECT;
+    friend class CD3DX12_RAYTRACING_PIPELINE_CONFIG_SUBOBJECT;
+    friend class CD3DX12_GLOBAL_ROOT_SIGNATURE_SUBOBJECT;
+    friend class CD3DX12_LOCAL_ROOT_SIGNATURE_SUBOBJECT;
+    friend class CD3DX12_STATE_OBJECT_CONFIG_SUBOBJECT;
+    friend class CD3DX12_NODE_MASK_SUBOBJECT;
+};
+
+//------------------------------------------------------------------------------------------------
+class CD3DX12_DXIL_LIBRARY_SUBOBJECT 
+    : public CD3DX12_STATE_OBJECT_DESC::SUBOBJECT_HELPER_BASE
+{
+public:
+    CD3DX12_DXIL_LIBRARY_SUBOBJECT()
+    {
+        Init();
+    }
+    CD3DX12_DXIL_LIBRARY_SUBOBJECT(CD3DX12_STATE_OBJECT_DESC& ContainingStateObject)
+    {
+        Init();
+        AddToStateObject(ContainingStateObject);
+    }
+    void SetDXILLibrary(D3D12_SHADER_BYTECODE*pCode) 
+    { 
+        static const D3D12_SHADER_BYTECODE Default = {}; 
+        m_Desc.DXILLibrary = pCode ? *pCode : Default; 
+    }
+    void DefineExport(
+        LPCWSTR Name, 
+        LPCWSTR ExportToRename = nullptr, 
+        D3D12_EXPORT_FLAGS Flags = D3D12_EXPORT_FLAG_NONE)
+    {
+        D3D12_EXPORT_DESC Export;
+        Export.Name = m_Strings.LocalCopy(Name);
+        Export.ExportToRename = m_Strings.LocalCopy(ExportToRename);
+        Export.Flags = Flags;
+        m_Exports.push_back(Export);
+        m_Desc.pExports = &m_Exports[0];  // using ugly way to get pointer in case .data() is not defined
+        m_Desc.NumExports = static_cast<UINT>(m_Exports.size());
+    }
+    template<size_t N>
+    void DefineExports(LPCWSTR(&Exports)[N])
+    {
+        for (UINT i = 0; i < N; i++)
+        {
+            DefineExport(Exports[i]);
+        }
+    }
+    void DefineExports(LPCWSTR* Exports, UINT N)
+    {
+        for (UINT i = 0; i < N; i++)
+        {
+            DefineExport(Exports[i]);
+        }
+    }    
+    D3D12_STATE_SUBOBJECT_TYPE Type() const 
+    { 
+        return D3D12_STATE_SUBOBJECT_TYPE_DXIL_LIBRARY; 
+    }
+    operator const D3D12_STATE_SUBOBJECT&() const { return *m_pSubobject; }
+    operator const D3D12_DXIL_LIBRARY_DESC&() const { return m_Desc; }
+private:
+    void Init()
+    {
+        SUBOBJECT_HELPER_BASE::Init();
+        m_Desc = {};
+        m_Strings.clear();
+        m_Exports.clear();
+    }
+    void* Data() { return &m_Desc; }
+    D3D12_DXIL_LIBRARY_DESC m_Desc;
+    CD3DX12_STATE_OBJECT_DESC::StringContainer m_Strings;
+    std::vector<D3D12_EXPORT_DESC> m_Exports;
+};
+
+//------------------------------------------------------------------------------------------------
+class CD3DX12_EXISTING_COLLECTION_SUBOBJECT 
+    : public CD3DX12_STATE_OBJECT_DESC::SUBOBJECT_HELPER_BASE
+{
+public:
+    CD3DX12_EXISTING_COLLECTION_SUBOBJECT()
+    {
+        Init();
+    }
+    CD3DX12_EXISTING_COLLECTION_SUBOBJECT(CD3DX12_STATE_OBJECT_DESC& ContainingStateObject)
+    {
+        Init();
+        AddToStateObject(ContainingStateObject);
+    }
+    void SetExistingCollection(ID3D12StateObject*pExistingCollection) 
+    { 
+        m_Desc.pExistingCollection = pExistingCollection; 
+        m_CollectionRef = pExistingCollection; 
+    }
+    void DefineExport(
+        LPCWSTR Name, 
+        LPCWSTR ExportToRename = nullptr, 
+        D3D12_EXPORT_FLAGS Flags = D3D12_EXPORT_FLAG_NONE)
+    {
+        D3D12_EXPORT_DESC Export;
+        Export.Name = m_Strings.LocalCopy(Name);
+        Export.ExportToRename = m_Strings.LocalCopy(ExportToRename);
+        Export.Flags = Flags;
+        m_Exports.push_back(Export);
+        m_Desc.pExports = &m_Exports[0]; // using ugly way to get pointer in case .data() is not defined
+        m_Desc.NumExports = static_cast<UINT>(m_Exports.size());
+    }
+    template<size_t N>
+    void DefineExports(LPCWSTR(&Exports)[N])
+    {
+        for (UINT i = 0; i < N; i++)
+        {
+            DefineExport(Exports[i]);
+        }
+    }
+    void DefineExports(LPCWSTR* Exports, UINT N)
+    {
+        for (UINT i = 0; i < N; i++)
+        {
+            DefineExport(Exports[i]);
+        }
+    }    
+    D3D12_STATE_SUBOBJECT_TYPE Type() const
+    { 
+        return D3D12_STATE_SUBOBJECT_TYPE_EXISTING_COLLECTION; 
+    }
+    operator const D3D12_STATE_SUBOBJECT&() const { return *m_pSubobject; }
+    operator const D3D12_EXISTING_COLLECTION_DESC&() const { return m_Desc; }
+private:
+    void Init()
+    {
+        SUBOBJECT_HELPER_BASE::Init();
+        m_Desc = {};
+        m_CollectionRef = nullptr;
+        m_Strings.clear();
+        m_Exports.clear();
+    }
+    void* Data() { return &m_Desc; }
+    D3D12_EXISTING_COLLECTION_DESC m_Desc;
+    Microsoft::WRL::ComPtr<ID3D12StateObject> m_CollectionRef;
+    CD3DX12_STATE_OBJECT_DESC::StringContainer m_Strings;
+    std::vector<D3D12_EXPORT_DESC> m_Exports;
+};
+
+//------------------------------------------------------------------------------------------------
+class CD3DX12_SUBOBJECT_TO_EXPORTS_ASSOCIATION_SUBOBJECT 
+    : public CD3DX12_STATE_OBJECT_DESC::SUBOBJECT_HELPER_BASE
+{
+public:
+    CD3DX12_SUBOBJECT_TO_EXPORTS_ASSOCIATION_SUBOBJECT()
+    {
+        Init();
+    }
+    CD3DX12_SUBOBJECT_TO_EXPORTS_ASSOCIATION_SUBOBJECT(CD3DX12_STATE_OBJECT_DESC& ContainingStateObject)
+    {
+        Init();
+        AddToStateObject(ContainingStateObject);
+    }
+    void SetSubobjectToAssociate(const D3D12_STATE_SUBOBJECT& SubobjectToAssociate) 
+    { 
+        m_Desc.pSubobjectToAssociate = &SubobjectToAssociate; 
+    }
+    void AddExport(LPCWSTR Export)
+    {
+        m_Desc.NumExports++;
+        m_Exports.push_back(m_Strings.LocalCopy(Export));
+        m_Desc.pExports = &m_Exports[0];  // using ugly way to get pointer in case .data() is not defined
+    }
+    template<size_t N>
+    void AddExports(LPCWSTR (&Exports)[N])
+    {
+        for (UINT i = 0; i < N; i++)
+        {
+            AddExport(Exports[i]);
+        }
+    }
+    void AddExports(LPCWSTR* Exports, UINT N)
+    {
+        for (UINT i = 0; i < N; i++)
+        {
+            AddExport(Exports[i]);
+        }
+    }    
+    D3D12_STATE_SUBOBJECT_TYPE Type() const 
+    { 
+        return D3D12_STATE_SUBOBJECT_TYPE_SUBOBJECT_TO_EXPORTS_ASSOCIATION; 
+    }
+    operator const D3D12_STATE_SUBOBJECT&() const { return *m_pSubobject; }
+    operator const D3D12_SUBOBJECT_TO_EXPORTS_ASSOCIATION&() const { return m_Desc; }
+private:
+    void Init()
+    {
+        SUBOBJECT_HELPER_BASE::Init();
+        m_Desc = {};
+        m_Strings.clear();
+        m_Exports.clear();
+    }
+    void* Data() { return &m_Desc; }
+    D3D12_SUBOBJECT_TO_EXPORTS_ASSOCIATION m_Desc;
+    CD3DX12_STATE_OBJECT_DESC::StringContainer m_Strings;
+    std::vector<LPCWSTR> m_Exports;
+};
+
+//------------------------------------------------------------------------------------------------
+class CD3DX12_DXIL_SUBOBJECT_TO_EXPORTS_ASSOCIATION 
+    : public CD3DX12_STATE_OBJECT_DESC::SUBOBJECT_HELPER_BASE
+{
+public:
+    CD3DX12_DXIL_SUBOBJECT_TO_EXPORTS_ASSOCIATION()
+    {
+        Init();
+    }
+    CD3DX12_DXIL_SUBOBJECT_TO_EXPORTS_ASSOCIATION(CD3DX12_STATE_OBJECT_DESC& ContainingStateObject)
+    {
+        Init();
+        AddToStateObject(ContainingStateObject);
+    }
+    void SetSubobjectNameToAssociate(LPCWSTR SubobjectToAssociate) 
+    {
+        m_Desc.SubobjectToAssociate = m_SubobjectName.LocalCopy(SubobjectToAssociate, true); 
+    }
+    void AddExport(LPCWSTR Export)
+    {
+        m_Desc.NumExports++;
+        m_Exports.push_back(m_Strings.LocalCopy(Export));
+        m_Desc.pExports = &m_Exports[0];  // using ugly way to get pointer in case .data() is not defined
+    }
+    template<size_t N>
+    void AddExports(LPCWSTR (&Exports)[N])
+    {
+        for (UINT i = 0; i < N; i++)
+        {
+            AddExport(Exports[i]);
+        }
+    }
+    void AddExports(LPCWSTR* Exports, UINT N)
+    {
+        for (UINT i = 0; i < N; i++)
+        {
+            AddExport(Exports[i]);
+        }
+    }    
+    D3D12_STATE_SUBOBJECT_TYPE Type() const
+    { 
+        return D3D12_STATE_SUBOBJECT_TYPE_DXIL_SUBOBJECT_TO_EXPORTS_ASSOCIATION; 
+    }
+    operator const D3D12_STATE_SUBOBJECT&() const { return *m_pSubobject; }
+    operator const D3D12_DXIL_SUBOBJECT_TO_EXPORTS_ASSOCIATION&() const { return m_Desc; }
+private:
+    void Init()
+    {
+        SUBOBJECT_HELPER_BASE::Init();
+        m_Desc = {};
+        m_Strings.clear();
+        m_SubobjectName.clear();
+        m_Exports.clear();
+    }
+    void* Data() { return &m_Desc; }
+    D3D12_DXIL_SUBOBJECT_TO_EXPORTS_ASSOCIATION m_Desc;
+    CD3DX12_STATE_OBJECT_DESC::StringContainer m_Strings;
+    CD3DX12_STATE_OBJECT_DESC::StringContainer m_SubobjectName;
+    std::vector<LPCWSTR> m_Exports;
+};
+
+//------------------------------------------------------------------------------------------------
+class CD3DX12_HIT_GROUP_SUBOBJECT 
+    : public CD3DX12_STATE_OBJECT_DESC::SUBOBJECT_HELPER_BASE
+{
+public:
+    CD3DX12_HIT_GROUP_SUBOBJECT()
+    {
+        Init();
+    }
+    CD3DX12_HIT_GROUP_SUBOBJECT(CD3DX12_STATE_OBJECT_DESC& ContainingStateObject)
+    {
+        Init();
+        AddToStateObject(ContainingStateObject);
+    }
+    void SetHitGroupExport(LPCWSTR exportName)
+    { 
+        m_Desc.HitGroupExport = m_Strings[0].LocalCopy(exportName, true); 
+    }
+    void SetHitGroupType(D3D12_HIT_GROUP_TYPE Type) { m_Desc.Type = Type; }
+    void SetAnyHitShaderImport(LPCWSTR importName)
+    { 
+        m_Desc.AnyHitShaderImport = m_Strings[1].LocalCopy(importName, true); 
+    }
+    void SetClosestHitShaderImport(LPCWSTR importName)
+    { 
+        m_Desc.ClosestHitShaderImport = m_Strings[2].LocalCopy(importName, true); 
+    }
+    void SetIntersectionShaderImport(LPCWSTR importName)
+    {
+        m_Desc.IntersectionShaderImport = m_Strings[3].LocalCopy(importName, true); 
+    }
+    D3D12_STATE_SUBOBJECT_TYPE Type() const
+    {
+        return D3D12_STATE_SUBOBJECT_TYPE_HIT_GROUP; 
+    }
+    operator const D3D12_STATE_SUBOBJECT&() const { return *m_pSubobject; }
+    operator const D3D12_HIT_GROUP_DESC&() const { return m_Desc; }
+private:
+    void Init()
+    {
+        SUBOBJECT_HELPER_BASE::Init();
+        m_Desc = {};
+        for (UINT i = 0; i < m_NumStrings; i++)
+        {
+            m_Strings[i].clear();
+        }
+    }
+    void* Data() { return &m_Desc; }
+    D3D12_HIT_GROUP_DESC m_Desc;
+    static const UINT m_NumStrings = 4;
+    CD3DX12_STATE_OBJECT_DESC::StringContainer 
+        m_Strings[m_NumStrings]; // one string for every entrypoint name
+};
+
+//------------------------------------------------------------------------------------------------
+class CD3DX12_RAYTRACING_SHADER_CONFIG_SUBOBJECT 
+    : public CD3DX12_STATE_OBJECT_DESC::SUBOBJECT_HELPER_BASE
+{
+public:
+    CD3DX12_RAYTRACING_SHADER_CONFIG_SUBOBJECT()
+    {
+        Init();
+    }
+    CD3DX12_RAYTRACING_SHADER_CONFIG_SUBOBJECT(CD3DX12_STATE_OBJECT_DESC& ContainingStateObject)
+    {
+        Init();
+        AddToStateObject(ContainingStateObject);
+    }
+    void Config(UINT MaxPayloadSizeInBytes, UINT MaxAttributeSizeInBytes)
+    {
+        m_Desc.MaxPayloadSizeInBytes = MaxPayloadSizeInBytes;
+        m_Desc.MaxAttributeSizeInBytes = MaxAttributeSizeInBytes;
+    }
+    D3D12_STATE_SUBOBJECT_TYPE Type() const
+    { 
+        return D3D12_STATE_SUBOBJECT_TYPE_RAYTRACING_SHADER_CONFIG; 
+    }
+    operator const D3D12_STATE_SUBOBJECT&() const { return *m_pSubobject; }
+    operator const D3D12_RAYTRACING_SHADER_CONFIG&() const { return m_Desc; }
+private:
+    void Init()
+    {
+        SUBOBJECT_HELPER_BASE::Init();
+        m_Desc = {};
+    }
+    void* Data() { return &m_Desc; }
+    D3D12_RAYTRACING_SHADER_CONFIG m_Desc;
+};
+
+//------------------------------------------------------------------------------------------------
+class CD3DX12_RAYTRACING_PIPELINE_CONFIG_SUBOBJECT 
+    : public CD3DX12_STATE_OBJECT_DESC::SUBOBJECT_HELPER_BASE
+{
+public:
+    CD3DX12_RAYTRACING_PIPELINE_CONFIG_SUBOBJECT()
+    {
+        Init();
+    }
+    CD3DX12_RAYTRACING_PIPELINE_CONFIG_SUBOBJECT(CD3DX12_STATE_OBJECT_DESC& ContainingStateObject)
+    {
+        Init();
+        AddToStateObject(ContainingStateObject);
+    }
+    void Config(UINT MaxTraceRecursionDepth)
+    {
+        m_Desc.MaxTraceRecursionDepth = MaxTraceRecursionDepth;
+    }
+    D3D12_STATE_SUBOBJECT_TYPE Type() const
+    { 
+        return D3D12_STATE_SUBOBJECT_TYPE_RAYTRACING_PIPELINE_CONFIG; 
+    }
+    operator const D3D12_STATE_SUBOBJECT&() const { return *m_pSubobject; }
+    operator const D3D12_RAYTRACING_PIPELINE_CONFIG&() const { return m_Desc; }
+private:
+    void Init()
+    {
+        SUBOBJECT_HELPER_BASE::Init();
+        m_Desc = {};
+    }
+    void* Data() { return &m_Desc; }
+    D3D12_RAYTRACING_PIPELINE_CONFIG m_Desc;
+};
+
+//------------------------------------------------------------------------------------------------
+class CD3DX12_GLOBAL_ROOT_SIGNATURE_SUBOBJECT 
+    : public CD3DX12_STATE_OBJECT_DESC::SUBOBJECT_HELPER_BASE
+{
+public:
+    CD3DX12_GLOBAL_ROOT_SIGNATURE_SUBOBJECT()
+    {
+        Init();
+    }
+    CD3DX12_GLOBAL_ROOT_SIGNATURE_SUBOBJECT(CD3DX12_STATE_OBJECT_DESC& ContainingStateObject)
+    {
+        Init();
+        AddToStateObject(ContainingStateObject);
+    }
+    void SetRootSignature(ID3D12RootSignature* pRootSig)
+    {
+        m_pRootSig = pRootSig;
+    }
+    D3D12_STATE_SUBOBJECT_TYPE Type() const
+    { 
+        return D3D12_STATE_SUBOBJECT_TYPE_GLOBAL_ROOT_SIGNATURE; 
+    }
+    operator const D3D12_STATE_SUBOBJECT&() const { return *m_pSubobject; }
+    operator ID3D12RootSignature*() const { return m_pRootSig.Get(); }
+private:
+    void Init()
+    {
+        SUBOBJECT_HELPER_BASE::Init();
+        m_pRootSig = nullptr;
+    }
+    void* Data() { return m_pRootSig.GetAddressOf(); }
+    Microsoft::WRL::ComPtr<ID3D12RootSignature> m_pRootSig;
+};
+
+//------------------------------------------------------------------------------------------------
+class CD3DX12_LOCAL_ROOT_SIGNATURE_SUBOBJECT 
+    : public CD3DX12_STATE_OBJECT_DESC::SUBOBJECT_HELPER_BASE
+{
+public:
+    CD3DX12_LOCAL_ROOT_SIGNATURE_SUBOBJECT()
+    {
+        Init();
+    }
+    CD3DX12_LOCAL_ROOT_SIGNATURE_SUBOBJECT(CD3DX12_STATE_OBJECT_DESC& ContainingStateObject)
+    {
+        Init();
+        AddToStateObject(ContainingStateObject);
+    }
+    void SetRootSignature(ID3D12RootSignature* pRootSig)
+    {
+        m_pRootSig = pRootSig;
+    }
+    D3D12_STATE_SUBOBJECT_TYPE Type() const
+    { 
+        return D3D12_STATE_SUBOBJECT_TYPE_LOCAL_ROOT_SIGNATURE; 
+    }
+    operator const D3D12_STATE_SUBOBJECT&() const { return *m_pSubobject; }
+    operator ID3D12RootSignature*() const { return m_pRootSig.Get(); }
+private:
+    void Init()
+    {
+        SUBOBJECT_HELPER_BASE::Init();
+        m_pRootSig = nullptr;
+    }
+    void* Data() { return m_pRootSig.GetAddressOf(); }
+    Microsoft::WRL::ComPtr<ID3D12RootSignature> m_pRootSig;
+};
+
+//------------------------------------------------------------------------------------------------
+class CD3DX12_STATE_OBJECT_CONFIG_SUBOBJECT 
+    : public CD3DX12_STATE_OBJECT_DESC::SUBOBJECT_HELPER_BASE
+{
+public:
+    CD3DX12_STATE_OBJECT_CONFIG_SUBOBJECT()
+    {
+        Init();
+    }
+    CD3DX12_STATE_OBJECT_CONFIG_SUBOBJECT(CD3DX12_STATE_OBJECT_DESC& ContainingStateObject)
+    {
+        Init();
+        AddToStateObject(ContainingStateObject);
+    }
+    void SetFlags(D3D12_STATE_OBJECT_FLAGS Flags)
+    {
+        m_Desc.Flags = Flags;
+    }
+    D3D12_STATE_SUBOBJECT_TYPE Type() const
+    { 
+        return D3D12_STATE_SUBOBJECT_TYPE_STATE_OBJECT_CONFIG; 
+    }
+    operator const D3D12_STATE_SUBOBJECT&() const { return *m_pSubobject; }
+    operator const D3D12_STATE_OBJECT_CONFIG&() const { return m_Desc; }
+private:
+    void Init()
+    {
+        SUBOBJECT_HELPER_BASE::Init();
+        m_Desc = {};
+    }
+    void* Data() { return &m_Desc; }
+    D3D12_STATE_OBJECT_CONFIG m_Desc;
+};
+
+//------------------------------------------------------------------------------------------------
+class CD3DX12_NODE_MASK_SUBOBJECT 
+    : public CD3DX12_STATE_OBJECT_DESC::SUBOBJECT_HELPER_BASE
+{
+public:
+    CD3DX12_NODE_MASK_SUBOBJECT()
+    {
+        Init();
+    }
+    CD3DX12_NODE_MASK_SUBOBJECT(CD3DX12_STATE_OBJECT_DESC& ContainingStateObject)
+    {
+        Init();
+        AddToStateObject(ContainingStateObject);
+    }
+    void SetNodeMask(UINT NodeMask)
+    {
+        m_Desc.NodeMask = NodeMask;
+    }
+    D3D12_STATE_SUBOBJECT_TYPE Type() const
+    { 
+        return D3D12_STATE_SUBOBJECT_TYPE_NODE_MASK; 
+    }
+    operator const D3D12_STATE_SUBOBJECT&() const { return *m_pSubobject; }
+    operator const D3D12_NODE_MASK&() const { return m_Desc; }
+private:
+    void Init()
+    {
+        SUBOBJECT_HELPER_BASE::Init();
+        m_Desc = {};
+    }
+    void* Data() { return &m_Desc; }
+    D3D12_NODE_MASK m_Desc;
+};
+
+#endif // #ifndef D3DX12_NO_STATE_OBJECT_HELPERS
 
 #endif // defined( __cplusplus )
 
 #endif //__D3DX12_H__
 
 
-
diff --git a/examples/viewer/viewer.vcxproj b/examples/viewer/viewer.vcxproj
index a30ef8e..6cd6179 100644
--- a/examples/viewer/viewer.vcxproj
+++ b/examples/viewer/viewer.vcxproj
@@ -15,7 +15,7 @@
     <ProjectGuid>{D49DC3E4-3F9B-4F15-8767-C2CF5735182F}</ProjectGuid>
     <Keyword>Win32Proj</Keyword>
     <RootNamespace>viewer</RootNamespace>
-    <WindowsTargetPlatformVersion>10.0</WindowsTargetPlatformVersion>
+    <WindowsTargetPlatformVersion>10.0.17763.0</WindowsTargetPlatformVersion>
   </PropertyGroup>
   <Import Project="$(VCTargetsPath)\Microsoft.Cpp.Default.props" />
   <PropertyGroup Condition="'$(Configuration)|$(Platform)'=='Debug|x64'" Label="Configuration">
@@ -27,7 +27,7 @@
   <PropertyGroup Condition="'$(Configuration)|$(Platform)'=='Release|x64'" Label="Configuration">
     <ConfigurationType>Application</ConfigurationType>
     <UseDebugLibraries>false</UseDebugLibraries>
-    <PlatformToolset>v142</PlatformToolset>
+    <PlatformToolset>v141</PlatformToolset>
     <WholeProgramOptimization>true</WholeProgramOptimization>
     <CharacterSet>Unicode</CharacterSet>
   </PropertyGroup>
@@ -149,20 +149,24 @@
     <None Include=".clang-format" />
     <None Include="README.md" />
   </ItemGroup>
-  <ItemGroup>
-    <None Include="DirectX\Shaders\*.*">
-      <CopyToOutputDirectory>PreserveNewest</CopyToOutputDirectory>
-      <TargetPath>DirectX\Shaders</TargetPath>
-    </None>
-    <None Include="Assets\*.*">
-      <CopyToOutputDirectory>PreserveNewest</CopyToOutputDirectory>
-      <TargetPath>Assets</TargetPath>
-    </None>
-    <None Include="Assets\Environment\*.*">
-      <CopyToOutputDirectory>PreserveNewest</CopyToOutputDirectory>
-      <TargetPath>Assets\Environment</TargetPath>
-    </None>
-  </ItemGroup>
+  <Target Name="CopyAdditionalFiles" BeforeTargets="PrepareForBuild">
+    <ItemGroup>
+      <Shaders_DirectX Include="DirectX\Shaders\*.*" />
+      <Assets Include="Assets\*.*" />
+      <Assets_Env Include="Assets\Environment\*.*" />
+    </ItemGroup>
+    <ItemGroup>
+      <CopyFileToFolders Include="@(Shaders_DirectX)">
+        <DestinationFolders>$(OutDir)\DirectX\Shaders</DestinationFolders>
+      </CopyFileToFolders>
+      <CopyFileToFolders Include="@(Assets)">
+        <DestinationFolders>$(OutDir)\Assets</DestinationFolders>
+      </CopyFileToFolders>
+      <CopyFileToFolders Include="@(Assets_Env)">
+        <DestinationFolders>$(OutDir)\Assets\Environment</DestinationFolders>
+      </CopyFileToFolders>
+    </ItemGroup>
+  </Target>
   <Import Project="$(VCTargetsPath)\Microsoft.Cpp.targets" />
   <ImportGroup Label="ExtensionTargets" />
 </Project>
\ No newline at end of file
diff --git a/include/fx/gltf.h b/include/fx/gltf.h
index 8f82473..64ff5d1 100644
--- a/include/fx/gltf.h
+++ b/include/fx/gltf.h
@@ -1676,18 +1676,25 @@ namespace gltf
                 }
                 else if (dataContext.binaryData != nullptr)
                 {
-                    detail::ChunkHeader header;
-
                     std::vector<uint8_t> & binary = *dataContext.binaryData;
+
+                    const std::size_t HeaderEndOffset = dataContext.binaryOffset + detail::ChunkHeaderSize;
+                    if (binary.size() < HeaderEndOffset)
+                    {
+                        throw invalid_gltf_document("Invalid GLB buffer data");
+                    }
+
+                    detail::ChunkHeader header;
                     std::memcpy(&header, &binary[dataContext.binaryOffset], detail::ChunkHeaderSize);
 
-                    if (header.chunkType != detail::GLBChunkBIN || header.chunkLength < buffer.byteLength)
+                    const std::size_t BufferEndOffset = HeaderEndOffset + buffer.byteLength;
+                    if (header.chunkType != detail::GLBChunkBIN || header.chunkLength < buffer.byteLength || binary.size() < BufferEndOffset)
                     {
                         throw invalid_gltf_document("Invalid GLB buffer data");
                     }
 
                     buffer.data.resize(buffer.byteLength);
-                    std::memcpy(&buffer.data[0], &binary[dataContext.binaryOffset + detail::ChunkHeaderSize], buffer.byteLength);
+                    std::memcpy(&buffer.data[0], &binary[HeaderEndOffset], buffer.byteLength);
                 }
             }
 
@@ -1863,7 +1870,8 @@ namespace gltf
             std::memcpy(&header, &binary[0], detail::HeaderSize);
             if (header.magic != detail::GLBHeaderMagic ||
                 header.jsonHeader.chunkType != detail::GLBChunkJSON ||
-                header.jsonHeader.chunkLength + detail::HeaderSize > header.length)
+                header.jsonHeader.chunkLength + detail::HeaderSize > header.length ||
+                header.jsonHeader.chunkLength + detail::HeaderSize > binary.size())
             {
                 throw invalid_gltf_document("Invalid GLB header");
             }
diff --git a/test/data/glTF-Sample-Models b/test/data/glTF-Sample-Models
index ec88004..77f1a29 160000
--- a/test/data/glTF-Sample-Models
+++ b/test/data/glTF-Sample-Models
@@ -1 +1 @@
-Subproject commit ec880043ae0cead374d7e3a965cc8323c51b06e1
+Subproject commit 77f1a295e65c3a59c7131e6a15552c69817c9449
diff --git a/test/src/unit-roundtrip.cpp b/test/src/unit-roundtrip.cpp
index bca1a80..ea312b5 100644
--- a/test/src/unit-roundtrip.cpp
+++ b/test/src/unit-roundtrip.cpp
@@ -52,15 +52,18 @@ void RoundtripCompare(std::string const & filePath, bool checkExtensions = false
         // Ensure used extensions are actually still referenced...
         if (checkExtensions)
         {
-            for (auto e : doc.extensionsUsed)
+            for (auto & e : doc.extensionsUsed)
             {
                 bool found = false;
-                for (auto & m : doc.materials)
+                for (auto & m : doc.meshes)
                 {
-                    found |= FindExtension(e, m.extensionsAndExtras);
-                    if (found)
+                    for (auto & p : m.primitives)
                     {
-                        break;
+                        found |= FindExtension(e, p.extensionsAndExtras);
+                        if (found)
+                        {
+                            break;
+                        }
                     }
                 }
 
@@ -217,29 +220,25 @@ TEST_CASE("roundtrip")
     {
         for (auto & filePath :
             {
-                "data/glTF-Sample-Models/2.0/2CylinderEngine/glTF-pbrSpecularGlossiness/2CylinderEngine.gltf",
-                "data/glTF-Sample-Models/2.0/Avocado/glTF-pbrSpecularGlossiness/Avocado.gltf",
-                "data/glTF-Sample-Models/2.0/BarramundiFish/glTF-pbrSpecularGlossiness/BarramundiFish.gltf",
-                "data/glTF-Sample-Models/2.0/BoomBox/glTF-pbrSpecularGlossiness/BoomBox.gltf",
-                "data/glTF-Sample-Models/2.0/Box/glTF-pbrSpecularGlossiness/Box.gltf",
-                "data/glTF-Sample-Models/2.0/BoxAnimated/glTF-pbrSpecularGlossiness/BoxAnimated.gltf",
-                //"data/glTF-Sample-Models/2.0/BoxInterleaved/glTF-pbrSpecularGlossiness/BoxInterleaved.gltf",  // Uses/Requires extension but does not actually use it
-                "data/glTF-Sample-Models/2.0/BoxTextured/glTF-pbrSpecularGlossiness/BoxTextured.gltf",
-                "data/glTF-Sample-Models/2.0/BoxTexturedNonPowerOfTwo/glTF-pbrSpecularGlossiness/BoxTexturedNonPowerOfTwo.gltf",
-                "data/glTF-Sample-Models/2.0/BrainStem/glTF-pbrSpecularGlossiness/BrainStem.gltf",
-                "data/glTF-Sample-Models/2.0/Buggy/glTF-pbrSpecularGlossiness/Buggy.gltf",
-                "data/glTF-Sample-Models/2.0/CesiumMan/glTF-pbrSpecularGlossiness/CesiumMan.gltf",
-                "data/glTF-Sample-Models/2.0/CesiumMilkTruck/glTF-pbrSpecularGlossiness/CesiumMilkTruck.gltf",
-                "data/glTF-Sample-Models/2.0/Corset/glTF-pbrSpecularGlossiness/Corset.gltf",
-                "data/glTF-Sample-Models/2.0/Duck/glTF-pbrSpecularGlossiness/Duck.gltf",
-                "data/glTF-Sample-Models/2.0/GearboxAssy/glTF-pbrSpecularGlossiness/GearboxAssy.gltf",
-                "data/glTF-Sample-Models/2.0/Lantern/glTF-pbrSpecularGlossiness/Lantern.gltf",
-                "data/glTF-Sample-Models/2.0/Monster/glTF-pbrSpecularGlossiness/Monster.gltf",
-                "data/glTF-Sample-Models/2.0/ReciprocatingSaw/glTF-pbrSpecularGlossiness/ReciprocatingSaw.gltf",
-                "data/glTF-Sample-Models/2.0/RiggedFigure/glTF-pbrSpecularGlossiness/RiggedFigure.gltf",
-                "data/glTF-Sample-Models/2.0/RiggedSimple/glTF-pbrSpecularGlossiness/RiggedSimple.gltf",
-                "data/glTF-Sample-Models/2.0/VC/glTF-pbrSpecularGlossiness/VC.gltf",
-                "data/glTF-Sample-Models/2.0/WaterBottle/glTF-pbrSpecularGlossiness/WaterBottle.gltf"
+                "data/glTF-Sample-Models/2.0/2CylinderEngine/glTF-Draco/2CylinderEngine.gltf",
+                "data/glTF-Sample-Models/2.0/Avocado/glTF-Draco/Avocado.gltf",
+                "data/glTF-Sample-Models/2.0/BarramundiFish/glTF-Draco/BarramundiFish.gltf",
+                "data/glTF-Sample-Models/2.0/BoomBox/glTF-Draco/BoomBox.gltf",
+                "data/glTF-Sample-Models/2.0/Box/glTF-Draco/Box.gltf",
+                "data/glTF-Sample-Models/2.0/BrainStem/glTF-Draco/BrainStem.gltf",
+                "data/glTF-Sample-Models/2.0/Buggy/glTF-Draco/Buggy.gltf",
+                "data/glTF-Sample-Models/2.0/CesiumMan/glTF-Draco/CesiumMan.gltf",
+                "data/glTF-Sample-Models/2.0/CesiumMilkTruck/glTF-Draco/CesiumMilkTruck.gltf",
+                "data/glTF-Sample-Models/2.0/Corset/glTF-Draco/Corset.gltf",
+                "data/glTF-Sample-Models/2.0/Duck/glTF-Draco/Duck.gltf",
+                "data/glTF-Sample-Models/2.0/GearboxAssy/glTF-Draco/GearboxAssy.gltf",
+                "data/glTF-Sample-Models/2.0/Lantern/glTF-Draco/Lantern.gltf",
+                "data/glTF-Sample-Models/2.0/Monster/glTF-Draco/Monster.gltf",
+                "data/glTF-Sample-Models/2.0/ReciprocatingSaw/glTF-Draco/ReciprocatingSaw.gltf",
+                "data/glTF-Sample-Models/2.0/RiggedFigure/glTF-Draco/RiggedFigure.gltf",
+                "data/glTF-Sample-Models/2.0/RiggedSimple/glTF-Draco/RiggedSimple.gltf",
+                "data/glTF-Sample-Models/2.0/VC/glTF-Draco/VC.gltf",
+                "data/glTF-Sample-Models/2.0/WaterBottle/glTF-Draco/WaterBottle.gltf"
             })
         {
             RoundtripCompare(filePath, true);
diff --git a/test/thirdparty/catch2/catch.hpp b/test/thirdparty/catch2/catch.hpp
index cc3f97c..1850fff 100644
--- a/test/thirdparty/catch2/catch.hpp
+++ b/test/thirdparty/catch2/catch.hpp
@@ -1,6 +1,6 @@
 /*
- *  Catch v2.6.0
- *  Generated: 2019-01-31 22:25:55.560884
+ *  Catch v2.7.0
+ *  Generated: 2019-03-07 21:34:30.252164
  *  ----------------------------------------------------------
  *  This file has been merged from multiple headers. Please don't edit it directly
  *  Copyright (c) 2019 Two Blue Cubes Ltd. All rights reserved.
@@ -14,7 +14,7 @@
 
 
 #define CATCH_VERSION_MAJOR 2
-#define CATCH_VERSION_MINOR 6
+#define CATCH_VERSION_MINOR 7
 #define CATCH_VERSION_PATCH 0
 
 #ifdef __clang__
@@ -711,6 +711,16 @@ struct is_unique<T0, T1, Rest...> : std::integral_constant
 #define INTERNAL_CATCH_EXPAND2(...) INTERNAL_CATCH_NO## __VA_ARGS__
 #define INTERNAL_CATCH_DEF(...) INTERNAL_CATCH_DEF __VA_ARGS__
 #define INTERNAL_CATCH_NOINTERNAL_CATCH_DEF
+#define INTERNAL_CATCH_STRINGIZE(...) INTERNAL_CATCH_STRINGIZE2(__VA_ARGS__)
+#ifndef CATCH_CONFIG_TRADITIONAL_MSVC_PREPROCESSOR
+#define INTERNAL_CATCH_STRINGIZE2(...) #__VA_ARGS__
+#define INTERNAL_CATCH_STRINGIZE_WITHOUT_PARENS(param) INTERNAL_CATCH_STRINGIZE(INTERNAL_CATCH_REMOVE_PARENS(param))
+#else
+// MSVC is adding extra space and needs another indirection to expand INTERNAL_CATCH_NOINTERNAL_CATCH_DEF
+#define INTERNAL_CATCH_STRINGIZE2(...) INTERNAL_CATCH_STRINGIZE3(__VA_ARGS__)
+#define INTERNAL_CATCH_STRINGIZE3(...) #__VA_ARGS__
+#define INTERNAL_CATCH_STRINGIZE_WITHOUT_PARENS(param) (INTERNAL_CATCH_STRINGIZE(INTERNAL_CATCH_REMOVE_PARENS(param)) + 1)
+#endif
 
 #define INTERNAL_CATCH_REMOVE_PARENS(...) INTERNAL_CATCH_EXPAND1(INTERNAL_CATCH_DEF __VA_ARGS__)
 
@@ -725,7 +735,7 @@ struct is_unique<T0, T1, Rest...> : std::integral_constant
 #define INTERNAL_CATCH_TEMPLATE_UNIQUE_NAME(Name, ...) INTERNAL_CATCH_TEMPLATE_UNIQUE_NAME1(Name, INTERNAL_CATCH_EXPAND_VARGS(INTERNAL_CATCH_REMOVE_PARENS(__VA_ARGS__)))
 #endif
 
-#define INTERNAL_CATCH_MAKE_TYPE_LIST(types) TypeList<INTERNAL_CATCH_REMOVE_PARENS(types)>
+#define INTERNAL_CATCH_MAKE_TYPE_LIST(types) Catch::TypeList<INTERNAL_CATCH_REMOVE_PARENS(types)>
 
 #define INTERNAL_CATCH_MAKE_TYPE_LISTS_FROM_TYPES(types)\
     CATCH_REC_LIST(INTERNAL_CATCH_MAKE_TYPE_LIST,INTERNAL_CATCH_REMOVE_PARENS(types))
@@ -736,65 +746,59 @@ struct is_unique<T0, T1, Rest...> : std::integral_constant
 
 #include <type_traits>
 
+namespace Catch {
 template< typename... >
-struct TypeList{};
+struct TypeList {};
 
 template< typename... >
 struct append;
 
 template< template<typename...> class L1
-	, typename...E1
-	, template<typename...> class L2
-	, typename...E2
-	>
-struct append< L1<E1...>, L2<E2...> >
-{
-	using type = L1<E1..., E2...>;
+    , typename...E1
+    , template<typename...> class L2
+    , typename...E2
+>
+struct append< L1<E1...>, L2<E2...> > {
+    using type = L1<E1..., E2...>;
 };
 
 template< template<typename...> class L1
-	, typename...E1
-	, template<typename...> class L2
-	, typename...E2
-	, typename...Rest
-	>
-struct append< L1<E1...>, L2<E2...>, Rest...>
-{
-	using type = typename append< L1<E1..., E2...>, Rest... >::type;
+    , typename...E1
+    , template<typename...> class L2
+    , typename...E2
+    , typename...Rest
+>
+struct append< L1<E1...>, L2<E2...>, Rest...> {
+    using type = typename append< L1<E1..., E2...>, Rest... >::type;
 };
 
 template< template<typename...> class
-        , typename...
-        >
+    , typename...
+>
 struct rewrap;
 
 template< template<typename...> class Container
-        , template<typename...> class List
-        , typename...elems
-        >
-struct rewrap<Container, List<elems...>>
-{
+    , template<typename...> class List
+    , typename...elems
+>
+struct rewrap<Container, List<elems...>> {
     using type = TypeList< Container< elems... > >;
 };
 
 template< template<typename...> class Container
-        , template<typename...> class List
-        , class...Elems
-        , typename...Elements>
-struct rewrap<Container, List<Elems...>, Elements...>
-{
+    , template<typename...> class List
+    , class...Elems
+    , typename...Elements>
+    struct rewrap<Container, List<Elems...>, Elements...> {
     using type = typename append<TypeList<Container<Elems...>>, typename rewrap<Container, Elements...>::type>::type;
 };
 
 template< template<typename...> class...Containers >
-struct combine
-{
+struct combine {
     template< typename...Types >
-    struct with_types
-    {
+    struct with_types {
         template< template <typename...> class Final >
-        struct into
-        {
+        struct into {
             using type = typename append<Final<>, typename rewrap<Containers, Types...>::type...>::type;
         };
     };
@@ -803,6 +807,8 @@ struct combine
 template<typename T>
 struct always_false : std::false_type {};
 
+} // namespace Catch
+
 // end catch_meta.hpp
 namespace Catch {
 
@@ -949,11 +955,14 @@ struct AutoReg : NonCopyable {
                     CATCH_INTERNAL_CHECK_UNIQUE_TYPES(Types...)       \
                     int index = 0;                                    \
                     using expander = int[];                           \
-                    (void)expander{(Catch::AutoReg( Catch::makeTestInvoker( &TestFuncName<Types> ), CATCH_INTERNAL_LINEINFO, Catch::StringRef(), Catch::NameAndTags{ Name " - " + Catch::StringMaker<int>::convert(index++), Tags } ), 0)... };/* NOLINT */ \
+                    constexpr char const* tmpl_types[] = {CATCH_REC_LIST(INTERNAL_CATCH_STRINGIZE_WITHOUT_PARENS, INTERNAL_CATCH_REMOVE_PARENS(TmplTypes))};\
+                    constexpr char const* types_list[] = {CATCH_REC_LIST(INTERNAL_CATCH_STRINGIZE_WITHOUT_PARENS, INTERNAL_CATCH_REMOVE_PARENS(TypesList))};\
+                    constexpr auto num_types = sizeof(types_list) / sizeof(types_list[0]);\
+                    (void)expander{(Catch::AutoReg( Catch::makeTestInvoker( &TestFuncName<Types> ), CATCH_INTERNAL_LINEINFO, Catch::StringRef(), Catch::NameAndTags{ Name " - " + std::string(tmpl_types[index / num_types]) + "<" + std::string(types_list[index % num_types]) + ">", Tags } ), index++, 0)... };/* NOLINT */\
                 }                                                     \
             };                                                        \
             static int INTERNAL_CATCH_UNIQUE_NAME( globalRegistrar ) = [](){ \
-                using TestInit = combine<INTERNAL_CATCH_REMOVE_PARENS(TmplTypes)> \
+                using TestInit = Catch::combine<INTERNAL_CATCH_REMOVE_PARENS(TmplTypes)> \
                             ::with_types<INTERNAL_CATCH_MAKE_TYPE_LISTS_FROM_TYPES(TypesList)>::into<TestName>::type; \
                 TestInit();                                           \
                 return 0;                                             \
@@ -1014,11 +1023,14 @@ struct AutoReg : NonCopyable {
                     CATCH_INTERNAL_CHECK_UNIQUE_TYPES(Types...)\
                     int index = 0;\
                     using expander = int[];\
-                    (void)expander{(Catch::AutoReg( Catch::makeTestInvoker( &TestName<Types>::test ), CATCH_INTERNAL_LINEINFO, #ClassName, Catch::NameAndTags{ Name " - " + Catch::StringMaker<int>::convert(index++), Tags } ), 0)... };/* NOLINT */ \
+                    constexpr char const* tmpl_types[] = {CATCH_REC_LIST(INTERNAL_CATCH_STRINGIZE_WITHOUT_PARENS, INTERNAL_CATCH_REMOVE_PARENS(TmplTypes))};\
+                    constexpr char const* types_list[] = {CATCH_REC_LIST(INTERNAL_CATCH_STRINGIZE_WITHOUT_PARENS, INTERNAL_CATCH_REMOVE_PARENS(TypesList))};\
+                    constexpr auto num_types = sizeof(types_list) / sizeof(types_list[0]);\
+                    (void)expander{(Catch::AutoReg( Catch::makeTestInvoker( &TestName<Types>::test ), CATCH_INTERNAL_LINEINFO, #ClassName, Catch::NameAndTags{ Name " - " + std::string(tmpl_types[index / num_types]) + "<" + std::string(types_list[index % num_types]) + ">", Tags } ), index++, 0)... };/* NOLINT */ \
                 }\
             };\
             static int INTERNAL_CATCH_UNIQUE_NAME( globalRegistrar ) = [](){\
-                using TestInit = combine<INTERNAL_CATCH_REMOVE_PARENS(TmplTypes)>\
+                using TestInit = Catch::combine<INTERNAL_CATCH_REMOVE_PARENS(TmplTypes)>\
                             ::with_types<INTERNAL_CATCH_MAKE_TYPE_LISTS_FROM_TYPES(TypesList)>::into<TestNameClass>::type;\
                 TestInit();\
                 return 0;\
@@ -2062,6 +2074,7 @@ namespace Catch {
     struct SectionInfo;
     struct SectionEndInfo;
     struct MessageInfo;
+    struct MessageBuilder;
     struct Counts;
     struct BenchmarkInfo;
     struct BenchmarkStats;
@@ -2088,6 +2101,8 @@ namespace Catch {
         virtual void pushScopedMessage( MessageInfo const& message ) = 0;
         virtual void popScopedMessage( MessageInfo const& message ) = 0;
 
+        virtual void emplaceUnscopedMessage( MessageBuilder const& builder ) = 0;
+
         virtual void handleFatalErrorCondition( StringRef message ) = 0;
 
         virtual void handleExpr
@@ -2251,9 +2266,12 @@ namespace Catch {
     class ScopedMessage {
     public:
         explicit ScopedMessage( MessageBuilder const& builder );
+        ScopedMessage( ScopedMessage& duplicate ) = delete;
+        ScopedMessage( ScopedMessage&& old );
         ~ScopedMessage();
 
         MessageInfo m_info;
+        bool m_moved;
     };
 
     class Capturer {
@@ -2316,7 +2334,7 @@ namespace Catch {
             CATCH_INTERNAL_UNSUPPRESS_PARENTHESES_WARNINGS \
         } INTERNAL_CATCH_CATCH( catchAssertionHandler ) \
         INTERNAL_CATCH_REACT( catchAssertionHandler ) \
-    } while( (void)0, false && static_cast<bool>( !!(__VA_ARGS__) ) ) // the expression here is never evaluated at runtime but it forces the compiler to give it a look
+    } while( (void)0, (false) && static_cast<bool>( !!(__VA_ARGS__) ) ) // the expression here is never evaluated at runtime but it forces the compiler to give it a look
     // The double negation silences MSVC's C4800 warning, the static_cast forces short-circuit evaluation if the type has overloaded &&.
 
 ///////////////////////////////////////////////////////////////////////////////
@@ -2397,6 +2415,10 @@ namespace Catch {
 #define INTERNAL_CATCH_INFO( macroName, log ) \
     Catch::ScopedMessage INTERNAL_CATCH_UNIQUE_NAME( scopedMessage )( Catch::MessageBuilder( macroName##_catch_sr, CATCH_INTERNAL_LINEINFO, Catch::ResultWas::Info ) << log );
 
+///////////////////////////////////////////////////////////////////////////////
+#define INTERNAL_CATCH_UNSCOPED_INFO( macroName, log ) \
+    Catch::getResultCapture().emplaceUnscopedMessage( Catch::MessageBuilder( macroName##_catch_sr, CATCH_INTERNAL_LINEINFO, Catch::ResultWas::Info ) << log )
+
 ///////////////////////////////////////////////////////////////////////////////
 // Although this is matcher-based, it can be used with just a string
 #define INTERNAL_CATCH_THROWS_STR_MATCHES( macroName, resultDisposition, matcher, ... ) \
@@ -3642,6 +3664,36 @@ namespace Generators {
         return makeGenerators( value( T( std::forward<U>( val ) ) ), std::forward<Gs>( moreGenerators )... );
     }
 
+    auto acquireGeneratorTracker( SourceLineInfo const& lineInfo ) -> IGeneratorTracker&;
+
+    template<typename L>
+    // Note: The type after -> is weird, because VS2015 cannot parse
+    //       the expression used in the typedef inside, when it is in
+    //       return type. Yeah.
+    auto generate( SourceLineInfo const& lineInfo, L const& generatorExpression ) -> decltype(std::declval<decltype(generatorExpression())>().get()) {
+        using UnderlyingType = typename decltype(generatorExpression())::type;
+
+        IGeneratorTracker& tracker = acquireGeneratorTracker( lineInfo );
+        if (!tracker.hasGenerator()) {
+            tracker.setGenerator(pf::make_unique<Generators<UnderlyingType>>(generatorExpression()));
+        }
+
+        auto const& generator = static_cast<IGenerator<UnderlyingType> const&>( *tracker.getGenerator() );
+        return generator.get();
+    }
+
+} // namespace Generators
+} // namespace Catch
+
+#define GENERATE( ... ) \
+    Catch::Generators::generate( CATCH_INTERNAL_LINEINFO, []{ using namespace Catch::Generators; return makeGenerators( __VA_ARGS__ ); } )
+
+// end catch_generators.hpp
+// start catch_generators_generic.hpp
+
+namespace Catch {
+namespace Generators {
+
     template <typename T>
     class TakeGenerator : public IGenerator<T> {
         GeneratorWrapper<T> m_generator;
@@ -3810,31 +3862,297 @@ namespace Generators {
         );
     }
 
-    auto acquireGeneratorTracker( SourceLineInfo const& lineInfo ) -> IGeneratorTracker&;
-
-    template<typename L>
-    // Note: The type after -> is weird, because VS2015 cannot parse
-    //       the expression used in the typedef inside, when it is in
-    //       return type. Yeah, ¯\_(ツ)_/¯
-    auto generate( SourceLineInfo const& lineInfo, L const& generatorExpression ) -> decltype(std::declval<decltype(generatorExpression())>().get()) {
-        using UnderlyingType = typename decltype(generatorExpression())::type;
-
-        IGeneratorTracker& tracker = acquireGeneratorTracker( lineInfo );
-        if (!tracker.hasGenerator()) {
-            tracker.setGenerator(pf::make_unique<Generators<UnderlyingType>>(generatorExpression()));
+    template <typename T>
+    class ChunkGenerator final : public IGenerator<std::vector<T>> {
+        std::vector<T> m_chunk;
+        size_t m_chunk_size;
+        GeneratorWrapper<T> m_generator;
+        bool m_used_up = false;
+    public:
+        ChunkGenerator(size_t size, GeneratorWrapper<T> generator) :
+            m_chunk_size(size), m_generator(std::move(generator))
+        {
+            m_chunk.reserve(m_chunk_size);
+            m_chunk.push_back(m_generator.get());
+            for (size_t i = 1; i < m_chunk_size; ++i) {
+                if (!m_generator.next()) {
+                    Catch::throw_exception(GeneratorException("Not enough values to initialize the first chunk"));
+                }
+                m_chunk.push_back(m_generator.get());
+            }
         }
+        std::vector<T> const& get() const override {
+            return m_chunk;
+        }
+        bool next() override {
+            m_chunk.clear();
+            for (size_t idx = 0; idx < m_chunk_size; ++idx) {
+                if (!m_generator.next()) {
+                    return false;
+                }
+                m_chunk.push_back(m_generator.get());
+            }
+            return true;
+        }
+    };
 
-        auto const& generator = static_cast<IGenerator<UnderlyingType> const&>( *tracker.getGenerator() );
-        return generator.get();
+    template <typename T>
+    GeneratorWrapper<std::vector<T>> chunk(size_t size, GeneratorWrapper<T>&& generator) {
+        return GeneratorWrapper<std::vector<T>>(
+            pf::make_unique<ChunkGenerator<T>>(size, std::move(generator))
+        );
     }
 
 } // namespace Generators
 } // namespace Catch
 
-#define GENERATE( ... ) \
-    Catch::Generators::generate( CATCH_INTERNAL_LINEINFO, []{ using namespace Catch::Generators; return makeGenerators( __VA_ARGS__ ); } )
+// end catch_generators_generic.hpp
+// start catch_generators_specific.hpp
 
-// end catch_generators.hpp
+// start catch_context.h
+
+#include <memory>
+
+namespace Catch {
+
+    struct IResultCapture;
+    struct IRunner;
+    struct IConfig;
+    struct IMutableContext;
+
+    using IConfigPtr = std::shared_ptr<IConfig const>;
+
+    struct IContext
+    {
+        virtual ~IContext();
+
+        virtual IResultCapture* getResultCapture() = 0;
+        virtual IRunner* getRunner() = 0;
+        virtual IConfigPtr const& getConfig() const = 0;
+    };
+
+    struct IMutableContext : IContext
+    {
+        virtual ~IMutableContext();
+        virtual void setResultCapture( IResultCapture* resultCapture ) = 0;
+        virtual void setRunner( IRunner* runner ) = 0;
+        virtual void setConfig( IConfigPtr const& config ) = 0;
+
+    private:
+        static IMutableContext *currentContext;
+        friend IMutableContext& getCurrentMutableContext();
+        friend void cleanUpContext();
+        static void createContext();
+    };
+
+    inline IMutableContext& getCurrentMutableContext()
+    {
+        if( !IMutableContext::currentContext )
+            IMutableContext::createContext();
+        return *IMutableContext::currentContext;
+    }
+
+    inline IContext& getCurrentContext()
+    {
+        return getCurrentMutableContext();
+    }
+
+    void cleanUpContext();
+}
+
+// end catch_context.h
+// start catch_interfaces_config.h
+
+#include <iosfwd>
+#include <string>
+#include <vector>
+#include <memory>
+
+namespace Catch {
+
+    enum class Verbosity {
+        Quiet = 0,
+        Normal,
+        High
+    };
+
+    struct WarnAbout { enum What {
+        Nothing = 0x00,
+        NoAssertions = 0x01,
+        NoTests = 0x02
+    }; };
+
+    struct ShowDurations { enum OrNot {
+        DefaultForReporter,
+        Always,
+        Never
+    }; };
+    struct RunTests { enum InWhatOrder {
+        InDeclarationOrder,
+        InLexicographicalOrder,
+        InRandomOrder
+    }; };
+    struct UseColour { enum YesOrNo {
+        Auto,
+        Yes,
+        No
+    }; };
+    struct WaitForKeypress { enum When {
+        Never,
+        BeforeStart = 1,
+        BeforeExit = 2,
+        BeforeStartAndExit = BeforeStart | BeforeExit
+    }; };
+
+    class TestSpec;
+
+    struct IConfig : NonCopyable {
+
+        virtual ~IConfig();
+
+        virtual bool allowThrows() const = 0;
+        virtual std::ostream& stream() const = 0;
+        virtual std::string name() const = 0;
+        virtual bool includeSuccessfulResults() const = 0;
+        virtual bool shouldDebugBreak() const = 0;
+        virtual bool warnAboutMissingAssertions() const = 0;
+        virtual bool warnAboutNoTests() const = 0;
+        virtual int abortAfter() const = 0;
+        virtual bool showInvisibles() const = 0;
+        virtual ShowDurations::OrNot showDurations() const = 0;
+        virtual TestSpec const& testSpec() const = 0;
+        virtual bool hasTestFilters() const = 0;
+        virtual RunTests::InWhatOrder runOrder() const = 0;
+        virtual unsigned int rngSeed() const = 0;
+        virtual int benchmarkResolutionMultiple() const = 0;
+        virtual UseColour::YesOrNo useColour() const = 0;
+        virtual std::vector<std::string> const& getSectionsToRun() const = 0;
+        virtual Verbosity verbosity() const = 0;
+    };
+
+    using IConfigPtr = std::shared_ptr<IConfig const>;
+}
+
+// end catch_interfaces_config.h
+#include <random>
+
+namespace Catch {
+namespace Generators {
+
+template <typename Float>
+class RandomFloatingGenerator final : public IGenerator<Float> {
+    // FIXME: What is the right seed?
+    std::minstd_rand m_rand;
+    std::uniform_real_distribution<Float> m_dist;
+    Float m_current_number;
+public:
+
+    RandomFloatingGenerator(Float a, Float b):
+        m_rand(getCurrentContext().getConfig()->rngSeed()),
+        m_dist(a, b) {
+        static_cast<void>(next());
+    }
+
+    Float const& get() const override {
+        return m_current_number;
+    }
+    bool next() override {
+        m_current_number = m_dist(m_rand);
+        return true;
+    }
+};
+
+template <typename Integer>
+class RandomIntegerGenerator final : public IGenerator<Integer> {
+    std::minstd_rand m_rand;
+    std::uniform_int_distribution<Integer> m_dist;
+    Integer m_current_number;
+public:
+
+    RandomIntegerGenerator(Integer a, Integer b):
+        m_rand(getCurrentContext().getConfig()->rngSeed()),
+        m_dist(a, b) {
+        static_cast<void>(next());
+    }
+
+    Integer const& get() const override {
+        return m_current_number;
+    }
+    bool next() override {
+        m_current_number = m_dist(m_rand);
+        return true;
+    }
+};
+
+// TODO: Ideally this would be also constrained against the various char types,
+//       but I don't expect users to run into that in practice.
+template <typename T>
+typename std::enable_if<std::is_integral<T>::value && !std::is_same<T, bool>::value,
+GeneratorWrapper<T>>::type
+random(T a, T b) {
+    return GeneratorWrapper<T>(
+        pf::make_unique<RandomIntegerGenerator<T>>(a, b)
+    );
+}
+
+template <typename T>
+typename std::enable_if<std::is_floating_point<T>::value,
+GeneratorWrapper<T>>::type
+random(T a, T b) {
+    return GeneratorWrapper<T>(
+        pf::make_unique<RandomFloatingGenerator<T>>(a, b)
+    );
+}
+
+template <typename T>
+class RangeGenerator final : public IGenerator<T> {
+    T m_current;
+    T m_end;
+    T m_step;
+    bool m_positive;
+
+public:
+    RangeGenerator(T const& start, T const& end, T const& step):
+        m_current(start),
+        m_end(end),
+        m_step(step),
+        m_positive(m_step > T(0))
+    {
+        assert(m_current != m_end && "Range start and end cannot be equal");
+        assert(m_step != T(0) && "Step size cannot be zero");
+        assert(((m_positive && m_current <= m_end) || (!m_positive && m_current >= m_end)) && "Step moves away from end");
+    }
+
+    RangeGenerator(T const& start, T const& end):
+        RangeGenerator(start, end, (start < end) ? T(1) : T(-1))
+    {}
+
+    T const& get() const override {
+        return m_current;
+    }
+
+    bool next() override {
+        m_current += m_step;
+        return (m_positive) ? (m_current < m_end) : (m_current > m_end);
+    }
+};
+
+template <typename T>
+GeneratorWrapper<T> range(T const& start, T const& end, T const& step) {
+    static_assert(std::is_integral<T>::value && !std::is_same<T, bool>::value, "Type must be an integer");
+    return GeneratorWrapper<T>(pf::make_unique<RangeGenerator<T>>(start, end, step));
+}
+
+template <typename T>
+GeneratorWrapper<T> range(T const& start, T const& end) {
+    static_assert(std::is_integral<T>::value && !std::is_same<T, bool>::value, "Type must be an integer");
+    return GeneratorWrapper<T>(pf::make_unique<RangeGenerator<T>>(start, end));
+}
+
+} // namespace Generators
+} // namespace Catch
+
+// end catch_generators_specific.hpp
 
 // These files are included here so the single_include script doesn't put them
 // in the conditionally compiled sections
@@ -4321,79 +4639,6 @@ namespace Catch {
 #endif
 
 // end catch_test_spec_parser.h
-// start catch_interfaces_config.h
-
-#include <iosfwd>
-#include <string>
-#include <vector>
-#include <memory>
-
-namespace Catch {
-
-    enum class Verbosity {
-        Quiet = 0,
-        Normal,
-        High
-    };
-
-    struct WarnAbout { enum What {
-        Nothing = 0x00,
-        NoAssertions = 0x01,
-        NoTests = 0x02
-    }; };
-
-    struct ShowDurations { enum OrNot {
-        DefaultForReporter,
-        Always,
-        Never
-    }; };
-    struct RunTests { enum InWhatOrder {
-        InDeclarationOrder,
-        InLexicographicalOrder,
-        InRandomOrder
-    }; };
-    struct UseColour { enum YesOrNo {
-        Auto,
-        Yes,
-        No
-    }; };
-    struct WaitForKeypress { enum When {
-        Never,
-        BeforeStart = 1,
-        BeforeExit = 2,
-        BeforeStartAndExit = BeforeStart | BeforeExit
-    }; };
-
-    class TestSpec;
-
-    struct IConfig : NonCopyable {
-
-        virtual ~IConfig();
-
-        virtual bool allowThrows() const = 0;
-        virtual std::ostream& stream() const = 0;
-        virtual std::string name() const = 0;
-        virtual bool includeSuccessfulResults() const = 0;
-        virtual bool shouldDebugBreak() const = 0;
-        virtual bool warnAboutMissingAssertions() const = 0;
-        virtual bool warnAboutNoTests() const = 0;
-        virtual int abortAfter() const = 0;
-        virtual bool showInvisibles() const = 0;
-        virtual ShowDurations::OrNot showDurations() const = 0;
-        virtual TestSpec const& testSpec() const = 0;
-        virtual bool hasTestFilters() const = 0;
-        virtual RunTests::InWhatOrder runOrder() const = 0;
-        virtual unsigned int rngSeed() const = 0;
-        virtual int benchmarkResolutionMultiple() const = 0;
-        virtual UseColour::YesOrNo useColour() const = 0;
-        virtual std::vector<std::string> const& getSectionsToRun() const = 0;
-        virtual Verbosity verbosity() const = 0;
-    };
-
-    using IConfigPtr = std::shared_ptr<IConfig const>;
-}
-
-// end catch_interfaces_config.h
 // Libstdc++ doesn't like incomplete classes for unique_ptr
 
 #include <memory>
@@ -4673,8 +4918,8 @@ namespace Catch {
 
         AssertionStats( AssertionStats const& )              = default;
         AssertionStats( AssertionStats && )                  = default;
-        AssertionStats& operator = ( AssertionStats const& ) = default;
-        AssertionStats& operator = ( AssertionStats && )     = default;
+        AssertionStats& operator = ( AssertionStats const& ) = delete;
+        AssertionStats& operator = ( AssertionStats && )     = delete;
         virtual ~AssertionStats();
 
         AssertionResult assertionResult;
@@ -5758,58 +6003,6 @@ std::string StringMaker<Catch::Detail::Approx>::convert(Catch::Detail::Approx co
 // end catch_approx.cpp
 // start catch_assertionhandler.cpp
 
-// start catch_context.h
-
-#include <memory>
-
-namespace Catch {
-
-    struct IResultCapture;
-    struct IRunner;
-    struct IConfig;
-    struct IMutableContext;
-
-    using IConfigPtr = std::shared_ptr<IConfig const>;
-
-    struct IContext
-    {
-        virtual ~IContext();
-
-        virtual IResultCapture* getResultCapture() = 0;
-        virtual IRunner* getRunner() = 0;
-        virtual IConfigPtr const& getConfig() const = 0;
-    };
-
-    struct IMutableContext : IContext
-    {
-        virtual ~IMutableContext();
-        virtual void setResultCapture( IResultCapture* resultCapture ) = 0;
-        virtual void setRunner( IRunner* runner ) = 0;
-        virtual void setConfig( IConfigPtr const& config ) = 0;
-
-    private:
-        static IMutableContext *currentContext;
-        friend IMutableContext& getCurrentMutableContext();
-        friend void cleanUpContext();
-        static void createContext();
-    };
-
-    inline IMutableContext& getCurrentMutableContext()
-    {
-        if( !IMutableContext::currentContext )
-            IMutableContext::createContext();
-        return *IMutableContext::currentContext;
-    }
-
-    inline IContext& getCurrentContext()
-    {
-        return getCurrentMutableContext();
-    }
-
-    void cleanUpContext();
-}
-
-// end catch_context.h
 // start catch_debugger.h
 
 namespace Catch {
@@ -5996,6 +6189,8 @@ namespace Catch {
         void pushScopedMessage( MessageInfo const& message ) override;
         void popScopedMessage( MessageInfo const& message ) override;
 
+        void emplaceUnscopedMessage( MessageBuilder const& builder ) override;
+
         std::string getCurrentTestName() const override;
 
         const AssertionResult* getLastResult() const override;
@@ -6043,6 +6238,7 @@ namespace Catch {
         Totals m_totals;
         IStreamingReporterPtr m_reporter;
         std::vector<MessageInfo> m_messages;
+        std::vector<ScopedMessage> m_messageScopes; /* Keeps owners of so-called unscoped messages. */
         AssertionInfo m_lastAssertionInfo;
         std::vector<SectionEndInfo> m_unfinishedSections;
         std::vector<ITracker*> m_activeSections;
@@ -6679,6 +6875,7 @@ inline auto Column::operator + (Column const& other) -> Columns {
 // ----------- end of #include from clara_textflow.hpp -----------
 // ........... back in clara.hpp
 
+#include <cctype>
 #include <string>
 #include <memory>
 #include <set>
@@ -6971,7 +7168,7 @@ namespace detail {
     }
     inline auto convertInto( std::string const &source, bool &target ) -> ParserResult {
         std::string srcLC = source;
-        std::transform( srcLC.begin(), srcLC.end(), srcLC.begin(), []( char c ) { return static_cast<char>( ::tolower(c) ); } );
+        std::transform( srcLC.begin(), srcLC.end(), srcLC.begin(), []( char c ) { return static_cast<char>( std::tolower(c) ); } );
         if (srcLC == "y" || srcLC == "1" || srcLC == "true" || srcLC == "yes" || srcLC == "on")
             target = true;
         else if (srcLC == "n" || srcLC == "0" || srcLC == "false" || srcLC == "no" || srcLC == "off")
@@ -8881,7 +9078,7 @@ namespace Catch {
 
     std::size_t listReporters();
 
-    Option<std::size_t> list( Config const& config );
+    Option<std::size_t> list( std::shared_ptr<Config> const& config );
 
 } // end namespace Catch
 
@@ -9019,15 +9216,16 @@ namespace Catch {
         return factories.size();
     }
 
-    Option<std::size_t> list( Config const& config ) {
+    Option<std::size_t> list( std::shared_ptr<Config> const& config ) {
         Option<std::size_t> listedCount;
-        if( config.listTests() )
-            listedCount = listedCount.valueOr(0) + listTests( config );
-        if( config.listTestNamesOnly() )
-            listedCount = listedCount.valueOr(0) + listTestsNamesOnly( config );
-        if( config.listTags() )
-            listedCount = listedCount.valueOr(0) + listTags( config );
-        if( config.listReporters() )
+        getCurrentMutableContext().setConfig( config );
+        if( config->listTests() )
+            listedCount = listedCount.valueOr(0) + listTests( *config );
+        if( config->listTestNamesOnly() )
+            listedCount = listedCount.valueOr(0) + listTestsNamesOnly( *config );
+        if( config->listTags() )
+            listedCount = listedCount.valueOr(0) + listTags( *config );
+        if( config->listReporters() )
             listedCount = listedCount.valueOr(0) + listReporters();
         return listedCount;
     }
@@ -9373,14 +9571,20 @@ namespace Catch {
     ////////////////////////////////////////////////////////////////////////////
 
     ScopedMessage::ScopedMessage( MessageBuilder const& builder )
-    : m_info( builder.m_info )
+    : m_info( builder.m_info ), m_moved()
     {
         m_info.message = builder.m_stream.str();
         getResultCapture().pushScopedMessage( m_info );
     }
 
+    ScopedMessage::ScopedMessage( ScopedMessage&& old )
+    : m_info( old.m_info ), m_moved()
+    {
+        old.m_moved = true;
+    }
+
     ScopedMessage::~ScopedMessage() {
-        if ( !uncaught_exceptions() ){
+        if ( !uncaught_exceptions() && !m_moved ){
             getResultCapture().popScopedMessage(m_info);
         }
     }
@@ -9488,6 +9692,22 @@ namespace Catch {
         auto str() const -> std::string;
     };
 
+    class RedirectedStreams {
+    public:
+        RedirectedStreams(RedirectedStreams const&) = delete;
+        RedirectedStreams& operator=(RedirectedStreams const&) = delete;
+        RedirectedStreams(RedirectedStreams&&) = delete;
+        RedirectedStreams& operator=(RedirectedStreams&&) = delete;
+
+        RedirectedStreams(std::string& redirectedCout, std::string& redirectedCerr);
+        ~RedirectedStreams();
+    private:
+        std::string& m_redirectedCout;
+        std::string& m_redirectedCerr;
+        RedirectedStdOut m_redirectedStdOut;
+        RedirectedStdErr m_redirectedStdErr;
+    };
+
 #if defined(CATCH_CONFIG_NEW_CAPTURE)
 
     // Windows's implementation of std::tmpfile is terrible (it tries
@@ -9579,6 +9799,16 @@ namespace Catch {
     {}
     auto RedirectedStdErr::str() const -> std::string { return m_rss.str(); }
 
+    RedirectedStreams::RedirectedStreams(std::string& redirectedCout, std::string& redirectedCerr)
+    :   m_redirectedCout(redirectedCout),
+        m_redirectedCerr(redirectedCerr)
+    {}
+
+    RedirectedStreams::~RedirectedStreams() {
+        m_redirectedCout += m_redirectedStdOut.str();
+        m_redirectedCerr += m_redirectedStdErr.str();
+    }
+
 #if defined(CATCH_CONFIG_NEW_CAPTURE)
 
 #if defined(_MSC_VER)
@@ -10160,6 +10390,9 @@ namespace Catch {
         // and should be let to clear themselves out.
         static_cast<void>(m_reporter->assertionEnded(AssertionStats(result, m_messages, m_totals)));
 
+        if (result.getResultType() != ResultWas::Warning)
+            m_messageScopes.clear();
+
         // Reset working state
         resetAssertionInfo();
         m_lastResult = result;
@@ -10214,6 +10447,7 @@ namespace Catch {
 
         m_reporter->sectionEnded(SectionStats(endInfo.sectionInfo, assertions, endInfo.durationInSeconds, missingAssertions));
         m_messages.clear();
+        m_messageScopes.clear();
     }
 
     void RunContext::sectionEndedEarly(SectionEndInfo const & endInfo) {
@@ -10240,6 +10474,10 @@ namespace Catch {
         m_messages.erase(std::remove(m_messages.begin(), m_messages.end(), message), m_messages.end());
     }
 
+    void RunContext::emplaceUnscopedMessage( MessageBuilder const& builder ) {
+        m_messageScopes.emplace_back( builder );
+    }
+
     std::string RunContext::getCurrentTestName() const {
         return m_activeTestCase
             ? m_activeTestCase->getTestCaseInfo().name
@@ -10300,6 +10538,7 @@ namespace Catch {
         m_lastAssertionPassed = true;
         ++m_totals.assertions.passed;
         resetAssertionInfo();
+        m_messageScopes.clear();
     }
 
     bool RunContext::aborting() const {
@@ -10321,13 +10560,10 @@ namespace Catch {
         CATCH_TRY {
             if (m_reporter->getPreferences().shouldRedirectStdOut) {
 #if !defined(CATCH_CONFIG_EXPERIMENTAL_REDIRECT)
-                RedirectedStdOut redirectedStdOut;
-                RedirectedStdErr redirectedStdErr;
+                RedirectedStreams redirectedStreams(redirectedCout, redirectedCerr);
 
                 timer.start();
                 invokeActiveTestCase();
-                redirectedCout += redirectedStdOut.str();
-                redirectedCerr += redirectedStdErr.str();
 #else
                 OutputRedirect r(redirectedCout, redirectedCerr);
                 timer.start();
@@ -10354,6 +10590,7 @@ namespace Catch {
         m_testCaseTracker->close();
         handleUnfinishedSections();
         m_messages.clear();
+        m_messageScopes.clear();
 
         SectionStats testCaseSectionStats(testCaseSection, assertions, duration, missingAssertions);
         m_reporter->sectionEnded(testCaseSectionStats);
@@ -10762,6 +10999,8 @@ namespace Catch {
 
         auto result = m_cli.parse( clara::Args( argc, argv ) );
         if( !result ) {
+            config();
+            getCurrentMutableContext().setConfig(m_config);
             Catch::cerr()
                 << Colour( Colour::Red )
                 << "\nError(s) in input:\n"
@@ -10853,7 +11092,7 @@ namespace Catch {
                 applyFilenamesAsTags( *m_config );
 
             // Handle list request
-            if( Option<std::size_t> listed = list( config() ) )
+            if( Option<std::size_t> listed = list( m_config ) )
                 return static_cast<int>( *listed );
 
             auto totals = runTests( m_config );
@@ -12426,7 +12665,7 @@ namespace Catch {
     }
 
     Version const& libraryVersion() {
-        static Version version( 2, 6, 0, "", 0 );
+        static Version version( 2, 7, 0, "", 0 );
         return version;
     }
 
@@ -12778,7 +13017,7 @@ namespace Catch {
 #ifdef _MSC_VER
         sprintf_s(buffer, "%.3f", duration);
 #else
-        sprintf(buffer, "%.3f", duration);
+        std::sprintf(buffer, "%.3f", duration);
 #endif
         return std::string(buffer);
     }
@@ -13312,7 +13551,7 @@ class Duration {
         case Unit::Nanoseconds:
             return "ns";
         case Unit::Microseconds:
-            return "µs";
+            return "us";
         case Unit::Milliseconds:
             return "ms";
         case Unit::Seconds:
@@ -13761,6 +14000,13 @@ namespace Catch {
     void JunitReporter::testRunStarting( TestRunInfo const& runInfo )  {
         CumulativeReporterBase::testRunStarting( runInfo );
         xml.startElement( "testsuites" );
+        if( m_config->rngSeed() != 0 ) {
+            xml.startElement( "properties" );
+            xml.scopedElement( "property" )
+                .writeAttribute( "name", "random-seed" )
+                .writeAttribute( "value", m_config->rngSeed() );
+            xml.endElement();
+        }
     }
 
     void JunitReporter::testGroupStarting( GroupInfo const& groupInfo ) {
@@ -14345,7 +14591,7 @@ int main (int argc, char * const argv[]) {
 #define CATCH_REQUIRE( ... ) INTERNAL_CATCH_TEST( "CATCH_REQUIRE", Catch::ResultDisposition::Normal, __VA_ARGS__ )
 #define CATCH_REQUIRE_FALSE( ... ) INTERNAL_CATCH_TEST( "CATCH_REQUIRE_FALSE", Catch::ResultDisposition::Normal | Catch::ResultDisposition::FalseTest, __VA_ARGS__ )
 
-#define CATCH_REQUIRE_THROWS( ... ) INTERNAL_CATCH_THROWS( "CATCH_REQUIRE_THROWS", Catch::ResultDisposition::Normal, "", __VA_ARGS__ )
+#define CATCH_REQUIRE_THROWS( ... ) INTERNAL_CATCH_THROWS( "CATCH_REQUIRE_THROWS", Catch::ResultDisposition::Normal, __VA_ARGS__ )
 #define CATCH_REQUIRE_THROWS_AS( expr, exceptionType ) INTERNAL_CATCH_THROWS_AS( "CATCH_REQUIRE_THROWS_AS", exceptionType, Catch::ResultDisposition::Normal, expr )
 #define CATCH_REQUIRE_THROWS_WITH( expr, matcher ) INTERNAL_CATCH_THROWS_STR_MATCHES( "CATCH_REQUIRE_THROWS_WITH", Catch::ResultDisposition::Normal, matcher, expr )
 #if !defined(CATCH_CONFIG_DISABLE_MATCHERS)
@@ -14359,7 +14605,7 @@ int main (int argc, char * const argv[]) {
 #define CATCH_CHECKED_ELSE( ... ) INTERNAL_CATCH_ELSE( "CATCH_CHECKED_ELSE", Catch::ResultDisposition::ContinueOnFailure, __VA_ARGS__ )
 #define CATCH_CHECK_NOFAIL( ... ) INTERNAL_CATCH_TEST( "CATCH_CHECK_NOFAIL", Catch::ResultDisposition::ContinueOnFailure | Catch::ResultDisposition::SuppressFail, __VA_ARGS__ )
 
-#define CATCH_CHECK_THROWS( ... )  INTERNAL_CATCH_THROWS( "CATCH_CHECK_THROWS", Catch::ResultDisposition::ContinueOnFailure, "", __VA_ARGS__ )
+#define CATCH_CHECK_THROWS( ... )  INTERNAL_CATCH_THROWS( "CATCH_CHECK_THROWS", Catch::ResultDisposition::ContinueOnFailure, __VA_ARGS__ )
 #define CATCH_CHECK_THROWS_AS( expr, exceptionType ) INTERNAL_CATCH_THROWS_AS( "CATCH_CHECK_THROWS_AS", exceptionType, Catch::ResultDisposition::ContinueOnFailure, expr )
 #define CATCH_CHECK_THROWS_WITH( expr, matcher ) INTERNAL_CATCH_THROWS_STR_MATCHES( "CATCH_CHECK_THROWS_WITH", Catch::ResultDisposition::ContinueOnFailure, matcher, expr )
 #if !defined(CATCH_CONFIG_DISABLE_MATCHERS)
@@ -14454,6 +14700,7 @@ int main (int argc, char * const argv[]) {
 #endif // CATCH_CONFIG_DISABLE_MATCHERS
 
 #define INFO( msg ) INTERNAL_CATCH_INFO( "INFO", msg )
+#define UNSCOPED_INFO( msg ) INTERNAL_CATCH_UNSCOPED_INFO( "UNSCOPED_INFO", msg )
 #define WARN( msg ) INTERNAL_CATCH_MSG( "WARN", Catch::ResultWas::Warning, Catch::ResultDisposition::ContinueOnFailure, msg )
 #define CAPTURE( ... ) INTERNAL_CATCH_CAPTURE( INTERNAL_CATCH_UNIQUE_NAME(capturer), "CAPTURE",__VA_ARGS__ )
 
diff --git a/test/thirdparty/nlohmann/json.hpp b/test/thirdparty/nlohmann/json.hpp
index c9af0be..5003a4f 100644
--- a/test/thirdparty/nlohmann/json.hpp
+++ b/test/thirdparty/nlohmann/json.hpp
@@ -1,12 +1,12 @@
 /*
     __ _____ _____ _____
  __|  |   __|     |   | |  JSON for Modern C++
-|  |  |__   |  |  | | | |  version 3.5.0
+|  |  |__   |  |  | | | |  version 3.6.1
 |_____|_____|_____|_|___|  https://github.com/nlohmann/json
 
 Licensed under the MIT License <http://opensource.org/licenses/MIT>.
 SPDX-License-Identifier: MIT
-Copyright (c) 2013-2018 Niels Lohmann <http://nlohmann.me>.
+Copyright (c) 2013-2019 Niels Lohmann <http://nlohmann.me>.
 
 Permission is hereby  granted, free of charge, to any  person obtaining a copy
 of this software and associated  documentation files (the "Software"), to deal
@@ -27,12 +27,12 @@ OUT OF OR IN CONNECTION WITH THE SOFTWARE  OR THE USE OR OTHER DEALINGS IN THE
 SOFTWARE.
 */
 
-#ifndef NLOHMANN_JSON_HPP
-#define NLOHMANN_JSON_HPP
+#ifndef INCLUDE_NLOHMANN_JSON_HPP_
+#define INCLUDE_NLOHMANN_JSON_HPP_
 
 #define NLOHMANN_JSON_VERSION_MAJOR 3
-#define NLOHMANN_JSON_VERSION_MINOR 5
-#define NLOHMANN_JSON_VERSION_PATCH 0
+#define NLOHMANN_JSON_VERSION_MINOR 6
+#define NLOHMANN_JSON_VERSION_PATCH 1
 
 #include <algorithm> // all_of, find, for_each
 #include <cassert> // assert
@@ -42,1132 +42,1171 @@ SOFTWARE.
 #include <initializer_list> // initializer_list
 #include <iosfwd> // istream, ostream
 #include <iterator> // random_access_iterator_tag
+#include <memory> // unique_ptr
 #include <numeric> // accumulate
 #include <string> // string, stoi, to_string
 #include <utility> // declval, forward, move, pair, swap
+#include <vector> // vector
 
-// #include <nlohmann/json_fwd.hpp>
-#ifndef NLOHMANN_JSON_FWD_HPP
-#define NLOHMANN_JSON_FWD_HPP
+// #include <nlohmann/adl_serializer.hpp>
 
-#include <cstdint> // int64_t, uint64_t
+
+#include <utility>
+
+// #include <nlohmann/detail/conversions/from_json.hpp>
+
+
+#include <algorithm> // transform
+#include <array> // array
+#include <ciso646> // and, not
+#include <forward_list> // forward_list
+#include <iterator> // inserter, front_inserter, end
 #include <map> // map
-#include <memory> // allocator
 #include <string> // string
-#include <vector> // vector
+#include <tuple> // tuple, make_tuple
+#include <type_traits> // is_arithmetic, is_same, is_enum, underlying_type, is_convertible
+#include <unordered_map> // unordered_map
+#include <utility> // pair, declval
+#include <valarray> // valarray
+
+// #include <nlohmann/detail/exceptions.hpp>
+
+
+#include <exception> // exception
+#include <stdexcept> // runtime_error
+#include <string> // to_string
+
+// #include <nlohmann/detail/input/position_t.hpp>
+
+
+#include <cstddef> // size_t
 
-/*!
-@brief namespace for Niels Lohmann
-@see https://github.com/nlohmann
-@since version 1.0.0
-*/
 namespace nlohmann
 {
-/*!
-@brief default JSONSerializer template argument
+namespace detail
+{
+/// struct to capture the start position of the current token
+struct position_t
+{
+    /// the total number of characters read
+    std::size_t chars_read_total = 0;
+    /// the number of characters read in the current line
+    std::size_t chars_read_current_line = 0;
+    /// the number of lines read
+    std::size_t lines_read = 0;
 
-This serializer ignores the template arguments and uses ADL
-([argument-dependent lookup](https://en.cppreference.com/w/cpp/language/adl))
-for serialization.
-*/
-template<typename T = void, typename SFINAE = void>
-struct adl_serializer;
+    /// conversion to size_t to preserve SAX interface
+    constexpr operator size_t() const
+    {
+        return chars_read_total;
+    }
+};
 
-template<template<typename U, typename V, typename... Args> class ObjectType =
-         std::map,
-         template<typename U, typename... Args> class ArrayType = std::vector,
-         class StringType = std::string, class BooleanType = bool,
-         class NumberIntegerType = std::int64_t,
-         class NumberUnsignedType = std::uint64_t,
-         class NumberFloatType = double,
-         template<typename U> class AllocatorType = std::allocator,
-         template<typename T, typename SFINAE = void> class JSONSerializer =
-         adl_serializer>
-class basic_json;
+} // namespace detail
+} // namespace nlohmann
 
-/*!
-@brief JSON Pointer
 
-A JSON pointer defines a string syntax for identifying a specific value
-within a JSON document. It can be used with functions `at` and
-`operator[]`. Furthermore, JSON pointers are the base for JSON patches.
+namespace nlohmann
+{
+namespace detail
+{
+////////////////
+// exceptions //
+////////////////
 
-@sa [RFC 6901](https://tools.ietf.org/html/rfc6901)
+/*!
+@brief general exception of the @ref basic_json class
 
-@since version 2.0.0
-*/
-template<typename BasicJsonType>
-class json_pointer;
+This class is an extension of `std::exception` objects with a member @a id for
+exception ids. It is used as the base class for all exceptions thrown by the
+@ref basic_json class. This class can hence be used as "wildcard" to catch
+exceptions.
 
-/*!
-@brief default JSON class
+Subclasses:
+- @ref parse_error for exceptions indicating a parse error
+- @ref invalid_iterator for exceptions indicating errors with iterators
+- @ref type_error for exceptions indicating executing a member function with
+                  a wrong type
+- @ref out_of_range for exceptions indicating access out of the defined range
+- @ref other_error for exceptions indicating other library errors
 
-This type is the default specialization of the @ref basic_json class which
-uses the standard template types.
+@internal
+@note To have nothrow-copy-constructible exceptions, we internally use
+      `std::runtime_error` which can cope with arbitrary-length error messages.
+      Intermediate strings are built with static functions and then passed to
+      the actual constructor.
+@endinternal
 
-@since version 1.0.0
+@liveexample{The following code shows how arbitrary library exceptions can be
+caught.,exception}
+
+@since version 3.0.0
 */
-using json = basic_json<>;
-}  // namespace nlohmann
+class exception : public std::exception
+{
+  public:
+    /// returns the explanatory string
+    const char* what() const noexcept override
+    {
+        return m.what();
+    }
 
-#endif
+    /// the id of the exception
+    const int id;
 
-// #include <nlohmann/detail/macro_scope.hpp>
+  protected:
+    exception(int id_, const char* what_arg) : id(id_), m(what_arg) {}
 
+    static std::string name(const std::string& ename, int id_)
+    {
+        return "[json.exception." + ename + "." + std::to_string(id_) + "] ";
+    }
 
-// This file contains all internal macro definitions
-// You MUST include macro_unscope.hpp at the end of json.hpp to undef all of them
+  private:
+    /// an exception object as storage for error messages
+    std::runtime_error m;
+};
 
-// exclude unsupported compilers
-#if !defined(JSON_SKIP_UNSUPPORTED_COMPILER_CHECK)
-    #if defined(__clang__)
-        #if (__clang_major__ * 10000 + __clang_minor__ * 100 + __clang_patchlevel__) < 30400
-            #error "unsupported Clang version - see https://github.com/nlohmann/json#supported-compilers"
-        #endif
-    #elif defined(__GNUC__) && !(defined(__ICC) || defined(__INTEL_COMPILER))
-        #if (__GNUC__ * 10000 + __GNUC_MINOR__ * 100 + __GNUC_PATCHLEVEL__) < 40800
-            #error "unsupported GCC version - see https://github.com/nlohmann/json#supported-compilers"
-        #endif
-    #endif
-#endif
+/*!
+@brief exception indicating a parse error
 
-// disable float-equal warnings on GCC/clang
-#if defined(__clang__) || defined(__GNUC__) || defined(__GNUG__)
-    #pragma GCC diagnostic push
-    #pragma GCC diagnostic ignored "-Wfloat-equal"
-#endif
+This exception is thrown by the library when a parse error occurs. Parse errors
+can occur during the deserialization of JSON text, CBOR, MessagePack, as well
+as when using JSON Patch.
 
-// disable documentation warnings on clang
-#if defined(__clang__)
-    #pragma GCC diagnostic push
-    #pragma GCC diagnostic ignored "-Wdocumentation"
-#endif
+Member @a byte holds the byte index of the last read character in the input
+file.
 
-// allow for portable deprecation warnings
-#if defined(__clang__) || defined(__GNUC__) || defined(__GNUG__)
-    #define JSON_DEPRECATED __attribute__((deprecated))
-#elif defined(_MSC_VER)
-    #define JSON_DEPRECATED __declspec(deprecated)
-#else
-    #define JSON_DEPRECATED
-#endif
+Exceptions have ids 1xx.
 
-// allow to disable exceptions
-#if (defined(__cpp_exceptions) || defined(__EXCEPTIONS) || defined(_CPPUNWIND)) && !defined(JSON_NOEXCEPTION)
-    #define JSON_THROW(exception) throw exception
-    #define JSON_TRY try
-    #define JSON_CATCH(exception) catch(exception)
-    #define JSON_INTERNAL_CATCH(exception) catch(exception)
-#else
-    #define JSON_THROW(exception) std::abort()
-    #define JSON_TRY if(true)
-    #define JSON_CATCH(exception) if(false)
-    #define JSON_INTERNAL_CATCH(exception) if(false)
-#endif
+name / id                      | example message | description
+------------------------------ | --------------- | -------------------------
+json.exception.parse_error.101 | parse error at 2: unexpected end of input; expected string literal | This error indicates a syntax error while deserializing a JSON text. The error message describes that an unexpected token (character) was encountered, and the member @a byte indicates the error position.
+json.exception.parse_error.102 | parse error at 14: missing or wrong low surrogate | JSON uses the `\uxxxx` format to describe Unicode characters. Code points above above 0xFFFF are split into two `\uxxxx` entries ("surrogate pairs"). This error indicates that the surrogate pair is incomplete or contains an invalid code point.
+json.exception.parse_error.103 | parse error: code points above 0x10FFFF are invalid | Unicode supports code points up to 0x10FFFF. Code points above 0x10FFFF are invalid.
+json.exception.parse_error.104 | parse error: JSON patch must be an array of objects | [RFC 6902](https://tools.ietf.org/html/rfc6902) requires a JSON Patch document to be a JSON document that represents an array of objects.
+json.exception.parse_error.105 | parse error: operation must have string member 'op' | An operation of a JSON Patch document must contain exactly one "op" member, whose value indicates the operation to perform. Its value must be one of "add", "remove", "replace", "move", "copy", or "test"; other values are errors.
+json.exception.parse_error.106 | parse error: array index '01' must not begin with '0' | An array index in a JSON Pointer ([RFC 6901](https://tools.ietf.org/html/rfc6901)) may be `0` or any number without a leading `0`.
+json.exception.parse_error.107 | parse error: JSON pointer must be empty or begin with '/' - was: 'foo' | A JSON Pointer must be a Unicode string containing a sequence of zero or more reference tokens, each prefixed by a `/` character.
+json.exception.parse_error.108 | parse error: escape character '~' must be followed with '0' or '1' | In a JSON Pointer, only `~0` and `~1` are valid escape sequences.
+json.exception.parse_error.109 | parse error: array index 'one' is not a number | A JSON Pointer array index must be a number.
+json.exception.parse_error.110 | parse error at 1: cannot read 2 bytes from vector | When parsing CBOR or MessagePack, the byte vector ends before the complete value has been read.
+json.exception.parse_error.112 | parse error at 1: error reading CBOR; last byte: 0xF8 | Not all types of CBOR or MessagePack are supported. This exception occurs if an unsupported byte was read.
+json.exception.parse_error.113 | parse error at 2: expected a CBOR string; last byte: 0x98 | While parsing a map key, a value that is not a string has been read.
+json.exception.parse_error.114 | parse error: Unsupported BSON record type 0x0F | The parsing of the corresponding BSON record type is not implemented (yet).
 
-// override exception macros
-#if defined(JSON_THROW_USER)
-    #undef JSON_THROW
-    #define JSON_THROW JSON_THROW_USER
-#endif
-#if defined(JSON_TRY_USER)
-    #undef JSON_TRY
-    #define JSON_TRY JSON_TRY_USER
-#endif
-#if defined(JSON_CATCH_USER)
-    #undef JSON_CATCH
-    #define JSON_CATCH JSON_CATCH_USER
-    #undef JSON_INTERNAL_CATCH
-    #define JSON_INTERNAL_CATCH JSON_CATCH_USER
-#endif
-#if defined(JSON_INTERNAL_CATCH_USER)
-    #undef JSON_INTERNAL_CATCH
-    #define JSON_INTERNAL_CATCH JSON_INTERNAL_CATCH_USER
-#endif
+@note For an input with n bytes, 1 is the index of the first character and n+1
+      is the index of the terminating null byte or the end of file. This also
+      holds true when reading a byte vector (CBOR or MessagePack).
 
-// manual branch prediction
-#if defined(__clang__) || defined(__GNUC__) || defined(__GNUG__)
-    #define JSON_LIKELY(x)      __builtin_expect(!!(x), 1)
-    #define JSON_UNLIKELY(x)    __builtin_expect(!!(x), 0)
-#else
-    #define JSON_LIKELY(x)      x
-    #define JSON_UNLIKELY(x)    x
-#endif
+@liveexample{The following code shows how a `parse_error` exception can be
+caught.,parse_error}
 
-// C++ language standard detection
-#if (defined(__cplusplus) && __cplusplus >= 201703L) || (defined(_HAS_CXX17) && _HAS_CXX17 == 1) // fix for issue #464
-    #define JSON_HAS_CPP_17
-    #define JSON_HAS_CPP_14
-#elif (defined(__cplusplus) && __cplusplus >= 201402L) || (defined(_HAS_CXX14) && _HAS_CXX14 == 1)
-    #define JSON_HAS_CPP_14
-#endif
+@sa - @ref exception for the base class of the library exceptions
+@sa - @ref invalid_iterator for exceptions indicating errors with iterators
+@sa - @ref type_error for exceptions indicating executing a member function with
+                    a wrong type
+@sa - @ref out_of_range for exceptions indicating access out of the defined range
+@sa - @ref other_error for exceptions indicating other library errors
 
-/*!
-@brief macro to briefly define a mapping between an enum and JSON
-@def NLOHMANN_JSON_SERIALIZE_ENUM
-@since version 3.4.0
+@since version 3.0.0
 */
-#define NLOHMANN_JSON_SERIALIZE_ENUM(ENUM_TYPE, ...)                                           \
-    template<typename BasicJsonType>                                                           \
-    inline void to_json(BasicJsonType& j, const ENUM_TYPE& e)                                  \
-    {                                                                                          \
-        static_assert(std::is_enum<ENUM_TYPE>::value, #ENUM_TYPE " must be an enum!");         \
-        static const std::pair<ENUM_TYPE, BasicJsonType> m[] = __VA_ARGS__;                    \
-        auto it = std::find_if(std::begin(m), std::end(m),                                     \
-                               [e](const std::pair<ENUM_TYPE, BasicJsonType>& ej_pair) -> bool \
-        {                                                                                      \
-            return ej_pair.first == e;                                                         \
-        });                                                                                    \
-        j = ((it != std::end(m)) ? it : std::begin(m))->second;                                \
-    }                                                                                          \
-    template<typename BasicJsonType>                                                           \
-    inline void from_json(const BasicJsonType& j, ENUM_TYPE& e)                                \
-    {                                                                                          \
-        static_assert(std::is_enum<ENUM_TYPE>::value, #ENUM_TYPE " must be an enum!");         \
-        static const std::pair<ENUM_TYPE, BasicJsonType> m[] = __VA_ARGS__;                    \
-        auto it = std::find_if(std::begin(m), std::end(m),                                     \
-                               [j](const std::pair<ENUM_TYPE, BasicJsonType>& ej_pair) -> bool \
-        {                                                                                      \
-            return ej_pair.second == j;                                                        \
-        });                                                                                    \
-        e = ((it != std::end(m)) ? it : std::begin(m))->first;                                 \
+class parse_error : public exception
+{
+  public:
+    /*!
+    @brief create a parse error exception
+    @param[in] id_       the id of the exception
+    @param[in] pos       the position where the error occurred (or with
+                         chars_read_total=0 if the position cannot be
+                         determined)
+    @param[in] what_arg  the explanatory string
+    @return parse_error object
+    */
+    static parse_error create(int id_, const position_t& pos, const std::string& what_arg)
+    {
+        std::string w = exception::name("parse_error", id_) + "parse error" +
+                        position_string(pos) + ": " + what_arg;
+        return parse_error(id_, pos.chars_read_total, w.c_str());
     }
 
-// Ugly macros to avoid uglier copy-paste when specializing basic_json. They
-// may be removed in the future once the class is split.
-
-#define NLOHMANN_BASIC_JSON_TPL_DECLARATION                                \
-    template<template<typename, typename, typename...> class ObjectType,   \
-             template<typename, typename...> class ArrayType,              \
-             class StringType, class BooleanType, class NumberIntegerType, \
-             class NumberUnsignedType, class NumberFloatType,              \
-             template<typename> class AllocatorType,                       \
-             template<typename, typename = void> class JSONSerializer>
-
-#define NLOHMANN_BASIC_JSON_TPL                                            \
-    basic_json<ObjectType, ArrayType, StringType, BooleanType,             \
-    NumberIntegerType, NumberUnsignedType, NumberFloatType,                \
-    AllocatorType, JSONSerializer>
-
-// #include <nlohmann/detail/meta/cpp_future.hpp>
+    static parse_error create(int id_, std::size_t byte_, const std::string& what_arg)
+    {
+        std::string w = exception::name("parse_error", id_) + "parse error" +
+                        (byte_ != 0 ? (" at byte " + std::to_string(byte_)) : "") +
+                        ": " + what_arg;
+        return parse_error(id_, byte_, w.c_str());
+    }
 
+    /*!
+    @brief byte index of the parse error
 
-#include <ciso646> // not
-#include <cstddef> // size_t
-#include <type_traits> // conditional, enable_if, false_type, integral_constant, is_constructible, is_integral, is_same, remove_cv, remove_reference, true_type
+    The byte index of the last read character in the input file.
 
-namespace nlohmann
-{
-namespace detail
-{
-// alias templates to reduce boilerplate
-template<bool B, typename T = void>
-using enable_if_t = typename std::enable_if<B, T>::type;
+    @note For an input with n bytes, 1 is the index of the first character and
+          n+1 is the index of the terminating null byte or the end of file.
+          This also holds true when reading a byte vector (CBOR or MessagePack).
+    */
+    const std::size_t byte;
 
-template<typename T>
-using uncvref_t = typename std::remove_cv<typename std::remove_reference<T>::type>::type;
+  private:
+    parse_error(int id_, std::size_t byte_, const char* what_arg)
+        : exception(id_, what_arg), byte(byte_) {}
 
-// implementation of C++14 index_sequence and affiliates
-// source: https://stackoverflow.com/a/32223343
-template<std::size_t... Ints>
-struct index_sequence
-{
-    using type = index_sequence;
-    using value_type = std::size_t;
-    static constexpr std::size_t size() noexcept
+    static std::string position_string(const position_t& pos)
     {
-        return sizeof...(Ints);
+        return " at line " + std::to_string(pos.lines_read + 1) +
+               ", column " + std::to_string(pos.chars_read_current_line);
     }
 };
 
-template<class Sequence1, class Sequence2>
-struct merge_and_renumber;
+/*!
+@brief exception indicating errors with iterators
 
-template<std::size_t... I1, std::size_t... I2>
-struct merge_and_renumber<index_sequence<I1...>, index_sequence<I2...>>
-        : index_sequence < I1..., (sizeof...(I1) + I2)... > {};
+This exception is thrown if iterators passed to a library function do not match
+the expected semantics.
 
-template<std::size_t N>
-struct make_index_sequence
-    : merge_and_renumber < typename make_index_sequence < N / 2 >::type,
-      typename make_index_sequence < N - N / 2 >::type > {};
+Exceptions have ids 2xx.
 
-template<> struct make_index_sequence<0> : index_sequence<> {};
-template<> struct make_index_sequence<1> : index_sequence<0> {};
+name / id                           | example message | description
+----------------------------------- | --------------- | -------------------------
+json.exception.invalid_iterator.201 | iterators are not compatible | The iterators passed to constructor @ref basic_json(InputIT first, InputIT last) are not compatible, meaning they do not belong to the same container. Therefore, the range (@a first, @a last) is invalid.
+json.exception.invalid_iterator.202 | iterator does not fit current value | In an erase or insert function, the passed iterator @a pos does not belong to the JSON value for which the function was called. It hence does not define a valid position for the deletion/insertion.
+json.exception.invalid_iterator.203 | iterators do not fit current value | Either iterator passed to function @ref erase(IteratorType first, IteratorType last) does not belong to the JSON value from which values shall be erased. It hence does not define a valid range to delete values from.
+json.exception.invalid_iterator.204 | iterators out of range | When an iterator range for a primitive type (number, boolean, or string) is passed to a constructor or an erase function, this range has to be exactly (@ref begin(), @ref end()), because this is the only way the single stored value is expressed. All other ranges are invalid.
+json.exception.invalid_iterator.205 | iterator out of range | When an iterator for a primitive type (number, boolean, or string) is passed to an erase function, the iterator has to be the @ref begin() iterator, because it is the only way to address the stored value. All other iterators are invalid.
+json.exception.invalid_iterator.206 | cannot construct with iterators from null | The iterators passed to constructor @ref basic_json(InputIT first, InputIT last) belong to a JSON null value and hence to not define a valid range.
+json.exception.invalid_iterator.207 | cannot use key() for non-object iterators | The key() member function can only be used on iterators belonging to a JSON object, because other types do not have a concept of a key.
+json.exception.invalid_iterator.208 | cannot use operator[] for object iterators | The operator[] to specify a concrete offset cannot be used on iterators belonging to a JSON object, because JSON objects are unordered.
+json.exception.invalid_iterator.209 | cannot use offsets with object iterators | The offset operators (+, -, +=, -=) cannot be used on iterators belonging to a JSON object, because JSON objects are unordered.
+json.exception.invalid_iterator.210 | iterators do not fit | The iterator range passed to the insert function are not compatible, meaning they do not belong to the same container. Therefore, the range (@a first, @a last) is invalid.
+json.exception.invalid_iterator.211 | passed iterators may not belong to container | The iterator range passed to the insert function must not be a subrange of the container to insert to.
+json.exception.invalid_iterator.212 | cannot compare iterators of different containers | When two iterators are compared, they must belong to the same container.
+json.exception.invalid_iterator.213 | cannot compare order of object iterators | The order of object iterators cannot be compared, because JSON objects are unordered.
+json.exception.invalid_iterator.214 | cannot get value | Cannot get value for iterator: Either the iterator belongs to a null value or it is an iterator to a primitive type (number, boolean, or string), but the iterator is different to @ref begin().
 
-template<typename... Ts>
-using index_sequence_for = make_index_sequence<sizeof...(Ts)>;
+@liveexample{The following code shows how an `invalid_iterator` exception can be
+caught.,invalid_iterator}
 
-// dispatch utility (taken from ranges-v3)
-template<unsigned N> struct priority_tag : priority_tag < N - 1 > {};
-template<> struct priority_tag<0> {};
+@sa - @ref exception for the base class of the library exceptions
+@sa - @ref parse_error for exceptions indicating a parse error
+@sa - @ref type_error for exceptions indicating executing a member function with
+                    a wrong type
+@sa - @ref out_of_range for exceptions indicating access out of the defined range
+@sa - @ref other_error for exceptions indicating other library errors
 
-// taken from ranges-v3
-template<typename T>
-struct static_const
+@since version 3.0.0
+*/
+class invalid_iterator : public exception
 {
-    static constexpr T value{};
+  public:
+    static invalid_iterator create(int id_, const std::string& what_arg)
+    {
+        std::string w = exception::name("invalid_iterator", id_) + what_arg;
+        return invalid_iterator(id_, w.c_str());
+    }
+
+  private:
+    invalid_iterator(int id_, const char* what_arg)
+        : exception(id_, what_arg) {}
 };
 
-template<typename T>
-constexpr T static_const<T>::value;
-}  // namespace detail
-}  // namespace nlohmann
+/*!
+@brief exception indicating executing a member function with a wrong type
 
-// #include <nlohmann/detail/meta/type_traits.hpp>
+This exception is thrown in case of a type error; that is, a library function is
+executed on a JSON value whose type does not match the expected semantics.
 
+Exceptions have ids 3xx.
 
-#include <ciso646> // not
-#include <limits> // numeric_limits
-#include <type_traits> // false_type, is_constructible, is_integral, is_same, true_type
-#include <utility> // declval
+name / id                     | example message | description
+----------------------------- | --------------- | -------------------------
+json.exception.type_error.301 | cannot create object from initializer list | To create an object from an initializer list, the initializer list must consist only of a list of pairs whose first element is a string. When this constraint is violated, an array is created instead.
+json.exception.type_error.302 | type must be object, but is array | During implicit or explicit value conversion, the JSON type must be compatible to the target type. For instance, a JSON string can only be converted into string types, but not into numbers or boolean types.
+json.exception.type_error.303 | incompatible ReferenceType for get_ref, actual type is object | To retrieve a reference to a value stored in a @ref basic_json object with @ref get_ref, the type of the reference must match the value type. For instance, for a JSON array, the @a ReferenceType must be @ref array_t &.
+json.exception.type_error.304 | cannot use at() with string | The @ref at() member functions can only be executed for certain JSON types.
+json.exception.type_error.305 | cannot use operator[] with string | The @ref operator[] member functions can only be executed for certain JSON types.
+json.exception.type_error.306 | cannot use value() with string | The @ref value() member functions can only be executed for certain JSON types.
+json.exception.type_error.307 | cannot use erase() with string | The @ref erase() member functions can only be executed for certain JSON types.
+json.exception.type_error.308 | cannot use push_back() with string | The @ref push_back() and @ref operator+= member functions can only be executed for certain JSON types.
+json.exception.type_error.309 | cannot use insert() with | The @ref insert() member functions can only be executed for certain JSON types.
+json.exception.type_error.310 | cannot use swap() with number | The @ref swap() member functions can only be executed for certain JSON types.
+json.exception.type_error.311 | cannot use emplace_back() with string | The @ref emplace_back() member function can only be executed for certain JSON types.
+json.exception.type_error.312 | cannot use update() with string | The @ref update() member functions can only be executed for certain JSON types.
+json.exception.type_error.313 | invalid value to unflatten | The @ref unflatten function converts an object whose keys are JSON Pointers back into an arbitrary nested JSON value. The JSON Pointers must not overlap, because then the resulting value would not be well defined.
+json.exception.type_error.314 | only objects can be unflattened | The @ref unflatten function only works for an object whose keys are JSON Pointers.
+json.exception.type_error.315 | values in object must be primitive | The @ref unflatten function only works for an object whose keys are JSON Pointers and whose values are primitive.
+json.exception.type_error.316 | invalid UTF-8 byte at index 10: 0x7E | The @ref dump function only works with UTF-8 encoded strings; that is, if you assign a `std::string` to a JSON value, make sure it is UTF-8 encoded. |
+json.exception.type_error.317 | JSON value cannot be serialized to requested format | The dynamic type of the object cannot be represented in the requested serialization format (e.g. a raw `true` or `null` JSON object cannot be serialized to BSON) |
 
-// #include <nlohmann/json_fwd.hpp>
+@liveexample{The following code shows how a `type_error` exception can be
+caught.,type_error}
 
-// #include <nlohmann/detail/iterators/iterator_traits.hpp>
+@sa - @ref exception for the base class of the library exceptions
+@sa - @ref parse_error for exceptions indicating a parse error
+@sa - @ref invalid_iterator for exceptions indicating errors with iterators
+@sa - @ref out_of_range for exceptions indicating access out of the defined range
+@sa - @ref other_error for exceptions indicating other library errors
 
+@since version 3.0.0
+*/
+class type_error : public exception
+{
+  public:
+    static type_error create(int id_, const std::string& what_arg)
+    {
+        std::string w = exception::name("type_error", id_) + what_arg;
+        return type_error(id_, w.c_str());
+    }
 
-#include <iterator> // random_access_iterator_tag
+  private:
+    type_error(int id_, const char* what_arg) : exception(id_, what_arg) {}
+};
 
-// #include <nlohmann/detail/meta/void_t.hpp>
+/*!
+@brief exception indicating access out of the defined range
 
+This exception is thrown in case a library function is called on an input
+parameter that exceeds the expected range, for instance in case of array
+indices or nonexisting object keys.
 
-namespace nlohmann
-{
-namespace detail
-{
-template <typename ...Ts> struct make_void
-{
-    using type = void;
-};
-template <typename ...Ts> using void_t = typename make_void<Ts...>::type;
-} // namespace detail
-}  // namespace nlohmann
+Exceptions have ids 4xx.
 
-// #include <nlohmann/detail/meta/cpp_future.hpp>
+name / id                       | example message | description
+------------------------------- | --------------- | -------------------------
+json.exception.out_of_range.401 | array index 3 is out of range | The provided array index @a i is larger than @a size-1.
+json.exception.out_of_range.402 | array index '-' (3) is out of range | The special array index `-` in a JSON Pointer never describes a valid element of the array, but the index past the end. That is, it can only be used to add elements at this position, but not to read it.
+json.exception.out_of_range.403 | key 'foo' not found | The provided key was not found in the JSON object.
+json.exception.out_of_range.404 | unresolved reference token 'foo' | A reference token in a JSON Pointer could not be resolved.
+json.exception.out_of_range.405 | JSON pointer has no parent | The JSON Patch operations 'remove' and 'add' can not be applied to the root element of the JSON value.
+json.exception.out_of_range.406 | number overflow parsing '10E1000' | A parsed number could not be stored as without changing it to NaN or INF.
+json.exception.out_of_range.407 | number overflow serializing '9223372036854775808' | UBJSON and BSON only support integer numbers up to 9223372036854775807. |
+json.exception.out_of_range.408 | excessive array size: 8658170730974374167 | The size (following `#`) of an UBJSON array or object exceeds the maximal capacity. |
+json.exception.out_of_range.409 | BSON key cannot contain code point U+0000 (at byte 2) | Key identifiers to be serialized to BSON cannot contain code point U+0000, since the key is stored as zero-terminated c-string |
 
+@liveexample{The following code shows how an `out_of_range` exception can be
+caught.,out_of_range}
 
-namespace nlohmann
-{
-namespace detail
-{
-template <typename It, typename = void>
-struct iterator_types {};
+@sa - @ref exception for the base class of the library exceptions
+@sa - @ref parse_error for exceptions indicating a parse error
+@sa - @ref invalid_iterator for exceptions indicating errors with iterators
+@sa - @ref type_error for exceptions indicating executing a member function with
+                    a wrong type
+@sa - @ref other_error for exceptions indicating other library errors
 
-template <typename It>
-struct iterator_types <
-    It,
-    void_t<typename It::difference_type, typename It::value_type, typename It::pointer,
-    typename It::reference, typename It::iterator_category >>
+@since version 3.0.0
+*/
+class out_of_range : public exception
 {
-    using difference_type = typename It::difference_type;
-    using value_type = typename It::value_type;
-    using pointer = typename It::pointer;
-    using reference = typename It::reference;
-    using iterator_category = typename It::iterator_category;
-};
-
-// This is required as some compilers implement std::iterator_traits in a way that
-// doesn't work with SFINAE. See https://github.com/nlohmann/json/issues/1341.
-template <typename T, typename = void>
-struct iterator_traits
-{
-};
-
-template <typename T>
-struct iterator_traits < T, enable_if_t < !std::is_pointer<T>::value >>
-            : iterator_types<T>
-{
-};
+  public:
+    static out_of_range create(int id_, const std::string& what_arg)
+    {
+        std::string w = exception::name("out_of_range", id_) + what_arg;
+        return out_of_range(id_, w.c_str());
+    }
 
-template <typename T>
-struct iterator_traits<T*, enable_if_t<std::is_object<T>::value>>
-{
-    using iterator_category = std::random_access_iterator_tag;
-    using value_type = T;
-    using difference_type = ptrdiff_t;
-    using pointer = T*;
-    using reference = T&;
+  private:
+    out_of_range(int id_, const char* what_arg) : exception(id_, what_arg) {}
 };
-}
-}
-
-// #include <nlohmann/detail/meta/cpp_future.hpp>
 
-// #include <nlohmann/detail/meta/detected.hpp>
+/*!
+@brief exception indicating other library errors
 
+This exception is thrown in case of errors that cannot be classified with the
+other exception types.
 
-#include <type_traits>
+Exceptions have ids 5xx.
 
-// #include <nlohmann/detail/meta/void_t.hpp>
+name / id                      | example message | description
+------------------------------ | --------------- | -------------------------
+json.exception.other_error.501 | unsuccessful: {"op":"test","path":"/baz", "value":"bar"} | A JSON Patch operation 'test' failed. The unsuccessful operation is also printed.
 
+@sa - @ref exception for the base class of the library exceptions
+@sa - @ref parse_error for exceptions indicating a parse error
+@sa - @ref invalid_iterator for exceptions indicating errors with iterators
+@sa - @ref type_error for exceptions indicating executing a member function with
+                    a wrong type
+@sa - @ref out_of_range for exceptions indicating access out of the defined range
 
-// http://en.cppreference.com/w/cpp/experimental/is_detected
-namespace nlohmann
-{
-namespace detail
-{
-struct nonesuch
-{
-    nonesuch() = delete;
-    ~nonesuch() = delete;
-    nonesuch(nonesuch const&) = delete;
-    void operator=(nonesuch const&) = delete;
-};
+@liveexample{The following code shows how an `other_error` exception can be
+caught.,other_error}
 
-template <class Default,
-          class AlwaysVoid,
-          template <class...> class Op,
-          class... Args>
-struct detector
+@since version 3.0.0
+*/
+class other_error : public exception
 {
-    using value_t = std::false_type;
-    using type = Default;
-};
+  public:
+    static other_error create(int id_, const std::string& what_arg)
+    {
+        std::string w = exception::name("other_error", id_) + what_arg;
+        return other_error(id_, w.c_str());
+    }
 
-template <class Default, template <class...> class Op, class... Args>
-struct detector<Default, void_t<Op<Args...>>, Op, Args...>
-{
-    using value_t = std::true_type;
-    using type = Op<Args...>;
+  private:
+    other_error(int id_, const char* what_arg) : exception(id_, what_arg) {}
 };
-
-template <template <class...> class Op, class... Args>
-using is_detected = typename detector<nonesuch, void, Op, Args...>::value_t;
-
-template <template <class...> class Op, class... Args>
-using detected_t = typename detector<nonesuch, void, Op, Args...>::type;
-
-template <class Default, template <class...> class Op, class... Args>
-using detected_or = detector<Default, void, Op, Args...>;
-
-template <class Default, template <class...> class Op, class... Args>
-using detected_or_t = typename detected_or<Default, Op, Args...>::type;
-
-template <class Expected, template <class...> class Op, class... Args>
-using is_detected_exact = std::is_same<Expected, detected_t<Op, Args...>>;
-
-template <class To, template <class...> class Op, class... Args>
-using is_detected_convertible =
-    std::is_convertible<detected_t<Op, Args...>, To>;
 }  // namespace detail
 }  // namespace nlohmann
 
 // #include <nlohmann/detail/macro_scope.hpp>
 
 
-namespace nlohmann
-{
-/*!
-@brief detail namespace with internal helper functions
+#include <utility> // pair
 
-This namespace collects functions that should not be exposed,
-implementations of some @ref basic_json methods, and meta-programming helpers.
+// This file contains all internal macro definitions
+// You MUST include macro_unscope.hpp at the end of json.hpp to undef all of them
 
-@since version 2.1.0
-*/
-namespace detail
-{
-/////////////
-// helpers //
-/////////////
+// exclude unsupported compilers
+#if !defined(JSON_SKIP_UNSUPPORTED_COMPILER_CHECK)
+    #if defined(__clang__)
+        #if (__clang_major__ * 10000 + __clang_minor__ * 100 + __clang_patchlevel__) < 30400
+            #error "unsupported Clang version - see https://github.com/nlohmann/json#supported-compilers"
+        #endif
+    #elif defined(__GNUC__) && !(defined(__ICC) || defined(__INTEL_COMPILER))
+        #if (__GNUC__ * 10000 + __GNUC_MINOR__ * 100 + __GNUC_PATCHLEVEL__) < 40800
+            #error "unsupported GCC version - see https://github.com/nlohmann/json#supported-compilers"
+        #endif
+    #endif
+#endif
 
-// Note to maintainers:
-//
-// Every trait in this file expects a non CV-qualified type.
-// The only exceptions are in the 'aliases for detected' section
-// (i.e. those of the form: decltype(T::member_function(std::declval<T>())))
-//
-// In this case, T has to be properly CV-qualified to constraint the function arguments
-// (e.g. to_json(BasicJsonType&, const T&))
+// disable float-equal warnings on GCC/clang
+#if defined(__clang__) || defined(__GNUC__) || defined(__GNUG__)
+    #pragma GCC diagnostic push
+    #pragma GCC diagnostic ignored "-Wfloat-equal"
+#endif
 
-template<typename> struct is_basic_json : std::false_type {};
+// disable documentation warnings on clang
+#if defined(__clang__)
+    #pragma GCC diagnostic push
+    #pragma GCC diagnostic ignored "-Wdocumentation"
+#endif
 
-NLOHMANN_BASIC_JSON_TPL_DECLARATION
-struct is_basic_json<NLOHMANN_BASIC_JSON_TPL> : std::true_type {};
+// allow for portable deprecation warnings
+#if defined(__clang__) || defined(__GNUC__) || defined(__GNUG__)
+    #define JSON_DEPRECATED __attribute__((deprecated))
+#elif defined(_MSC_VER)
+    #define JSON_DEPRECATED __declspec(deprecated)
+#else
+    #define JSON_DEPRECATED
+#endif
 
-//////////////////////////
-// aliases for detected //
-//////////////////////////
+// allow for portable nodiscard warnings
+#if defined(__has_cpp_attribute)
+    #if __has_cpp_attribute(nodiscard)
+        #define JSON_NODISCARD [[nodiscard]]
+    #elif __has_cpp_attribute(gnu::warn_unused_result)
+        #define JSON_NODISCARD [[gnu::warn_unused_result]]
+    #else
+        #define JSON_NODISCARD
+    #endif
+#else
+    #define JSON_NODISCARD
+#endif
 
-template <typename T>
-using mapped_type_t = typename T::mapped_type;
+// allow to disable exceptions
+#if (defined(__cpp_exceptions) || defined(__EXCEPTIONS) || defined(_CPPUNWIND)) && !defined(JSON_NOEXCEPTION)
+    #define JSON_THROW(exception) throw exception
+    #define JSON_TRY try
+    #define JSON_CATCH(exception) catch(exception)
+    #define JSON_INTERNAL_CATCH(exception) catch(exception)
+#else
+    #include <cstdlib>
+    #define JSON_THROW(exception) std::abort()
+    #define JSON_TRY if(true)
+    #define JSON_CATCH(exception) if(false)
+    #define JSON_INTERNAL_CATCH(exception) if(false)
+#endif
 
-template <typename T>
-using key_type_t = typename T::key_type;
+// override exception macros
+#if defined(JSON_THROW_USER)
+    #undef JSON_THROW
+    #define JSON_THROW JSON_THROW_USER
+#endif
+#if defined(JSON_TRY_USER)
+    #undef JSON_TRY
+    #define JSON_TRY JSON_TRY_USER
+#endif
+#if defined(JSON_CATCH_USER)
+    #undef JSON_CATCH
+    #define JSON_CATCH JSON_CATCH_USER
+    #undef JSON_INTERNAL_CATCH
+    #define JSON_INTERNAL_CATCH JSON_CATCH_USER
+#endif
+#if defined(JSON_INTERNAL_CATCH_USER)
+    #undef JSON_INTERNAL_CATCH
+    #define JSON_INTERNAL_CATCH JSON_INTERNAL_CATCH_USER
+#endif
 
-template <typename T>
-using value_type_t = typename T::value_type;
+// manual branch prediction
+#if defined(__clang__) || defined(__GNUC__) || defined(__GNUG__)
+    #define JSON_LIKELY(x)      __builtin_expect(x, 1)
+    #define JSON_UNLIKELY(x)    __builtin_expect(x, 0)
+#else
+    #define JSON_LIKELY(x)      x
+    #define JSON_UNLIKELY(x)    x
+#endif
 
-template <typename T>
-using difference_type_t = typename T::difference_type;
+// C++ language standard detection
+#if (defined(__cplusplus) && __cplusplus >= 201703L) || (defined(_HAS_CXX17) && _HAS_CXX17 == 1) // fix for issue #464
+    #define JSON_HAS_CPP_17
+    #define JSON_HAS_CPP_14
+#elif (defined(__cplusplus) && __cplusplus >= 201402L) || (defined(_HAS_CXX14) && _HAS_CXX14 == 1)
+    #define JSON_HAS_CPP_14
+#endif
 
-template <typename T>
-using pointer_t = typename T::pointer;
+/*!
+@brief macro to briefly define a mapping between an enum and JSON
+@def NLOHMANN_JSON_SERIALIZE_ENUM
+@since version 3.4.0
+*/
+#define NLOHMANN_JSON_SERIALIZE_ENUM(ENUM_TYPE, ...)                                           \
+    template<typename BasicJsonType>                                                           \
+    inline void to_json(BasicJsonType& j, const ENUM_TYPE& e)                                  \
+    {                                                                                          \
+        static_assert(std::is_enum<ENUM_TYPE>::value, #ENUM_TYPE " must be an enum!");         \
+        static const std::pair<ENUM_TYPE, BasicJsonType> m[] = __VA_ARGS__;                    \
+        auto it = std::find_if(std::begin(m), std::end(m),                                     \
+                               [e](const std::pair<ENUM_TYPE, BasicJsonType>& ej_pair) -> bool \
+        {                                                                                      \
+            return ej_pair.first == e;                                                         \
+        });                                                                                    \
+        j = ((it != std::end(m)) ? it : std::begin(m))->second;                                \
+    }                                                                                          \
+    template<typename BasicJsonType>                                                           \
+    inline void from_json(const BasicJsonType& j, ENUM_TYPE& e)                                \
+    {                                                                                          \
+        static_assert(std::is_enum<ENUM_TYPE>::value, #ENUM_TYPE " must be an enum!");         \
+        static const std::pair<ENUM_TYPE, BasicJsonType> m[] = __VA_ARGS__;                    \
+        auto it = std::find_if(std::begin(m), std::end(m),                                     \
+                               [j](const std::pair<ENUM_TYPE, BasicJsonType>& ej_pair) -> bool \
+        {                                                                                      \
+            return ej_pair.second == j;                                                        \
+        });                                                                                    \
+        e = ((it != std::end(m)) ? it : std::begin(m))->first;                                 \
+    }
 
-template <typename T>
-using reference_t = typename T::reference;
+// Ugly macros to avoid uglier copy-paste when specializing basic_json. They
+// may be removed in the future once the class is split.
 
-template <typename T>
-using iterator_category_t = typename T::iterator_category;
-
-template <typename T>
-using iterator_t = typename T::iterator;
+#define NLOHMANN_BASIC_JSON_TPL_DECLARATION                                \
+    template<template<typename, typename, typename...> class ObjectType,   \
+             template<typename, typename...> class ArrayType,              \
+             class StringType, class BooleanType, class NumberIntegerType, \
+             class NumberUnsignedType, class NumberFloatType,              \
+             template<typename> class AllocatorType,                       \
+             template<typename, typename = void> class JSONSerializer>
 
-template <typename T, typename... Args>
-using to_json_function = decltype(T::to_json(std::declval<Args>()...));
+#define NLOHMANN_BASIC_JSON_TPL                                            \
+    basic_json<ObjectType, ArrayType, StringType, BooleanType,             \
+    NumberIntegerType, NumberUnsignedType, NumberFloatType,                \
+    AllocatorType, JSONSerializer>
 
-template <typename T, typename... Args>
-using from_json_function = decltype(T::from_json(std::declval<Args>()...));
+// #include <nlohmann/detail/meta/cpp_future.hpp>
 
-template <typename T, typename U>
-using get_template_function = decltype(std::declval<T>().template get<U>());
 
-// trait checking if JSONSerializer<T>::from_json(json const&, udt&) exists
-template <typename BasicJsonType, typename T, typename = void>
-struct has_from_json : std::false_type {};
+#include <ciso646> // not
+#include <cstddef> // size_t
+#include <type_traits> // conditional, enable_if, false_type, integral_constant, is_constructible, is_integral, is_same, remove_cv, remove_reference, true_type
 
-template <typename BasicJsonType, typename T>
-struct has_from_json<BasicJsonType, T,
-           enable_if_t<not is_basic_json<T>::value>>
+namespace nlohmann
 {
-    using serializer = typename BasicJsonType::template json_serializer<T, void>;
-
-    static constexpr bool value =
-        is_detected_exact<void, from_json_function, serializer,
-        const BasicJsonType&, T&>::value;
-};
+namespace detail
+{
+// alias templates to reduce boilerplate
+template<bool B, typename T = void>
+using enable_if_t = typename std::enable_if<B, T>::type;
 
-// This trait checks if JSONSerializer<T>::from_json(json const&) exists
-// this overload is used for non-default-constructible user-defined-types
-template <typename BasicJsonType, typename T, typename = void>
-struct has_non_default_from_json : std::false_type {};
+template<typename T>
+using uncvref_t = typename std::remove_cv<typename std::remove_reference<T>::type>::type;
 
-template<typename BasicJsonType, typename T>
-struct has_non_default_from_json<BasicJsonType, T, enable_if_t<not is_basic_json<T>::value>>
+// implementation of C++14 index_sequence and affiliates
+// source: https://stackoverflow.com/a/32223343
+template<std::size_t... Ints>
+struct index_sequence
 {
-    using serializer = typename BasicJsonType::template json_serializer<T, void>;
-
-    static constexpr bool value =
-        is_detected_exact<T, from_json_function, serializer,
-        const BasicJsonType&>::value;
+    using type = index_sequence;
+    using value_type = std::size_t;
+    static constexpr std::size_t size() noexcept
+    {
+        return sizeof...(Ints);
+    }
 };
 
-// This trait checks if BasicJsonType::json_serializer<T>::to_json exists
-// Do not evaluate the trait when T is a basic_json type, to avoid template instantiation infinite recursion.
-template <typename BasicJsonType, typename T, typename = void>
-struct has_to_json : std::false_type {};
+template<class Sequence1, class Sequence2>
+struct merge_and_renumber;
 
-template <typename BasicJsonType, typename T>
-struct has_to_json<BasicJsonType, T, enable_if_t<not is_basic_json<T>::value>>
-{
-    using serializer = typename BasicJsonType::template json_serializer<T, void>;
+template<std::size_t... I1, std::size_t... I2>
+struct merge_and_renumber<index_sequence<I1...>, index_sequence<I2...>>
+        : index_sequence < I1..., (sizeof...(I1) + I2)... > {};
 
-    static constexpr bool value =
-        is_detected_exact<void, to_json_function, serializer, BasicJsonType&,
-        T>::value;
-};
+template<std::size_t N>
+struct make_index_sequence
+    : merge_and_renumber < typename make_index_sequence < N / 2 >::type,
+      typename make_index_sequence < N - N / 2 >::type > {};
 
+template<> struct make_index_sequence<0> : index_sequence<> {};
+template<> struct make_index_sequence<1> : index_sequence<0> {};
 
-///////////////////
-// is_ functions //
-///////////////////
+template<typename... Ts>
+using index_sequence_for = make_index_sequence<sizeof...(Ts)>;
 
-template <typename T, typename = void>
-struct is_iterator_traits : std::false_type {};
+// dispatch utility (taken from ranges-v3)
+template<unsigned N> struct priority_tag : priority_tag < N - 1 > {};
+template<> struct priority_tag<0> {};
 
-template <typename T>
-struct is_iterator_traits<iterator_traits<T>>
+// taken from ranges-v3
+template<typename T>
+struct static_const
 {
-  private:
-    using traits = iterator_traits<T>;
-
-  public:
-    static constexpr auto value =
-        is_detected<value_type_t, traits>::value &&
-        is_detected<difference_type_t, traits>::value &&
-        is_detected<pointer_t, traits>::value &&
-        is_detected<iterator_category_t, traits>::value &&
-        is_detected<reference_t, traits>::value;
+    static constexpr T value{};
 };
 
-// source: https://stackoverflow.com/a/37193089/4116453
+template<typename T>
+constexpr T static_const<T>::value;
+}  // namespace detail
+}  // namespace nlohmann
 
-template <typename T, typename = void>
-struct is_complete_type : std::false_type {};
+// #include <nlohmann/detail/meta/type_traits.hpp>
 
-template <typename T>
-struct is_complete_type<T, decltype(void(sizeof(T)))> : std::true_type {};
 
-template <typename BasicJsonType, typename CompatibleObjectType,
-          typename = void>
-struct is_compatible_object_type_impl : std::false_type {};
+#include <ciso646> // not
+#include <limits> // numeric_limits
+#include <type_traits> // false_type, is_constructible, is_integral, is_same, true_type
+#include <utility> // declval
 
-template <typename BasicJsonType, typename CompatibleObjectType>
-struct is_compatible_object_type_impl <
-    BasicJsonType, CompatibleObjectType,
-    enable_if_t<is_detected<mapped_type_t, CompatibleObjectType>::value and
-    is_detected<key_type_t, CompatibleObjectType>::value >>
-{
+// #include <nlohmann/detail/iterators/iterator_traits.hpp>
 
-    using object_t = typename BasicJsonType::object_t;
 
-    // macOS's is_constructible does not play well with nonesuch...
-    static constexpr bool value =
-        std::is_constructible<typename object_t::key_type,
-        typename CompatibleObjectType::key_type>::value and
-        std::is_constructible<typename object_t::mapped_type,
-        typename CompatibleObjectType::mapped_type>::value;
-};
+#include <iterator> // random_access_iterator_tag
 
-template <typename BasicJsonType, typename CompatibleObjectType>
-struct is_compatible_object_type
-    : is_compatible_object_type_impl<BasicJsonType, CompatibleObjectType> {};
+// #include <nlohmann/detail/meta/void_t.hpp>
 
-template <typename BasicJsonType, typename ConstructibleObjectType,
-          typename = void>
-struct is_constructible_object_type_impl : std::false_type {};
 
-template <typename BasicJsonType, typename ConstructibleObjectType>
-struct is_constructible_object_type_impl <
-    BasicJsonType, ConstructibleObjectType,
-    enable_if_t<is_detected<mapped_type_t, ConstructibleObjectType>::value and
-    is_detected<key_type_t, ConstructibleObjectType>::value >>
+namespace nlohmann
 {
-    using object_t = typename BasicJsonType::object_t;
-
-    static constexpr bool value =
-        (std::is_constructible<typename ConstructibleObjectType::key_type, typename object_t::key_type>::value and
-         std::is_same<typename object_t::mapped_type, typename ConstructibleObjectType::mapped_type>::value) or
-        (has_from_json<BasicJsonType, typename ConstructibleObjectType::mapped_type>::value or
-         has_non_default_from_json<BasicJsonType, typename ConstructibleObjectType::mapped_type >::value);
+namespace detail
+{
+template <typename ...Ts> struct make_void
+{
+    using type = void;
 };
+template <typename ...Ts> using void_t = typename make_void<Ts...>::type;
+} // namespace detail
+}  // namespace nlohmann
 
-template <typename BasicJsonType, typename ConstructibleObjectType>
-struct is_constructible_object_type
-    : is_constructible_object_type_impl<BasicJsonType,
-      ConstructibleObjectType> {};
+// #include <nlohmann/detail/meta/cpp_future.hpp>
 
-template <typename BasicJsonType, typename CompatibleStringType,
-          typename = void>
-struct is_compatible_string_type_impl : std::false_type {};
 
-template <typename BasicJsonType, typename CompatibleStringType>
-struct is_compatible_string_type_impl <
-    BasicJsonType, CompatibleStringType,
-    enable_if_t<is_detected_exact<typename BasicJsonType::string_t::value_type,
-    value_type_t, CompatibleStringType>::value >>
+namespace nlohmann
 {
-    static constexpr auto value =
-        std::is_constructible<typename BasicJsonType::string_t, CompatibleStringType>::value;
+namespace detail
+{
+template <typename It, typename = void>
+struct iterator_types {};
+
+template <typename It>
+struct iterator_types <
+    It,
+    void_t<typename It::difference_type, typename It::value_type, typename It::pointer,
+    typename It::reference, typename It::iterator_category >>
+{
+    using difference_type = typename It::difference_type;
+    using value_type = typename It::value_type;
+    using pointer = typename It::pointer;
+    using reference = typename It::reference;
+    using iterator_category = typename It::iterator_category;
 };
 
-template <typename BasicJsonType, typename ConstructibleStringType>
-struct is_compatible_string_type
-    : is_compatible_string_type_impl<BasicJsonType, ConstructibleStringType> {};
+// This is required as some compilers implement std::iterator_traits in a way that
+// doesn't work with SFINAE. See https://github.com/nlohmann/json/issues/1341.
+template <typename T, typename = void>
+struct iterator_traits
+{
+};
 
-template <typename BasicJsonType, typename ConstructibleStringType,
-          typename = void>
-struct is_constructible_string_type_impl : std::false_type {};
+template <typename T>
+struct iterator_traits < T, enable_if_t < !std::is_pointer<T>::value >>
+            : iterator_types<T>
+{
+};
 
-template <typename BasicJsonType, typename ConstructibleStringType>
-struct is_constructible_string_type_impl <
-    BasicJsonType, ConstructibleStringType,
-    enable_if_t<is_detected_exact<typename BasicJsonType::string_t::value_type,
-    value_type_t, ConstructibleStringType>::value >>
+template <typename T>
+struct iterator_traits<T*, enable_if_t<std::is_object<T>::value>>
 {
-    static constexpr auto value =
-        std::is_constructible<ConstructibleStringType,
-        typename BasicJsonType::string_t>::value;
+    using iterator_category = std::random_access_iterator_tag;
+    using value_type = T;
+    using difference_type = ptrdiff_t;
+    using pointer = T*;
+    using reference = T&;
 };
+} // namespace detail
+} // namespace nlohmann
 
-template <typename BasicJsonType, typename ConstructibleStringType>
-struct is_constructible_string_type
-    : is_constructible_string_type_impl<BasicJsonType, ConstructibleStringType> {};
+// #include <nlohmann/detail/macro_scope.hpp>
 
-template <typename BasicJsonType, typename CompatibleArrayType, typename = void>
-struct is_compatible_array_type_impl : std::false_type {};
+// #include <nlohmann/detail/meta/cpp_future.hpp>
 
-template <typename BasicJsonType, typename CompatibleArrayType>
-struct is_compatible_array_type_impl <
-    BasicJsonType, CompatibleArrayType,
-    enable_if_t<is_detected<value_type_t, CompatibleArrayType>::value and
-    is_detected<iterator_t, CompatibleArrayType>::value and
-// This is needed because json_reverse_iterator has a ::iterator type...
-// Therefore it is detected as a CompatibleArrayType.
-// The real fix would be to have an Iterable concept.
-    not is_iterator_traits<
-    iterator_traits<CompatibleArrayType>>::value >>
-{
-    static constexpr bool value =
-        std::is_constructible<BasicJsonType,
-        typename CompatibleArrayType::value_type>::value;
-};
+// #include <nlohmann/detail/meta/detected.hpp>
 
-template <typename BasicJsonType, typename CompatibleArrayType>
-struct is_compatible_array_type
-    : is_compatible_array_type_impl<BasicJsonType, CompatibleArrayType> {};
 
-template <typename BasicJsonType, typename ConstructibleArrayType, typename = void>
-struct is_constructible_array_type_impl : std::false_type {};
+#include <type_traits>
 
-template <typename BasicJsonType, typename ConstructibleArrayType>
-struct is_constructible_array_type_impl <
-    BasicJsonType, ConstructibleArrayType,
-    enable_if_t<std::is_same<ConstructibleArrayType,
-    typename BasicJsonType::value_type>::value >>
-            : std::true_type {};
+// #include <nlohmann/detail/meta/void_t.hpp>
 
-template <typename BasicJsonType, typename ConstructibleArrayType>
-struct is_constructible_array_type_impl <
-    BasicJsonType, ConstructibleArrayType,
-    enable_if_t<not std::is_same<ConstructibleArrayType,
-    typename BasicJsonType::value_type>::value and
-    is_detected<value_type_t, ConstructibleArrayType>::value and
-    is_detected<iterator_t, ConstructibleArrayType>::value and
-    is_complete_type<
-    detected_t<value_type_t, ConstructibleArrayType>>::value >>
-{
-    static constexpr bool value =
-        // This is needed because json_reverse_iterator has a ::iterator type,
-        // furthermore, std::back_insert_iterator (and other iterators) have a base class `iterator`...
-        // Therefore it is detected as a ConstructibleArrayType.
-        // The real fix would be to have an Iterable concept.
-        not is_iterator_traits <
-        iterator_traits<ConstructibleArrayType >>::value and
 
-        (std::is_same<typename ConstructibleArrayType::value_type, typename BasicJsonType::array_t::value_type>::value or
-         has_from_json<BasicJsonType,
-         typename ConstructibleArrayType::value_type>::value or
-         has_non_default_from_json <
-         BasicJsonType, typename ConstructibleArrayType::value_type >::value);
+// http://en.cppreference.com/w/cpp/experimental/is_detected
+namespace nlohmann
+{
+namespace detail
+{
+struct nonesuch
+{
+    nonesuch() = delete;
+    ~nonesuch() = delete;
+    nonesuch(nonesuch const&) = delete;
+    nonesuch(nonesuch const&&) = delete;
+    void operator=(nonesuch const&) = delete;
+    void operator=(nonesuch&&) = delete;
 };
 
-template <typename BasicJsonType, typename ConstructibleArrayType>
-struct is_constructible_array_type
-    : is_constructible_array_type_impl<BasicJsonType, ConstructibleArrayType> {};
-
-template <typename RealIntegerType, typename CompatibleNumberIntegerType,
-          typename = void>
-struct is_compatible_integer_type_impl : std::false_type {};
-
-template <typename RealIntegerType, typename CompatibleNumberIntegerType>
-struct is_compatible_integer_type_impl <
-    RealIntegerType, CompatibleNumberIntegerType,
-    enable_if_t<std::is_integral<RealIntegerType>::value and
-    std::is_integral<CompatibleNumberIntegerType>::value and
-    not std::is_same<bool, CompatibleNumberIntegerType>::value >>
+template <class Default,
+          class AlwaysVoid,
+          template <class...> class Op,
+          class... Args>
+struct detector
 {
-    // is there an assert somewhere on overflows?
-    using RealLimits = std::numeric_limits<RealIntegerType>;
-    using CompatibleLimits = std::numeric_limits<CompatibleNumberIntegerType>;
-
-    static constexpr auto value =
-        std::is_constructible<RealIntegerType,
-        CompatibleNumberIntegerType>::value and
-        CompatibleLimits::is_integer and
-        RealLimits::is_signed == CompatibleLimits::is_signed;
+    using value_t = std::false_type;
+    using type = Default;
 };
 
-template <typename RealIntegerType, typename CompatibleNumberIntegerType>
-struct is_compatible_integer_type
-    : is_compatible_integer_type_impl<RealIntegerType,
-      CompatibleNumberIntegerType> {};
-
-template <typename BasicJsonType, typename CompatibleType, typename = void>
-struct is_compatible_type_impl: std::false_type {};
-
-template <typename BasicJsonType, typename CompatibleType>
-struct is_compatible_type_impl <
-    BasicJsonType, CompatibleType,
-    enable_if_t<is_complete_type<CompatibleType>::value >>
+template <class Default, template <class...> class Op, class... Args>
+struct detector<Default, void_t<Op<Args...>>, Op, Args...>
 {
-    static constexpr bool value =
-        has_to_json<BasicJsonType, CompatibleType>::value;
+    using value_t = std::true_type;
+    using type = Op<Args...>;
 };
 
-template <typename BasicJsonType, typename CompatibleType>
-struct is_compatible_type
-    : is_compatible_type_impl<BasicJsonType, CompatibleType> {};
-}  // namespace detail
-}  // namespace nlohmann
-
-// #include <nlohmann/detail/exceptions.hpp>
-
-
-#include <exception> // exception
-#include <stdexcept> // runtime_error
-#include <string> // to_string
+template <template <class...> class Op, class... Args>
+using is_detected = typename detector<nonesuch, void, Op, Args...>::value_t;
 
-// #include <nlohmann/detail/input/position_t.hpp>
+template <template <class...> class Op, class... Args>
+using detected_t = typename detector<nonesuch, void, Op, Args...>::type;
 
+template <class Default, template <class...> class Op, class... Args>
+using detected_or = detector<Default, void, Op, Args...>;
 
-#include <cstddef> // size_t
+template <class Default, template <class...> class Op, class... Args>
+using detected_or_t = typename detected_or<Default, Op, Args...>::type;
 
-namespace nlohmann
-{
-namespace detail
-{
-/// struct to capture the start position of the current token
-struct position_t
-{
-    /// the total number of characters read
-    std::size_t chars_read_total = 0;
-    /// the number of characters read in the current line
-    std::size_t chars_read_current_line = 0;
-    /// the number of lines read
-    std::size_t lines_read = 0;
+template <class Expected, template <class...> class Op, class... Args>
+using is_detected_exact = std::is_same<Expected, detected_t<Op, Args...>>;
 
-    /// conversion to size_t to preserve SAX interface
-    constexpr operator size_t() const
-    {
-        return chars_read_total;
-    }
-};
+template <class To, template <class...> class Op, class... Args>
+using is_detected_convertible =
+    std::is_convertible<detected_t<Op, Args...>, To>;
+}  // namespace detail
+}  // namespace nlohmann
 
-}
-}
+// #include <nlohmann/json_fwd.hpp>
+#ifndef INCLUDE_NLOHMANN_JSON_FWD_HPP_
+#define INCLUDE_NLOHMANN_JSON_FWD_HPP_
 
+#include <cstdint> // int64_t, uint64_t
+#include <map> // map
+#include <memory> // allocator
+#include <string> // string
+#include <vector> // vector
 
+/*!
+@brief namespace for Niels Lohmann
+@see https://github.com/nlohmann
+@since version 1.0.0
+*/
 namespace nlohmann
 {
-namespace detail
-{
-////////////////
-// exceptions //
-////////////////
-
 /*!
-@brief general exception of the @ref basic_json class
+@brief default JSONSerializer template argument
 
-This class is an extension of `std::exception` objects with a member @a id for
-exception ids. It is used as the base class for all exceptions thrown by the
-@ref basic_json class. This class can hence be used as "wildcard" to catch
-exceptions.
+This serializer ignores the template arguments and uses ADL
+([argument-dependent lookup](https://en.cppreference.com/w/cpp/language/adl))
+for serialization.
+*/
+template<typename T = void, typename SFINAE = void>
+struct adl_serializer;
 
-Subclasses:
-- @ref parse_error for exceptions indicating a parse error
-- @ref invalid_iterator for exceptions indicating errors with iterators
-- @ref type_error for exceptions indicating executing a member function with
-                  a wrong type
-- @ref out_of_range for exceptions indicating access out of the defined range
-- @ref other_error for exceptions indicating other library errors
+template<template<typename U, typename V, typename... Args> class ObjectType =
+         std::map,
+         template<typename U, typename... Args> class ArrayType = std::vector,
+         class StringType = std::string, class BooleanType = bool,
+         class NumberIntegerType = std::int64_t,
+         class NumberUnsignedType = std::uint64_t,
+         class NumberFloatType = double,
+         template<typename U> class AllocatorType = std::allocator,
+         template<typename T, typename SFINAE = void> class JSONSerializer =
+         adl_serializer>
+class basic_json;
 
-@internal
-@note To have nothrow-copy-constructible exceptions, we internally use
-      `std::runtime_error` which can cope with arbitrary-length error messages.
-      Intermediate strings are built with static functions and then passed to
-      the actual constructor.
-@endinternal
+/*!
+@brief JSON Pointer
 
-@liveexample{The following code shows how arbitrary library exceptions can be
-caught.,exception}
+A JSON pointer defines a string syntax for identifying a specific value
+within a JSON document. It can be used with functions `at` and
+`operator[]`. Furthermore, JSON pointers are the base for JSON patches.
 
-@since version 3.0.0
+@sa [RFC 6901](https://tools.ietf.org/html/rfc6901)
+
+@since version 2.0.0
 */
-class exception : public std::exception
-{
-  public:
-    /// returns the explanatory string
-    const char* what() const noexcept override
-    {
-        return m.what();
-    }
+template<typename BasicJsonType>
+class json_pointer;
 
-    /// the id of the exception
-    const int id;
+/*!
+@brief default JSON class
 
-  protected:
-    exception(int id_, const char* what_arg) : id(id_), m(what_arg) {}
+This type is the default specialization of the @ref basic_json class which
+uses the standard template types.
 
-    static std::string name(const std::string& ename, int id_)
-    {
-        return "[json.exception." + ename + "." + std::to_string(id_) + "] ";
-    }
+@since version 1.0.0
+*/
+using json = basic_json<>;
+}  // namespace nlohmann
 
-  private:
-    /// an exception object as storage for error messages
-    std::runtime_error m;
-};
+#endif  // INCLUDE_NLOHMANN_JSON_FWD_HPP_
 
-/*!
-@brief exception indicating a parse error
 
-This exception is thrown by the library when a parse error occurs. Parse errors
-can occur during the deserialization of JSON text, CBOR, MessagePack, as well
-as when using JSON Patch.
+namespace nlohmann
+{
+/*!
+@brief detail namespace with internal helper functions
 
-Member @a byte holds the byte index of the last read character in the input
-file.
+This namespace collects functions that should not be exposed,
+implementations of some @ref basic_json methods, and meta-programming helpers.
 
-Exceptions have ids 1xx.
+@since version 2.1.0
+*/
+namespace detail
+{
+/////////////
+// helpers //
+/////////////
 
-name / id                      | example message | description
------------------------------- | --------------- | -------------------------
-json.exception.parse_error.101 | parse error at 2: unexpected end of input; expected string literal | This error indicates a syntax error while deserializing a JSON text. The error message describes that an unexpected token (character) was encountered, and the member @a byte indicates the error position.
-json.exception.parse_error.102 | parse error at 14: missing or wrong low surrogate | JSON uses the `\uxxxx` format to describe Unicode characters. Code points above above 0xFFFF are split into two `\uxxxx` entries ("surrogate pairs"). This error indicates that the surrogate pair is incomplete or contains an invalid code point.
-json.exception.parse_error.103 | parse error: code points above 0x10FFFF are invalid | Unicode supports code points up to 0x10FFFF. Code points above 0x10FFFF are invalid.
-json.exception.parse_error.104 | parse error: JSON patch must be an array of objects | [RFC 6902](https://tools.ietf.org/html/rfc6902) requires a JSON Patch document to be a JSON document that represents an array of objects.
-json.exception.parse_error.105 | parse error: operation must have string member 'op' | An operation of a JSON Patch document must contain exactly one "op" member, whose value indicates the operation to perform. Its value must be one of "add", "remove", "replace", "move", "copy", or "test"; other values are errors.
-json.exception.parse_error.106 | parse error: array index '01' must not begin with '0' | An array index in a JSON Pointer ([RFC 6901](https://tools.ietf.org/html/rfc6901)) may be `0` or any number without a leading `0`.
-json.exception.parse_error.107 | parse error: JSON pointer must be empty or begin with '/' - was: 'foo' | A JSON Pointer must be a Unicode string containing a sequence of zero or more reference tokens, each prefixed by a `/` character.
-json.exception.parse_error.108 | parse error: escape character '~' must be followed with '0' or '1' | In a JSON Pointer, only `~0` and `~1` are valid escape sequences.
-json.exception.parse_error.109 | parse error: array index 'one' is not a number | A JSON Pointer array index must be a number.
-json.exception.parse_error.110 | parse error at 1: cannot read 2 bytes from vector | When parsing CBOR or MessagePack, the byte vector ends before the complete value has been read.
-json.exception.parse_error.112 | parse error at 1: error reading CBOR; last byte: 0xF8 | Not all types of CBOR or MessagePack are supported. This exception occurs if an unsupported byte was read.
-json.exception.parse_error.113 | parse error at 2: expected a CBOR string; last byte: 0x98 | While parsing a map key, a value that is not a string has been read.
-json.exception.parse_error.114 | parse error: Unsupported BSON record type 0x0F | The parsing of the corresponding BSON record type is not implemented (yet).
+// Note to maintainers:
+//
+// Every trait in this file expects a non CV-qualified type.
+// The only exceptions are in the 'aliases for detected' section
+// (i.e. those of the form: decltype(T::member_function(std::declval<T>())))
+//
+// In this case, T has to be properly CV-qualified to constraint the function arguments
+// (e.g. to_json(BasicJsonType&, const T&))
 
-@note For an input with n bytes, 1 is the index of the first character and n+1
-      is the index of the terminating null byte or the end of file. This also
-      holds true when reading a byte vector (CBOR or MessagePack).
+template<typename> struct is_basic_json : std::false_type {};
 
-@liveexample{The following code shows how a `parse_error` exception can be
-caught.,parse_error}
+NLOHMANN_BASIC_JSON_TPL_DECLARATION
+struct is_basic_json<NLOHMANN_BASIC_JSON_TPL> : std::true_type {};
 
-@sa @ref exception for the base class of the library exceptions
-@sa @ref invalid_iterator for exceptions indicating errors with iterators
-@sa @ref type_error for exceptions indicating executing a member function with
-                    a wrong type
-@sa @ref out_of_range for exceptions indicating access out of the defined range
-@sa @ref other_error for exceptions indicating other library errors
+//////////////////////////
+// aliases for detected //
+//////////////////////////
 
-@since version 3.0.0
-*/
-class parse_error : public exception
-{
-  public:
-    /*!
-    @brief create a parse error exception
-    @param[in] id_       the id of the exception
-    @param[in] position  the position where the error occurred (or with
-                         chars_read_total=0 if the position cannot be
-                         determined)
-    @param[in] what_arg  the explanatory string
-    @return parse_error object
-    */
-    static parse_error create(int id_, const position_t& pos, const std::string& what_arg)
-    {
-        std::string w = exception::name("parse_error", id_) + "parse error" +
-                        position_string(pos) + ": " + what_arg;
-        return parse_error(id_, pos.chars_read_total, w.c_str());
-    }
+template <typename T>
+using mapped_type_t = typename T::mapped_type;
 
-    static parse_error create(int id_, std::size_t byte_, const std::string& what_arg)
-    {
-        std::string w = exception::name("parse_error", id_) + "parse error" +
-                        (byte_ != 0 ? (" at byte " + std::to_string(byte_)) : "") +
-                        ": " + what_arg;
-        return parse_error(id_, byte_, w.c_str());
-    }
+template <typename T>
+using key_type_t = typename T::key_type;
 
-    /*!
-    @brief byte index of the parse error
+template <typename T>
+using value_type_t = typename T::value_type;
 
-    The byte index of the last read character in the input file.
+template <typename T>
+using difference_type_t = typename T::difference_type;
 
-    @note For an input with n bytes, 1 is the index of the first character and
-          n+1 is the index of the terminating null byte or the end of file.
-          This also holds true when reading a byte vector (CBOR or MessagePack).
-    */
-    const std::size_t byte;
+template <typename T>
+using pointer_t = typename T::pointer;
 
-  private:
-    parse_error(int id_, std::size_t byte_, const char* what_arg)
-        : exception(id_, what_arg), byte(byte_) {}
+template <typename T>
+using reference_t = typename T::reference;
 
-    static std::string position_string(const position_t& pos)
-    {
-        return " at line " + std::to_string(pos.lines_read + 1) +
-               ", column " + std::to_string(pos.chars_read_current_line);
-    }
-};
+template <typename T>
+using iterator_category_t = typename T::iterator_category;
 
-/*!
-@brief exception indicating errors with iterators
+template <typename T>
+using iterator_t = typename T::iterator;
 
-This exception is thrown if iterators passed to a library function do not match
-the expected semantics.
+template <typename T, typename... Args>
+using to_json_function = decltype(T::to_json(std::declval<Args>()...));
 
-Exceptions have ids 2xx.
+template <typename T, typename... Args>
+using from_json_function = decltype(T::from_json(std::declval<Args>()...));
 
-name / id                           | example message | description
------------------------------------ | --------------- | -------------------------
-json.exception.invalid_iterator.201 | iterators are not compatible | The iterators passed to constructor @ref basic_json(InputIT first, InputIT last) are not compatible, meaning they do not belong to the same container. Therefore, the range (@a first, @a last) is invalid.
-json.exception.invalid_iterator.202 | iterator does not fit current value | In an erase or insert function, the passed iterator @a pos does not belong to the JSON value for which the function was called. It hence does not define a valid position for the deletion/insertion.
-json.exception.invalid_iterator.203 | iterators do not fit current value | Either iterator passed to function @ref erase(IteratorType first, IteratorType last) does not belong to the JSON value from which values shall be erased. It hence does not define a valid range to delete values from.
-json.exception.invalid_iterator.204 | iterators out of range | When an iterator range for a primitive type (number, boolean, or string) is passed to a constructor or an erase function, this range has to be exactly (@ref begin(), @ref end()), because this is the only way the single stored value is expressed. All other ranges are invalid.
-json.exception.invalid_iterator.205 | iterator out of range | When an iterator for a primitive type (number, boolean, or string) is passed to an erase function, the iterator has to be the @ref begin() iterator, because it is the only way to address the stored value. All other iterators are invalid.
-json.exception.invalid_iterator.206 | cannot construct with iterators from null | The iterators passed to constructor @ref basic_json(InputIT first, InputIT last) belong to a JSON null value and hence to not define a valid range.
-json.exception.invalid_iterator.207 | cannot use key() for non-object iterators | The key() member function can only be used on iterators belonging to a JSON object, because other types do not have a concept of a key.
-json.exception.invalid_iterator.208 | cannot use operator[] for object iterators | The operator[] to specify a concrete offset cannot be used on iterators belonging to a JSON object, because JSON objects are unordered.
-json.exception.invalid_iterator.209 | cannot use offsets with object iterators | The offset operators (+, -, +=, -=) cannot be used on iterators belonging to a JSON object, because JSON objects are unordered.
-json.exception.invalid_iterator.210 | iterators do not fit | The iterator range passed to the insert function are not compatible, meaning they do not belong to the same container. Therefore, the range (@a first, @a last) is invalid.
-json.exception.invalid_iterator.211 | passed iterators may not belong to container | The iterator range passed to the insert function must not be a subrange of the container to insert to.
-json.exception.invalid_iterator.212 | cannot compare iterators of different containers | When two iterators are compared, they must belong to the same container.
-json.exception.invalid_iterator.213 | cannot compare order of object iterators | The order of object iterators cannot be compared, because JSON objects are unordered.
-json.exception.invalid_iterator.214 | cannot get value | Cannot get value for iterator: Either the iterator belongs to a null value or it is an iterator to a primitive type (number, boolean, or string), but the iterator is different to @ref begin().
+template <typename T, typename U>
+using get_template_function = decltype(std::declval<T>().template get<U>());
 
-@liveexample{The following code shows how an `invalid_iterator` exception can be
-caught.,invalid_iterator}
+// trait checking if JSONSerializer<T>::from_json(json const&, udt&) exists
+template <typename BasicJsonType, typename T, typename = void>
+struct has_from_json : std::false_type {};
 
-@sa @ref exception for the base class of the library exceptions
-@sa @ref parse_error for exceptions indicating a parse error
-@sa @ref type_error for exceptions indicating executing a member function with
-                    a wrong type
-@sa @ref out_of_range for exceptions indicating access out of the defined range
-@sa @ref other_error for exceptions indicating other library errors
+template <typename BasicJsonType, typename T>
+struct has_from_json<BasicJsonType, T,
+           enable_if_t<not is_basic_json<T>::value>>
+{
+    using serializer = typename BasicJsonType::template json_serializer<T, void>;
 
-@since version 3.0.0
-*/
-class invalid_iterator : public exception
+    static constexpr bool value =
+        is_detected_exact<void, from_json_function, serializer,
+        const BasicJsonType&, T&>::value;
+};
+
+// This trait checks if JSONSerializer<T>::from_json(json const&) exists
+// this overload is used for non-default-constructible user-defined-types
+template <typename BasicJsonType, typename T, typename = void>
+struct has_non_default_from_json : std::false_type {};
+
+template<typename BasicJsonType, typename T>
+struct has_non_default_from_json<BasicJsonType, T, enable_if_t<not is_basic_json<T>::value>>
 {
-  public:
-    static invalid_iterator create(int id_, const std::string& what_arg)
-    {
-        std::string w = exception::name("invalid_iterator", id_) + what_arg;
-        return invalid_iterator(id_, w.c_str());
-    }
+    using serializer = typename BasicJsonType::template json_serializer<T, void>;
 
-  private:
-    invalid_iterator(int id_, const char* what_arg)
-        : exception(id_, what_arg) {}
+    static constexpr bool value =
+        is_detected_exact<T, from_json_function, serializer,
+        const BasicJsonType&>::value;
 };
 
-/*!
-@brief exception indicating executing a member function with a wrong type
+// This trait checks if BasicJsonType::json_serializer<T>::to_json exists
+// Do not evaluate the trait when T is a basic_json type, to avoid template instantiation infinite recursion.
+template <typename BasicJsonType, typename T, typename = void>
+struct has_to_json : std::false_type {};
 
-This exception is thrown in case of a type error; that is, a library function is
-executed on a JSON value whose type does not match the expected semantics.
+template <typename BasicJsonType, typename T>
+struct has_to_json<BasicJsonType, T, enable_if_t<not is_basic_json<T>::value>>
+{
+    using serializer = typename BasicJsonType::template json_serializer<T, void>;
 
-Exceptions have ids 3xx.
+    static constexpr bool value =
+        is_detected_exact<void, to_json_function, serializer, BasicJsonType&,
+        T>::value;
+};
 
-name / id                     | example message | description
------------------------------ | --------------- | -------------------------
-json.exception.type_error.301 | cannot create object from initializer list | To create an object from an initializer list, the initializer list must consist only of a list of pairs whose first element is a string. When this constraint is violated, an array is created instead.
-json.exception.type_error.302 | type must be object, but is array | During implicit or explicit value conversion, the JSON type must be compatible to the target type. For instance, a JSON string can only be converted into string types, but not into numbers or boolean types.
-json.exception.type_error.303 | incompatible ReferenceType for get_ref, actual type is object | To retrieve a reference to a value stored in a @ref basic_json object with @ref get_ref, the type of the reference must match the value type. For instance, for a JSON array, the @a ReferenceType must be @ref array_t&.
-json.exception.type_error.304 | cannot use at() with string | The @ref at() member functions can only be executed for certain JSON types.
-json.exception.type_error.305 | cannot use operator[] with string | The @ref operator[] member functions can only be executed for certain JSON types.
-json.exception.type_error.306 | cannot use value() with string | The @ref value() member functions can only be executed for certain JSON types.
-json.exception.type_error.307 | cannot use erase() with string | The @ref erase() member functions can only be executed for certain JSON types.
-json.exception.type_error.308 | cannot use push_back() with string | The @ref push_back() and @ref operator+= member functions can only be executed for certain JSON types.
-json.exception.type_error.309 | cannot use insert() with | The @ref insert() member functions can only be executed for certain JSON types.
-json.exception.type_error.310 | cannot use swap() with number | The @ref swap() member functions can only be executed for certain JSON types.
-json.exception.type_error.311 | cannot use emplace_back() with string | The @ref emplace_back() member function can only be executed for certain JSON types.
-json.exception.type_error.312 | cannot use update() with string | The @ref update() member functions can only be executed for certain JSON types.
-json.exception.type_error.313 | invalid value to unflatten | The @ref unflatten function converts an object whose keys are JSON Pointers back into an arbitrary nested JSON value. The JSON Pointers must not overlap, because then the resulting value would not be well defined.
-json.exception.type_error.314 | only objects can be unflattened | The @ref unflatten function only works for an object whose keys are JSON Pointers.
-json.exception.type_error.315 | values in object must be primitive | The @ref unflatten function only works for an object whose keys are JSON Pointers and whose values are primitive.
-json.exception.type_error.316 | invalid UTF-8 byte at index 10: 0x7E | The @ref dump function only works with UTF-8 encoded strings; that is, if you assign a `std::string` to a JSON value, make sure it is UTF-8 encoded. |
-json.exception.type_error.317 | JSON value cannot be serialized to requested format | The dynamic type of the object cannot be represented in the requested serialization format (e.g. a raw `true` or `null` JSON object cannot be serialized to BSON) |
 
-@liveexample{The following code shows how a `type_error` exception can be
-caught.,type_error}
+///////////////////
+// is_ functions //
+///////////////////
 
-@sa @ref exception for the base class of the library exceptions
-@sa @ref parse_error for exceptions indicating a parse error
-@sa @ref invalid_iterator for exceptions indicating errors with iterators
-@sa @ref out_of_range for exceptions indicating access out of the defined range
-@sa @ref other_error for exceptions indicating other library errors
+template <typename T, typename = void>
+struct is_iterator_traits : std::false_type {};
 
-@since version 3.0.0
-*/
-class type_error : public exception
+template <typename T>
+struct is_iterator_traits<iterator_traits<T>>
 {
-  public:
-    static type_error create(int id_, const std::string& what_arg)
-    {
-        std::string w = exception::name("type_error", id_) + what_arg;
-        return type_error(id_, w.c_str());
-    }
-
   private:
-    type_error(int id_, const char* what_arg) : exception(id_, what_arg) {}
+    using traits = iterator_traits<T>;
+
+  public:
+    static constexpr auto value =
+        is_detected<value_type_t, traits>::value &&
+        is_detected<difference_type_t, traits>::value &&
+        is_detected<pointer_t, traits>::value &&
+        is_detected<iterator_category_t, traits>::value &&
+        is_detected<reference_t, traits>::value;
 };
 
-/*!
-@brief exception indicating access out of the defined range
+// source: https://stackoverflow.com/a/37193089/4116453
 
-This exception is thrown in case a library function is called on an input
-parameter that exceeds the expected range, for instance in case of array
-indices or nonexisting object keys.
+template <typename T, typename = void>
+struct is_complete_type : std::false_type {};
 
-Exceptions have ids 4xx.
+template <typename T>
+struct is_complete_type<T, decltype(void(sizeof(T)))> : std::true_type {};
 
-name / id                       | example message | description
-------------------------------- | --------------- | -------------------------
-json.exception.out_of_range.401 | array index 3 is out of range | The provided array index @a i is larger than @a size-1.
-json.exception.out_of_range.402 | array index '-' (3) is out of range | The special array index `-` in a JSON Pointer never describes a valid element of the array, but the index past the end. That is, it can only be used to add elements at this position, but not to read it.
-json.exception.out_of_range.403 | key 'foo' not found | The provided key was not found in the JSON object.
-json.exception.out_of_range.404 | unresolved reference token 'foo' | A reference token in a JSON Pointer could not be resolved.
-json.exception.out_of_range.405 | JSON pointer has no parent | The JSON Patch operations 'remove' and 'add' can not be applied to the root element of the JSON value.
-json.exception.out_of_range.406 | number overflow parsing '10E1000' | A parsed number could not be stored as without changing it to NaN or INF.
-json.exception.out_of_range.407 | number overflow serializing '9223372036854775808' | UBJSON and BSON only support integer numbers up to 9223372036854775807. |
-json.exception.out_of_range.408 | excessive array size: 8658170730974374167 | The size (following `#`) of an UBJSON array or object exceeds the maximal capacity. |
-json.exception.out_of_range.409 | BSON key cannot contain code point U+0000 (at byte 2) | Key identifiers to be serialized to BSON cannot contain code point U+0000, since the key is stored as zero-terminated c-string |
+template <typename BasicJsonType, typename CompatibleObjectType,
+          typename = void>
+struct is_compatible_object_type_impl : std::false_type {};
 
-@liveexample{The following code shows how an `out_of_range` exception can be
-caught.,out_of_range}
+template <typename BasicJsonType, typename CompatibleObjectType>
+struct is_compatible_object_type_impl <
+    BasicJsonType, CompatibleObjectType,
+    enable_if_t<is_detected<mapped_type_t, CompatibleObjectType>::value and
+    is_detected<key_type_t, CompatibleObjectType>::value >>
+{
 
-@sa @ref exception for the base class of the library exceptions
-@sa @ref parse_error for exceptions indicating a parse error
-@sa @ref invalid_iterator for exceptions indicating errors with iterators
-@sa @ref type_error for exceptions indicating executing a member function with
-                    a wrong type
-@sa @ref other_error for exceptions indicating other library errors
+    using object_t = typename BasicJsonType::object_t;
 
-@since version 3.0.0
-*/
-class out_of_range : public exception
+    // macOS's is_constructible does not play well with nonesuch...
+    static constexpr bool value =
+        std::is_constructible<typename object_t::key_type,
+        typename CompatibleObjectType::key_type>::value and
+        std::is_constructible<typename object_t::mapped_type,
+        typename CompatibleObjectType::mapped_type>::value;
+};
+
+template <typename BasicJsonType, typename CompatibleObjectType>
+struct is_compatible_object_type
+    : is_compatible_object_type_impl<BasicJsonType, CompatibleObjectType> {};
+
+template <typename BasicJsonType, typename ConstructibleObjectType,
+          typename = void>
+struct is_constructible_object_type_impl : std::false_type {};
+
+template <typename BasicJsonType, typename ConstructibleObjectType>
+struct is_constructible_object_type_impl <
+    BasicJsonType, ConstructibleObjectType,
+    enable_if_t<is_detected<mapped_type_t, ConstructibleObjectType>::value and
+    is_detected<key_type_t, ConstructibleObjectType>::value >>
 {
-  public:
-    static out_of_range create(int id_, const std::string& what_arg)
-    {
-        std::string w = exception::name("out_of_range", id_) + what_arg;
-        return out_of_range(id_, w.c_str());
-    }
+    using object_t = typename BasicJsonType::object_t;
 
-  private:
-    out_of_range(int id_, const char* what_arg) : exception(id_, what_arg) {}
+    static constexpr bool value =
+        (std::is_constructible<typename ConstructibleObjectType::key_type, typename object_t::key_type>::value and
+         std::is_same<typename object_t::mapped_type, typename ConstructibleObjectType::mapped_type>::value) or
+        (has_from_json<BasicJsonType, typename ConstructibleObjectType::mapped_type>::value or
+         has_non_default_from_json<BasicJsonType, typename ConstructibleObjectType::mapped_type >::value);
 };
 
-/*!
-@brief exception indicating other library errors
+template <typename BasicJsonType, typename ConstructibleObjectType>
+struct is_constructible_object_type
+    : is_constructible_object_type_impl<BasicJsonType,
+      ConstructibleObjectType> {};
 
-This exception is thrown in case of errors that cannot be classified with the
-other exception types.
+template <typename BasicJsonType, typename CompatibleStringType,
+          typename = void>
+struct is_compatible_string_type_impl : std::false_type {};
 
-Exceptions have ids 5xx.
+template <typename BasicJsonType, typename CompatibleStringType>
+struct is_compatible_string_type_impl <
+    BasicJsonType, CompatibleStringType,
+    enable_if_t<is_detected_exact<typename BasicJsonType::string_t::value_type,
+    value_type_t, CompatibleStringType>::value >>
+{
+    static constexpr auto value =
+        std::is_constructible<typename BasicJsonType::string_t, CompatibleStringType>::value;
+};
 
-name / id                      | example message | description
------------------------------- | --------------- | -------------------------
-json.exception.other_error.501 | unsuccessful: {"op":"test","path":"/baz", "value":"bar"} | A JSON Patch operation 'test' failed. The unsuccessful operation is also printed.
+template <typename BasicJsonType, typename ConstructibleStringType>
+struct is_compatible_string_type
+    : is_compatible_string_type_impl<BasicJsonType, ConstructibleStringType> {};
 
-@sa @ref exception for the base class of the library exceptions
-@sa @ref parse_error for exceptions indicating a parse error
-@sa @ref invalid_iterator for exceptions indicating errors with iterators
-@sa @ref type_error for exceptions indicating executing a member function with
-                    a wrong type
-@sa @ref out_of_range for exceptions indicating access out of the defined range
+template <typename BasicJsonType, typename ConstructibleStringType,
+          typename = void>
+struct is_constructible_string_type_impl : std::false_type {};
 
-@liveexample{The following code shows how an `other_error` exception can be
-caught.,other_error}
+template <typename BasicJsonType, typename ConstructibleStringType>
+struct is_constructible_string_type_impl <
+    BasicJsonType, ConstructibleStringType,
+    enable_if_t<is_detected_exact<typename BasicJsonType::string_t::value_type,
+    value_type_t, ConstructibleStringType>::value >>
+{
+    static constexpr auto value =
+        std::is_constructible<ConstructibleStringType,
+        typename BasicJsonType::string_t>::value;
+};
 
-@since version 3.0.0
-*/
-class other_error : public exception
+template <typename BasicJsonType, typename ConstructibleStringType>
+struct is_constructible_string_type
+    : is_constructible_string_type_impl<BasicJsonType, ConstructibleStringType> {};
+
+template <typename BasicJsonType, typename CompatibleArrayType, typename = void>
+struct is_compatible_array_type_impl : std::false_type {};
+
+template <typename BasicJsonType, typename CompatibleArrayType>
+struct is_compatible_array_type_impl <
+    BasicJsonType, CompatibleArrayType,
+    enable_if_t<is_detected<value_type_t, CompatibleArrayType>::value and
+    is_detected<iterator_t, CompatibleArrayType>::value and
+// This is needed because json_reverse_iterator has a ::iterator type...
+// Therefore it is detected as a CompatibleArrayType.
+// The real fix would be to have an Iterable concept.
+    not is_iterator_traits<
+    iterator_traits<CompatibleArrayType>>::value >>
 {
-  public:
-    static other_error create(int id_, const std::string& what_arg)
-    {
-        std::string w = exception::name("other_error", id_) + what_arg;
-        return other_error(id_, w.c_str());
-    }
+    static constexpr bool value =
+        std::is_constructible<BasicJsonType,
+        typename CompatibleArrayType::value_type>::value;
+};
 
-  private:
-    other_error(int id_, const char* what_arg) : exception(id_, what_arg) {}
+template <typename BasicJsonType, typename CompatibleArrayType>
+struct is_compatible_array_type
+    : is_compatible_array_type_impl<BasicJsonType, CompatibleArrayType> {};
+
+template <typename BasicJsonType, typename ConstructibleArrayType, typename = void>
+struct is_constructible_array_type_impl : std::false_type {};
+
+template <typename BasicJsonType, typename ConstructibleArrayType>
+struct is_constructible_array_type_impl <
+    BasicJsonType, ConstructibleArrayType,
+    enable_if_t<std::is_same<ConstructibleArrayType,
+    typename BasicJsonType::value_type>::value >>
+            : std::true_type {};
+
+template <typename BasicJsonType, typename ConstructibleArrayType>
+struct is_constructible_array_type_impl <
+    BasicJsonType, ConstructibleArrayType,
+    enable_if_t<not std::is_same<ConstructibleArrayType,
+    typename BasicJsonType::value_type>::value and
+    is_detected<value_type_t, ConstructibleArrayType>::value and
+    is_detected<iterator_t, ConstructibleArrayType>::value and
+    is_complete_type<
+    detected_t<value_type_t, ConstructibleArrayType>>::value >>
+{
+    static constexpr bool value =
+        // This is needed because json_reverse_iterator has a ::iterator type,
+        // furthermore, std::back_insert_iterator (and other iterators) have a base class `iterator`...
+        // Therefore it is detected as a ConstructibleArrayType.
+        // The real fix would be to have an Iterable concept.
+        not is_iterator_traits <
+        iterator_traits<ConstructibleArrayType >>::value and
+
+        (std::is_same<typename ConstructibleArrayType::value_type, typename BasicJsonType::array_t::value_type>::value or
+         has_from_json<BasicJsonType,
+         typename ConstructibleArrayType::value_type>::value or
+         has_non_default_from_json <
+         BasicJsonType, typename ConstructibleArrayType::value_type >::value);
+};
+
+template <typename BasicJsonType, typename ConstructibleArrayType>
+struct is_constructible_array_type
+    : is_constructible_array_type_impl<BasicJsonType, ConstructibleArrayType> {};
+
+template <typename RealIntegerType, typename CompatibleNumberIntegerType,
+          typename = void>
+struct is_compatible_integer_type_impl : std::false_type {};
+
+template <typename RealIntegerType, typename CompatibleNumberIntegerType>
+struct is_compatible_integer_type_impl <
+    RealIntegerType, CompatibleNumberIntegerType,
+    enable_if_t<std::is_integral<RealIntegerType>::value and
+    std::is_integral<CompatibleNumberIntegerType>::value and
+    not std::is_same<bool, CompatibleNumberIntegerType>::value >>
+{
+    // is there an assert somewhere on overflows?
+    using RealLimits = std::numeric_limits<RealIntegerType>;
+    using CompatibleLimits = std::numeric_limits<CompatibleNumberIntegerType>;
+
+    static constexpr auto value =
+        std::is_constructible<RealIntegerType,
+        CompatibleNumberIntegerType>::value and
+        CompatibleLimits::is_integer and
+        RealLimits::is_signed == CompatibleLimits::is_signed;
+};
+
+template <typename RealIntegerType, typename CompatibleNumberIntegerType>
+struct is_compatible_integer_type
+    : is_compatible_integer_type_impl<RealIntegerType,
+      CompatibleNumberIntegerType> {};
+
+template <typename BasicJsonType, typename CompatibleType, typename = void>
+struct is_compatible_type_impl: std::false_type {};
+
+template <typename BasicJsonType, typename CompatibleType>
+struct is_compatible_type_impl <
+    BasicJsonType, CompatibleType,
+    enable_if_t<is_complete_type<CompatibleType>::value >>
+{
+    static constexpr bool value =
+        has_to_json<BasicJsonType, CompatibleType>::value;
 };
+
+template <typename BasicJsonType, typename CompatibleType>
+struct is_compatible_type
+    : is_compatible_type_impl<BasicJsonType, CompatibleType> {};
 }  // namespace detail
 }  // namespace nlohmann
 
@@ -1178,6 +1217,7 @@ class other_error : public exception
 #include <ciso646> // and
 #include <cstddef> // size_t
 #include <cstdint> // uint8_t
+#include <string> // string
 
 namespace nlohmann
 {
@@ -1249,32 +1289,6 @@ inline bool operator<(const value_t lhs, const value_t rhs) noexcept
 }  // namespace detail
 }  // namespace nlohmann
 
-// #include <nlohmann/detail/conversions/from_json.hpp>
-
-
-#include <algorithm> // transform
-#include <array> // array
-#include <ciso646> // and, not
-#include <forward_list> // forward_list
-#include <iterator> // inserter, front_inserter, end
-#include <map> // map
-#include <string> // string
-#include <tuple> // tuple, make_tuple
-#include <type_traits> // is_arithmetic, is_same, is_enum, underlying_type, is_convertible
-#include <unordered_map> // unordered_map
-#include <utility> // pair, declval
-#include <valarray> // valarray
-
-// #include <nlohmann/detail/exceptions.hpp>
-
-// #include <nlohmann/detail/macro_scope.hpp>
-
-// #include <nlohmann/detail/meta/cpp_future.hpp>
-
-// #include <nlohmann/detail/meta/type_traits.hpp>
-
-// #include <nlohmann/detail/value_t.hpp>
-
 
 namespace nlohmann
 {
@@ -1629,32 +1643,28 @@ constexpr const auto& from_json = detail::static_const<detail::from_json_fn>::va
 // #include <nlohmann/detail/conversions/to_json.hpp>
 
 
+#include <algorithm> // copy
 #include <ciso646> // or, and, not
 #include <iterator> // begin, end
+#include <string> // string
 #include <tuple> // tuple, get
 #include <type_traits> // is_same, is_constructible, is_floating_point, is_enum, underlying_type
 #include <utility> // move, forward, declval, pair
 #include <valarray> // valarray
 #include <vector> // vector
 
-// #include <nlohmann/detail/meta/cpp_future.hpp>
-
-// #include <nlohmann/detail/meta/type_traits.hpp>
-
-// #include <nlohmann/detail/value_t.hpp>
-
 // #include <nlohmann/detail/iterators/iteration_proxy.hpp>
 
 
 #include <cstddef> // size_t
-#include <string> // string, to_string
 #include <iterator> // input_iterator_tag
+#include <string> // string, to_string
 #include <tuple> // tuple_size, get, tuple_element
 
-// #include <nlohmann/detail/value_t.hpp>
-
 // #include <nlohmann/detail/meta/type_traits.hpp>
 
+// #include <nlohmann/detail/value_t.hpp>
+
 
 namespace nlohmann
 {
@@ -1700,13 +1710,13 @@ template <typename IteratorType> class iteration_proxy_value
     }
 
     /// equality operator (needed for InputIterator)
-    bool operator==(const iteration_proxy_value& o) const noexcept
+    bool operator==(const iteration_proxy_value& o) const
     {
         return anchor == o.anchor;
     }
 
     /// inequality operator (needed for range-based for)
-    bool operator!=(const iteration_proxy_value& o) const noexcept
+    bool operator!=(const iteration_proxy_value& o) const
     {
         return anchor != o.anchor;
     }
@@ -1795,6 +1805,11 @@ auto get(const nlohmann::detail::iteration_proxy_value<IteratorType>& i) -> decl
 // And see https://github.com/nlohmann/json/pull/1391
 namespace std
 {
+#if defined(__clang__)
+    // Fix: https://github.com/nlohmann/json/issues/1401
+    #pragma clang diagnostic push
+    #pragma clang diagnostic ignored "-Wmismatched-tags"
+#endif
 template <typename IteratorType>
 class tuple_size<::nlohmann::detail::iteration_proxy_value<IteratorType>>
             : public std::integral_constant<std::size_t, 2> {};
@@ -1807,7 +1822,17 @@ class tuple_element<N, ::nlohmann::detail::iteration_proxy_value<IteratorType >>
                      get<N>(std::declval <
                             ::nlohmann::detail::iteration_proxy_value<IteratorType >> ()));
 };
-}
+#if defined(__clang__)
+    #pragma clang diagnostic pop
+#endif
+} // namespace std
+
+// #include <nlohmann/detail/meta/cpp_future.hpp>
+
+// #include <nlohmann/detail/meta/type_traits.hpp>
+
+// #include <nlohmann/detail/value_t.hpp>
+
 
 namespace nlohmann
 {
@@ -2137,11 +2162,81 @@ constexpr const auto& to_json = detail::static_const<detail::to_json_fn>::value;
 } // namespace
 }  // namespace nlohmann
 
+
+namespace nlohmann
+{
+
+template<typename, typename>
+struct adl_serializer
+{
+    /*!
+    @brief convert a JSON value to any value type
+
+    This function is usually called by the `get()` function of the
+    @ref basic_json class (either explicit or via conversion operators).
+
+    @param[in] j        JSON value to read from
+    @param[in,out] val  value to write to
+    */
+    template<typename BasicJsonType, typename ValueType>
+    static auto from_json(BasicJsonType&& j, ValueType& val) noexcept(
+        noexcept(::nlohmann::from_json(std::forward<BasicJsonType>(j), val)))
+    -> decltype(::nlohmann::from_json(std::forward<BasicJsonType>(j), val), void())
+    {
+        ::nlohmann::from_json(std::forward<BasicJsonType>(j), val);
+    }
+
+    /*!
+    @brief convert any value type to a JSON value
+
+    This function is usually called by the constructors of the @ref basic_json
+    class.
+
+    @param[in,out] j  JSON value to write to
+    @param[in] val    value to read from
+    */
+    template <typename BasicJsonType, typename ValueType>
+    static auto to_json(BasicJsonType& j, ValueType&& val) noexcept(
+        noexcept(::nlohmann::to_json(j, std::forward<ValueType>(val))))
+    -> decltype(::nlohmann::to_json(j, std::forward<ValueType>(val)), void())
+    {
+        ::nlohmann::to_json(j, std::forward<ValueType>(val));
+    }
+};
+
+}  // namespace nlohmann
+
+// #include <nlohmann/detail/conversions/from_json.hpp>
+
+// #include <nlohmann/detail/conversions/to_json.hpp>
+
+// #include <nlohmann/detail/exceptions.hpp>
+
+// #include <nlohmann/detail/input/binary_reader.hpp>
+
+
+#include <algorithm> // generate_n
+#include <array> // array
+#include <cassert> // assert
+#include <cmath> // ldexp
+#include <cstddef> // size_t
+#include <cstdint> // uint8_t, uint16_t, uint32_t, uint64_t
+#include <cstdio> // snprintf
+#include <cstring> // memcpy
+#include <iterator> // back_inserter
+#include <limits> // numeric_limits
+#include <string> // char_traits, string
+#include <utility> // make_pair, move
+
+// #include <nlohmann/detail/exceptions.hpp>
+
 // #include <nlohmann/detail/input/input_adapters.hpp>
 
 
+#include <array> // array
 #include <cassert> // assert
 #include <cstddef> // size_t
+#include <cstdio> //FILE *
 #include <cstring> // strlen
 #include <istream> // istream
 #include <iterator> // begin, end, iterator_traits, random_access_iterator_tag, distance, next
@@ -2150,7 +2245,8 @@ constexpr const auto& to_json = detail::static_const<detail::to_json_fn>::value;
 #include <string> // string, char_traits
 #include <type_traits> // enable_if, is_base_of, is_pointer, is_integral, remove_pointer
 #include <utility> // pair, declval
-#include <cstdio> //FILE *
+
+// #include <nlohmann/detail/iterators/iterator_traits.hpp>
 
 // #include <nlohmann/detail/macro_scope.hpp>
 
@@ -2198,10 +2294,18 @@ class file_input_adapter : public input_adapter_protocol
         : m_file(f)
     {}
 
+    // make class move-only
+    file_input_adapter(const file_input_adapter&) = delete;
+    file_input_adapter(file_input_adapter&&) = default;
+    file_input_adapter& operator=(const file_input_adapter&) = delete;
+    file_input_adapter& operator=(file_input_adapter&&) = default;
+    ~file_input_adapter() override = default;
+
     std::char_traits<char>::int_type get_character() noexcept override
     {
         return std::fgetc(m_file);
     }
+
   private:
     /// the file pointer to read from
     std::FILE* m_file;
@@ -2293,7 +2397,11 @@ template<typename WideStringType, size_t T>
 struct wide_string_input_helper
 {
     // UTF-32
-    static void fill_buffer(const WideStringType& str, size_t& current_wchar, std::array<std::char_traits<char>::int_type, 4>& utf8_bytes, size_t& utf8_bytes_index, size_t& utf8_bytes_filled)
+    static void fill_buffer(const WideStringType& str,
+                            size_t& current_wchar,
+                            std::array<std::char_traits<char>::int_type, 4>& utf8_bytes,
+                            size_t& utf8_bytes_index,
+                            size_t& utf8_bytes_filled)
     {
         utf8_bytes_index = 0;
 
@@ -2305,39 +2413,39 @@ struct wide_string_input_helper
         else
         {
             // get the current character
-            const auto wc = static_cast<int>(str[current_wchar++]);
+            const auto wc = static_cast<unsigned int>(str[current_wchar++]);
 
             // UTF-32 to UTF-8 encoding
             if (wc < 0x80)
             {
-                utf8_bytes[0] = wc;
+                utf8_bytes[0] = static_cast<std::char_traits<char>::int_type>(wc);
                 utf8_bytes_filled = 1;
             }
             else if (wc <= 0x7FF)
             {
-                utf8_bytes[0] = 0xC0 | ((wc >> 6) & 0x1F);
-                utf8_bytes[1] = 0x80 | (wc & 0x3F);
+                utf8_bytes[0] = static_cast<std::char_traits<char>::int_type>(0xC0u | ((wc >> 6u) & 0x1Fu));
+                utf8_bytes[1] = static_cast<std::char_traits<char>::int_type>(0x80u | (wc & 0x3Fu));
                 utf8_bytes_filled = 2;
             }
             else if (wc <= 0xFFFF)
             {
-                utf8_bytes[0] = 0xE0 | ((wc >> 12) & 0x0F);
-                utf8_bytes[1] = 0x80 | ((wc >> 6) & 0x3F);
-                utf8_bytes[2] = 0x80 | (wc & 0x3F);
+                utf8_bytes[0] = static_cast<std::char_traits<char>::int_type>(0xE0u | ((wc >> 12u) & 0x0Fu));
+                utf8_bytes[1] = static_cast<std::char_traits<char>::int_type>(0x80u | ((wc >> 6u) & 0x3Fu));
+                utf8_bytes[2] = static_cast<std::char_traits<char>::int_type>(0x80u | (wc & 0x3Fu));
                 utf8_bytes_filled = 3;
             }
             else if (wc <= 0x10FFFF)
             {
-                utf8_bytes[0] = 0xF0 | ((wc >> 18) & 0x07);
-                utf8_bytes[1] = 0x80 | ((wc >> 12) & 0x3F);
-                utf8_bytes[2] = 0x80 | ((wc >> 6) & 0x3F);
-                utf8_bytes[3] = 0x80 | (wc & 0x3F);
+                utf8_bytes[0] = static_cast<std::char_traits<char>::int_type>(0xF0u | ((wc >> 18u) & 0x07u));
+                utf8_bytes[1] = static_cast<std::char_traits<char>::int_type>(0x80u | ((wc >> 12u) & 0x3Fu));
+                utf8_bytes[2] = static_cast<std::char_traits<char>::int_type>(0x80u | ((wc >> 6u) & 0x3Fu));
+                utf8_bytes[3] = static_cast<std::char_traits<char>::int_type>(0x80u | (wc & 0x3Fu));
                 utf8_bytes_filled = 4;
             }
             else
             {
                 // unknown character
-                utf8_bytes[0] = wc;
+                utf8_bytes[0] = static_cast<std::char_traits<char>::int_type>(wc);
                 utf8_bytes_filled = 1;
             }
         }
@@ -2348,7 +2456,11 @@ template<typename WideStringType>
 struct wide_string_input_helper<WideStringType, 2>
 {
     // UTF-16
-    static void fill_buffer(const WideStringType& str, size_t& current_wchar, std::array<std::char_traits<char>::int_type, 4>& utf8_bytes, size_t& utf8_bytes_index, size_t& utf8_bytes_filled)
+    static void fill_buffer(const WideStringType& str,
+                            size_t& current_wchar,
+                            std::array<std::char_traits<char>::int_type, 4>& utf8_bytes,
+                            size_t& utf8_bytes_index,
+                            size_t& utf8_bytes_filled)
     {
         utf8_bytes_index = 0;
 
@@ -2360,44 +2472,44 @@ struct wide_string_input_helper<WideStringType, 2>
         else
         {
             // get the current character
-            const auto wc = static_cast<int>(str[current_wchar++]);
+            const auto wc = static_cast<unsigned int>(str[current_wchar++]);
 
             // UTF-16 to UTF-8 encoding
             if (wc < 0x80)
             {
-                utf8_bytes[0] = wc;
+                utf8_bytes[0] = static_cast<std::char_traits<char>::int_type>(wc);
                 utf8_bytes_filled = 1;
             }
             else if (wc <= 0x7FF)
             {
-                utf8_bytes[0] = 0xC0 | ((wc >> 6));
-                utf8_bytes[1] = 0x80 | (wc & 0x3F);
+                utf8_bytes[0] = static_cast<std::char_traits<char>::int_type>(0xC0u | ((wc >> 6u)));
+                utf8_bytes[1] = static_cast<std::char_traits<char>::int_type>(0x80u | (wc & 0x3Fu));
                 utf8_bytes_filled = 2;
             }
             else if (0xD800 > wc or wc >= 0xE000)
             {
-                utf8_bytes[0] = 0xE0 | ((wc >> 12));
-                utf8_bytes[1] = 0x80 | ((wc >> 6) & 0x3F);
-                utf8_bytes[2] = 0x80 | (wc & 0x3F);
+                utf8_bytes[0] = static_cast<std::char_traits<char>::int_type>(0xE0u | ((wc >> 12u)));
+                utf8_bytes[1] = static_cast<std::char_traits<char>::int_type>(0x80u | ((wc >> 6u) & 0x3Fu));
+                utf8_bytes[2] = static_cast<std::char_traits<char>::int_type>(0x80u | (wc & 0x3Fu));
                 utf8_bytes_filled = 3;
             }
             else
             {
                 if (current_wchar < str.size())
                 {
-                    const auto wc2 = static_cast<int>(str[current_wchar++]);
-                    const int charcode = 0x10000 + (((wc & 0x3FF) << 10) | (wc2 & 0x3FF));
-                    utf8_bytes[0] = 0xf0 | (charcode >> 18);
-                    utf8_bytes[1] = 0x80 | ((charcode >> 12) & 0x3F);
-                    utf8_bytes[2] = 0x80 | ((charcode >> 6) & 0x3F);
-                    utf8_bytes[3] = 0x80 | (charcode & 0x3F);
+                    const auto wc2 = static_cast<unsigned int>(str[current_wchar++]);
+                    const auto charcode = 0x10000u + (((wc & 0x3FFu) << 10u) | (wc2 & 0x3FFu));
+                    utf8_bytes[0] = static_cast<std::char_traits<char>::int_type>(0xF0u | (charcode >> 18u));
+                    utf8_bytes[1] = static_cast<std::char_traits<char>::int_type>(0x80u | ((charcode >> 12u) & 0x3Fu));
+                    utf8_bytes[2] = static_cast<std::char_traits<char>::int_type>(0x80u | ((charcode >> 6u) & 0x3Fu));
+                    utf8_bytes[3] = static_cast<std::char_traits<char>::int_type>(0x80u | (charcode & 0x3Fu));
                     utf8_bytes_filled = 4;
                 }
                 else
                 {
                     // unknown character
                     ++current_wchar;
-                    utf8_bytes[0] = wc;
+                    utf8_bytes[0] = static_cast<std::char_traits<char>::int_type>(wc);
                     utf8_bytes_filled = 1;
                 }
             }
@@ -2409,7 +2521,7 @@ template<typename WideStringType>
 class wide_string_input_adapter : public input_adapter_protocol
 {
   public:
-    explicit wide_string_input_adapter(const WideStringType& w)  noexcept
+    explicit wide_string_input_adapter(const WideStringType& w) noexcept
         : str(w)
     {}
 
@@ -2561,9894 +2673,10169 @@ class input_adapter
 }  // namespace detail
 }  // namespace nlohmann
 
-// #include <nlohmann/detail/input/lexer.hpp>
+// #include <nlohmann/detail/input/json_sax.hpp>
 
 
-#include <clocale> // localeconv
-#include <cstddef> // size_t
-#include <cstdlib> // strtof, strtod, strtold, strtoll, strtoull
-#include <cstdio> // snprintf
-#include <initializer_list> // initializer_list
-#include <string> // char_traits, string
+#include <cassert> // assert
+#include <cstddef>
+#include <string> // string
+#include <utility> // move
 #include <vector> // vector
 
-// #include <nlohmann/detail/macro_scope.hpp>
-
-// #include <nlohmann/detail/input/input_adapters.hpp>
+// #include <nlohmann/detail/exceptions.hpp>
 
-// #include <nlohmann/detail/input/position_t.hpp>
+// #include <nlohmann/detail/macro_scope.hpp>
 
 
 namespace nlohmann
 {
-namespace detail
-{
-///////////
-// lexer //
-///////////
 
 /*!
-@brief lexical analysis
+@brief SAX interface
 
-This class organizes the lexical analysis during JSON deserialization.
+This class describes the SAX interface used by @ref nlohmann::json::sax_parse.
+Each function is called in different situations while the input is parsed. The
+boolean return value informs the parser whether to continue processing the
+input.
 */
 template<typename BasicJsonType>
-class lexer
+struct json_sax
 {
+    /// type for (signed) integers
     using number_integer_t = typename BasicJsonType::number_integer_t;
+    /// type for unsigned integers
     using number_unsigned_t = typename BasicJsonType::number_unsigned_t;
+    /// type for floating-point numbers
     using number_float_t = typename BasicJsonType::number_float_t;
+    /// type for strings
     using string_t = typename BasicJsonType::string_t;
 
-  public:
-    /// token types for the parser
-    enum class token_type
-    {
-        uninitialized,    ///< indicating the scanner is uninitialized
-        literal_true,     ///< the `true` literal
-        literal_false,    ///< the `false` literal
-        literal_null,     ///< the `null` literal
-        value_string,     ///< a string -- use get_string() for actual value
-        value_unsigned,   ///< an unsigned integer -- use get_number_unsigned() for actual value
-        value_integer,    ///< a signed integer -- use get_number_integer() for actual value
-        value_float,      ///< an floating point number -- use get_number_float() for actual value
-        begin_array,      ///< the character for array begin `[`
-        begin_object,     ///< the character for object begin `{`
-        end_array,        ///< the character for array end `]`
-        end_object,       ///< the character for object end `}`
-        name_separator,   ///< the name separator `:`
-        value_separator,  ///< the value separator `,`
-        parse_error,      ///< indicating a parse error
-        end_of_input,     ///< indicating the end of the input buffer
-        literal_or_value  ///< a literal or the begin of a value (only for diagnostics)
-    };
-
-    /// return name of values of type token_type (only used for errors)
-    static const char* token_type_name(const token_type t) noexcept
-    {
-        switch (t)
-        {
-            case token_type::uninitialized:
-                return "<uninitialized>";
-            case token_type::literal_true:
-                return "true literal";
-            case token_type::literal_false:
-                return "false literal";
-            case token_type::literal_null:
-                return "null literal";
-            case token_type::value_string:
-                return "string literal";
-            case lexer::token_type::value_unsigned:
-            case lexer::token_type::value_integer:
-            case lexer::token_type::value_float:
-                return "number literal";
-            case token_type::begin_array:
-                return "'['";
-            case token_type::begin_object:
-                return "'{'";
-            case token_type::end_array:
-                return "']'";
-            case token_type::end_object:
-                return "'}'";
-            case token_type::name_separator:
-                return "':'";
-            case token_type::value_separator:
-                return "','";
-            case token_type::parse_error:
-                return "<parse error>";
-            case token_type::end_of_input:
-                return "end of input";
-            case token_type::literal_or_value:
-                return "'[', '{', or a literal";
-            // LCOV_EXCL_START
-            default: // catch non-enum values
-                return "unknown token";
-                // LCOV_EXCL_STOP
-        }
-    }
+    /*!
+    @brief a null value was read
+    @return whether parsing should proceed
+    */
+    virtual bool null() = 0;
 
-    explicit lexer(detail::input_adapter_t&& adapter)
-        : ia(std::move(adapter)), decimal_point_char(get_decimal_point()) {}
+    /*!
+    @brief a boolean value was read
+    @param[in] val  boolean value
+    @return whether parsing should proceed
+    */
+    virtual bool boolean(bool val) = 0;
 
-    // delete because of pointer members
-    lexer(const lexer&) = delete;
-    lexer(lexer&&) = delete;
-    lexer& operator=(lexer&) = delete;
-    lexer& operator=(lexer&&) = delete;
-    ~lexer() = default;
+    /*!
+    @brief an integer number was read
+    @param[in] val  integer value
+    @return whether parsing should proceed
+    */
+    virtual bool number_integer(number_integer_t val) = 0;
 
-  private:
-    /////////////////////
-    // locales
-    /////////////////////
+    /*!
+    @brief an unsigned integer number was read
+    @param[in] val  unsigned integer value
+    @return whether parsing should proceed
+    */
+    virtual bool number_unsigned(number_unsigned_t val) = 0;
 
-    /// return the locale-dependent decimal point
-    static char get_decimal_point() noexcept
-    {
-        const auto loc = localeconv();
-        assert(loc != nullptr);
-        return (loc->decimal_point == nullptr) ? '.' : *(loc->decimal_point);
-    }
+    /*!
+    @brief an floating-point number was read
+    @param[in] val  floating-point value
+    @param[in] s    raw token value
+    @return whether parsing should proceed
+    */
+    virtual bool number_float(number_float_t val, const string_t& s) = 0;
 
-    /////////////////////
-    // scan functions
-    /////////////////////
+    /*!
+    @brief a string was read
+    @param[in] val  string value
+    @return whether parsing should proceed
+    @note It is safe to move the passed string.
+    */
+    virtual bool string(string_t& val) = 0;
 
     /*!
-    @brief get codepoint from 4 hex characters following `\u`
+    @brief the beginning of an object was read
+    @param[in] elements  number of object elements or -1 if unknown
+    @return whether parsing should proceed
+    @note binary formats may report the number of elements
+    */
+    virtual bool start_object(std::size_t elements) = 0;
 
-    For input "\u c1 c2 c3 c4" the codepoint is:
-      (c1 * 0x1000) + (c2 * 0x0100) + (c3 * 0x0010) + c4
-    = (c1 << 12) + (c2 << 8) + (c3 << 4) + (c4 << 0)
+    /*!
+    @brief an object key was read
+    @param[in] val  object key
+    @return whether parsing should proceed
+    @note It is safe to move the passed string.
+    */
+    virtual bool key(string_t& val) = 0;
 
-    Furthermore, the possible characters '0'..'9', 'A'..'F', and 'a'..'f'
-    must be converted to the integers 0x0..0x9, 0xA..0xF, 0xA..0xF, resp. The
-    conversion is done by subtracting the offset (0x30, 0x37, and 0x57)
-    between the ASCII value of the character and the desired integer value.
+    /*!
+    @brief the end of an object was read
+    @return whether parsing should proceed
+    */
+    virtual bool end_object() = 0;
 
-    @return codepoint (0x0000..0xFFFF) or -1 in case of an error (e.g. EOF or
-            non-hex character)
+    /*!
+    @brief the beginning of an array was read
+    @param[in] elements  number of array elements or -1 if unknown
+    @return whether parsing should proceed
+    @note binary formats may report the number of elements
     */
-    int get_codepoint()
-    {
-        // this function only makes sense after reading `\u`
-        assert(current == 'u');
-        int codepoint = 0;
+    virtual bool start_array(std::size_t elements) = 0;
 
-        const auto factors = { 12, 8, 4, 0 };
-        for (const auto factor : factors)
-        {
-            get();
+    /*!
+    @brief the end of an array was read
+    @return whether parsing should proceed
+    */
+    virtual bool end_array() = 0;
 
-            if (current >= '0' and current <= '9')
-            {
-                codepoint += ((current - 0x30) << factor);
-            }
-            else if (current >= 'A' and current <= 'F')
-            {
-                codepoint += ((current - 0x37) << factor);
-            }
-            else if (current >= 'a' and current <= 'f')
-            {
-                codepoint += ((current - 0x57) << factor);
-            }
-            else
-            {
-                return -1;
-            }
-        }
+    /*!
+    @brief a parse error occurred
+    @param[in] position    the position in the input where the error occurs
+    @param[in] last_token  the last read token
+    @param[in] ex          an exception object describing the error
+    @return whether parsing should proceed (must return false)
+    */
+    virtual bool parse_error(std::size_t position,
+                             const std::string& last_token,
+                             const detail::exception& ex) = 0;
 
-        assert(0x0000 <= codepoint and codepoint <= 0xFFFF);
-        return codepoint;
-    }
+    virtual ~json_sax() = default;
+};
 
-    /*!
-    @brief check if the next byte(s) are inside a given range
 
-    Adds the current byte and, for each passed range, reads a new byte and
-    checks if it is inside the range. If a violation was detected, set up an
-    error message and return false. Otherwise, return true.
+namespace detail
+{
+/*!
+@brief SAX implementation to create a JSON value from SAX events
 
-    @param[in] ranges  list of integers; interpreted as list of pairs of
-                       inclusive lower and upper bound, respectively
+This class implements the @ref json_sax interface and processes the SAX events
+to create a JSON value which makes it basically a DOM parser. The structure or
+hierarchy of the JSON value is managed by the stack `ref_stack` which contains
+a pointer to the respective array or object for each recursion depth.
 
-    @pre The passed list @a ranges must have 2, 4, or 6 elements; that is,
-         1, 2, or 3 pairs. This precondition is enforced by an assertion.
+After successful parsing, the value that is passed by reference to the
+constructor contains the parsed value.
 
-    @return true if and only if no range violation was detected
+@tparam BasicJsonType  the JSON type
+*/
+template<typename BasicJsonType>
+class json_sax_dom_parser
+{
+  public:
+    using number_integer_t = typename BasicJsonType::number_integer_t;
+    using number_unsigned_t = typename BasicJsonType::number_unsigned_t;
+    using number_float_t = typename BasicJsonType::number_float_t;
+    using string_t = typename BasicJsonType::string_t;
+
+    /*!
+    @param[in, out] r  reference to a JSON value that is manipulated while
+                       parsing
+    @param[in] allow_exceptions_  whether parse errors yield exceptions
     */
-    bool next_byte_in_range(std::initializer_list<int> ranges)
-    {
-        assert(ranges.size() == 2 or ranges.size() == 4 or ranges.size() == 6);
-        add(current);
+    explicit json_sax_dom_parser(BasicJsonType& r, const bool allow_exceptions_ = true)
+        : root(r), allow_exceptions(allow_exceptions_)
+    {}
 
-        for (auto range = ranges.begin(); range != ranges.end(); ++range)
-        {
-            get();
-            if (JSON_LIKELY(*range <= current and current <= *(++range)))
-            {
-                add(current);
-            }
-            else
-            {
-                error_message = "invalid string: ill-formed UTF-8 byte";
-                return false;
-            }
-        }
+    // make class move-only
+    json_sax_dom_parser(const json_sax_dom_parser&) = delete;
+    json_sax_dom_parser(json_sax_dom_parser&&) = default;
+    json_sax_dom_parser& operator=(const json_sax_dom_parser&) = delete;
+    json_sax_dom_parser& operator=(json_sax_dom_parser&&) = default;
+    ~json_sax_dom_parser() = default;
 
+    bool null()
+    {
+        handle_value(nullptr);
         return true;
     }
 
-    /*!
-    @brief scan a string literal
+    bool boolean(bool val)
+    {
+        handle_value(val);
+        return true;
+    }
 
-    This function scans a string according to Sect. 7 of RFC 7159. While
-    scanning, bytes are escaped and copied into buffer token_buffer. Then the
-    function returns successfully, token_buffer is *not* null-terminated (as it
-    may contain \0 bytes), and token_buffer.size() is the number of bytes in the
-    string.
+    bool number_integer(number_integer_t val)
+    {
+        handle_value(val);
+        return true;
+    }
 
-    @return token_type::value_string if string could be successfully scanned,
-            token_type::parse_error otherwise
+    bool number_unsigned(number_unsigned_t val)
+    {
+        handle_value(val);
+        return true;
+    }
 
-    @note In case of errors, variable error_message contains a textual
-          description.
-    */
-    token_type scan_string()
+    bool number_float(number_float_t val, const string_t& /*unused*/)
     {
-        // reset token_buffer (ignore opening quote)
-        reset();
+        handle_value(val);
+        return true;
+    }
 
-        // we entered the function by reading an open quote
-        assert(current == '\"');
+    bool string(string_t& val)
+    {
+        handle_value(val);
+        return true;
+    }
 
-        while (true)
+    bool start_object(std::size_t len)
+    {
+        ref_stack.push_back(handle_value(BasicJsonType::value_t::object));
+
+        if (JSON_UNLIKELY(len != std::size_t(-1) and len > ref_stack.back()->max_size()))
         {
-            // get next character
-            switch (get())
-            {
-                // end of file while parsing string
-                case std::char_traits<char>::eof():
-                {
-                    error_message = "invalid string: missing closing quote";
-                    return token_type::parse_error;
-                }
+            JSON_THROW(out_of_range::create(408,
+                                            "excessive object size: " + std::to_string(len)));
+        }
 
-                // closing quote
-                case '\"':
-                {
-                    return token_type::value_string;
-                }
+        return true;
+    }
 
-                // escapes
-                case '\\':
-                {
-                    switch (get())
-                    {
-                        // quotation mark
-                        case '\"':
-                            add('\"');
-                            break;
-                        // reverse solidus
-                        case '\\':
-                            add('\\');
-                            break;
-                        // solidus
-                        case '/':
-                            add('/');
-                            break;
-                        // backspace
-                        case 'b':
-                            add('\b');
-                            break;
-                        // form feed
-                        case 'f':
-                            add('\f');
-                            break;
-                        // line feed
-                        case 'n':
-                            add('\n');
-                            break;
-                        // carriage return
-                        case 'r':
-                            add('\r');
-                            break;
-                        // tab
-                        case 't':
-                            add('\t');
-                            break;
+    bool key(string_t& val)
+    {
+        // add null at given key and store the reference for later
+        object_element = &(ref_stack.back()->m_value.object->operator[](val));
+        return true;
+    }
 
-                        // unicode escapes
-                        case 'u':
-                        {
-                            const int codepoint1 = get_codepoint();
-                            int codepoint = codepoint1; // start with codepoint1
+    bool end_object()
+    {
+        ref_stack.pop_back();
+        return true;
+    }
 
-                            if (JSON_UNLIKELY(codepoint1 == -1))
-                            {
-                                error_message = "invalid string: '\\u' must be followed by 4 hex digits";
-                                return token_type::parse_error;
-                            }
+    bool start_array(std::size_t len)
+    {
+        ref_stack.push_back(handle_value(BasicJsonType::value_t::array));
 
-                            // check if code point is a high surrogate
-                            if (0xD800 <= codepoint1 and codepoint1 <= 0xDBFF)
-                            {
-                                // expect next \uxxxx entry
-                                if (JSON_LIKELY(get() == '\\' and get() == 'u'))
-                                {
-                                    const int codepoint2 = get_codepoint();
+        if (JSON_UNLIKELY(len != std::size_t(-1) and len > ref_stack.back()->max_size()))
+        {
+            JSON_THROW(out_of_range::create(408,
+                                            "excessive array size: " + std::to_string(len)));
+        }
 
-                                    if (JSON_UNLIKELY(codepoint2 == -1))
-                                    {
-                                        error_message = "invalid string: '\\u' must be followed by 4 hex digits";
-                                        return token_type::parse_error;
-                                    }
+        return true;
+    }
 
-                                    // check if codepoint2 is a low surrogate
-                                    if (JSON_LIKELY(0xDC00 <= codepoint2 and codepoint2 <= 0xDFFF))
-                                    {
-                                        // overwrite codepoint
-                                        codepoint =
-                                            // high surrogate occupies the most significant 22 bits
-                                            (codepoint1 << 10)
-                                            // low surrogate occupies the least significant 15 bits
-                                            + codepoint2
-                                            // there is still the 0xD800, 0xDC00 and 0x10000 noise
-                                            // in the result so we have to subtract with:
-                                            // (0xD800 << 10) + DC00 - 0x10000 = 0x35FDC00
-                                            - 0x35FDC00;
-                                    }
-                                    else
-                                    {
-                                        error_message = "invalid string: surrogate U+DC00..U+DFFF must be followed by U+DC00..U+DFFF";
-                                        return token_type::parse_error;
-                                    }
-                                }
-                                else
-                                {
-                                    error_message = "invalid string: surrogate U+DC00..U+DFFF must be followed by U+DC00..U+DFFF";
-                                    return token_type::parse_error;
-                                }
-                            }
-                            else
-                            {
-                                if (JSON_UNLIKELY(0xDC00 <= codepoint1 and codepoint1 <= 0xDFFF))
-                                {
-                                    error_message = "invalid string: surrogate U+DC00..U+DFFF must follow U+D800..U+DBFF";
-                                    return token_type::parse_error;
-                                }
-                            }
+    bool end_array()
+    {
+        ref_stack.pop_back();
+        return true;
+    }
 
-                            // result of the above calculation yields a proper codepoint
-                            assert(0x00 <= codepoint and codepoint <= 0x10FFFF);
+    bool parse_error(std::size_t /*unused*/, const std::string& /*unused*/,
+                     const detail::exception& ex)
+    {
+        errored = true;
+        if (allow_exceptions)
+        {
+            // determine the proper exception type from the id
+            switch ((ex.id / 100) % 100)
+            {
+                case 1:
+                    JSON_THROW(*static_cast<const detail::parse_error*>(&ex));
+                case 4:
+                    JSON_THROW(*static_cast<const detail::out_of_range*>(&ex));
+                // LCOV_EXCL_START
+                case 2:
+                    JSON_THROW(*static_cast<const detail::invalid_iterator*>(&ex));
+                case 3:
+                    JSON_THROW(*static_cast<const detail::type_error*>(&ex));
+                case 5:
+                    JSON_THROW(*static_cast<const detail::other_error*>(&ex));
+                default:
+                    assert(false);
+                    // LCOV_EXCL_STOP
+            }
+        }
+        return false;
+    }
 
-                            // translate codepoint into bytes
-                            if (codepoint < 0x80)
-                            {
-                                // 1-byte characters: 0xxxxxxx (ASCII)
-                                add(codepoint);
-                            }
-                            else if (codepoint <= 0x7FF)
-                            {
-                                // 2-byte characters: 110xxxxx 10xxxxxx
-                                add(0xC0 | (codepoint >> 6));
-                                add(0x80 | (codepoint & 0x3F));
-                            }
-                            else if (codepoint <= 0xFFFF)
-                            {
-                                // 3-byte characters: 1110xxxx 10xxxxxx 10xxxxxx
-                                add(0xE0 | (codepoint >> 12));
-                                add(0x80 | ((codepoint >> 6) & 0x3F));
-                                add(0x80 | (codepoint & 0x3F));
-                            }
-                            else
-                            {
-                                // 4-byte characters: 11110xxx 10xxxxxx 10xxxxxx 10xxxxxx
-                                add(0xF0 | (codepoint >> 18));
-                                add(0x80 | ((codepoint >> 12) & 0x3F));
-                                add(0x80 | ((codepoint >> 6) & 0x3F));
-                                add(0x80 | (codepoint & 0x3F));
-                            }
+    constexpr bool is_errored() const
+    {
+        return errored;
+    }
 
-                            break;
-                        }
+  private:
+    /*!
+    @invariant If the ref stack is empty, then the passed value will be the new
+               root.
+    @invariant If the ref stack contains a value, then it is an array or an
+               object to which we can add elements
+    */
+    template<typename Value>
+    BasicJsonType* handle_value(Value&& v)
+    {
+        if (ref_stack.empty())
+        {
+            root = BasicJsonType(std::forward<Value>(v));
+            return &root;
+        }
 
-                        // other characters after escape
-                        default:
-                            error_message = "invalid string: forbidden character after backslash";
-                            return token_type::parse_error;
-                    }
+        assert(ref_stack.back()->is_array() or ref_stack.back()->is_object());
 
-                    break;
-                }
+        if (ref_stack.back()->is_array())
+        {
+            ref_stack.back()->m_value.array->emplace_back(std::forward<Value>(v));
+            return &(ref_stack.back()->m_value.array->back());
+        }
 
-                // invalid control characters
-                case 0x00:
-                {
-                    error_message = "invalid string: control character U+0000 (NUL) must be escaped to \\u0000";
-                    return token_type::parse_error;
-                }
+        assert(ref_stack.back()->is_object());
+        assert(object_element);
+        *object_element = BasicJsonType(std::forward<Value>(v));
+        return object_element;
+    }
 
-                case 0x01:
-                {
-                    error_message = "invalid string: control character U+0001 (SOH) must be escaped to \\u0001";
-                    return token_type::parse_error;
-                }
+    /// the parsed JSON value
+    BasicJsonType& root;
+    /// stack to model hierarchy of values
+    std::vector<BasicJsonType*> ref_stack {};
+    /// helper to hold the reference for the next object element
+    BasicJsonType* object_element = nullptr;
+    /// whether a syntax error occurred
+    bool errored = false;
+    /// whether to throw exceptions in case of errors
+    const bool allow_exceptions = true;
+};
 
-                case 0x02:
-                {
-                    error_message = "invalid string: control character U+0002 (STX) must be escaped to \\u0002";
-                    return token_type::parse_error;
-                }
+template<typename BasicJsonType>
+class json_sax_dom_callback_parser
+{
+  public:
+    using number_integer_t = typename BasicJsonType::number_integer_t;
+    using number_unsigned_t = typename BasicJsonType::number_unsigned_t;
+    using number_float_t = typename BasicJsonType::number_float_t;
+    using string_t = typename BasicJsonType::string_t;
+    using parser_callback_t = typename BasicJsonType::parser_callback_t;
+    using parse_event_t = typename BasicJsonType::parse_event_t;
 
-                case 0x03:
-                {
-                    error_message = "invalid string: control character U+0003 (ETX) must be escaped to \\u0003";
-                    return token_type::parse_error;
-                }
+    json_sax_dom_callback_parser(BasicJsonType& r,
+                                 const parser_callback_t cb,
+                                 const bool allow_exceptions_ = true)
+        : root(r), callback(cb), allow_exceptions(allow_exceptions_)
+    {
+        keep_stack.push_back(true);
+    }
 
-                case 0x04:
-                {
-                    error_message = "invalid string: control character U+0004 (EOT) must be escaped to \\u0004";
-                    return token_type::parse_error;
-                }
+    // make class move-only
+    json_sax_dom_callback_parser(const json_sax_dom_callback_parser&) = delete;
+    json_sax_dom_callback_parser(json_sax_dom_callback_parser&&) = default;
+    json_sax_dom_callback_parser& operator=(const json_sax_dom_callback_parser&) = delete;
+    json_sax_dom_callback_parser& operator=(json_sax_dom_callback_parser&&) = default;
+    ~json_sax_dom_callback_parser() = default;
 
-                case 0x05:
-                {
-                    error_message = "invalid string: control character U+0005 (ENQ) must be escaped to \\u0005";
-                    return token_type::parse_error;
-                }
+    bool null()
+    {
+        handle_value(nullptr);
+        return true;
+    }
 
-                case 0x06:
-                {
-                    error_message = "invalid string: control character U+0006 (ACK) must be escaped to \\u0006";
-                    return token_type::parse_error;
-                }
+    bool boolean(bool val)
+    {
+        handle_value(val);
+        return true;
+    }
 
-                case 0x07:
-                {
-                    error_message = "invalid string: control character U+0007 (BEL) must be escaped to \\u0007";
-                    return token_type::parse_error;
-                }
+    bool number_integer(number_integer_t val)
+    {
+        handle_value(val);
+        return true;
+    }
 
-                case 0x08:
-                {
-                    error_message = "invalid string: control character U+0008 (BS) must be escaped to \\u0008 or \\b";
-                    return token_type::parse_error;
-                }
+    bool number_unsigned(number_unsigned_t val)
+    {
+        handle_value(val);
+        return true;
+    }
 
-                case 0x09:
-                {
-                    error_message = "invalid string: control character U+0009 (HT) must be escaped to \\u0009 or \\t";
-                    return token_type::parse_error;
-                }
+    bool number_float(number_float_t val, const string_t& /*unused*/)
+    {
+        handle_value(val);
+        return true;
+    }
 
-                case 0x0A:
-                {
-                    error_message = "invalid string: control character U+000A (LF) must be escaped to \\u000A or \\n";
-                    return token_type::parse_error;
-                }
+    bool string(string_t& val)
+    {
+        handle_value(val);
+        return true;
+    }
 
-                case 0x0B:
-                {
-                    error_message = "invalid string: control character U+000B (VT) must be escaped to \\u000B";
-                    return token_type::parse_error;
-                }
+    bool start_object(std::size_t len)
+    {
+        // check callback for object start
+        const bool keep = callback(static_cast<int>(ref_stack.size()), parse_event_t::object_start, discarded);
+        keep_stack.push_back(keep);
 
-                case 0x0C:
-                {
-                    error_message = "invalid string: control character U+000C (FF) must be escaped to \\u000C or \\f";
-                    return token_type::parse_error;
-                }
+        auto val = handle_value(BasicJsonType::value_t::object, true);
+        ref_stack.push_back(val.second);
 
-                case 0x0D:
-                {
-                    error_message = "invalid string: control character U+000D (CR) must be escaped to \\u000D or \\r";
-                    return token_type::parse_error;
-                }
-
-                case 0x0E:
-                {
-                    error_message = "invalid string: control character U+000E (SO) must be escaped to \\u000E";
-                    return token_type::parse_error;
-                }
+        // check object limit
+        if (ref_stack.back() and JSON_UNLIKELY(len != std::size_t(-1) and len > ref_stack.back()->max_size()))
+        {
+            JSON_THROW(out_of_range::create(408, "excessive object size: " + std::to_string(len)));
+        }
 
-                case 0x0F:
-                {
-                    error_message = "invalid string: control character U+000F (SI) must be escaped to \\u000F";
-                    return token_type::parse_error;
-                }
+        return true;
+    }
 
-                case 0x10:
-                {
-                    error_message = "invalid string: control character U+0010 (DLE) must be escaped to \\u0010";
-                    return token_type::parse_error;
-                }
+    bool key(string_t& val)
+    {
+        BasicJsonType k = BasicJsonType(val);
 
-                case 0x11:
-                {
-                    error_message = "invalid string: control character U+0011 (DC1) must be escaped to \\u0011";
-                    return token_type::parse_error;
-                }
+        // check callback for key
+        const bool keep = callback(static_cast<int>(ref_stack.size()), parse_event_t::key, k);
+        key_keep_stack.push_back(keep);
 
-                case 0x12:
-                {
-                    error_message = "invalid string: control character U+0012 (DC2) must be escaped to \\u0012";
-                    return token_type::parse_error;
-                }
+        // add discarded value at given key and store the reference for later
+        if (keep and ref_stack.back())
+        {
+            object_element = &(ref_stack.back()->m_value.object->operator[](val) = discarded);
+        }
 
-                case 0x13:
-                {
-                    error_message = "invalid string: control character U+0013 (DC3) must be escaped to \\u0013";
-                    return token_type::parse_error;
-                }
+        return true;
+    }
 
-                case 0x14:
-                {
-                    error_message = "invalid string: control character U+0014 (DC4) must be escaped to \\u0014";
-                    return token_type::parse_error;
-                }
+    bool end_object()
+    {
+        if (ref_stack.back() and not callback(static_cast<int>(ref_stack.size()) - 1, parse_event_t::object_end, *ref_stack.back()))
+        {
+            // discard object
+            *ref_stack.back() = discarded;
+        }
 
-                case 0x15:
-                {
-                    error_message = "invalid string: control character U+0015 (NAK) must be escaped to \\u0015";
-                    return token_type::parse_error;
-                }
+        assert(not ref_stack.empty());
+        assert(not keep_stack.empty());
+        ref_stack.pop_back();
+        keep_stack.pop_back();
 
-                case 0x16:
+        if (not ref_stack.empty() and ref_stack.back() and ref_stack.back()->is_object())
+        {
+            // remove discarded value
+            for (auto it = ref_stack.back()->begin(); it != ref_stack.back()->end(); ++it)
+            {
+                if (it->is_discarded())
                 {
-                    error_message = "invalid string: control character U+0016 (SYN) must be escaped to \\u0016";
-                    return token_type::parse_error;
+                    ref_stack.back()->erase(it);
+                    break;
                 }
+            }
+        }
 
-                case 0x17:
-                {
-                    error_message = "invalid string: control character U+0017 (ETB) must be escaped to \\u0017";
-                    return token_type::parse_error;
-                }
+        return true;
+    }
 
-                case 0x18:
-                {
-                    error_message = "invalid string: control character U+0018 (CAN) must be escaped to \\u0018";
-                    return token_type::parse_error;
-                }
+    bool start_array(std::size_t len)
+    {
+        const bool keep = callback(static_cast<int>(ref_stack.size()), parse_event_t::array_start, discarded);
+        keep_stack.push_back(keep);
 
-                case 0x19:
-                {
-                    error_message = "invalid string: control character U+0019 (EM) must be escaped to \\u0019";
-                    return token_type::parse_error;
-                }
+        auto val = handle_value(BasicJsonType::value_t::array, true);
+        ref_stack.push_back(val.second);
 
-                case 0x1A:
-                {
-                    error_message = "invalid string: control character U+001A (SUB) must be escaped to \\u001A";
-                    return token_type::parse_error;
-                }
+        // check array limit
+        if (ref_stack.back() and JSON_UNLIKELY(len != std::size_t(-1) and len > ref_stack.back()->max_size()))
+        {
+            JSON_THROW(out_of_range::create(408, "excessive array size: " + std::to_string(len)));
+        }
 
-                case 0x1B:
-                {
-                    error_message = "invalid string: control character U+001B (ESC) must be escaped to \\u001B";
-                    return token_type::parse_error;
-                }
+        return true;
+    }
 
-                case 0x1C:
-                {
-                    error_message = "invalid string: control character U+001C (FS) must be escaped to \\u001C";
-                    return token_type::parse_error;
-                }
+    bool end_array()
+    {
+        bool keep = true;
 
-                case 0x1D:
-                {
-                    error_message = "invalid string: control character U+001D (GS) must be escaped to \\u001D";
-                    return token_type::parse_error;
-                }
+        if (ref_stack.back())
+        {
+            keep = callback(static_cast<int>(ref_stack.size()) - 1, parse_event_t::array_end, *ref_stack.back());
+            if (not keep)
+            {
+                // discard array
+                *ref_stack.back() = discarded;
+            }
+        }
 
-                case 0x1E:
-                {
-                    error_message = "invalid string: control character U+001E (RS) must be escaped to \\u001E";
-                    return token_type::parse_error;
-                }
+        assert(not ref_stack.empty());
+        assert(not keep_stack.empty());
+        ref_stack.pop_back();
+        keep_stack.pop_back();
 
-                case 0x1F:
-                {
-                    error_message = "invalid string: control character U+001F (US) must be escaped to \\u001F";
-                    return token_type::parse_error;
-                }
+        // remove discarded value
+        if (not keep and not ref_stack.empty() and ref_stack.back()->is_array())
+        {
+            ref_stack.back()->m_value.array->pop_back();
+        }
 
-                // U+0020..U+007F (except U+0022 (quote) and U+005C (backspace))
-                case 0x20:
-                case 0x21:
-                case 0x23:
-                case 0x24:
-                case 0x25:
-                case 0x26:
-                case 0x27:
-                case 0x28:
-                case 0x29:
-                case 0x2A:
-                case 0x2B:
-                case 0x2C:
-                case 0x2D:
-                case 0x2E:
-                case 0x2F:
-                case 0x30:
-                case 0x31:
-                case 0x32:
-                case 0x33:
-                case 0x34:
-                case 0x35:
-                case 0x36:
-                case 0x37:
-                case 0x38:
-                case 0x39:
-                case 0x3A:
-                case 0x3B:
-                case 0x3C:
-                case 0x3D:
-                case 0x3E:
-                case 0x3F:
-                case 0x40:
-                case 0x41:
-                case 0x42:
-                case 0x43:
-                case 0x44:
-                case 0x45:
-                case 0x46:
-                case 0x47:
-                case 0x48:
-                case 0x49:
-                case 0x4A:
-                case 0x4B:
-                case 0x4C:
-                case 0x4D:
-                case 0x4E:
-                case 0x4F:
-                case 0x50:
-                case 0x51:
-                case 0x52:
-                case 0x53:
-                case 0x54:
-                case 0x55:
-                case 0x56:
-                case 0x57:
-                case 0x58:
-                case 0x59:
-                case 0x5A:
-                case 0x5B:
-                case 0x5D:
-                case 0x5E:
-                case 0x5F:
-                case 0x60:
-                case 0x61:
-                case 0x62:
-                case 0x63:
-                case 0x64:
-                case 0x65:
-                case 0x66:
-                case 0x67:
-                case 0x68:
-                case 0x69:
-                case 0x6A:
-                case 0x6B:
-                case 0x6C:
-                case 0x6D:
-                case 0x6E:
-                case 0x6F:
-                case 0x70:
-                case 0x71:
-                case 0x72:
-                case 0x73:
-                case 0x74:
-                case 0x75:
-                case 0x76:
-                case 0x77:
-                case 0x78:
-                case 0x79:
-                case 0x7A:
-                case 0x7B:
-                case 0x7C:
-                case 0x7D:
-                case 0x7E:
-                case 0x7F:
-                {
-                    add(current);
-                    break;
-                }
+        return true;
+    }
 
-                // U+0080..U+07FF: bytes C2..DF 80..BF
-                case 0xC2:
-                case 0xC3:
-                case 0xC4:
-                case 0xC5:
-                case 0xC6:
-                case 0xC7:
-                case 0xC8:
-                case 0xC9:
-                case 0xCA:
-                case 0xCB:
-                case 0xCC:
-                case 0xCD:
-                case 0xCE:
-                case 0xCF:
-                case 0xD0:
-                case 0xD1:
-                case 0xD2:
-                case 0xD3:
-                case 0xD4:
-                case 0xD5:
-                case 0xD6:
-                case 0xD7:
-                case 0xD8:
-                case 0xD9:
-                case 0xDA:
-                case 0xDB:
-                case 0xDC:
-                case 0xDD:
-                case 0xDE:
-                case 0xDF:
-                {
-                    if (JSON_UNLIKELY(not next_byte_in_range({0x80, 0xBF})))
-                    {
-                        return token_type::parse_error;
-                    }
-                    break;
-                }
-
-                // U+0800..U+0FFF: bytes E0 A0..BF 80..BF
-                case 0xE0:
-                {
-                    if (JSON_UNLIKELY(not (next_byte_in_range({0xA0, 0xBF, 0x80, 0xBF}))))
-                    {
-                        return token_type::parse_error;
-                    }
-                    break;
-                }
-
-                // U+1000..U+CFFF: bytes E1..EC 80..BF 80..BF
-                // U+E000..U+FFFF: bytes EE..EF 80..BF 80..BF
-                case 0xE1:
-                case 0xE2:
-                case 0xE3:
-                case 0xE4:
-                case 0xE5:
-                case 0xE6:
-                case 0xE7:
-                case 0xE8:
-                case 0xE9:
-                case 0xEA:
-                case 0xEB:
-                case 0xEC:
-                case 0xEE:
-                case 0xEF:
-                {
-                    if (JSON_UNLIKELY(not (next_byte_in_range({0x80, 0xBF, 0x80, 0xBF}))))
-                    {
-                        return token_type::parse_error;
-                    }
-                    break;
-                }
-
-                // U+D000..U+D7FF: bytes ED 80..9F 80..BF
-                case 0xED:
-                {
-                    if (JSON_UNLIKELY(not (next_byte_in_range({0x80, 0x9F, 0x80, 0xBF}))))
-                    {
-                        return token_type::parse_error;
-                    }
-                    break;
-                }
-
-                // U+10000..U+3FFFF F0 90..BF 80..BF 80..BF
-                case 0xF0:
-                {
-                    if (JSON_UNLIKELY(not (next_byte_in_range({0x90, 0xBF, 0x80, 0xBF, 0x80, 0xBF}))))
-                    {
-                        return token_type::parse_error;
-                    }
-                    break;
-                }
-
-                // U+40000..U+FFFFF F1..F3 80..BF 80..BF 80..BF
-                case 0xF1:
-                case 0xF2:
-                case 0xF3:
-                {
-                    if (JSON_UNLIKELY(not (next_byte_in_range({0x80, 0xBF, 0x80, 0xBF, 0x80, 0xBF}))))
-                    {
-                        return token_type::parse_error;
-                    }
-                    break;
-                }
-
-                // U+100000..U+10FFFF F4 80..8F 80..BF 80..BF
-                case 0xF4:
-                {
-                    if (JSON_UNLIKELY(not (next_byte_in_range({0x80, 0x8F, 0x80, 0xBF, 0x80, 0xBF}))))
-                    {
-                        return token_type::parse_error;
-                    }
-                    break;
-                }
-
-                // remaining bytes (80..C1 and F5..FF) are ill-formed
+    bool parse_error(std::size_t /*unused*/, const std::string& /*unused*/,
+                     const detail::exception& ex)
+    {
+        errored = true;
+        if (allow_exceptions)
+        {
+            // determine the proper exception type from the id
+            switch ((ex.id / 100) % 100)
+            {
+                case 1:
+                    JSON_THROW(*static_cast<const detail::parse_error*>(&ex));
+                case 4:
+                    JSON_THROW(*static_cast<const detail::out_of_range*>(&ex));
+                // LCOV_EXCL_START
+                case 2:
+                    JSON_THROW(*static_cast<const detail::invalid_iterator*>(&ex));
+                case 3:
+                    JSON_THROW(*static_cast<const detail::type_error*>(&ex));
+                case 5:
+                    JSON_THROW(*static_cast<const detail::other_error*>(&ex));
                 default:
-                {
-                    error_message = "invalid string: ill-formed UTF-8 byte";
-                    return token_type::parse_error;
-                }
+                    assert(false);
+                    // LCOV_EXCL_STOP
             }
         }
+        return false;
     }
 
-    static void strtof(float& f, const char* str, char** endptr) noexcept
+    constexpr bool is_errored() const
     {
-        f = std::strtof(str, endptr);
+        return errored;
     }
 
-    static void strtof(double& f, const char* str, char** endptr) noexcept
-    {
-        f = std::strtod(str, endptr);
-    }
+  private:
+    /*!
+    @param[in] v  value to add to the JSON value we build during parsing
+    @param[in] skip_callback  whether we should skip calling the callback
+               function; this is required after start_array() and
+               start_object() SAX events, because otherwise we would call the
+               callback function with an empty array or object, respectively.
 
-    static void strtof(long double& f, const char* str, char** endptr) noexcept
+    @invariant If the ref stack is empty, then the passed value will be the new
+               root.
+    @invariant If the ref stack contains a value, then it is an array or an
+               object to which we can add elements
+
+    @return pair of boolean (whether value should be kept) and pointer (to the
+            passed value in the ref_stack hierarchy; nullptr if not kept)
+    */
+    template<typename Value>
+    std::pair<bool, BasicJsonType*> handle_value(Value&& v, const bool skip_callback = false)
     {
-        f = std::strtold(str, endptr);
-    }
+        assert(not keep_stack.empty());
 
-    /*!
-    @brief scan a number literal
+        // do not handle this value if we know it would be added to a discarded
+        // container
+        if (not keep_stack.back())
+        {
+            return {false, nullptr};
+        }
 
-    This function scans a string according to Sect. 6 of RFC 7159.
+        // create value
+        auto value = BasicJsonType(std::forward<Value>(v));
 
-    The function is realized with a deterministic finite state machine derived
-    from the grammar described in RFC 7159. Starting in state "init", the
-    input is read and used to determined the next state. Only state "done"
-    accepts the number. State "error" is a trap state to model errors. In the
-    table below, "anything" means any character but the ones listed before.
+        // check callback
+        const bool keep = skip_callback or callback(static_cast<int>(ref_stack.size()), parse_event_t::value, value);
 
-    state    | 0        | 1-9      | e E      | +       | -       | .        | anything
-    ---------|----------|----------|----------|---------|---------|----------|-----------
-    init     | zero     | any1     | [error]  | [error] | minus   | [error]  | [error]
-    minus    | zero     | any1     | [error]  | [error] | [error] | [error]  | [error]
-    zero     | done     | done     | exponent | done    | done    | decimal1 | done
-    any1     | any1     | any1     | exponent | done    | done    | decimal1 | done
-    decimal1 | decimal2 | [error]  | [error]  | [error] | [error] | [error]  | [error]
-    decimal2 | decimal2 | decimal2 | exponent | done    | done    | done     | done
-    exponent | any2     | any2     | [error]  | sign    | sign    | [error]  | [error]
-    sign     | any2     | any2     | [error]  | [error] | [error] | [error]  | [error]
-    any2     | any2     | any2     | done     | done    | done    | done     | done
+        // do not handle this value if we just learnt it shall be discarded
+        if (not keep)
+        {
+            return {false, nullptr};
+        }
 
-    The state machine is realized with one label per state (prefixed with
-    "scan_number_") and `goto` statements between them. The state machine
-    contains cycles, but any cycle can be left when EOF is read. Therefore,
-    the function is guaranteed to terminate.
+        if (ref_stack.empty())
+        {
+            root = std::move(value);
+            return {true, &root};
+        }
 
-    During scanning, the read bytes are stored in token_buffer. This string is
-    then converted to a signed integer, an unsigned integer, or a
-    floating-point number.
+        // skip this value if we already decided to skip the parent
+        // (https://github.com/nlohmann/json/issues/971#issuecomment-413678360)
+        if (not ref_stack.back())
+        {
+            return {false, nullptr};
+        }
 
-    @return token_type::value_unsigned, token_type::value_integer, or
-            token_type::value_float if number could be successfully scanned,
-            token_type::parse_error otherwise
+        // we now only expect arrays and objects
+        assert(ref_stack.back()->is_array() or ref_stack.back()->is_object());
 
-    @note The scanner is independent of the current locale. Internally, the
-          locale's decimal point is used instead of `.` to work with the
-          locale-dependent converters.
-    */
-    token_type scan_number()  // lgtm [cpp/use-of-goto]
-    {
-        // reset token_buffer to store the number's bytes
-        reset();
+        // array
+        if (ref_stack.back()->is_array())
+        {
+            ref_stack.back()->m_value.array->push_back(std::move(value));
+            return {true, &(ref_stack.back()->m_value.array->back())};
+        }
 
-        // the type of the parsed number; initially set to unsigned; will be
-        // changed if minus sign, decimal point or exponent is read
-        token_type number_type = token_type::value_unsigned;
+        // object
+        assert(ref_stack.back()->is_object());
+        // check if we should store an element for the current key
+        assert(not key_keep_stack.empty());
+        const bool store_element = key_keep_stack.back();
+        key_keep_stack.pop_back();
 
-        // state (init): we just found out we need to scan a number
-        switch (current)
+        if (not store_element)
         {
-            case '-':
-            {
-                add(current);
-                goto scan_number_minus;
-            }
+            return {false, nullptr};
+        }
 
-            case '0':
-            {
-                add(current);
-                goto scan_number_zero;
-            }
+        assert(object_element);
+        *object_element = std::move(value);
+        return {true, object_element};
+    }
 
-            case '1':
-            case '2':
-            case '3':
-            case '4':
-            case '5':
-            case '6':
-            case '7':
-            case '8':
-            case '9':
-            {
-                add(current);
-                goto scan_number_any1;
-            }
+    /// the parsed JSON value
+    BasicJsonType& root;
+    /// stack to model hierarchy of values
+    std::vector<BasicJsonType*> ref_stack {};
+    /// stack to manage which values to keep
+    std::vector<bool> keep_stack {};
+    /// stack to manage which object keys to keep
+    std::vector<bool> key_keep_stack {};
+    /// helper to hold the reference for the next object element
+    BasicJsonType* object_element = nullptr;
+    /// whether a syntax error occurred
+    bool errored = false;
+    /// callback function
+    const parser_callback_t callback = nullptr;
+    /// whether to throw exceptions in case of errors
+    const bool allow_exceptions = true;
+    /// a discarded value for the callback
+    BasicJsonType discarded = BasicJsonType::value_t::discarded;
+};
 
-            // LCOV_EXCL_START
-            default:
-            {
-                // all other characters are rejected outside scan_number()
-                assert(false);
-            }
-                // LCOV_EXCL_STOP
-        }
+template<typename BasicJsonType>
+class json_sax_acceptor
+{
+  public:
+    using number_integer_t = typename BasicJsonType::number_integer_t;
+    using number_unsigned_t = typename BasicJsonType::number_unsigned_t;
+    using number_float_t = typename BasicJsonType::number_float_t;
+    using string_t = typename BasicJsonType::string_t;
 
-scan_number_minus:
-        // state: we just parsed a leading minus sign
-        number_type = token_type::value_integer;
-        switch (get())
-        {
-            case '0':
-            {
-                add(current);
-                goto scan_number_zero;
-            }
+    bool null()
+    {
+        return true;
+    }
 
-            case '1':
-            case '2':
-            case '3':
-            case '4':
-            case '5':
-            case '6':
-            case '7':
-            case '8':
-            case '9':
-            {
-                add(current);
-                goto scan_number_any1;
-            }
+    bool boolean(bool /*unused*/)
+    {
+        return true;
+    }
 
-            default:
-            {
-                error_message = "invalid number; expected digit after '-'";
-                return token_type::parse_error;
-            }
-        }
+    bool number_integer(number_integer_t /*unused*/)
+    {
+        return true;
+    }
 
-scan_number_zero:
-        // state: we just parse a zero (maybe with a leading minus sign)
-        switch (get())
-        {
-            case '.':
-            {
-                add(decimal_point_char);
-                goto scan_number_decimal1;
-            }
+    bool number_unsigned(number_unsigned_t /*unused*/)
+    {
+        return true;
+    }
 
-            case 'e':
-            case 'E':
-            {
-                add(current);
-                goto scan_number_exponent;
-            }
+    bool number_float(number_float_t /*unused*/, const string_t& /*unused*/)
+    {
+        return true;
+    }
 
-            default:
-                goto scan_number_done;
-        }
+    bool string(string_t& /*unused*/)
+    {
+        return true;
+    }
 
-scan_number_any1:
-        // state: we just parsed a number 0-9 (maybe with a leading minus sign)
-        switch (get())
-        {
-            case '0':
-            case '1':
-            case '2':
-            case '3':
-            case '4':
-            case '5':
-            case '6':
-            case '7':
-            case '8':
-            case '9':
-            {
-                add(current);
-                goto scan_number_any1;
-            }
+    bool start_object(std::size_t  /*unused*/ = std::size_t(-1))
+    {
+        return true;
+    }
 
-            case '.':
-            {
-                add(decimal_point_char);
-                goto scan_number_decimal1;
-            }
+    bool key(string_t& /*unused*/)
+    {
+        return true;
+    }
 
-            case 'e':
-            case 'E':
-            {
-                add(current);
-                goto scan_number_exponent;
-            }
+    bool end_object()
+    {
+        return true;
+    }
 
-            default:
-                goto scan_number_done;
-        }
+    bool start_array(std::size_t  /*unused*/ = std::size_t(-1))
+    {
+        return true;
+    }
 
-scan_number_decimal1:
-        // state: we just parsed a decimal point
-        number_type = token_type::value_float;
-        switch (get())
-        {
-            case '0':
-            case '1':
-            case '2':
-            case '3':
-            case '4':
-            case '5':
-            case '6':
-            case '7':
-            case '8':
-            case '9':
-            {
-                add(current);
-                goto scan_number_decimal2;
-            }
+    bool end_array()
+    {
+        return true;
+    }
 
-            default:
-            {
-                error_message = "invalid number; expected digit after '.'";
-                return token_type::parse_error;
-            }
-        }
+    bool parse_error(std::size_t /*unused*/, const std::string& /*unused*/, const detail::exception& /*unused*/)
+    {
+        return false;
+    }
+};
+}  // namespace detail
 
-scan_number_decimal2:
-        // we just parsed at least one number after a decimal point
-        switch (get())
-        {
-            case '0':
-            case '1':
-            case '2':
-            case '3':
-            case '4':
-            case '5':
-            case '6':
-            case '7':
-            case '8':
-            case '9':
-            {
-                add(current);
-                goto scan_number_decimal2;
-            }
+}  // namespace nlohmann
 
-            case 'e':
-            case 'E':
-            {
-                add(current);
-                goto scan_number_exponent;
-            }
+// #include <nlohmann/detail/macro_scope.hpp>
 
-            default:
-                goto scan_number_done;
-        }
+// #include <nlohmann/detail/meta/is_sax.hpp>
 
-scan_number_exponent:
-        // we just parsed an exponent
-        number_type = token_type::value_float;
-        switch (get())
-        {
-            case '+':
-            case '-':
-            {
-                add(current);
-                goto scan_number_sign;
-            }
 
-            case '0':
-            case '1':
-            case '2':
-            case '3':
-            case '4':
-            case '5':
-            case '6':
-            case '7':
-            case '8':
-            case '9':
-            {
-                add(current);
-                goto scan_number_any2;
-            }
+#include <cstdint> // size_t
+#include <utility> // declval
+#include <string> // string
 
-            default:
-            {
-                error_message =
-                    "invalid number; expected '+', '-', or digit after exponent";
-                return token_type::parse_error;
-            }
-        }
+// #include <nlohmann/detail/meta/detected.hpp>
 
-scan_number_sign:
-        // we just parsed an exponent sign
-        switch (get())
-        {
-            case '0':
-            case '1':
-            case '2':
-            case '3':
-            case '4':
-            case '5':
-            case '6':
-            case '7':
-            case '8':
-            case '9':
-            {
-                add(current);
-                goto scan_number_any2;
-            }
+// #include <nlohmann/detail/meta/type_traits.hpp>
 
-            default:
-            {
-                error_message = "invalid number; expected digit after exponent sign";
-                return token_type::parse_error;
-            }
-        }
 
-scan_number_any2:
-        // we just parsed a number after the exponent or exponent sign
-        switch (get())
-        {
-            case '0':
-            case '1':
-            case '2':
-            case '3':
-            case '4':
-            case '5':
-            case '6':
-            case '7':
-            case '8':
-            case '9':
-            {
-                add(current);
-                goto scan_number_any2;
-            }
+namespace nlohmann
+{
+namespace detail
+{
+template <typename T>
+using null_function_t = decltype(std::declval<T&>().null());
 
-            default:
-                goto scan_number_done;
-        }
+template <typename T>
+using boolean_function_t =
+    decltype(std::declval<T&>().boolean(std::declval<bool>()));
 
-scan_number_done:
-        // unget the character after the number (we only read it to know that
-        // we are done scanning a number)
-        unget();
+template <typename T, typename Integer>
+using number_integer_function_t =
+    decltype(std::declval<T&>().number_integer(std::declval<Integer>()));
 
-        char* endptr = nullptr;
-        errno = 0;
+template <typename T, typename Unsigned>
+using number_unsigned_function_t =
+    decltype(std::declval<T&>().number_unsigned(std::declval<Unsigned>()));
 
-        // try to parse integers first and fall back to floats
-        if (number_type == token_type::value_unsigned)
-        {
-            const auto x = std::strtoull(token_buffer.data(), &endptr, 10);
+template <typename T, typename Float, typename String>
+using number_float_function_t = decltype(std::declval<T&>().number_float(
+                                    std::declval<Float>(), std::declval<const String&>()));
 
-            // we checked the number format before
-            assert(endptr == token_buffer.data() + token_buffer.size());
+template <typename T, typename String>
+using string_function_t =
+    decltype(std::declval<T&>().string(std::declval<String&>()));
 
-            if (errno == 0)
-            {
-                value_unsigned = static_cast<number_unsigned_t>(x);
-                if (value_unsigned == x)
-                {
-                    return token_type::value_unsigned;
-                }
-            }
-        }
-        else if (number_type == token_type::value_integer)
-        {
-            const auto x = std::strtoll(token_buffer.data(), &endptr, 10);
+template <typename T>
+using start_object_function_t =
+    decltype(std::declval<T&>().start_object(std::declval<std::size_t>()));
 
-            // we checked the number format before
-            assert(endptr == token_buffer.data() + token_buffer.size());
+template <typename T, typename String>
+using key_function_t =
+    decltype(std::declval<T&>().key(std::declval<String&>()));
 
-            if (errno == 0)
-            {
-                value_integer = static_cast<number_integer_t>(x);
-                if (value_integer == x)
-                {
-                    return token_type::value_integer;
-                }
-            }
-        }
+template <typename T>
+using end_object_function_t = decltype(std::declval<T&>().end_object());
 
-        // this code is reached if we parse a floating-point number or if an
-        // integer conversion above failed
-        strtof(value_float, token_buffer.data(), &endptr);
+template <typename T>
+using start_array_function_t =
+    decltype(std::declval<T&>().start_array(std::declval<std::size_t>()));
 
-        // we checked the number format before
-        assert(endptr == token_buffer.data() + token_buffer.size());
+template <typename T>
+using end_array_function_t = decltype(std::declval<T&>().end_array());
 
-        return token_type::value_float;
-    }
+template <typename T, typename Exception>
+using parse_error_function_t = decltype(std::declval<T&>().parse_error(
+        std::declval<std::size_t>(), std::declval<const std::string&>(),
+        std::declval<const Exception&>()));
 
-    /*!
-    @param[in] literal_text  the literal text to expect
-    @param[in] length        the length of the passed literal text
-    @param[in] return_type   the token type to return on success
-    */
-    token_type scan_literal(const char* literal_text, const std::size_t length,
-                            token_type return_type)
-    {
-        assert(current == literal_text[0]);
-        for (std::size_t i = 1; i < length; ++i)
-        {
-            if (JSON_UNLIKELY(get() != literal_text[i]))
-            {
-                error_message = "invalid literal";
-                return token_type::parse_error;
-            }
-        }
-        return return_type;
-    }
+template <typename SAX, typename BasicJsonType>
+struct is_sax
+{
+  private:
+    static_assert(is_basic_json<BasicJsonType>::value,
+                  "BasicJsonType must be of type basic_json<...>");
 
-    /////////////////////
-    // input management
-    /////////////////////
+    using number_integer_t = typename BasicJsonType::number_integer_t;
+    using number_unsigned_t = typename BasicJsonType::number_unsigned_t;
+    using number_float_t = typename BasicJsonType::number_float_t;
+    using string_t = typename BasicJsonType::string_t;
+    using exception_t = typename BasicJsonType::exception;
 
-    /// reset token_buffer; current character is beginning of token
-    void reset() noexcept
-    {
-        token_buffer.clear();
-        token_string.clear();
-        token_string.push_back(std::char_traits<char>::to_char_type(current));
-    }
+  public:
+    static constexpr bool value =
+        is_detected_exact<bool, null_function_t, SAX>::value &&
+        is_detected_exact<bool, boolean_function_t, SAX>::value &&
+        is_detected_exact<bool, number_integer_function_t, SAX,
+        number_integer_t>::value &&
+        is_detected_exact<bool, number_unsigned_function_t, SAX,
+        number_unsigned_t>::value &&
+        is_detected_exact<bool, number_float_function_t, SAX, number_float_t,
+        string_t>::value &&
+        is_detected_exact<bool, string_function_t, SAX, string_t>::value &&
+        is_detected_exact<bool, start_object_function_t, SAX>::value &&
+        is_detected_exact<bool, key_function_t, SAX, string_t>::value &&
+        is_detected_exact<bool, end_object_function_t, SAX>::value &&
+        is_detected_exact<bool, start_array_function_t, SAX>::value &&
+        is_detected_exact<bool, end_array_function_t, SAX>::value &&
+        is_detected_exact<bool, parse_error_function_t, SAX, exception_t>::value;
+};
 
-    /*
-    @brief get next character from the input
+template <typename SAX, typename BasicJsonType>
+struct is_sax_static_asserts
+{
+  private:
+    static_assert(is_basic_json<BasicJsonType>::value,
+                  "BasicJsonType must be of type basic_json<...>");
 
-    This function provides the interface to the used input adapter. It does
-    not throw in case the input reached EOF, but returns a
-    `std::char_traits<char>::eof()` in that case.  Stores the scanned characters
-    for use in error messages.
+    using number_integer_t = typename BasicJsonType::number_integer_t;
+    using number_unsigned_t = typename BasicJsonType::number_unsigned_t;
+    using number_float_t = typename BasicJsonType::number_float_t;
+    using string_t = typename BasicJsonType::string_t;
+    using exception_t = typename BasicJsonType::exception;
 
-    @return character read from the input
-    */
-    std::char_traits<char>::int_type get()
-    {
-        ++position.chars_read_total;
-        ++position.chars_read_current_line;
+  public:
+    static_assert(is_detected_exact<bool, null_function_t, SAX>::value,
+                  "Missing/invalid function: bool null()");
+    static_assert(is_detected_exact<bool, boolean_function_t, SAX>::value,
+                  "Missing/invalid function: bool boolean(bool)");
+    static_assert(is_detected_exact<bool, boolean_function_t, SAX>::value,
+                  "Missing/invalid function: bool boolean(bool)");
+    static_assert(
+        is_detected_exact<bool, number_integer_function_t, SAX,
+        number_integer_t>::value,
+        "Missing/invalid function: bool number_integer(number_integer_t)");
+    static_assert(
+        is_detected_exact<bool, number_unsigned_function_t, SAX,
+        number_unsigned_t>::value,
+        "Missing/invalid function: bool number_unsigned(number_unsigned_t)");
+    static_assert(is_detected_exact<bool, number_float_function_t, SAX,
+                  number_float_t, string_t>::value,
+                  "Missing/invalid function: bool number_float(number_float_t, const string_t&)");
+    static_assert(
+        is_detected_exact<bool, string_function_t, SAX, string_t>::value,
+        "Missing/invalid function: bool string(string_t&)");
+    static_assert(is_detected_exact<bool, start_object_function_t, SAX>::value,
+                  "Missing/invalid function: bool start_object(std::size_t)");
+    static_assert(is_detected_exact<bool, key_function_t, SAX, string_t>::value,
+                  "Missing/invalid function: bool key(string_t&)");
+    static_assert(is_detected_exact<bool, end_object_function_t, SAX>::value,
+                  "Missing/invalid function: bool end_object()");
+    static_assert(is_detected_exact<bool, start_array_function_t, SAX>::value,
+                  "Missing/invalid function: bool start_array(std::size_t)");
+    static_assert(is_detected_exact<bool, end_array_function_t, SAX>::value,
+                  "Missing/invalid function: bool end_array()");
+    static_assert(
+        is_detected_exact<bool, parse_error_function_t, SAX, exception_t>::value,
+        "Missing/invalid function: bool parse_error(std::size_t, const "
+        "std::string&, const exception&)");
+};
+}  // namespace detail
+}  // namespace nlohmann
 
-        if (next_unget)
-        {
-            // just reset the next_unget variable and work with current
-            next_unget = false;
-        }
-        else
-        {
-            current = ia->get_character();
-        }
+// #include <nlohmann/detail/value_t.hpp>
 
-        if (JSON_LIKELY(current != std::char_traits<char>::eof()))
-        {
-            token_string.push_back(std::char_traits<char>::to_char_type(current));
-        }
 
-        if (current == '\n')
-        {
-            ++position.lines_read;
-            ++position.chars_read_current_line = 0;
-        }
+namespace nlohmann
+{
+namespace detail
+{
+///////////////////
+// binary reader //
+///////////////////
 
-        return current;
+/*!
+@brief deserialization of CBOR, MessagePack, and UBJSON values
+*/
+template<typename BasicJsonType, typename SAX = json_sax_dom_parser<BasicJsonType>>
+class binary_reader
+{
+    using number_integer_t = typename BasicJsonType::number_integer_t;
+    using number_unsigned_t = typename BasicJsonType::number_unsigned_t;
+    using number_float_t = typename BasicJsonType::number_float_t;
+    using string_t = typename BasicJsonType::string_t;
+    using json_sax_t = SAX;
+
+  public:
+    /*!
+    @brief create a binary reader
+
+    @param[in] adapter  input adapter to read from
+    */
+    explicit binary_reader(input_adapter_t adapter) : ia(std::move(adapter))
+    {
+        (void)detail::is_sax_static_asserts<SAX, BasicJsonType> {};
+        assert(ia);
     }
 
+    // make class move-only
+    binary_reader(const binary_reader&) = delete;
+    binary_reader(binary_reader&&) = default;
+    binary_reader& operator=(const binary_reader&) = delete;
+    binary_reader& operator=(binary_reader&&) = default;
+    ~binary_reader() = default;
+
     /*!
-    @brief unget current character (read it again on next get)
+    @param[in] format  the binary format to parse
+    @param[in] sax_    a SAX event processor
+    @param[in] strict  whether to expect the input to be consumed completed
 
-    We implement unget by setting variable next_unget to true. The input is not
-    changed - we just simulate ungetting by modifying chars_read_total,
-    chars_read_current_line, and token_string. The next call to get() will
-    behave as if the unget character is read again.
+    @return
     */
-    void unget()
+    bool sax_parse(const input_format_t format,
+                   json_sax_t* sax_,
+                   const bool strict = true)
     {
-        next_unget = true;
+        sax = sax_;
+        bool result = false;
 
-        --position.chars_read_total;
+        switch (format)
+        {
+            case input_format_t::bson:
+                result = parse_bson_internal();
+                break;
 
-        // in case we "unget" a newline, we have to also decrement the lines_read
-        if (position.chars_read_current_line == 0)
+            case input_format_t::cbor:
+                result = parse_cbor_internal();
+                break;
+
+            case input_format_t::msgpack:
+                result = parse_msgpack_internal();
+                break;
+
+            case input_format_t::ubjson:
+                result = parse_ubjson_internal();
+                break;
+
+            default:            // LCOV_EXCL_LINE
+                assert(false);  // LCOV_EXCL_LINE
+        }
+
+        // strict mode: next byte must be EOF
+        if (result and strict)
         {
-            if (position.lines_read > 0)
+            if (format == input_format_t::ubjson)
             {
-                --position.lines_read;
+                get_ignore_noop();
+            }
+            else
+            {
+                get();
             }
-        }
-        else
-        {
-            --position.chars_read_current_line;
-        }
 
-        if (JSON_LIKELY(current != std::char_traits<char>::eof()))
-        {
-            assert(token_string.size() != 0);
-            token_string.pop_back();
+            if (JSON_UNLIKELY(current != std::char_traits<char>::eof()))
+            {
+                return sax->parse_error(chars_read, get_token_string(),
+                                        parse_error::create(110, chars_read, exception_message(format, "expected end of input; last byte: 0x" + get_token_string(), "value")));
+            }
         }
-    }
 
-    /// add a character to token_buffer
-    void add(int c)
-    {
-        token_buffer.push_back(std::char_traits<char>::to_char_type(c));
+        return result;
     }
 
-  public:
-    /////////////////////
-    // value getters
-    /////////////////////
+    /*!
+    @brief determine system byte order
 
-    /// return integer value
-    constexpr number_integer_t get_number_integer() const noexcept
-    {
-        return value_integer;
-    }
+    @return true if and only if system's byte order is little endian
 
-    /// return unsigned integer value
-    constexpr number_unsigned_t get_number_unsigned() const noexcept
+    @note from http://stackoverflow.com/a/1001328/266378
+    */
+    static constexpr bool little_endianess(int num = 1) noexcept
     {
-        return value_unsigned;
+        return *reinterpret_cast<char*>(&num) == 1;
     }
 
-    /// return floating-point value
-    constexpr number_float_t get_number_float() const noexcept
-    {
-        return value_float;
-    }
+  private:
+    //////////
+    // BSON //
+    //////////
 
-    /// return current string value (implicitly resets the token; useful only once)
-    string_t& get_string()
+    /*!
+    @brief Reads in a BSON-object and passes it to the SAX-parser.
+    @return whether a valid BSON-value was passed to the SAX parser
+    */
+    bool parse_bson_internal()
     {
-        return token_buffer;
-    }
+        std::int32_t document_size;
+        get_number<std::int32_t, true>(input_format_t::bson, document_size);
 
-    /////////////////////
-    // diagnostics
-    /////////////////////
+        if (JSON_UNLIKELY(not sax->start_object(std::size_t(-1))))
+        {
+            return false;
+        }
 
-    /// return position of last read token
-    constexpr position_t get_position() const noexcept
-    {
-        return position;
+        if (JSON_UNLIKELY(not parse_bson_element_list(/*is_array*/false)))
+        {
+            return false;
+        }
+
+        return sax->end_object();
     }
 
-    /// return the last read token (for errors only).  Will never contain EOF
-    /// (an arbitrary value that is not a valid char value, often -1), because
-    /// 255 may legitimately occur.  May contain NUL, which should be escaped.
-    std::string get_token_string() const
+    /*!
+    @brief Parses a C-style string from the BSON input.
+    @param[in, out] result  A reference to the string variable where the read
+                            string is to be stored.
+    @return `true` if the \x00-byte indicating the end of the string was
+             encountered before the EOF; false` indicates an unexpected EOF.
+    */
+    bool get_bson_cstr(string_t& result)
     {
-        // escape control characters
-        std::string result;
-        for (const auto c : token_string)
+        auto out = std::back_inserter(result);
+        while (true)
         {
-            if ('\x00' <= c and c <= '\x1F')
+            get();
+            if (JSON_UNLIKELY(not unexpect_eof(input_format_t::bson, "cstring")))
             {
-                // escape control characters
-                char cs[9];
-                (std::snprintf)(cs, 9, "<U+%.4X>", static_cast<unsigned char>(c));
-                result += cs;
+                return false;
             }
-            else
+            if (current == 0x00)
             {
-                // add character as is
-                result.push_back(c);
+                return true;
             }
+            *out++ = static_cast<char>(current);
         }
 
-        return result;
-    }
-
-    /// return syntax error message
-    constexpr const char* get_error_message() const noexcept
-    {
-        return error_message;
+        return true;
     }
 
-    /////////////////////
-    // actual scanner
-    /////////////////////
-
     /*!
-    @brief skip the UTF-8 byte order mark
-    @return true iff there is no BOM or the correct BOM has been skipped
+    @brief Parses a zero-terminated string of length @a len from the BSON
+           input.
+    @param[in] len  The length (including the zero-byte at the end) of the
+                    string to be read.
+    @param[in, out] result  A reference to the string variable where the read
+                            string is to be stored.
+    @tparam NumberType The type of the length @a len
+    @pre len >= 1
+    @return `true` if the string was successfully parsed
     */
-    bool skip_bom()
+    template<typename NumberType>
+    bool get_bson_string(const NumberType len, string_t& result)
     {
-        if (get() == 0xEF)
+        if (JSON_UNLIKELY(len < 1))
         {
-            // check if we completely parse the BOM
-            return get() == 0xBB and get() == 0xBF;
+            auto last_token = get_token_string();
+            return sax->parse_error(chars_read, last_token, parse_error::create(112, chars_read, exception_message(input_format_t::bson, "string length must be at least 1, is " + std::to_string(len), "string")));
         }
 
-        // the first character is not the beginning of the BOM; unget it to
-        // process is later
-        unget();
-        return true;
+        return get_string(input_format_t::bson, len - static_cast<NumberType>(1), result) and get() != std::char_traits<char>::eof();
     }
 
-    token_type scan()
+    /*!
+    @brief Read a BSON document element of the given @a element_type.
+    @param[in] element_type The BSON element type, c.f. http://bsonspec.org/spec.html
+    @param[in] element_type_parse_position The position in the input stream,
+               where the `element_type` was read.
+    @warning Not all BSON element types are supported yet. An unsupported
+             @a element_type will give rise to a parse_error.114:
+             Unsupported BSON record type 0x...
+    @return whether a valid BSON-object/array was passed to the SAX parser
+    */
+    bool parse_bson_element_internal(const int element_type,
+                                     const std::size_t element_type_parse_position)
     {
-        // initially, skip the BOM
-        if (position.chars_read_total == 0 and not skip_bom())
+        switch (element_type)
         {
-            error_message = "invalid BOM; must be 0xEF 0xBB 0xBF if given";
-            return token_type::parse_error;
-        }
+            case 0x01: // double
+            {
+                double number;
+                return get_number<double, true>(input_format_t::bson, number) and sax->number_float(static_cast<number_float_t>(number), "");
+            }
 
-        // read next character and ignore whitespace
-        do
-        {
-            get();
-        }
-        while (current == ' ' or current == '\t' or current == '\n' or current == '\r');
+            case 0x02: // string
+            {
+                std::int32_t len;
+                string_t value;
+                return get_number<std::int32_t, true>(input_format_t::bson, len) and get_bson_string(len, value) and sax->string(value);
+            }
 
-        switch (current)
-        {
-            // structural characters
-            case '[':
-                return token_type::begin_array;
-            case ']':
-                return token_type::end_array;
-            case '{':
-                return token_type::begin_object;
-            case '}':
-                return token_type::end_object;
-            case ':':
-                return token_type::name_separator;
-            case ',':
-                return token_type::value_separator;
+            case 0x03: // object
+            {
+                return parse_bson_internal();
+            }
 
-            // literals
-            case 't':
-                return scan_literal("true", 4, token_type::literal_true);
-            case 'f':
-                return scan_literal("false", 5, token_type::literal_false);
-            case 'n':
-                return scan_literal("null", 4, token_type::literal_null);
+            case 0x04: // array
+            {
+                return parse_bson_array();
+            }
 
-            // string
-            case '\"':
-                return scan_string();
+            case 0x08: // boolean
+            {
+                return sax->boolean(get() != 0);
+            }
 
-            // number
-            case '-':
-            case '0':
-            case '1':
-            case '2':
-            case '3':
-            case '4':
-            case '5':
-            case '6':
-            case '7':
-            case '8':
-            case '9':
-                return scan_number();
+            case 0x0A: // null
+            {
+                return sax->null();
+            }
 
-            // end of input (the null byte is needed when parsing from
-            // string literals)
-            case '\0':
-            case std::char_traits<char>::eof():
-                return token_type::end_of_input;
+            case 0x10: // int32
+            {
+                std::int32_t value;
+                return get_number<std::int32_t, true>(input_format_t::bson, value) and sax->number_integer(value);
+            }
 
-            // error
-            default:
-                error_message = "invalid literal";
-                return token_type::parse_error;
+            case 0x12: // int64
+            {
+                std::int64_t value;
+                return get_number<std::int64_t, true>(input_format_t::bson, value) and sax->number_integer(value);
+            }
+
+            default: // anything else not supported (yet)
+            {
+                std::array<char, 3> cr{{}};
+                (std::snprintf)(cr.data(), cr.size(), "%.2hhX", static_cast<unsigned char>(element_type));
+                return sax->parse_error(element_type_parse_position, std::string(cr.data()), parse_error::create(114, element_type_parse_position, "Unsupported BSON record type 0x" + std::string(cr.data())));
+            }
         }
     }
 
-  private:
-    /// input adapter
-    detail::input_adapter_t ia = nullptr;
-
-    /// the current character
-    std::char_traits<char>::int_type current = std::char_traits<char>::eof();
-
-    /// whether the next get() call should just return current
-    bool next_unget = false;
-
-    /// the start position of the current token
-    position_t position;
-
-    /// raw input token string (for error messages)
-    std::vector<char> token_string {};
+    /*!
+    @brief Read a BSON element list (as specified in the BSON-spec)
 
-    /// buffer for variable-length tokens (numbers, strings)
-    string_t token_buffer {};
+    The same binary layout is used for objects and arrays, hence it must be
+    indicated with the argument @a is_array which one is expected
+    (true --> array, false --> object).
 
-    /// a description of occurred lexer errors
-    const char* error_message = "";
+    @param[in] is_array Determines if the element list being read is to be
+                        treated as an object (@a is_array == false), or as an
+                        array (@a is_array == true).
+    @return whether a valid BSON-object/array was passed to the SAX parser
+    */
+    bool parse_bson_element_list(const bool is_array)
+    {
+        string_t key;
+        while (int element_type = get())
+        {
+            if (JSON_UNLIKELY(not unexpect_eof(input_format_t::bson, "element list")))
+            {
+                return false;
+            }
 
-    // number values
-    number_integer_t value_integer = 0;
-    number_unsigned_t value_unsigned = 0;
-    number_float_t value_float = 0;
+            const std::size_t element_type_parse_position = chars_read;
+            if (JSON_UNLIKELY(not get_bson_cstr(key)))
+            {
+                return false;
+            }
 
-    /// the decimal point
-    const char decimal_point_char = '.';
-};
-}  // namespace detail
-}  // namespace nlohmann
+            if (not is_array and not sax->key(key))
+            {
+                return false;
+            }
 
-// #include <nlohmann/detail/input/parser.hpp>
+            if (JSON_UNLIKELY(not parse_bson_element_internal(element_type, element_type_parse_position)))
+            {
+                return false;
+            }
 
+            // get_bson_cstr only appends
+            key.clear();
+        }
 
-#include <cassert> // assert
-#include <cmath> // isfinite
-#include <cstdint> // uint8_t
-#include <functional> // function
-#include <string> // string
-#include <utility> // move
+        return true;
+    }
 
-// #include <nlohmann/detail/exceptions.hpp>
+    /*!
+    @brief Reads an array from the BSON input and passes it to the SAX-parser.
+    @return whether a valid BSON-array was passed to the SAX parser
+    */
+    bool parse_bson_array()
+    {
+        std::int32_t document_size;
+        get_number<std::int32_t, true>(input_format_t::bson, document_size);
 
-// #include <nlohmann/detail/macro_scope.hpp>
+        if (JSON_UNLIKELY(not sax->start_array(std::size_t(-1))))
+        {
+            return false;
+        }
 
-// #include <nlohmann/detail/meta/is_sax.hpp>
+        if (JSON_UNLIKELY(not parse_bson_element_list(/*is_array*/true)))
+        {
+            return false;
+        }
 
+        return sax->end_array();
+    }
 
-#include <cstdint> // size_t
-#include <utility> // declval
+    //////////
+    // CBOR //
+    //////////
 
-// #include <nlohmann/detail/meta/detected.hpp>
+    /*!
+    @param[in] get_char  whether a new character should be retrieved from the
+                         input (true, default) or whether the last read
+                         character should be considered instead
 
-// #include <nlohmann/detail/meta/type_traits.hpp>
+    @return whether a valid CBOR value was passed to the SAX parser
+    */
+    bool parse_cbor_internal(const bool get_char = true)
+    {
+        switch (get_char ? get() : current)
+        {
+            // EOF
+            case std::char_traits<char>::eof():
+                return unexpect_eof(input_format_t::cbor, "value");
 
+            // Integer 0x00..0x17 (0..23)
+            case 0x00:
+            case 0x01:
+            case 0x02:
+            case 0x03:
+            case 0x04:
+            case 0x05:
+            case 0x06:
+            case 0x07:
+            case 0x08:
+            case 0x09:
+            case 0x0A:
+            case 0x0B:
+            case 0x0C:
+            case 0x0D:
+            case 0x0E:
+            case 0x0F:
+            case 0x10:
+            case 0x11:
+            case 0x12:
+            case 0x13:
+            case 0x14:
+            case 0x15:
+            case 0x16:
+            case 0x17:
+                return sax->number_unsigned(static_cast<number_unsigned_t>(current));
 
-namespace nlohmann
-{
-namespace detail
-{
-template <typename T>
-using null_function_t = decltype(std::declval<T&>().null());
+            case 0x18: // Unsigned integer (one-byte uint8_t follows)
+            {
+                std::uint8_t number;
+                return get_number(input_format_t::cbor, number) and sax->number_unsigned(number);
+            }
 
-template <typename T>
-using boolean_function_t =
-    decltype(std::declval<T&>().boolean(std::declval<bool>()));
+            case 0x19: // Unsigned integer (two-byte uint16_t follows)
+            {
+                std::uint16_t number;
+                return get_number(input_format_t::cbor, number) and sax->number_unsigned(number);
+            }
 
-template <typename T, typename Integer>
-using number_integer_function_t =
-    decltype(std::declval<T&>().number_integer(std::declval<Integer>()));
+            case 0x1A: // Unsigned integer (four-byte uint32_t follows)
+            {
+                std::uint32_t number;
+                return get_number(input_format_t::cbor, number) and sax->number_unsigned(number);
+            }
 
-template <typename T, typename Unsigned>
-using number_unsigned_function_t =
-    decltype(std::declval<T&>().number_unsigned(std::declval<Unsigned>()));
+            case 0x1B: // Unsigned integer (eight-byte uint64_t follows)
+            {
+                std::uint64_t number;
+                return get_number(input_format_t::cbor, number) and sax->number_unsigned(number);
+            }
 
-template <typename T, typename Float, typename String>
-using number_float_function_t = decltype(std::declval<T&>().number_float(
-                                    std::declval<Float>(), std::declval<const String&>()));
-
-template <typename T, typename String>
-using string_function_t =
-    decltype(std::declval<T&>().string(std::declval<String&>()));
-
-template <typename T>
-using start_object_function_t =
-    decltype(std::declval<T&>().start_object(std::declval<std::size_t>()));
+            // Negative integer -1-0x00..-1-0x17 (-1..-24)
+            case 0x20:
+            case 0x21:
+            case 0x22:
+            case 0x23:
+            case 0x24:
+            case 0x25:
+            case 0x26:
+            case 0x27:
+            case 0x28:
+            case 0x29:
+            case 0x2A:
+            case 0x2B:
+            case 0x2C:
+            case 0x2D:
+            case 0x2E:
+            case 0x2F:
+            case 0x30:
+            case 0x31:
+            case 0x32:
+            case 0x33:
+            case 0x34:
+            case 0x35:
+            case 0x36:
+            case 0x37:
+                return sax->number_integer(static_cast<std::int8_t>(0x20 - 1 - current));
 
-template <typename T, typename String>
-using key_function_t =
-    decltype(std::declval<T&>().key(std::declval<String&>()));
+            case 0x38: // Negative integer (one-byte uint8_t follows)
+            {
+                std::uint8_t number;
+                return get_number(input_format_t::cbor, number) and sax->number_integer(static_cast<number_integer_t>(-1) - number);
+            }
 
-template <typename T>
-using end_object_function_t = decltype(std::declval<T&>().end_object());
+            case 0x39: // Negative integer -1-n (two-byte uint16_t follows)
+            {
+                std::uint16_t number;
+                return get_number(input_format_t::cbor, number) and sax->number_integer(static_cast<number_integer_t>(-1) - number);
+            }
 
-template <typename T>
-using start_array_function_t =
-    decltype(std::declval<T&>().start_array(std::declval<std::size_t>()));
+            case 0x3A: // Negative integer -1-n (four-byte uint32_t follows)
+            {
+                std::uint32_t number;
+                return get_number(input_format_t::cbor, number) and sax->number_integer(static_cast<number_integer_t>(-1) - number);
+            }
 
-template <typename T>
-using end_array_function_t = decltype(std::declval<T&>().end_array());
+            case 0x3B: // Negative integer -1-n (eight-byte uint64_t follows)
+            {
+                std::uint64_t number;
+                return get_number(input_format_t::cbor, number) and sax->number_integer(static_cast<number_integer_t>(-1)
+                        - static_cast<number_integer_t>(number));
+            }
 
-template <typename T, typename Exception>
-using parse_error_function_t = decltype(std::declval<T&>().parse_error(
-        std::declval<std::size_t>(), std::declval<const std::string&>(),
-        std::declval<const Exception&>()));
+            // UTF-8 string (0x00..0x17 bytes follow)
+            case 0x60:
+            case 0x61:
+            case 0x62:
+            case 0x63:
+            case 0x64:
+            case 0x65:
+            case 0x66:
+            case 0x67:
+            case 0x68:
+            case 0x69:
+            case 0x6A:
+            case 0x6B:
+            case 0x6C:
+            case 0x6D:
+            case 0x6E:
+            case 0x6F:
+            case 0x70:
+            case 0x71:
+            case 0x72:
+            case 0x73:
+            case 0x74:
+            case 0x75:
+            case 0x76:
+            case 0x77:
+            case 0x78: // UTF-8 string (one-byte uint8_t for n follows)
+            case 0x79: // UTF-8 string (two-byte uint16_t for n follow)
+            case 0x7A: // UTF-8 string (four-byte uint32_t for n follow)
+            case 0x7B: // UTF-8 string (eight-byte uint64_t for n follow)
+            case 0x7F: // UTF-8 string (indefinite length)
+            {
+                string_t s;
+                return get_cbor_string(s) and sax->string(s);
+            }
 
-template <typename SAX, typename BasicJsonType>
-struct is_sax
-{
-  private:
-    static_assert(is_basic_json<BasicJsonType>::value,
-                  "BasicJsonType must be of type basic_json<...>");
+            // array (0x00..0x17 data items follow)
+            case 0x80:
+            case 0x81:
+            case 0x82:
+            case 0x83:
+            case 0x84:
+            case 0x85:
+            case 0x86:
+            case 0x87:
+            case 0x88:
+            case 0x89:
+            case 0x8A:
+            case 0x8B:
+            case 0x8C:
+            case 0x8D:
+            case 0x8E:
+            case 0x8F:
+            case 0x90:
+            case 0x91:
+            case 0x92:
+            case 0x93:
+            case 0x94:
+            case 0x95:
+            case 0x96:
+            case 0x97:
+                return get_cbor_array(static_cast<std::size_t>(static_cast<unsigned int>(current) & 0x1Fu));
 
-    using number_integer_t = typename BasicJsonType::number_integer_t;
-    using number_unsigned_t = typename BasicJsonType::number_unsigned_t;
-    using number_float_t = typename BasicJsonType::number_float_t;
-    using string_t = typename BasicJsonType::string_t;
-    using exception_t = typename BasicJsonType::exception;
+            case 0x98: // array (one-byte uint8_t for n follows)
+            {
+                std::uint8_t len;
+                return get_number(input_format_t::cbor, len) and get_cbor_array(static_cast<std::size_t>(len));
+            }
 
-  public:
-    static constexpr bool value =
-        is_detected_exact<bool, null_function_t, SAX>::value &&
-        is_detected_exact<bool, boolean_function_t, SAX>::value &&
-        is_detected_exact<bool, number_integer_function_t, SAX,
-        number_integer_t>::value &&
-        is_detected_exact<bool, number_unsigned_function_t, SAX,
-        number_unsigned_t>::value &&
-        is_detected_exact<bool, number_float_function_t, SAX, number_float_t,
-        string_t>::value &&
-        is_detected_exact<bool, string_function_t, SAX, string_t>::value &&
-        is_detected_exact<bool, start_object_function_t, SAX>::value &&
-        is_detected_exact<bool, key_function_t, SAX, string_t>::value &&
-        is_detected_exact<bool, end_object_function_t, SAX>::value &&
-        is_detected_exact<bool, start_array_function_t, SAX>::value &&
-        is_detected_exact<bool, end_array_function_t, SAX>::value &&
-        is_detected_exact<bool, parse_error_function_t, SAX, exception_t>::value;
-};
+            case 0x99: // array (two-byte uint16_t for n follow)
+            {
+                std::uint16_t len;
+                return get_number(input_format_t::cbor, len) and get_cbor_array(static_cast<std::size_t>(len));
+            }
 
-template <typename SAX, typename BasicJsonType>
-struct is_sax_static_asserts
-{
-  private:
-    static_assert(is_basic_json<BasicJsonType>::value,
-                  "BasicJsonType must be of type basic_json<...>");
+            case 0x9A: // array (four-byte uint32_t for n follow)
+            {
+                std::uint32_t len;
+                return get_number(input_format_t::cbor, len) and get_cbor_array(static_cast<std::size_t>(len));
+            }
 
-    using number_integer_t = typename BasicJsonType::number_integer_t;
-    using number_unsigned_t = typename BasicJsonType::number_unsigned_t;
-    using number_float_t = typename BasicJsonType::number_float_t;
-    using string_t = typename BasicJsonType::string_t;
-    using exception_t = typename BasicJsonType::exception;
+            case 0x9B: // array (eight-byte uint64_t for n follow)
+            {
+                std::uint64_t len;
+                return get_number(input_format_t::cbor, len) and get_cbor_array(static_cast<std::size_t>(len));
+            }
 
-  public:
-    static_assert(is_detected_exact<bool, null_function_t, SAX>::value,
-                  "Missing/invalid function: bool null()");
-    static_assert(is_detected_exact<bool, boolean_function_t, SAX>::value,
-                  "Missing/invalid function: bool boolean(bool)");
-    static_assert(is_detected_exact<bool, boolean_function_t, SAX>::value,
-                  "Missing/invalid function: bool boolean(bool)");
-    static_assert(
-        is_detected_exact<bool, number_integer_function_t, SAX,
-        number_integer_t>::value,
-        "Missing/invalid function: bool number_integer(number_integer_t)");
-    static_assert(
-        is_detected_exact<bool, number_unsigned_function_t, SAX,
-        number_unsigned_t>::value,
-        "Missing/invalid function: bool number_unsigned(number_unsigned_t)");
-    static_assert(is_detected_exact<bool, number_float_function_t, SAX,
-                  number_float_t, string_t>::value,
-                  "Missing/invalid function: bool number_float(number_float_t, const string_t&)");
-    static_assert(
-        is_detected_exact<bool, string_function_t, SAX, string_t>::value,
-        "Missing/invalid function: bool string(string_t&)");
-    static_assert(is_detected_exact<bool, start_object_function_t, SAX>::value,
-                  "Missing/invalid function: bool start_object(std::size_t)");
-    static_assert(is_detected_exact<bool, key_function_t, SAX, string_t>::value,
-                  "Missing/invalid function: bool key(string_t&)");
-    static_assert(is_detected_exact<bool, end_object_function_t, SAX>::value,
-                  "Missing/invalid function: bool end_object()");
-    static_assert(is_detected_exact<bool, start_array_function_t, SAX>::value,
-                  "Missing/invalid function: bool start_array(std::size_t)");
-    static_assert(is_detected_exact<bool, end_array_function_t, SAX>::value,
-                  "Missing/invalid function: bool end_array()");
-    static_assert(
-        is_detected_exact<bool, parse_error_function_t, SAX, exception_t>::value,
-        "Missing/invalid function: bool parse_error(std::size_t, const "
-        "std::string&, const exception&)");
-};
-}  // namespace detail
-}  // namespace nlohmann
+            case 0x9F: // array (indefinite length)
+                return get_cbor_array(std::size_t(-1));
 
-// #include <nlohmann/detail/input/input_adapters.hpp>
+            // map (0x00..0x17 pairs of data items follow)
+            case 0xA0:
+            case 0xA1:
+            case 0xA2:
+            case 0xA3:
+            case 0xA4:
+            case 0xA5:
+            case 0xA6:
+            case 0xA7:
+            case 0xA8:
+            case 0xA9:
+            case 0xAA:
+            case 0xAB:
+            case 0xAC:
+            case 0xAD:
+            case 0xAE:
+            case 0xAF:
+            case 0xB0:
+            case 0xB1:
+            case 0xB2:
+            case 0xB3:
+            case 0xB4:
+            case 0xB5:
+            case 0xB6:
+            case 0xB7:
+                return get_cbor_object(static_cast<std::size_t>(static_cast<unsigned int>(current) & 0x1Fu));
 
-// #include <nlohmann/detail/input/json_sax.hpp>
+            case 0xB8: // map (one-byte uint8_t for n follows)
+            {
+                std::uint8_t len;
+                return get_number(input_format_t::cbor, len) and get_cbor_object(static_cast<std::size_t>(len));
+            }
 
+            case 0xB9: // map (two-byte uint16_t for n follow)
+            {
+                std::uint16_t len;
+                return get_number(input_format_t::cbor, len) and get_cbor_object(static_cast<std::size_t>(len));
+            }
 
-#include <cstddef>
-#include <string>
-#include <vector>
-
-// #include <nlohmann/detail/input/parser.hpp>
+            case 0xBA: // map (four-byte uint32_t for n follow)
+            {
+                std::uint32_t len;
+                return get_number(input_format_t::cbor, len) and get_cbor_object(static_cast<std::size_t>(len));
+            }
 
-// #include <nlohmann/detail/exceptions.hpp>
+            case 0xBB: // map (eight-byte uint64_t for n follow)
+            {
+                std::uint64_t len;
+                return get_number(input_format_t::cbor, len) and get_cbor_object(static_cast<std::size_t>(len));
+            }
 
+            case 0xBF: // map (indefinite length)
+                return get_cbor_object(std::size_t(-1));
 
-namespace nlohmann
-{
+            case 0xF4: // false
+                return sax->boolean(false);
 
-/*!
-@brief SAX interface
+            case 0xF5: // true
+                return sax->boolean(true);
 
-This class describes the SAX interface used by @ref nlohmann::json::sax_parse.
-Each function is called in different situations while the input is parsed. The
-boolean return value informs the parser whether to continue processing the
-input.
-*/
-template<typename BasicJsonType>
-struct json_sax
-{
-    /// type for (signed) integers
-    using number_integer_t = typename BasicJsonType::number_integer_t;
-    /// type for unsigned integers
-    using number_unsigned_t = typename BasicJsonType::number_unsigned_t;
-    /// type for floating-point numbers
-    using number_float_t = typename BasicJsonType::number_float_t;
-    /// type for strings
-    using string_t = typename BasicJsonType::string_t;
+            case 0xF6: // null
+                return sax->null();
 
-    /*!
-    @brief a null value was read
-    @return whether parsing should proceed
-    */
-    virtual bool null() = 0;
+            case 0xF9: // Half-Precision Float (two-byte IEEE 754)
+            {
+                const int byte1_raw = get();
+                if (JSON_UNLIKELY(not unexpect_eof(input_format_t::cbor, "number")))
+                {
+                    return false;
+                }
+                const int byte2_raw = get();
+                if (JSON_UNLIKELY(not unexpect_eof(input_format_t::cbor, "number")))
+                {
+                    return false;
+                }
 
-    /*!
-    @brief a boolean value was read
-    @param[in] val  boolean value
-    @return whether parsing should proceed
-    */
-    virtual bool boolean(bool val) = 0;
+                const auto byte1 = static_cast<unsigned char>(byte1_raw);
+                const auto byte2 = static_cast<unsigned char>(byte2_raw);
 
-    /*!
-    @brief an integer number was read
-    @param[in] val  integer value
-    @return whether parsing should proceed
-    */
-    virtual bool number_integer(number_integer_t val) = 0;
+                // code from RFC 7049, Appendix D, Figure 3:
+                // As half-precision floating-point numbers were only added
+                // to IEEE 754 in 2008, today's programming platforms often
+                // still only have limited support for them. It is very
+                // easy to include at least decoding support for them even
+                // without such support. An example of a small decoder for
+                // half-precision floating-point numbers in the C language
+                // is shown in Fig. 3.
+                const auto half = static_cast<unsigned int>((byte1 << 8u) + byte2);
+                const double val = [&half]
+                {
+                    const int exp = (half >> 10u) & 0x1Fu;
+                    const unsigned int mant = half & 0x3FFu;
+                    assert(0 <= exp and exp <= 32);
+                    assert(0 <= mant and mant <= 1024);
+                    switch (exp)
+                    {
+                        case 0:
+                            return std::ldexp(mant, -24);
+                        case 31:
+                            return (mant == 0)
+                            ? std::numeric_limits<double>::infinity()
+                            : std::numeric_limits<double>::quiet_NaN();
+                        default:
+                            return std::ldexp(mant + 1024, exp - 25);
+                    }
+                }();
+                return sax->number_float((half & 0x8000u) != 0
+                                         ? static_cast<number_float_t>(-val)
+                                         : static_cast<number_float_t>(val), "");
+            }
 
-    /*!
-    @brief an unsigned integer number was read
-    @param[in] val  unsigned integer value
-    @return whether parsing should proceed
-    */
-    virtual bool number_unsigned(number_unsigned_t val) = 0;
+            case 0xFA: // Single-Precision Float (four-byte IEEE 754)
+            {
+                float number;
+                return get_number(input_format_t::cbor, number) and sax->number_float(static_cast<number_float_t>(number), "");
+            }
 
-    /*!
-    @brief an floating-point number was read
-    @param[in] val  floating-point value
-    @param[in] s    raw token value
-    @return whether parsing should proceed
-    */
-    virtual bool number_float(number_float_t val, const string_t& s) = 0;
+            case 0xFB: // Double-Precision Float (eight-byte IEEE 754)
+            {
+                double number;
+                return get_number(input_format_t::cbor, number) and sax->number_float(static_cast<number_float_t>(number), "");
+            }
 
-    /*!
-    @brief a string was read
-    @param[in] val  string value
-    @return whether parsing should proceed
-    @note It is safe to move the passed string.
-    */
-    virtual bool string(string_t& val) = 0;
+            default: // anything else (0xFF is handled inside the other types)
+            {
+                auto last_token = get_token_string();
+                return sax->parse_error(chars_read, last_token, parse_error::create(112, chars_read, exception_message(input_format_t::cbor, "invalid byte: 0x" + last_token, "value")));
+            }
+        }
+    }
 
     /*!
-    @brief the beginning of an object was read
-    @param[in] elements  number of object elements or -1 if unknown
-    @return whether parsing should proceed
-    @note binary formats may report the number of elements
-    */
-    virtual bool start_object(std::size_t elements) = 0;
+    @brief reads a CBOR string
 
-    /*!
-    @brief an object key was read
-    @param[in] val  object key
-    @return whether parsing should proceed
-    @note It is safe to move the passed string.
-    */
-    virtual bool key(string_t& val) = 0;
+    This function first reads starting bytes to determine the expected
+    string length and then copies this number of bytes into a string.
+    Additionally, CBOR's strings with indefinite lengths are supported.
 
-    /*!
-    @brief the end of an object was read
-    @return whether parsing should proceed
-    */
-    virtual bool end_object() = 0;
+    @param[out] result  created string
 
-    /*!
-    @brief the beginning of an array was read
-    @param[in] elements  number of array elements or -1 if unknown
-    @return whether parsing should proceed
-    @note binary formats may report the number of elements
+    @return whether string creation completed
     */
-    virtual bool start_array(std::size_t elements) = 0;
+    bool get_cbor_string(string_t& result)
+    {
+        if (JSON_UNLIKELY(not unexpect_eof(input_format_t::cbor, "string")))
+        {
+            return false;
+        }
 
-    /*!
-    @brief the end of an array was read
-    @return whether parsing should proceed
-    */
-    virtual bool end_array() = 0;
+        switch (current)
+        {
+            // UTF-8 string (0x00..0x17 bytes follow)
+            case 0x60:
+            case 0x61:
+            case 0x62:
+            case 0x63:
+            case 0x64:
+            case 0x65:
+            case 0x66:
+            case 0x67:
+            case 0x68:
+            case 0x69:
+            case 0x6A:
+            case 0x6B:
+            case 0x6C:
+            case 0x6D:
+            case 0x6E:
+            case 0x6F:
+            case 0x70:
+            case 0x71:
+            case 0x72:
+            case 0x73:
+            case 0x74:
+            case 0x75:
+            case 0x76:
+            case 0x77:
+            {
+                return get_string(input_format_t::cbor, static_cast<unsigned int>(current) & 0x1Fu, result);
+            }
 
-    /*!
-    @brief a parse error occurred
-    @param[in] position    the position in the input where the error occurs
-    @param[in] last_token  the last read token
-    @param[in] ex          an exception object describing the error
-    @return whether parsing should proceed (must return false)
-    */
-    virtual bool parse_error(std::size_t position,
-                             const std::string& last_token,
-                             const detail::exception& ex) = 0;
+            case 0x78: // UTF-8 string (one-byte uint8_t for n follows)
+            {
+                std::uint8_t len;
+                return get_number(input_format_t::cbor, len) and get_string(input_format_t::cbor, len, result);
+            }
 
-    virtual ~json_sax() = default;
-};
+            case 0x79: // UTF-8 string (two-byte uint16_t for n follow)
+            {
+                std::uint16_t len;
+                return get_number(input_format_t::cbor, len) and get_string(input_format_t::cbor, len, result);
+            }
 
+            case 0x7A: // UTF-8 string (four-byte uint32_t for n follow)
+            {
+                std::uint32_t len;
+                return get_number(input_format_t::cbor, len) and get_string(input_format_t::cbor, len, result);
+            }
 
-namespace detail
-{
-/*!
-@brief SAX implementation to create a JSON value from SAX events
+            case 0x7B: // UTF-8 string (eight-byte uint64_t for n follow)
+            {
+                std::uint64_t len;
+                return get_number(input_format_t::cbor, len) and get_string(input_format_t::cbor, len, result);
+            }
 
-This class implements the @ref json_sax interface and processes the SAX events
-to create a JSON value which makes it basically a DOM parser. The structure or
-hierarchy of the JSON value is managed by the stack `ref_stack` which contains
-a pointer to the respective array or object for each recursion depth.
+            case 0x7F: // UTF-8 string (indefinite length)
+            {
+                while (get() != 0xFF)
+                {
+                    string_t chunk;
+                    if (not get_cbor_string(chunk))
+                    {
+                        return false;
+                    }
+                    result.append(chunk);
+                }
+                return true;
+            }
 
-After successful parsing, the value that is passed by reference to the
-constructor contains the parsed value.
-
-@tparam BasicJsonType  the JSON type
-*/
-template<typename BasicJsonType>
-class json_sax_dom_parser
-{
-  public:
-    using number_integer_t = typename BasicJsonType::number_integer_t;
-    using number_unsigned_t = typename BasicJsonType::number_unsigned_t;
-    using number_float_t = typename BasicJsonType::number_float_t;
-    using string_t = typename BasicJsonType::string_t;
+            default:
+            {
+                auto last_token = get_token_string();
+                return sax->parse_error(chars_read, last_token, parse_error::create(113, chars_read, exception_message(input_format_t::cbor, "expected length specification (0x60-0x7B) or indefinite string type (0x7F); last byte: 0x" + last_token, "string")));
+            }
+        }
+    }
 
     /*!
-    @param[in, out] r  reference to a JSON value that is manipulated while
-                       parsing
-    @param[in] allow_exceptions_  whether parse errors yield exceptions
+    @param[in] len  the length of the array or std::size_t(-1) for an
+                    array of indefinite size
+    @return whether array creation completed
     */
-    explicit json_sax_dom_parser(BasicJsonType& r, const bool allow_exceptions_ = true)
-        : root(r), allow_exceptions(allow_exceptions_)
-    {}
-
-    bool null()
-    {
-        handle_value(nullptr);
-        return true;
-    }
-
-    bool boolean(bool val)
-    {
-        handle_value(val);
-        return true;
-    }
-
-    bool number_integer(number_integer_t val)
-    {
-        handle_value(val);
-        return true;
-    }
-
-    bool number_unsigned(number_unsigned_t val)
-    {
-        handle_value(val);
-        return true;
-    }
-
-    bool number_float(number_float_t val, const string_t& /*unused*/)
-    {
-        handle_value(val);
-        return true;
-    }
-
-    bool string(string_t& val)
-    {
-        handle_value(val);
-        return true;
-    }
-
-    bool start_object(std::size_t len)
+    bool get_cbor_array(const std::size_t len)
     {
-        ref_stack.push_back(handle_value(BasicJsonType::value_t::object));
-
-        if (JSON_UNLIKELY(len != std::size_t(-1) and len > ref_stack.back()->max_size()))
+        if (JSON_UNLIKELY(not sax->start_array(len)))
         {
-            JSON_THROW(out_of_range::create(408,
-                                            "excessive object size: " + std::to_string(len)));
+            return false;
         }
 
-        return true;
-    }
-
-    bool key(string_t& val)
-    {
-        // add null at given key and store the reference for later
-        object_element = &(ref_stack.back()->m_value.object->operator[](val));
-        return true;
-    }
-
-    bool end_object()
-    {
-        ref_stack.pop_back();
-        return true;
-    }
-
-    bool start_array(std::size_t len)
-    {
-        ref_stack.push_back(handle_value(BasicJsonType::value_t::array));
-
-        if (JSON_UNLIKELY(len != std::size_t(-1) and len > ref_stack.back()->max_size()))
+        if (len != std::size_t(-1))
         {
-            JSON_THROW(out_of_range::create(408,
-                                            "excessive array size: " + std::to_string(len)));
+            for (std::size_t i = 0; i < len; ++i)
+            {
+                if (JSON_UNLIKELY(not parse_cbor_internal()))
+                {
+                    return false;
+                }
+            }
         }
-
-        return true;
-    }
-
-    bool end_array()
-    {
-        ref_stack.pop_back();
-        return true;
-    }
-
-    bool parse_error(std::size_t /*unused*/, const std::string& /*unused*/,
-                     const detail::exception& ex)
-    {
-        errored = true;
-        if (allow_exceptions)
+        else
         {
-            // determine the proper exception type from the id
-            switch ((ex.id / 100) % 100)
+            while (get() != 0xFF)
             {
-                case 1:
-                    JSON_THROW(*reinterpret_cast<const detail::parse_error*>(&ex));
-                case 4:
-                    JSON_THROW(*reinterpret_cast<const detail::out_of_range*>(&ex));
-                // LCOV_EXCL_START
-                case 2:
-                    JSON_THROW(*reinterpret_cast<const detail::invalid_iterator*>(&ex));
-                case 3:
-                    JSON_THROW(*reinterpret_cast<const detail::type_error*>(&ex));
-                case 5:
-                    JSON_THROW(*reinterpret_cast<const detail::other_error*>(&ex));
-                default:
-                    assert(false);
-                    // LCOV_EXCL_STOP
+                if (JSON_UNLIKELY(not parse_cbor_internal(false)))
+                {
+                    return false;
+                }
             }
         }
-        return false;
-    }
 
-    constexpr bool is_errored() const
-    {
-        return errored;
+        return sax->end_array();
     }
 
-  private:
     /*!
-    @invariant If the ref stack is empty, then the passed value will be the new
-               root.
-    @invariant If the ref stack contains a value, then it is an array or an
-               object to which we can add elements
+    @param[in] len  the length of the object or std::size_t(-1) for an
+                    object of indefinite size
+    @return whether object creation completed
     */
-    template<typename Value>
-    BasicJsonType* handle_value(Value&& v)
+    bool get_cbor_object(const std::size_t len)
     {
-        if (ref_stack.empty())
+        if (JSON_UNLIKELY(not sax->start_object(len)))
         {
-            root = BasicJsonType(std::forward<Value>(v));
-            return &root;
+            return false;
         }
 
-        assert(ref_stack.back()->is_array() or ref_stack.back()->is_object());
-
-        if (ref_stack.back()->is_array())
+        string_t key;
+        if (len != std::size_t(-1))
         {
-            ref_stack.back()->m_value.array->emplace_back(std::forward<Value>(v));
-            return &(ref_stack.back()->m_value.array->back());
+            for (std::size_t i = 0; i < len; ++i)
+            {
+                get();
+                if (JSON_UNLIKELY(not get_cbor_string(key) or not sax->key(key)))
+                {
+                    return false;
+                }
+
+                if (JSON_UNLIKELY(not parse_cbor_internal()))
+                {
+                    return false;
+                }
+                key.clear();
+            }
         }
         else
         {
-            assert(object_element);
-            *object_element = BasicJsonType(std::forward<Value>(v));
-            return object_element;
-        }
-    }
-
-    /// the parsed JSON value
-    BasicJsonType& root;
-    /// stack to model hierarchy of values
-    std::vector<BasicJsonType*> ref_stack;
-    /// helper to hold the reference for the next object element
-    BasicJsonType* object_element = nullptr;
-    /// whether a syntax error occurred
-    bool errored = false;
-    /// whether to throw exceptions in case of errors
-    const bool allow_exceptions = true;
-};
-
-template<typename BasicJsonType>
-class json_sax_dom_callback_parser
-{
-  public:
-    using number_integer_t = typename BasicJsonType::number_integer_t;
-    using number_unsigned_t = typename BasicJsonType::number_unsigned_t;
-    using number_float_t = typename BasicJsonType::number_float_t;
-    using string_t = typename BasicJsonType::string_t;
-    using parser_callback_t = typename BasicJsonType::parser_callback_t;
-    using parse_event_t = typename BasicJsonType::parse_event_t;
-
-    json_sax_dom_callback_parser(BasicJsonType& r,
-                                 const parser_callback_t cb,
-                                 const bool allow_exceptions_ = true)
-        : root(r), callback(cb), allow_exceptions(allow_exceptions_)
-    {
-        keep_stack.push_back(true);
-    }
+            while (get() != 0xFF)
+            {
+                if (JSON_UNLIKELY(not get_cbor_string(key) or not sax->key(key)))
+                {
+                    return false;
+                }
 
-    bool null()
-    {
-        handle_value(nullptr);
-        return true;
-    }
+                if (JSON_UNLIKELY(not parse_cbor_internal()))
+                {
+                    return false;
+                }
+                key.clear();
+            }
+        }
 
-    bool boolean(bool val)
-    {
-        handle_value(val);
-        return true;
+        return sax->end_object();
     }
 
-    bool number_integer(number_integer_t val)
-    {
-        handle_value(val);
-        return true;
-    }
+    /////////////
+    // MsgPack //
+    /////////////
 
-    bool number_unsigned(number_unsigned_t val)
+    /*!
+    @return whether a valid MessagePack value was passed to the SAX parser
+    */
+    bool parse_msgpack_internal()
     {
-        handle_value(val);
-        return true;
-    }
+        switch (get())
+        {
+            // EOF
+            case std::char_traits<char>::eof():
+                return unexpect_eof(input_format_t::msgpack, "value");
 
-    bool number_float(number_float_t val, const string_t& /*unused*/)
-    {
-        handle_value(val);
-        return true;
-    }
-
-    bool string(string_t& val)
-    {
-        handle_value(val);
-        return true;
-    }
+            // positive fixint
+            case 0x00:
+            case 0x01:
+            case 0x02:
+            case 0x03:
+            case 0x04:
+            case 0x05:
+            case 0x06:
+            case 0x07:
+            case 0x08:
+            case 0x09:
+            case 0x0A:
+            case 0x0B:
+            case 0x0C:
+            case 0x0D:
+            case 0x0E:
+            case 0x0F:
+            case 0x10:
+            case 0x11:
+            case 0x12:
+            case 0x13:
+            case 0x14:
+            case 0x15:
+            case 0x16:
+            case 0x17:
+            case 0x18:
+            case 0x19:
+            case 0x1A:
+            case 0x1B:
+            case 0x1C:
+            case 0x1D:
+            case 0x1E:
+            case 0x1F:
+            case 0x20:
+            case 0x21:
+            case 0x22:
+            case 0x23:
+            case 0x24:
+            case 0x25:
+            case 0x26:
+            case 0x27:
+            case 0x28:
+            case 0x29:
+            case 0x2A:
+            case 0x2B:
+            case 0x2C:
+            case 0x2D:
+            case 0x2E:
+            case 0x2F:
+            case 0x30:
+            case 0x31:
+            case 0x32:
+            case 0x33:
+            case 0x34:
+            case 0x35:
+            case 0x36:
+            case 0x37:
+            case 0x38:
+            case 0x39:
+            case 0x3A:
+            case 0x3B:
+            case 0x3C:
+            case 0x3D:
+            case 0x3E:
+            case 0x3F:
+            case 0x40:
+            case 0x41:
+            case 0x42:
+            case 0x43:
+            case 0x44:
+            case 0x45:
+            case 0x46:
+            case 0x47:
+            case 0x48:
+            case 0x49:
+            case 0x4A:
+            case 0x4B:
+            case 0x4C:
+            case 0x4D:
+            case 0x4E:
+            case 0x4F:
+            case 0x50:
+            case 0x51:
+            case 0x52:
+            case 0x53:
+            case 0x54:
+            case 0x55:
+            case 0x56:
+            case 0x57:
+            case 0x58:
+            case 0x59:
+            case 0x5A:
+            case 0x5B:
+            case 0x5C:
+            case 0x5D:
+            case 0x5E:
+            case 0x5F:
+            case 0x60:
+            case 0x61:
+            case 0x62:
+            case 0x63:
+            case 0x64:
+            case 0x65:
+            case 0x66:
+            case 0x67:
+            case 0x68:
+            case 0x69:
+            case 0x6A:
+            case 0x6B:
+            case 0x6C:
+            case 0x6D:
+            case 0x6E:
+            case 0x6F:
+            case 0x70:
+            case 0x71:
+            case 0x72:
+            case 0x73:
+            case 0x74:
+            case 0x75:
+            case 0x76:
+            case 0x77:
+            case 0x78:
+            case 0x79:
+            case 0x7A:
+            case 0x7B:
+            case 0x7C:
+            case 0x7D:
+            case 0x7E:
+            case 0x7F:
+                return sax->number_unsigned(static_cast<number_unsigned_t>(current));
 
-    bool start_object(std::size_t len)
-    {
-        // check callback for object start
-        const bool keep = callback(static_cast<int>(ref_stack.size()), parse_event_t::object_start, discarded);
-        keep_stack.push_back(keep);
+            // fixmap
+            case 0x80:
+            case 0x81:
+            case 0x82:
+            case 0x83:
+            case 0x84:
+            case 0x85:
+            case 0x86:
+            case 0x87:
+            case 0x88:
+            case 0x89:
+            case 0x8A:
+            case 0x8B:
+            case 0x8C:
+            case 0x8D:
+            case 0x8E:
+            case 0x8F:
+                return get_msgpack_object(static_cast<std::size_t>(static_cast<unsigned int>(current) & 0x0Fu));
 
-        auto val = handle_value(BasicJsonType::value_t::object, true);
-        ref_stack.push_back(val.second);
+            // fixarray
+            case 0x90:
+            case 0x91:
+            case 0x92:
+            case 0x93:
+            case 0x94:
+            case 0x95:
+            case 0x96:
+            case 0x97:
+            case 0x98:
+            case 0x99:
+            case 0x9A:
+            case 0x9B:
+            case 0x9C:
+            case 0x9D:
+            case 0x9E:
+            case 0x9F:
+                return get_msgpack_array(static_cast<std::size_t>(static_cast<unsigned int>(current) & 0x0Fu));
 
-        // check object limit
-        if (ref_stack.back())
-        {
-            if (JSON_UNLIKELY(len != std::size_t(-1) and len > ref_stack.back()->max_size()))
+            // fixstr
+            case 0xA0:
+            case 0xA1:
+            case 0xA2:
+            case 0xA3:
+            case 0xA4:
+            case 0xA5:
+            case 0xA6:
+            case 0xA7:
+            case 0xA8:
+            case 0xA9:
+            case 0xAA:
+            case 0xAB:
+            case 0xAC:
+            case 0xAD:
+            case 0xAE:
+            case 0xAF:
+            case 0xB0:
+            case 0xB1:
+            case 0xB2:
+            case 0xB3:
+            case 0xB4:
+            case 0xB5:
+            case 0xB6:
+            case 0xB7:
+            case 0xB8:
+            case 0xB9:
+            case 0xBA:
+            case 0xBB:
+            case 0xBC:
+            case 0xBD:
+            case 0xBE:
+            case 0xBF:
             {
-                JSON_THROW(out_of_range::create(408,
-                                                "excessive object size: " + std::to_string(len)));
+                string_t s;
+                return get_msgpack_string(s) and sax->string(s);
             }
-        }
 
-        return true;
-    }
-
-    bool key(string_t& val)
-    {
-        BasicJsonType k = BasicJsonType(val);
+            case 0xC0: // nil
+                return sax->null();
 
-        // check callback for key
-        const bool keep = callback(static_cast<int>(ref_stack.size()), parse_event_t::key, k);
-        key_keep_stack.push_back(keep);
+            case 0xC2: // false
+                return sax->boolean(false);
 
-        // add discarded value at given key and store the reference for later
-        if (keep and ref_stack.back())
-        {
-            object_element = &(ref_stack.back()->m_value.object->operator[](val) = discarded);
-        }
+            case 0xC3: // true
+                return sax->boolean(true);
 
-        return true;
-    }
+            case 0xCA: // float 32
+            {
+                float number;
+                return get_number(input_format_t::msgpack, number) and sax->number_float(static_cast<number_float_t>(number), "");
+            }
 
-    bool end_object()
-    {
-        if (ref_stack.back())
-        {
-            if (not callback(static_cast<int>(ref_stack.size()) - 1, parse_event_t::object_end, *ref_stack.back()))
+            case 0xCB: // float 64
             {
-                // discard object
-                *ref_stack.back() = discarded;
+                double number;
+                return get_number(input_format_t::msgpack, number) and sax->number_float(static_cast<number_float_t>(number), "");
             }
-        }
 
-        assert(not ref_stack.empty());
-        assert(not keep_stack.empty());
-        ref_stack.pop_back();
-        keep_stack.pop_back();
+            case 0xCC: // uint 8
+            {
+                std::uint8_t number;
+                return get_number(input_format_t::msgpack, number) and sax->number_unsigned(number);
+            }
 
-        if (not ref_stack.empty() and ref_stack.back())
-        {
-            // remove discarded value
-            if (ref_stack.back()->is_object())
+            case 0xCD: // uint 16
             {
-                for (auto it = ref_stack.back()->begin(); it != ref_stack.back()->end(); ++it)
-                {
-                    if (it->is_discarded())
-                    {
-                        ref_stack.back()->erase(it);
-                        break;
-                    }
-                }
+                std::uint16_t number;
+                return get_number(input_format_t::msgpack, number) and sax->number_unsigned(number);
             }
-        }
 
-        return true;
-    }
+            case 0xCE: // uint 32
+            {
+                std::uint32_t number;
+                return get_number(input_format_t::msgpack, number) and sax->number_unsigned(number);
+            }
 
-    bool start_array(std::size_t len)
-    {
-        const bool keep = callback(static_cast<int>(ref_stack.size()), parse_event_t::array_start, discarded);
-        keep_stack.push_back(keep);
+            case 0xCF: // uint 64
+            {
+                std::uint64_t number;
+                return get_number(input_format_t::msgpack, number) and sax->number_unsigned(number);
+            }
 
-        auto val = handle_value(BasicJsonType::value_t::array, true);
-        ref_stack.push_back(val.second);
+            case 0xD0: // int 8
+            {
+                std::int8_t number;
+                return get_number(input_format_t::msgpack, number) and sax->number_integer(number);
+            }
 
-        // check array limit
-        if (ref_stack.back())
-        {
-            if (JSON_UNLIKELY(len != std::size_t(-1) and len > ref_stack.back()->max_size()))
+            case 0xD1: // int 16
             {
-                JSON_THROW(out_of_range::create(408,
-                                                "excessive array size: " + std::to_string(len)));
+                std::int16_t number;
+                return get_number(input_format_t::msgpack, number) and sax->number_integer(number);
             }
-        }
 
-        return true;
-    }
+            case 0xD2: // int 32
+            {
+                std::int32_t number;
+                return get_number(input_format_t::msgpack, number) and sax->number_integer(number);
+            }
 
-    bool end_array()
-    {
-        bool keep = true;
+            case 0xD3: // int 64
+            {
+                std::int64_t number;
+                return get_number(input_format_t::msgpack, number) and sax->number_integer(number);
+            }
 
-        if (ref_stack.back())
-        {
-            keep = callback(static_cast<int>(ref_stack.size()) - 1, parse_event_t::array_end, *ref_stack.back());
-            if (not keep)
+            case 0xD9: // str 8
+            case 0xDA: // str 16
+            case 0xDB: // str 32
             {
-                // discard array
-                *ref_stack.back() = discarded;
+                string_t s;
+                return get_msgpack_string(s) and sax->string(s);
             }
-        }
 
-        assert(not ref_stack.empty());
-        assert(not keep_stack.empty());
-        ref_stack.pop_back();
-        keep_stack.pop_back();
+            case 0xDC: // array 16
+            {
+                std::uint16_t len;
+                return get_number(input_format_t::msgpack, len) and get_msgpack_array(static_cast<std::size_t>(len));
+            }
 
-        // remove discarded value
-        if (not keep and not ref_stack.empty())
-        {
-            if (ref_stack.back()->is_array())
+            case 0xDD: // array 32
             {
-                ref_stack.back()->m_value.array->pop_back();
+                std::uint32_t len;
+                return get_number(input_format_t::msgpack, len) and get_msgpack_array(static_cast<std::size_t>(len));
             }
-        }
 
-        return true;
-    }
+            case 0xDE: // map 16
+            {
+                std::uint16_t len;
+                return get_number(input_format_t::msgpack, len) and get_msgpack_object(static_cast<std::size_t>(len));
+            }
 
-    bool parse_error(std::size_t /*unused*/, const std::string& /*unused*/,
-                     const detail::exception& ex)
-    {
-        errored = true;
-        if (allow_exceptions)
-        {
-            // determine the proper exception type from the id
-            switch ((ex.id / 100) % 100)
+            case 0xDF: // map 32
             {
-                case 1:
-                    JSON_THROW(*reinterpret_cast<const detail::parse_error*>(&ex));
-                case 4:
-                    JSON_THROW(*reinterpret_cast<const detail::out_of_range*>(&ex));
-                // LCOV_EXCL_START
-                case 2:
-                    JSON_THROW(*reinterpret_cast<const detail::invalid_iterator*>(&ex));
-                case 3:
-                    JSON_THROW(*reinterpret_cast<const detail::type_error*>(&ex));
-                case 5:
-                    JSON_THROW(*reinterpret_cast<const detail::other_error*>(&ex));
-                default:
-                    assert(false);
-                    // LCOV_EXCL_STOP
+                std::uint32_t len;
+                return get_number(input_format_t::msgpack, len) and get_msgpack_object(static_cast<std::size_t>(len));
             }
-        }
-        return false;
-    }
 
-    constexpr bool is_errored() const
-    {
-        return errored;
+            // negative fixint
+            case 0xE0:
+            case 0xE1:
+            case 0xE2:
+            case 0xE3:
+            case 0xE4:
+            case 0xE5:
+            case 0xE6:
+            case 0xE7:
+            case 0xE8:
+            case 0xE9:
+            case 0xEA:
+            case 0xEB:
+            case 0xEC:
+            case 0xED:
+            case 0xEE:
+            case 0xEF:
+            case 0xF0:
+            case 0xF1:
+            case 0xF2:
+            case 0xF3:
+            case 0xF4:
+            case 0xF5:
+            case 0xF6:
+            case 0xF7:
+            case 0xF8:
+            case 0xF9:
+            case 0xFA:
+            case 0xFB:
+            case 0xFC:
+            case 0xFD:
+            case 0xFE:
+            case 0xFF:
+                return sax->number_integer(static_cast<std::int8_t>(current));
+
+            default: // anything else
+            {
+                auto last_token = get_token_string();
+                return sax->parse_error(chars_read, last_token, parse_error::create(112, chars_read, exception_message(input_format_t::msgpack, "invalid byte: 0x" + last_token, "value")));
+            }
+        }
     }
 
-  private:
     /*!
-    @param[in] v  value to add to the JSON value we build during parsing
-    @param[in] skip_callback  whether we should skip calling the callback
-               function; this is required after start_array() and
-               start_object() SAX events, because otherwise we would call the
-               callback function with an empty array or object, respectively.
+    @brief reads a MessagePack string
 
-    @invariant If the ref stack is empty, then the passed value will be the new
-               root.
-    @invariant If the ref stack contains a value, then it is an array or an
-               object to which we can add elements
+    This function first reads starting bytes to determine the expected
+    string length and then copies this number of bytes into a string.
 
-    @return pair of boolean (whether value should be kept) and pointer (to the
-            passed value in the ref_stack hierarchy; nullptr if not kept)
+    @param[out] result  created string
+
+    @return whether string creation completed
     */
-    template<typename Value>
-    std::pair<bool, BasicJsonType*> handle_value(Value&& v, const bool skip_callback = false)
+    bool get_msgpack_string(string_t& result)
     {
-        assert(not keep_stack.empty());
-
-        // do not handle this value if we know it would be added to a discarded
-        // container
-        if (not keep_stack.back())
+        if (JSON_UNLIKELY(not unexpect_eof(input_format_t::msgpack, "string")))
         {
-            return {false, nullptr};
+            return false;
         }
 
-        // create value
-        auto value = BasicJsonType(std::forward<Value>(v));
+        switch (current)
+        {
+            // fixstr
+            case 0xA0:
+            case 0xA1:
+            case 0xA2:
+            case 0xA3:
+            case 0xA4:
+            case 0xA5:
+            case 0xA6:
+            case 0xA7:
+            case 0xA8:
+            case 0xA9:
+            case 0xAA:
+            case 0xAB:
+            case 0xAC:
+            case 0xAD:
+            case 0xAE:
+            case 0xAF:
+            case 0xB0:
+            case 0xB1:
+            case 0xB2:
+            case 0xB3:
+            case 0xB4:
+            case 0xB5:
+            case 0xB6:
+            case 0xB7:
+            case 0xB8:
+            case 0xB9:
+            case 0xBA:
+            case 0xBB:
+            case 0xBC:
+            case 0xBD:
+            case 0xBE:
+            case 0xBF:
+            {
+                return get_string(input_format_t::msgpack, static_cast<unsigned int>(current) & 0x1Fu, result);
+            }
 
-        // check callback
-        const bool keep = skip_callback or callback(static_cast<int>(ref_stack.size()), parse_event_t::value, value);
+            case 0xD9: // str 8
+            {
+                std::uint8_t len;
+                return get_number(input_format_t::msgpack, len) and get_string(input_format_t::msgpack, len, result);
+            }
 
-        // do not handle this value if we just learnt it shall be discarded
-        if (not keep)
-        {
-            return {false, nullptr};
-        }
+            case 0xDA: // str 16
+            {
+                std::uint16_t len;
+                return get_number(input_format_t::msgpack, len) and get_string(input_format_t::msgpack, len, result);
+            }
 
-        if (ref_stack.empty())
-        {
-            root = std::move(value);
-            return {true, &root};
-        }
+            case 0xDB: // str 32
+            {
+                std::uint32_t len;
+                return get_number(input_format_t::msgpack, len) and get_string(input_format_t::msgpack, len, result);
+            }
 
-        // skip this value if we already decided to skip the parent
-        // (https://github.com/nlohmann/json/issues/971#issuecomment-413678360)
-        if (not ref_stack.back())
-        {
-            return {false, nullptr};
+            default:
+            {
+                auto last_token = get_token_string();
+                return sax->parse_error(chars_read, last_token, parse_error::create(113, chars_read, exception_message(input_format_t::msgpack, "expected length specification (0xA0-0xBF, 0xD9-0xDB); last byte: 0x" + last_token, "string")));
+            }
         }
+    }
 
-        // we now only expect arrays and objects
-        assert(ref_stack.back()->is_array() or ref_stack.back()->is_object());
-
-        if (ref_stack.back()->is_array())
+    /*!
+    @param[in] len  the length of the array
+    @return whether array creation completed
+    */
+    bool get_msgpack_array(const std::size_t len)
+    {
+        if (JSON_UNLIKELY(not sax->start_array(len)))
         {
-            ref_stack.back()->m_value.array->push_back(std::move(value));
-            return {true, &(ref_stack.back()->m_value.array->back())};
+            return false;
         }
-        else
-        {
-            // check if we should store an element for the current key
-            assert(not key_keep_stack.empty());
-            const bool store_element = key_keep_stack.back();
-            key_keep_stack.pop_back();
 
-            if (not store_element)
+        for (std::size_t i = 0; i < len; ++i)
+        {
+            if (JSON_UNLIKELY(not parse_msgpack_internal()))
             {
-                return {false, nullptr};
+                return false;
             }
-
-            assert(object_element);
-            *object_element = std::move(value);
-            return {true, object_element};
         }
-    }
-
-    /// the parsed JSON value
-    BasicJsonType& root;
-    /// stack to model hierarchy of values
-    std::vector<BasicJsonType*> ref_stack;
-    /// stack to manage which values to keep
-    std::vector<bool> keep_stack;
-    /// stack to manage which object keys to keep
-    std::vector<bool> key_keep_stack;
-    /// helper to hold the reference for the next object element
-    BasicJsonType* object_element = nullptr;
-    /// whether a syntax error occurred
-    bool errored = false;
-    /// callback function
-    const parser_callback_t callback = nullptr;
-    /// whether to throw exceptions in case of errors
-    const bool allow_exceptions = true;
-    /// a discarded value for the callback
-    BasicJsonType discarded = BasicJsonType::value_t::discarded;
-};
-
-template<typename BasicJsonType>
-class json_sax_acceptor
-{
-  public:
-    using number_integer_t = typename BasicJsonType::number_integer_t;
-    using number_unsigned_t = typename BasicJsonType::number_unsigned_t;
-    using number_float_t = typename BasicJsonType::number_float_t;
-    using string_t = typename BasicJsonType::string_t;
 
-    bool null()
-    {
-        return true;
+        return sax->end_array();
     }
 
-    bool boolean(bool /*unused*/)
+    /*!
+    @param[in] len  the length of the object
+    @return whether object creation completed
+    */
+    bool get_msgpack_object(const std::size_t len)
     {
-        return true;
-    }
+        if (JSON_UNLIKELY(not sax->start_object(len)))
+        {
+            return false;
+        }
 
-    bool number_integer(number_integer_t /*unused*/)
-    {
-        return true;
-    }
+        string_t key;
+        for (std::size_t i = 0; i < len; ++i)
+        {
+            get();
+            if (JSON_UNLIKELY(not get_msgpack_string(key) or not sax->key(key)))
+            {
+                return false;
+            }
 
-    bool number_unsigned(number_unsigned_t /*unused*/)
-    {
-        return true;
-    }
+            if (JSON_UNLIKELY(not parse_msgpack_internal()))
+            {
+                return false;
+            }
+            key.clear();
+        }
 
-    bool number_float(number_float_t /*unused*/, const string_t& /*unused*/)
-    {
-        return true;
+        return sax->end_object();
     }
 
-    bool string(string_t& /*unused*/)
-    {
-        return true;
-    }
+    ////////////
+    // UBJSON //
+    ////////////
 
-    bool start_object(std::size_t  /*unused*/ = std::size_t(-1))
-    {
-        return true;
-    }
+    /*!
+    @param[in] get_char  whether a new character should be retrieved from the
+                         input (true, default) or whether the last read
+                         character should be considered instead
 
-    bool key(string_t& /*unused*/)
+    @return whether a valid UBJSON value was passed to the SAX parser
+    */
+    bool parse_ubjson_internal(const bool get_char = true)
     {
-        return true;
+        return get_ubjson_value(get_char ? get_ignore_noop() : current);
     }
 
-    bool end_object()
-    {
-        return true;
-    }
+    /*!
+    @brief reads a UBJSON string
 
-    bool start_array(std::size_t  /*unused*/ = std::size_t(-1))
-    {
-        return true;
-    }
+    This function is either called after reading the 'S' byte explicitly
+    indicating a string, or in case of an object key where the 'S' byte can be
+    left out.
 
-    bool end_array()
-    {
-        return true;
-    }
+    @param[out] result   created string
+    @param[in] get_char  whether a new character should be retrieved from the
+                         input (true, default) or whether the last read
+                         character should be considered instead
 
-    bool parse_error(std::size_t /*unused*/, const std::string& /*unused*/, const detail::exception& /*unused*/)
+    @return whether string creation completed
+    */
+    bool get_ubjson_string(string_t& result, const bool get_char = true)
     {
-        return false;
-    }
-};
-}  // namespace detail
-
-}  // namespace nlohmann
-
-// #include <nlohmann/detail/input/lexer.hpp>
-
-// #include <nlohmann/detail/value_t.hpp>
+        if (get_char)
+        {
+            get();  // TODO(niels): may we ignore N here?
+        }
 
+        if (JSON_UNLIKELY(not unexpect_eof(input_format_t::ubjson, "value")))
+        {
+            return false;
+        }
 
-namespace nlohmann
-{
-namespace detail
-{
-////////////
-// parser //
-////////////
+        switch (current)
+        {
+            case 'U':
+            {
+                std::uint8_t len;
+                return get_number(input_format_t::ubjson, len) and get_string(input_format_t::ubjson, len, result);
+            }
 
-/*!
-@brief syntax analysis
+            case 'i':
+            {
+                std::int8_t len;
+                return get_number(input_format_t::ubjson, len) and get_string(input_format_t::ubjson, len, result);
+            }
 
-This class implements a recursive decent parser.
-*/
-template<typename BasicJsonType>
-class parser
-{
-    using number_integer_t = typename BasicJsonType::number_integer_t;
-    using number_unsigned_t = typename BasicJsonType::number_unsigned_t;
-    using number_float_t = typename BasicJsonType::number_float_t;
-    using string_t = typename BasicJsonType::string_t;
-    using lexer_t = lexer<BasicJsonType>;
-    using token_type = typename lexer_t::token_type;
+            case 'I':
+            {
+                std::int16_t len;
+                return get_number(input_format_t::ubjson, len) and get_string(input_format_t::ubjson, len, result);
+            }
 
-  public:
-    enum class parse_event_t : uint8_t
-    {
-        /// the parser read `{` and started to process a JSON object
-        object_start,
-        /// the parser read `}` and finished processing a JSON object
-        object_end,
-        /// the parser read `[` and started to process a JSON array
-        array_start,
-        /// the parser read `]` and finished processing a JSON array
-        array_end,
-        /// the parser read a key of a value in an object
-        key,
-        /// the parser finished reading a JSON value
-        value
-    };
+            case 'l':
+            {
+                std::int32_t len;
+                return get_number(input_format_t::ubjson, len) and get_string(input_format_t::ubjson, len, result);
+            }
 
-    using parser_callback_t =
-        std::function<bool(int depth, parse_event_t event, BasicJsonType& parsed)>;
+            case 'L':
+            {
+                std::int64_t len;
+                return get_number(input_format_t::ubjson, len) and get_string(input_format_t::ubjson, len, result);
+            }
 
-    /// a parser reading from an input adapter
-    explicit parser(detail::input_adapter_t&& adapter,
-                    const parser_callback_t cb = nullptr,
-                    const bool allow_exceptions_ = true)
-        : callback(cb), m_lexer(std::move(adapter)), allow_exceptions(allow_exceptions_)
-    {
-        // read first token
-        get_token();
+            default:
+                auto last_token = get_token_string();
+                return sax->parse_error(chars_read, last_token, parse_error::create(113, chars_read, exception_message(input_format_t::ubjson, "expected length type specification (U, i, I, l, L); last byte: 0x" + last_token, "string")));
+        }
     }
 
     /*!
-    @brief public parser interface
-
-    @param[in] strict      whether to expect the last token to be EOF
-    @param[in,out] result  parsed JSON value
-
-    @throw parse_error.101 in case of an unexpected token
-    @throw parse_error.102 if to_unicode fails or surrogate error
-    @throw parse_error.103 if to_unicode fails
+    @param[out] result  determined size
+    @return whether size determination completed
     */
-    void parse(const bool strict, BasicJsonType& result)
+    bool get_ubjson_size_value(std::size_t& result)
     {
-        if (callback)
+        switch (get_ignore_noop())
         {
-            json_sax_dom_callback_parser<BasicJsonType> sdp(result, callback, allow_exceptions);
-            sax_parse_internal(&sdp);
-            result.assert_invariant();
+            case 'U':
+            {
+                std::uint8_t number;
+                if (JSON_UNLIKELY(not get_number(input_format_t::ubjson, number)))
+                {
+                    return false;
+                }
+                result = static_cast<std::size_t>(number);
+                return true;
+            }
 
-            // in strict mode, input must be completely read
-            if (strict and (get_token() != token_type::end_of_input))
+            case 'i':
             {
-                sdp.parse_error(m_lexer.get_position(),
-                                m_lexer.get_token_string(),
-                                parse_error::create(101, m_lexer.get_position(),
-                                                    exception_message(token_type::end_of_input, "value")));
+                std::int8_t number;
+                if (JSON_UNLIKELY(not get_number(input_format_t::ubjson, number)))
+                {
+                    return false;
+                }
+                result = static_cast<std::size_t>(number);
+                return true;
             }
 
-            // in case of an error, return discarded value
-            if (sdp.is_errored())
+            case 'I':
             {
-                result = value_t::discarded;
-                return;
+                std::int16_t number;
+                if (JSON_UNLIKELY(not get_number(input_format_t::ubjson, number)))
+                {
+                    return false;
+                }
+                result = static_cast<std::size_t>(number);
+                return true;
             }
 
-            // set top-level value to null if it was discarded by the callback
-            // function
-            if (result.is_discarded())
+            case 'l':
             {
-                result = nullptr;
+                std::int32_t number;
+                if (JSON_UNLIKELY(not get_number(input_format_t::ubjson, number)))
+                {
+                    return false;
+                }
+                result = static_cast<std::size_t>(number);
+                return true;
             }
-        }
-        else
-        {
-            json_sax_dom_parser<BasicJsonType> sdp(result, allow_exceptions);
-            sax_parse_internal(&sdp);
-            result.assert_invariant();
 
-            // in strict mode, input must be completely read
-            if (strict and (get_token() != token_type::end_of_input))
+            case 'L':
             {
-                sdp.parse_error(m_lexer.get_position(),
-                                m_lexer.get_token_string(),
-                                parse_error::create(101, m_lexer.get_position(),
-                                                    exception_message(token_type::end_of_input, "value")));
+                std::int64_t number;
+                if (JSON_UNLIKELY(not get_number(input_format_t::ubjson, number)))
+                {
+                    return false;
+                }
+                result = static_cast<std::size_t>(number);
+                return true;
             }
 
-            // in case of an error, return discarded value
-            if (sdp.is_errored())
+            default:
             {
-                result = value_t::discarded;
-                return;
+                auto last_token = get_token_string();
+                return sax->parse_error(chars_read, last_token, parse_error::create(113, chars_read, exception_message(input_format_t::ubjson, "expected length type specification (U, i, I, l, L) after '#'; last byte: 0x" + last_token, "size")));
             }
         }
     }
 
     /*!
-    @brief public accept interface
+    @brief determine the type and size for a container
 
-    @param[in] strict  whether to expect the last token to be EOF
-    @return whether the input is a proper JSON text
+    In the optimized UBJSON format, a type and a size can be provided to allow
+    for a more compact representation.
+
+    @param[out] result  pair of the size and the type
+
+    @return whether pair creation completed
     */
-    bool accept(const bool strict = true)
+    bool get_ubjson_size_type(std::pair<std::size_t, int>& result)
     {
-        json_sax_acceptor<BasicJsonType> sax_acceptor;
-        return sax_parse(&sax_acceptor, strict);
-    }
+        result.first = string_t::npos; // size
+        result.second = 0; // type
 
-    template <typename SAX>
-    bool sax_parse(SAX* sax, const bool strict = true)
-    {
-        (void)detail::is_sax_static_asserts<SAX, BasicJsonType> {};
-        const bool result = sax_parse_internal(sax);
+        get_ignore_noop();
 
-        // strict mode: next byte must be EOF
-        if (result and strict and (get_token() != token_type::end_of_input))
+        if (current == '$')
         {
-            return sax->parse_error(m_lexer.get_position(),
-                                    m_lexer.get_token_string(),
-                                    parse_error::create(101, m_lexer.get_position(),
-                                            exception_message(token_type::end_of_input, "value")));
+            result.second = get();  // must not ignore 'N', because 'N' maybe the type
+            if (JSON_UNLIKELY(not unexpect_eof(input_format_t::ubjson, "type")))
+            {
+                return false;
+            }
+
+            get_ignore_noop();
+            if (JSON_UNLIKELY(current != '#'))
+            {
+                if (JSON_UNLIKELY(not unexpect_eof(input_format_t::ubjson, "value")))
+                {
+                    return false;
+                }
+                auto last_token = get_token_string();
+                return sax->parse_error(chars_read, last_token, parse_error::create(112, chars_read, exception_message(input_format_t::ubjson, "expected '#' after type information; last byte: 0x" + last_token, "size")));
+            }
+
+            return get_ubjson_size_value(result.first);
         }
 
-        return result;
+        if (current == '#')
+        {
+            return get_ubjson_size_value(result.first);
+        }
+
+        return true;
     }
 
-  private:
-    template <typename SAX>
-    bool sax_parse_internal(SAX* sax)
+    /*!
+    @param prefix  the previously read or set type prefix
+    @return whether value creation completed
+    */
+    bool get_ubjson_value(const int prefix)
     {
-        // stack to remember the hierarchy of structured values we are parsing
-        // true = array; false = object
-        std::vector<bool> states;
-        // value to avoid a goto (see comment where set to true)
-        bool skip_to_state_evaluation = false;
-
-        while (true)
+        switch (prefix)
         {
-            if (not skip_to_state_evaluation)
-            {
-                // invariant: get_token() was called before each iteration
-                switch (last_token)
-                {
-                    case token_type::begin_object:
-                    {
-                        if (JSON_UNLIKELY(not sax->start_object(std::size_t(-1))))
-                        {
-                            return false;
-                        }
+            case std::char_traits<char>::eof():  // EOF
+                return unexpect_eof(input_format_t::ubjson, "value");
 
-                        // closing } -> we are done
-                        if (get_token() == token_type::end_object)
-                        {
-                            if (JSON_UNLIKELY(not sax->end_object()))
-                            {
-                                return false;
-                            }
-                            break;
-                        }
+            case 'T':  // true
+                return sax->boolean(true);
+            case 'F':  // false
+                return sax->boolean(false);
 
-                        // parse key
-                        if (JSON_UNLIKELY(last_token != token_type::value_string))
-                        {
-                            return sax->parse_error(m_lexer.get_position(),
-                                                    m_lexer.get_token_string(),
-                                                    parse_error::create(101, m_lexer.get_position(),
-                                                            exception_message(token_type::value_string, "object key")));
-                        }
-                        if (JSON_UNLIKELY(not sax->key(m_lexer.get_string())))
-                        {
-                            return false;
-                        }
+            case 'Z':  // null
+                return sax->null();
 
-                        // parse separator (:)
-                        if (JSON_UNLIKELY(get_token() != token_type::name_separator))
-                        {
-                            return sax->parse_error(m_lexer.get_position(),
-                                                    m_lexer.get_token_string(),
-                                                    parse_error::create(101, m_lexer.get_position(),
-                                                            exception_message(token_type::name_separator, "object separator")));
-                        }
+            case 'U':
+            {
+                std::uint8_t number;
+                return get_number(input_format_t::ubjson, number) and sax->number_unsigned(number);
+            }
 
-                        // remember we are now inside an object
-                        states.push_back(false);
+            case 'i':
+            {
+                std::int8_t number;
+                return get_number(input_format_t::ubjson, number) and sax->number_integer(number);
+            }
 
-                        // parse values
-                        get_token();
-                        continue;
-                    }
+            case 'I':
+            {
+                std::int16_t number;
+                return get_number(input_format_t::ubjson, number) and sax->number_integer(number);
+            }
 
-                    case token_type::begin_array:
-                    {
-                        if (JSON_UNLIKELY(not sax->start_array(std::size_t(-1))))
-                        {
-                            return false;
-                        }
+            case 'l':
+            {
+                std::int32_t number;
+                return get_number(input_format_t::ubjson, number) and sax->number_integer(number);
+            }
 
-                        // closing ] -> we are done
-                        if (get_token() == token_type::end_array)
-                        {
-                            if (JSON_UNLIKELY(not sax->end_array()))
-                            {
-                                return false;
-                            }
-                            break;
-                        }
+            case 'L':
+            {
+                std::int64_t number;
+                return get_number(input_format_t::ubjson, number) and sax->number_integer(number);
+            }
 
-                        // remember we are now inside an array
-                        states.push_back(true);
+            case 'd':
+            {
+                float number;
+                return get_number(input_format_t::ubjson, number) and sax->number_float(static_cast<number_float_t>(number), "");
+            }
 
-                        // parse values (no need to call get_token)
-                        continue;
-                    }
+            case 'D':
+            {
+                double number;
+                return get_number(input_format_t::ubjson, number) and sax->number_float(static_cast<number_float_t>(number), "");
+            }
 
-                    case token_type::value_float:
-                    {
-                        const auto res = m_lexer.get_number_float();
+            case 'C':  // char
+            {
+                get();
+                if (JSON_UNLIKELY(not unexpect_eof(input_format_t::ubjson, "char")))
+                {
+                    return false;
+                }
+                if (JSON_UNLIKELY(current > 127))
+                {
+                    auto last_token = get_token_string();
+                    return sax->parse_error(chars_read, last_token, parse_error::create(113, chars_read, exception_message(input_format_t::ubjson, "byte after 'C' must be in range 0x00..0x7F; last byte: 0x" + last_token, "char")));
+                }
+                string_t s(1, static_cast<char>(current));
+                return sax->string(s);
+            }
 
-                        if (JSON_UNLIKELY(not std::isfinite(res)))
-                        {
-                            return sax->parse_error(m_lexer.get_position(),
-                                                    m_lexer.get_token_string(),
-                                                    out_of_range::create(406, "number overflow parsing '" + m_lexer.get_token_string() + "'"));
-                        }
-                        else
-                        {
-                            if (JSON_UNLIKELY(not sax->number_float(res, m_lexer.get_string())))
-                            {
-                                return false;
-                            }
-                            break;
-                        }
-                    }
+            case 'S':  // string
+            {
+                string_t s;
+                return get_ubjson_string(s) and sax->string(s);
+            }
 
-                    case token_type::literal_false:
-                    {
-                        if (JSON_UNLIKELY(not sax->boolean(false)))
-                        {
-                            return false;
-                        }
-                        break;
-                    }
+            case '[':  // array
+                return get_ubjson_array();
 
-                    case token_type::literal_null:
-                    {
-                        if (JSON_UNLIKELY(not sax->null()))
-                        {
-                            return false;
-                        }
-                        break;
-                    }
+            case '{':  // object
+                return get_ubjson_object();
 
-                    case token_type::literal_true:
-                    {
-                        if (JSON_UNLIKELY(not sax->boolean(true)))
-                        {
-                            return false;
-                        }
-                        break;
-                    }
+            default: // anything else
+            {
+                auto last_token = get_token_string();
+                return sax->parse_error(chars_read, last_token, parse_error::create(112, chars_read, exception_message(input_format_t::ubjson, "invalid byte: 0x" + last_token, "value")));
+            }
+        }
+    }
 
-                    case token_type::value_integer:
-                    {
-                        if (JSON_UNLIKELY(not sax->number_integer(m_lexer.get_number_integer())))
-                        {
-                            return false;
-                        }
-                        break;
-                    }
+    /*!
+    @return whether array creation completed
+    */
+    bool get_ubjson_array()
+    {
+        std::pair<std::size_t, int> size_and_type;
+        if (JSON_UNLIKELY(not get_ubjson_size_type(size_and_type)))
+        {
+            return false;
+        }
 
-                    case token_type::value_string:
-                    {
-                        if (JSON_UNLIKELY(not sax->string(m_lexer.get_string())))
-                        {
-                            return false;
-                        }
-                        break;
-                    }
+        if (size_and_type.first != string_t::npos)
+        {
+            if (JSON_UNLIKELY(not sax->start_array(size_and_type.first)))
+            {
+                return false;
+            }
 
-                    case token_type::value_unsigned:
+            if (size_and_type.second != 0)
+            {
+                if (size_and_type.second != 'N')
+                {
+                    for (std::size_t i = 0; i < size_and_type.first; ++i)
                     {
-                        if (JSON_UNLIKELY(not sax->number_unsigned(m_lexer.get_number_unsigned())))
+                        if (JSON_UNLIKELY(not get_ubjson_value(size_and_type.second)))
                         {
                             return false;
                         }
-                        break;
-                    }
-
-                    case token_type::parse_error:
-                    {
-                        // using "uninitialized" to avoid "expected" message
-                        return sax->parse_error(m_lexer.get_position(),
-                                                m_lexer.get_token_string(),
-                                                parse_error::create(101, m_lexer.get_position(),
-                                                        exception_message(token_type::uninitialized, "value")));
                     }
-
-                    default: // the last token was unexpected
+                }
+            }
+            else
+            {
+                for (std::size_t i = 0; i < size_and_type.first; ++i)
+                {
+                    if (JSON_UNLIKELY(not parse_ubjson_internal()))
                     {
-                        return sax->parse_error(m_lexer.get_position(),
-                                                m_lexer.get_token_string(),
-                                                parse_error::create(101, m_lexer.get_position(),
-                                                        exception_message(token_type::literal_or_value, "value")));
+                        return false;
                     }
                 }
             }
-            else
+        }
+        else
+        {
+            if (JSON_UNLIKELY(not sax->start_array(std::size_t(-1))))
             {
-                skip_to_state_evaluation = false;
+                return false;
             }
 
-            // we reached this line after we successfully parsed a value
-            if (states.empty())
+            while (current != ']')
             {
-                // empty stack: we reached the end of the hierarchy: done
-                return true;
+                if (JSON_UNLIKELY(not parse_ubjson_internal(false)))
+                {
+                    return false;
+                }
+                get_ignore_noop();
             }
-            else
+        }
+
+        return sax->end_array();
+    }
+
+    /*!
+    @return whether object creation completed
+    */
+    bool get_ubjson_object()
+    {
+        std::pair<std::size_t, int> size_and_type;
+        if (JSON_UNLIKELY(not get_ubjson_size_type(size_and_type)))
+        {
+            return false;
+        }
+
+        string_t key;
+        if (size_and_type.first != string_t::npos)
+        {
+            if (JSON_UNLIKELY(not sax->start_object(size_and_type.first)))
             {
-                if (states.back())  // array
-                {
-                    // comma -> next value
-                    if (get_token() == token_type::value_separator)
-                    {
-                        // parse a new value
-                        get_token();
-                        continue;
-                    }
+                return false;
+            }
 
-                    // closing ]
-                    if (JSON_LIKELY(last_token == token_type::end_array))
+            if (size_and_type.second != 0)
+            {
+                for (std::size_t i = 0; i < size_and_type.first; ++i)
+                {
+                    if (JSON_UNLIKELY(not get_ubjson_string(key) or not sax->key(key)))
                     {
-                        if (JSON_UNLIKELY(not sax->end_array()))
-                        {
-                            return false;
-                        }
-
-                        // We are done with this array. Before we can parse a
-                        // new value, we need to evaluate the new state first.
-                        // By setting skip_to_state_evaluation to false, we
-                        // are effectively jumping to the beginning of this if.
-                        assert(not states.empty());
-                        states.pop_back();
-                        skip_to_state_evaluation = true;
-                        continue;
+                        return false;
                     }
-                    else
+                    if (JSON_UNLIKELY(not get_ubjson_value(size_and_type.second)))
                     {
-                        return sax->parse_error(m_lexer.get_position(),
-                                                m_lexer.get_token_string(),
-                                                parse_error::create(101, m_lexer.get_position(),
-                                                        exception_message(token_type::end_array, "array")));
+                        return false;
                     }
+                    key.clear();
                 }
-                else  // object
+            }
+            else
+            {
+                for (std::size_t i = 0; i < size_and_type.first; ++i)
                 {
-                    // comma -> next value
-                    if (get_token() == token_type::value_separator)
-                    {
-                        // parse key
-                        if (JSON_UNLIKELY(get_token() != token_type::value_string))
-                        {
-                            return sax->parse_error(m_lexer.get_position(),
-                                                    m_lexer.get_token_string(),
-                                                    parse_error::create(101, m_lexer.get_position(),
-                                                            exception_message(token_type::value_string, "object key")));
-                        }
-                        else
-                        {
-                            if (JSON_UNLIKELY(not sax->key(m_lexer.get_string())))
-                            {
-                                return false;
-                            }
-                        }
-
-                        // parse separator (:)
-                        if (JSON_UNLIKELY(get_token() != token_type::name_separator))
-                        {
-                            return sax->parse_error(m_lexer.get_position(),
-                                                    m_lexer.get_token_string(),
-                                                    parse_error::create(101, m_lexer.get_position(),
-                                                            exception_message(token_type::name_separator, "object separator")));
-                        }
-
-                        // parse values
-                        get_token();
-                        continue;
-                    }
-
-                    // closing }
-                    if (JSON_LIKELY(last_token == token_type::end_object))
+                    if (JSON_UNLIKELY(not get_ubjson_string(key) or not sax->key(key)))
                     {
-                        if (JSON_UNLIKELY(not sax->end_object()))
-                        {
-                            return false;
-                        }
-
-                        // We are done with this object. Before we can parse a
-                        // new value, we need to evaluate the new state first.
-                        // By setting skip_to_state_evaluation to false, we
-                        // are effectively jumping to the beginning of this if.
-                        assert(not states.empty());
-                        states.pop_back();
-                        skip_to_state_evaluation = true;
-                        continue;
+                        return false;
                     }
-                    else
+                    if (JSON_UNLIKELY(not parse_ubjson_internal()))
                     {
-                        return sax->parse_error(m_lexer.get_position(),
-                                                m_lexer.get_token_string(),
-                                                parse_error::create(101, m_lexer.get_position(),
-                                                        exception_message(token_type::end_object, "object")));
+                        return false;
                     }
+                    key.clear();
                 }
             }
         }
-    }
-
-    /// get next token from lexer
-    token_type get_token()
-    {
-        return (last_token = m_lexer.scan());
-    }
-
-    std::string exception_message(const token_type expected, const std::string& context)
-    {
-        std::string error_msg = "syntax error ";
-
-        if (not context.empty())
+        else
         {
-            error_msg += "while parsing " + context + " ";
+            if (JSON_UNLIKELY(not sax->start_object(std::size_t(-1))))
+            {
+                return false;
+            }
+
+            while (current != '}')
+            {
+                if (JSON_UNLIKELY(not get_ubjson_string(key, false) or not sax->key(key)))
+                {
+                    return false;
+                }
+                if (JSON_UNLIKELY(not parse_ubjson_internal()))
+                {
+                    return false;
+                }
+                get_ignore_noop();
+                key.clear();
+            }
         }
 
-        error_msg += "- ";
+        return sax->end_object();
+    }
 
-        if (last_token == token_type::parse_error)
-        {
-            error_msg += std::string(m_lexer.get_error_message()) + "; last read: '" +
-                         m_lexer.get_token_string() + "'";
-        }
-        else
-        {
-            error_msg += "unexpected " + std::string(lexer_t::token_type_name(last_token));
-        }
+    ///////////////////////
+    // Utility functions //
+    ///////////////////////
 
-        if (expected != token_type::uninitialized)
+    /*!
+    @brief get next character from the input
+
+    This function provides the interface to the used input adapter. It does
+    not throw in case the input reached EOF, but returns a -'ve valued
+    `std::char_traits<char>::eof()` in that case.
+
+    @return character read from the input
+    */
+    int get()
+    {
+        ++chars_read;
+        return current = ia->get_character();
+    }
+
+    /*!
+    @return character read from the input after ignoring all 'N' entries
+    */
+    int get_ignore_noop()
+    {
+        do
         {
-            error_msg += "; expected " + std::string(lexer_t::token_type_name(expected));
+            get();
         }
+        while (current == 'N');
 
-        return error_msg;
+        return current;
     }
 
-  private:
-    /// callback function
-    const parser_callback_t callback = nullptr;
-    /// the type of the last read token
-    token_type last_token = token_type::uninitialized;
-    /// the lexer
-    lexer_t m_lexer;
-    /// whether to throw exceptions in case of errors
-    const bool allow_exceptions = true;
-};
-}  // namespace detail
-}  // namespace nlohmann
+    /*
+    @brief read a number from the input
 
-// #include <nlohmann/detail/iterators/primitive_iterator.hpp>
+    @tparam NumberType the type of the number
+    @param[in] format   the current format (for diagnostics)
+    @param[out] result  number of type @a NumberType
 
+    @return whether conversion completed
 
-#include <cstddef> // ptrdiff_t
-#include <limits>  // numeric_limits
+    @note This function needs to respect the system's endianess, because
+          bytes in CBOR, MessagePack, and UBJSON are stored in network order
+          (big endian) and therefore need reordering on little endian systems.
+    */
+    template<typename NumberType, bool InputIsLittleEndian = false>
+    bool get_number(const input_format_t format, NumberType& result)
+    {
+        // step 1: read input into array with system's byte order
+        std::array<std::uint8_t, sizeof(NumberType)> vec;
+        for (std::size_t i = 0; i < sizeof(NumberType); ++i)
+        {
+            get();
+            if (JSON_UNLIKELY(not unexpect_eof(format, "number")))
+            {
+                return false;
+            }
 
-namespace nlohmann
-{
-namespace detail
-{
-/*
-@brief an iterator for primitive JSON types
+            // reverse byte order prior to conversion if necessary
+            if (is_little_endian != InputIsLittleEndian)
+            {
+                vec[sizeof(NumberType) - i - 1] = static_cast<std::uint8_t>(current);
+            }
+            else
+            {
+                vec[i] = static_cast<std::uint8_t>(current); // LCOV_EXCL_LINE
+            }
+        }
 
-This class models an iterator for primitive JSON types (boolean, number,
-string). It's only purpose is to allow the iterator/const_iterator classes
-to "iterate" over primitive values. Internally, the iterator is modeled by
-a `difference_type` variable. Value begin_value (`0`) models the begin,
-end_value (`1`) models past the end.
-*/
-class primitive_iterator_t
-{
-  private:
-    using difference_type = std::ptrdiff_t;
-    static constexpr difference_type begin_value = 0;
-    static constexpr difference_type end_value = begin_value + 1;
+        // step 2: convert array into number of type T and return
+        std::memcpy(&result, vec.data(), sizeof(NumberType));
+        return true;
+    }
 
-    /// iterator as signed integer type
-    difference_type m_it = (std::numeric_limits<std::ptrdiff_t>::min)();
+    /*!
+    @brief create a string by reading characters from the input
 
-  public:
-    constexpr difference_type get_value() const noexcept
-    {
-        return m_it;
-    }
+    @tparam NumberType the type of the number
+    @param[in] format the current format (for diagnostics)
+    @param[in] len number of characters to read
+    @param[out] result string created by reading @a len bytes
 
-    /// set iterator to a defined beginning
-    void set_begin() noexcept
-    {
-        m_it = begin_value;
-    }
+    @return whether string creation completed
 
-    /// set iterator to a defined past the end
-    void set_end() noexcept
+    @note We can not reserve @a len bytes for the result, because @a len
+          may be too large. Usually, @ref unexpect_eof() detects the end of
+          the input before we run out of string memory.
+    */
+    template<typename NumberType>
+    bool get_string(const input_format_t format,
+                    const NumberType len,
+                    string_t& result)
     {
-        m_it = end_value;
+        bool success = true;
+        std::generate_n(std::back_inserter(result), len, [this, &success, &format]()
+        {
+            get();
+            if (JSON_UNLIKELY(not unexpect_eof(format, "string")))
+            {
+                success = false;
+            }
+            return static_cast<char>(current);
+        });
+        return success;
     }
 
-    /// return whether the iterator can be dereferenced
-    constexpr bool is_begin() const noexcept
+    /*!
+    @param[in] format   the current format (for diagnostics)
+    @param[in] context  further context information (for diagnostics)
+    @return whether the last read character is not EOF
+    */
+    bool unexpect_eof(const input_format_t format, const char* context) const
     {
-        return m_it == begin_value;
+        if (JSON_UNLIKELY(current == std::char_traits<char>::eof()))
+        {
+            return sax->parse_error(chars_read, "<end of file>",
+                                    parse_error::create(110, chars_read, exception_message(format, "unexpected end of input", context)));
+        }
+        return true;
     }
 
-    /// return whether the iterator is at end
-    constexpr bool is_end() const noexcept
+    /*!
+    @return a string representation of the last read byte
+    */
+    std::string get_token_string() const
     {
-        return m_it == end_value;
+        std::array<char, 3> cr{{}};
+        (std::snprintf)(cr.data(), cr.size(), "%.2hhX", static_cast<unsigned char>(current));
+        return std::string{cr.data()};
     }
 
-    friend constexpr bool operator==(primitive_iterator_t lhs, primitive_iterator_t rhs) noexcept
+    /*!
+    @param[in] format   the current format
+    @param[in] detail   a detailed error message
+    @param[in] context  further contect information
+    @return a message string to use in the parse_error exceptions
+    */
+    std::string exception_message(const input_format_t format,
+                                  const std::string& detail,
+                                  const std::string& context) const
     {
-        return lhs.m_it == rhs.m_it;
-    }
+        std::string error_msg = "syntax error while parsing ";
 
-    friend constexpr bool operator<(primitive_iterator_t lhs, primitive_iterator_t rhs) noexcept
-    {
-        return lhs.m_it < rhs.m_it;
-    }
+        switch (format)
+        {
+            case input_format_t::cbor:
+                error_msg += "CBOR";
+                break;
 
-    primitive_iterator_t operator+(difference_type n) noexcept
-    {
-        auto result = *this;
-        result += n;
-        return result;
-    }
+            case input_format_t::msgpack:
+                error_msg += "MessagePack";
+                break;
 
-    friend constexpr difference_type operator-(primitive_iterator_t lhs, primitive_iterator_t rhs) noexcept
-    {
-        return lhs.m_it - rhs.m_it;
-    }
+            case input_format_t::ubjson:
+                error_msg += "UBJSON";
+                break;
 
-    primitive_iterator_t& operator++() noexcept
-    {
-        ++m_it;
-        return *this;
-    }
+            case input_format_t::bson:
+                error_msg += "BSON";
+                break;
 
-    primitive_iterator_t const operator++(int) noexcept
-    {
-        auto result = *this;
-        ++m_it;
-        return result;
-    }
+            default:            // LCOV_EXCL_LINE
+                assert(false);  // LCOV_EXCL_LINE
+        }
 
-    primitive_iterator_t& operator--() noexcept
-    {
-        --m_it;
-        return *this;
+        return error_msg + " " + context + ": " + detail;
     }
 
-    primitive_iterator_t const operator--(int) noexcept
-    {
-        auto result = *this;
-        --m_it;
-        return result;
-    }
+  private:
+    /// input adapter
+    input_adapter_t ia = nullptr;
 
-    primitive_iterator_t& operator+=(difference_type n) noexcept
-    {
-        m_it += n;
-        return *this;
-    }
+    /// the current character
+    int current = std::char_traits<char>::eof();
 
-    primitive_iterator_t& operator-=(difference_type n) noexcept
-    {
-        m_it -= n;
-        return *this;
-    }
+    /// the number of characters read
+    std::size_t chars_read = 0;
+
+    /// whether we can assume little endianess
+    const bool is_little_endian = little_endianess();
+
+    /// the SAX parser
+    json_sax_t* sax = nullptr;
 };
 }  // namespace detail
 }  // namespace nlohmann
 
-// #include <nlohmann/detail/iterators/internal_iterator.hpp>
-
+// #include <nlohmann/detail/input/input_adapters.hpp>
 
-// #include <nlohmann/detail/iterators/primitive_iterator.hpp>
+// #include <nlohmann/detail/input/lexer.hpp>
 
 
-namespace nlohmann
-{
-namespace detail
-{
-/*!
-@brief an iterator value
-
-@note This structure could easily be a union, but MSVC currently does not allow
-unions members with complex constructors, see https://github.com/nlohmann/json/pull/105.
-*/
-template<typename BasicJsonType> struct internal_iterator
-{
-    /// iterator for JSON objects
-    typename BasicJsonType::object_t::iterator object_iterator {};
-    /// iterator for JSON arrays
-    typename BasicJsonType::array_t::iterator array_iterator {};
-    /// generic iterator for all other types
-    primitive_iterator_t primitive_iterator {};
-};
-}  // namespace detail
-}  // namespace nlohmann
-
-// #include <nlohmann/detail/iterators/iter_impl.hpp>
-
-
-#include <ciso646> // not
-#include <iterator> // iterator, random_access_iterator_tag, bidirectional_iterator_tag, advance, next
-#include <type_traits> // conditional, is_const, remove_const
-
-// #include <nlohmann/detail/exceptions.hpp>
+#include <array> // array
+#include <clocale> // localeconv
+#include <cstddef> // size_t
+#include <cstdio> // snprintf
+#include <cstdlib> // strtof, strtod, strtold, strtoll, strtoull
+#include <initializer_list> // initializer_list
+#include <string> // char_traits, string
+#include <utility> // move
+#include <vector> // vector
 
-// #include <nlohmann/detail/iterators/internal_iterator.hpp>
+// #include <nlohmann/detail/input/input_adapters.hpp>
 
-// #include <nlohmann/detail/iterators/primitive_iterator.hpp>
+// #include <nlohmann/detail/input/position_t.hpp>
 
 // #include <nlohmann/detail/macro_scope.hpp>
 
-// #include <nlohmann/detail/meta/cpp_future.hpp>
-
-// #include <nlohmann/detail/value_t.hpp>
-
 
 namespace nlohmann
 {
 namespace detail
 {
-// forward declare, to be able to friend it later on
-template<typename IteratorType> class iteration_proxy;
-template<typename IteratorType> class iteration_proxy_value;
+///////////
+// lexer //
+///////////
 
 /*!
-@brief a template for a bidirectional iterator for the @ref basic_json class
-This class implements a both iterators (iterator and const_iterator) for the
-@ref basic_json class.
-@note An iterator is called *initialized* when a pointer to a JSON value has
-      been set (e.g., by a constructor or a copy assignment). If the iterator is
-      default-constructed, it is *uninitialized* and most methods are undefined.
-      **The library uses assertions to detect calls on uninitialized iterators.**
-@requirement The class satisfies the following concept requirements:
--
-[BidirectionalIterator](https://en.cppreference.com/w/cpp/named_req/BidirectionalIterator):
-  The iterator that can be moved can be moved in both directions (i.e.
-  incremented and decremented).
-@since version 1.0.0, simplified in version 2.0.9, change to bidirectional
-       iterators in version 3.0.0 (see https://github.com/nlohmann/json/issues/593)
+@brief lexical analysis
+
+This class organizes the lexical analysis during JSON deserialization.
 */
 template<typename BasicJsonType>
-class iter_impl
+class lexer
 {
-    /// allow basic_json to access private members
-    friend iter_impl<typename std::conditional<std::is_const<BasicJsonType>::value, typename std::remove_const<BasicJsonType>::type, const BasicJsonType>::type>;
-    friend BasicJsonType;
-    friend iteration_proxy<iter_impl>;
-    friend iteration_proxy_value<iter_impl>;
-
-    using object_t = typename BasicJsonType::object_t;
-    using array_t = typename BasicJsonType::array_t;
-    // make sure BasicJsonType is basic_json or const basic_json
-    static_assert(is_basic_json<typename std::remove_const<BasicJsonType>::type>::value,
-                  "iter_impl only accepts (const) basic_json");
+    using number_integer_t = typename BasicJsonType::number_integer_t;
+    using number_unsigned_t = typename BasicJsonType::number_unsigned_t;
+    using number_float_t = typename BasicJsonType::number_float_t;
+    using string_t = typename BasicJsonType::string_t;
 
   public:
+    /// token types for the parser
+    enum class token_type
+    {
+        uninitialized,    ///< indicating the scanner is uninitialized
+        literal_true,     ///< the `true` literal
+        literal_false,    ///< the `false` literal
+        literal_null,     ///< the `null` literal
+        value_string,     ///< a string -- use get_string() for actual value
+        value_unsigned,   ///< an unsigned integer -- use get_number_unsigned() for actual value
+        value_integer,    ///< a signed integer -- use get_number_integer() for actual value
+        value_float,      ///< an floating point number -- use get_number_float() for actual value
+        begin_array,      ///< the character for array begin `[`
+        begin_object,     ///< the character for object begin `{`
+        end_array,        ///< the character for array end `]`
+        end_object,       ///< the character for object end `}`
+        name_separator,   ///< the name separator `:`
+        value_separator,  ///< the value separator `,`
+        parse_error,      ///< indicating a parse error
+        end_of_input,     ///< indicating the end of the input buffer
+        literal_or_value  ///< a literal or the begin of a value (only for diagnostics)
+    };
 
-    /// The std::iterator class template (used as a base class to provide typedefs) is deprecated in C++17.
-    /// The C++ Standard has never required user-defined iterators to derive from std::iterator.
-    /// A user-defined iterator should provide publicly accessible typedefs named
-    /// iterator_category, value_type, difference_type, pointer, and reference.
-    /// Note that value_type is required to be non-const, even for constant iterators.
-    using iterator_category = std::bidirectional_iterator_tag;
+    /// return name of values of type token_type (only used for errors)
+    static const char* token_type_name(const token_type t) noexcept
+    {
+        switch (t)
+        {
+            case token_type::uninitialized:
+                return "<uninitialized>";
+            case token_type::literal_true:
+                return "true literal";
+            case token_type::literal_false:
+                return "false literal";
+            case token_type::literal_null:
+                return "null literal";
+            case token_type::value_string:
+                return "string literal";
+            case lexer::token_type::value_unsigned:
+            case lexer::token_type::value_integer:
+            case lexer::token_type::value_float:
+                return "number literal";
+            case token_type::begin_array:
+                return "'['";
+            case token_type::begin_object:
+                return "'{'";
+            case token_type::end_array:
+                return "']'";
+            case token_type::end_object:
+                return "'}'";
+            case token_type::name_separator:
+                return "':'";
+            case token_type::value_separator:
+                return "','";
+            case token_type::parse_error:
+                return "<parse error>";
+            case token_type::end_of_input:
+                return "end of input";
+            case token_type::literal_or_value:
+                return "'[', '{', or a literal";
+            // LCOV_EXCL_START
+            default: // catch non-enum values
+                return "unknown token";
+                // LCOV_EXCL_STOP
+        }
+    }
 
-    /// the type of the values when the iterator is dereferenced
-    using value_type = typename BasicJsonType::value_type;
-    /// a type to represent differences between iterators
-    using difference_type = typename BasicJsonType::difference_type;
-    /// defines a pointer to the type iterated over (value_type)
-    using pointer = typename std::conditional<std::is_const<BasicJsonType>::value,
-          typename BasicJsonType::const_pointer,
-          typename BasicJsonType::pointer>::type;
-    /// defines a reference to the type iterated over (value_type)
-    using reference =
-        typename std::conditional<std::is_const<BasicJsonType>::value,
-        typename BasicJsonType::const_reference,
-        typename BasicJsonType::reference>::type;
+    explicit lexer(detail::input_adapter_t&& adapter)
+        : ia(std::move(adapter)), decimal_point_char(get_decimal_point()) {}
 
-    /// default constructor
-    iter_impl() = default;
+    // delete because of pointer members
+    lexer(const lexer&) = delete;
+    lexer(lexer&&) = delete;
+    lexer& operator=(lexer&) = delete;
+    lexer& operator=(lexer&&) = delete;
+    ~lexer() = default;
+
+  private:
+    /////////////////////
+    // locales
+    /////////////////////
+
+    /// return the locale-dependent decimal point
+    static char get_decimal_point() noexcept
+    {
+        const auto loc = localeconv();
+        assert(loc != nullptr);
+        return (loc->decimal_point == nullptr) ? '.' : *(loc->decimal_point);
+    }
+
+    /////////////////////
+    // scan functions
+    /////////////////////
 
     /*!
-    @brief constructor for a given JSON instance
-    @param[in] object  pointer to a JSON object for this iterator
-    @pre object != nullptr
-    @post The iterator is initialized; i.e. `m_object != nullptr`.
+    @brief get codepoint from 4 hex characters following `\u`
+
+    For input "\u c1 c2 c3 c4" the codepoint is:
+      (c1 * 0x1000) + (c2 * 0x0100) + (c3 * 0x0010) + c4
+    = (c1 << 12) + (c2 << 8) + (c3 << 4) + (c4 << 0)
+
+    Furthermore, the possible characters '0'..'9', 'A'..'F', and 'a'..'f'
+    must be converted to the integers 0x0..0x9, 0xA..0xF, 0xA..0xF, resp. The
+    conversion is done by subtracting the offset (0x30, 0x37, and 0x57)
+    between the ASCII value of the character and the desired integer value.
+
+    @return codepoint (0x0000..0xFFFF) or -1 in case of an error (e.g. EOF or
+            non-hex character)
     */
-    explicit iter_impl(pointer object) noexcept : m_object(object)
+    int get_codepoint()
     {
-        assert(m_object != nullptr);
+        // this function only makes sense after reading `\u`
+        assert(current == 'u');
+        int codepoint = 0;
 
-        switch (m_object->m_type)
+        const auto factors = { 12u, 8u, 4u, 0u };
+        for (const auto factor : factors)
         {
-            case value_t::object:
+            get();
+
+            if (current >= '0' and current <= '9')
             {
-                m_it.object_iterator = typename object_t::iterator();
-                break;
+                codepoint += static_cast<int>((static_cast<unsigned int>(current) - 0x30u) << factor);
             }
-
-            case value_t::array:
+            else if (current >= 'A' and current <= 'F')
             {
-                m_it.array_iterator = typename array_t::iterator();
-                break;
+                codepoint += static_cast<int>((static_cast<unsigned int>(current) - 0x37u) << factor);
             }
-
-            default:
+            else if (current >= 'a' and current <= 'f')
             {
-                m_it.primitive_iterator = primitive_iterator_t();
-                break;
+                codepoint += static_cast<int>((static_cast<unsigned int>(current) - 0x57u) << factor);
+            }
+            else
+            {
+                return -1;
             }
         }
+
+        assert(0x0000 <= codepoint and codepoint <= 0xFFFF);
+        return codepoint;
     }
 
     /*!
-    @note The conventional copy constructor and copy assignment are implicitly
-          defined. Combined with the following converting constructor and
-          assignment, they support: (1) copy from iterator to iterator, (2)
-          copy from const iterator to const iterator, and (3) conversion from
-          iterator to const iterator. However conversion from const iterator
-          to iterator is not defined.
-    */
+    @brief check if the next byte(s) are inside a given range
 
-    /*!
-    @brief converting constructor
-    @param[in] other  non-const iterator to copy from
-    @note It is not checked whether @a other is initialized.
-    */
-    iter_impl(const iter_impl<typename std::remove_const<BasicJsonType>::type>& other) noexcept
-        : m_object(other.m_object), m_it(other.m_it) {}
+    Adds the current byte and, for each passed range, reads a new byte and
+    checks if it is inside the range. If a violation was detected, set up an
+    error message and return false. Otherwise, return true.
 
-    /*!
-    @brief converting assignment
-    @param[in,out] other  non-const iterator to copy from
-    @return const/non-const iterator
-    @note It is not checked whether @a other is initialized.
-    */
-    iter_impl& operator=(const iter_impl<typename std::remove_const<BasicJsonType>::type>& other) noexcept
-    {
-        m_object = other.m_object;
-        m_it = other.m_it;
-        return *this;
-    }
+    @param[in] ranges  list of integers; interpreted as list of pairs of
+                       inclusive lower and upper bound, respectively
 
-  private:
-    /*!
-    @brief set the iterator to the first value
-    @pre The iterator is initialized; i.e. `m_object != nullptr`.
+    @pre The passed list @a ranges must have 2, 4, or 6 elements; that is,
+         1, 2, or 3 pairs. This precondition is enforced by an assertion.
+
+    @return true if and only if no range violation was detected
     */
-    void set_begin() noexcept
+    bool next_byte_in_range(std::initializer_list<int> ranges)
     {
-        assert(m_object != nullptr);
+        assert(ranges.size() == 2 or ranges.size() == 4 or ranges.size() == 6);
+        add(current);
 
-        switch (m_object->m_type)
+        for (auto range = ranges.begin(); range != ranges.end(); ++range)
         {
-            case value_t::object:
-            {
-                m_it.object_iterator = m_object->m_value.object->begin();
-                break;
-            }
-
-            case value_t::array:
-            {
-                m_it.array_iterator = m_object->m_value.array->begin();
-                break;
-            }
-
-            case value_t::null:
+            get();
+            if (JSON_LIKELY(*range <= current and current <= *(++range)))
             {
-                // set to end so begin()==end() is true: null is empty
-                m_it.primitive_iterator.set_end();
-                break;
+                add(current);
             }
-
-            default:
+            else
             {
-                m_it.primitive_iterator.set_begin();
-                break;
+                error_message = "invalid string: ill-formed UTF-8 byte";
+                return false;
             }
         }
+
+        return true;
     }
 
     /*!
-    @brief set the iterator past the last value
-    @pre The iterator is initialized; i.e. `m_object != nullptr`.
-    */
-    void set_end() noexcept
-    {
-        assert(m_object != nullptr);
-
-        switch (m_object->m_type)
-        {
-            case value_t::object:
-            {
-                m_it.object_iterator = m_object->m_value.object->end();
-                break;
-            }
+    @brief scan a string literal
 
-            case value_t::array:
-            {
-                m_it.array_iterator = m_object->m_value.array->end();
-                break;
-            }
+    This function scans a string according to Sect. 7 of RFC 7159. While
+    scanning, bytes are escaped and copied into buffer token_buffer. Then the
+    function returns successfully, token_buffer is *not* null-terminated (as it
+    may contain \0 bytes), and token_buffer.size() is the number of bytes in the
+    string.
 
-            default:
-            {
-                m_it.primitive_iterator.set_end();
-                break;
-            }
-        }
-    }
+    @return token_type::value_string if string could be successfully scanned,
+            token_type::parse_error otherwise
 
-  public:
-    /*!
-    @brief return a reference to the value pointed to by the iterator
-    @pre The iterator is initialized; i.e. `m_object != nullptr`.
+    @note In case of errors, variable error_message contains a textual
+          description.
     */
-    reference operator*() const
+    token_type scan_string()
     {
-        assert(m_object != nullptr);
-
-        switch (m_object->m_type)
-        {
-            case value_t::object:
-            {
-                assert(m_it.object_iterator != m_object->m_value.object->end());
-                return m_it.object_iterator->second;
-            }
-
-            case value_t::array:
-            {
-                assert(m_it.array_iterator != m_object->m_value.array->end());
-                return *m_it.array_iterator;
-            }
+        // reset token_buffer (ignore opening quote)
+        reset();
 
-            case value_t::null:
-                JSON_THROW(invalid_iterator::create(214, "cannot get value"));
+        // we entered the function by reading an open quote
+        assert(current == '\"');
 
-            default:
+        while (true)
+        {
+            // get next character
+            switch (get())
             {
-                if (JSON_LIKELY(m_it.primitive_iterator.is_begin()))
+                // end of file while parsing string
+                case std::char_traits<char>::eof():
                 {
-                    return *m_object;
+                    error_message = "invalid string: missing closing quote";
+                    return token_type::parse_error;
                 }
 
-                JSON_THROW(invalid_iterator::create(214, "cannot get value"));
-            }
-        }
-    }
-
-    /*!
-    @brief dereference the iterator
-    @pre The iterator is initialized; i.e. `m_object != nullptr`.
-    */
-    pointer operator->() const
-    {
-        assert(m_object != nullptr);
-
-        switch (m_object->m_type)
-        {
-            case value_t::object:
-            {
-                assert(m_it.object_iterator != m_object->m_value.object->end());
-                return &(m_it.object_iterator->second);
-            }
-
-            case value_t::array:
-            {
-                assert(m_it.array_iterator != m_object->m_value.array->end());
-                return &*m_it.array_iterator;
-            }
-
-            default:
-            {
-                if (JSON_LIKELY(m_it.primitive_iterator.is_begin()))
+                // closing quote
+                case '\"':
                 {
-                    return m_object;
+                    return token_type::value_string;
                 }
 
-                JSON_THROW(invalid_iterator::create(214, "cannot get value"));
-            }
-        }
-    }
+                // escapes
+                case '\\':
+                {
+                    switch (get())
+                    {
+                        // quotation mark
+                        case '\"':
+                            add('\"');
+                            break;
+                        // reverse solidus
+                        case '\\':
+                            add('\\');
+                            break;
+                        // solidus
+                        case '/':
+                            add('/');
+                            break;
+                        // backspace
+                        case 'b':
+                            add('\b');
+                            break;
+                        // form feed
+                        case 'f':
+                            add('\f');
+                            break;
+                        // line feed
+                        case 'n':
+                            add('\n');
+                            break;
+                        // carriage return
+                        case 'r':
+                            add('\r');
+                            break;
+                        // tab
+                        case 't':
+                            add('\t');
+                            break;
 
-    /*!
-    @brief post-increment (it++)
-    @pre The iterator is initialized; i.e. `m_object != nullptr`.
-    */
-    iter_impl const operator++(int)
-    {
-        auto result = *this;
-        ++(*this);
-        return result;
-    }
+                        // unicode escapes
+                        case 'u':
+                        {
+                            const int codepoint1 = get_codepoint();
+                            int codepoint = codepoint1; // start with codepoint1
 
-    /*!
-    @brief pre-increment (++it)
-    @pre The iterator is initialized; i.e. `m_object != nullptr`.
-    */
-    iter_impl& operator++()
-    {
-        assert(m_object != nullptr);
+                            if (JSON_UNLIKELY(codepoint1 == -1))
+                            {
+                                error_message = "invalid string: '\\u' must be followed by 4 hex digits";
+                                return token_type::parse_error;
+                            }
 
-        switch (m_object->m_type)
-        {
-            case value_t::object:
-            {
-                std::advance(m_it.object_iterator, 1);
-                break;
-            }
+                            // check if code point is a high surrogate
+                            if (0xD800 <= codepoint1 and codepoint1 <= 0xDBFF)
+                            {
+                                // expect next \uxxxx entry
+                                if (JSON_LIKELY(get() == '\\' and get() == 'u'))
+                                {
+                                    const int codepoint2 = get_codepoint();
 
-            case value_t::array:
-            {
-                std::advance(m_it.array_iterator, 1);
-                break;
-            }
+                                    if (JSON_UNLIKELY(codepoint2 == -1))
+                                    {
+                                        error_message = "invalid string: '\\u' must be followed by 4 hex digits";
+                                        return token_type::parse_error;
+                                    }
 
-            default:
-            {
-                ++m_it.primitive_iterator;
-                break;
-            }
-        }
+                                    // check if codepoint2 is a low surrogate
+                                    if (JSON_LIKELY(0xDC00 <= codepoint2 and codepoint2 <= 0xDFFF))
+                                    {
+                                        // overwrite codepoint
+                                        codepoint = static_cast<int>(
+                                                        // high surrogate occupies the most significant 22 bits
+                                                        (static_cast<unsigned int>(codepoint1) << 10u)
+                                                        // low surrogate occupies the least significant 15 bits
+                                                        + static_cast<unsigned int>(codepoint2)
+                                                        // there is still the 0xD800, 0xDC00 and 0x10000 noise
+                                                        // in the result so we have to subtract with:
+                                                        // (0xD800 << 10) + DC00 - 0x10000 = 0x35FDC00
+                                                        - 0x35FDC00u);
+                                    }
+                                    else
+                                    {
+                                        error_message = "invalid string: surrogate U+DC00..U+DFFF must be followed by U+DC00..U+DFFF";
+                                        return token_type::parse_error;
+                                    }
+                                }
+                                else
+                                {
+                                    error_message = "invalid string: surrogate U+DC00..U+DFFF must be followed by U+DC00..U+DFFF";
+                                    return token_type::parse_error;
+                                }
+                            }
+                            else
+                            {
+                                if (JSON_UNLIKELY(0xDC00 <= codepoint1 and codepoint1 <= 0xDFFF))
+                                {
+                                    error_message = "invalid string: surrogate U+DC00..U+DFFF must follow U+D800..U+DBFF";
+                                    return token_type::parse_error;
+                                }
+                            }
 
-        return *this;
-    }
+                            // result of the above calculation yields a proper codepoint
+                            assert(0x00 <= codepoint and codepoint <= 0x10FFFF);
 
-    /*!
-    @brief post-decrement (it--)
-    @pre The iterator is initialized; i.e. `m_object != nullptr`.
-    */
-    iter_impl const operator--(int)
-    {
-        auto result = *this;
-        --(*this);
-        return result;
-    }
+                            // translate codepoint into bytes
+                            if (codepoint < 0x80)
+                            {
+                                // 1-byte characters: 0xxxxxxx (ASCII)
+                                add(codepoint);
+                            }
+                            else if (codepoint <= 0x7FF)
+                            {
+                                // 2-byte characters: 110xxxxx 10xxxxxx
+                                add(static_cast<int>(0xC0u | (static_cast<unsigned int>(codepoint) >> 6u)));
+                                add(static_cast<int>(0x80u | (static_cast<unsigned int>(codepoint) & 0x3Fu)));
+                            }
+                            else if (codepoint <= 0xFFFF)
+                            {
+                                // 3-byte characters: 1110xxxx 10xxxxxx 10xxxxxx
+                                add(static_cast<int>(0xE0u | (static_cast<unsigned int>(codepoint) >> 12u)));
+                                add(static_cast<int>(0x80u | ((static_cast<unsigned int>(codepoint) >> 6u) & 0x3Fu)));
+                                add(static_cast<int>(0x80u | (static_cast<unsigned int>(codepoint) & 0x3Fu)));
+                            }
+                            else
+                            {
+                                // 4-byte characters: 11110xxx 10xxxxxx 10xxxxxx 10xxxxxx
+                                add(static_cast<int>(0xF0u | (static_cast<unsigned int>(codepoint) >> 18u)));
+                                add(static_cast<int>(0x80u | ((static_cast<unsigned int>(codepoint) >> 12u) & 0x3Fu)));
+                                add(static_cast<int>(0x80u | ((static_cast<unsigned int>(codepoint) >> 6u) & 0x3Fu)));
+                                add(static_cast<int>(0x80u | (static_cast<unsigned int>(codepoint) & 0x3Fu)));
+                            }
 
-    /*!
-    @brief pre-decrement (--it)
-    @pre The iterator is initialized; i.e. `m_object != nullptr`.
-    */
-    iter_impl& operator--()
-    {
-        assert(m_object != nullptr);
+                            break;
+                        }
 
-        switch (m_object->m_type)
-        {
-            case value_t::object:
-            {
-                std::advance(m_it.object_iterator, -1);
-                break;
-            }
+                        // other characters after escape
+                        default:
+                            error_message = "invalid string: forbidden character after backslash";
+                            return token_type::parse_error;
+                    }
 
-            case value_t::array:
-            {
-                std::advance(m_it.array_iterator, -1);
-                break;
-            }
+                    break;
+                }
 
-            default:
-            {
-                --m_it.primitive_iterator;
-                break;
-            }
-        }
+                // invalid control characters
+                case 0x00:
+                {
+                    error_message = "invalid string: control character U+0000 (NUL) must be escaped to \\u0000";
+                    return token_type::parse_error;
+                }
 
-        return *this;
-    }
+                case 0x01:
+                {
+                    error_message = "invalid string: control character U+0001 (SOH) must be escaped to \\u0001";
+                    return token_type::parse_error;
+                }
 
-    /*!
-    @brief  comparison: equal
-    @pre The iterator is initialized; i.e. `m_object != nullptr`.
-    */
-    bool operator==(const iter_impl& other) const
-    {
-        // if objects are not the same, the comparison is undefined
-        if (JSON_UNLIKELY(m_object != other.m_object))
-        {
-            JSON_THROW(invalid_iterator::create(212, "cannot compare iterators of different containers"));
-        }
+                case 0x02:
+                {
+                    error_message = "invalid string: control character U+0002 (STX) must be escaped to \\u0002";
+                    return token_type::parse_error;
+                }
 
-        assert(m_object != nullptr);
+                case 0x03:
+                {
+                    error_message = "invalid string: control character U+0003 (ETX) must be escaped to \\u0003";
+                    return token_type::parse_error;
+                }
 
-        switch (m_object->m_type)
-        {
-            case value_t::object:
-                return (m_it.object_iterator == other.m_it.object_iterator);
+                case 0x04:
+                {
+                    error_message = "invalid string: control character U+0004 (EOT) must be escaped to \\u0004";
+                    return token_type::parse_error;
+                }
 
-            case value_t::array:
-                return (m_it.array_iterator == other.m_it.array_iterator);
+                case 0x05:
+                {
+                    error_message = "invalid string: control character U+0005 (ENQ) must be escaped to \\u0005";
+                    return token_type::parse_error;
+                }
 
-            default:
-                return (m_it.primitive_iterator == other.m_it.primitive_iterator);
-        }
-    }
+                case 0x06:
+                {
+                    error_message = "invalid string: control character U+0006 (ACK) must be escaped to \\u0006";
+                    return token_type::parse_error;
+                }
 
-    /*!
-    @brief  comparison: not equal
-    @pre The iterator is initialized; i.e. `m_object != nullptr`.
-    */
-    bool operator!=(const iter_impl& other) const
-    {
-        return not operator==(other);
-    }
+                case 0x07:
+                {
+                    error_message = "invalid string: control character U+0007 (BEL) must be escaped to \\u0007";
+                    return token_type::parse_error;
+                }
 
-    /*!
-    @brief  comparison: smaller
-    @pre The iterator is initialized; i.e. `m_object != nullptr`.
-    */
-    bool operator<(const iter_impl& other) const
-    {
-        // if objects are not the same, the comparison is undefined
-        if (JSON_UNLIKELY(m_object != other.m_object))
-        {
-            JSON_THROW(invalid_iterator::create(212, "cannot compare iterators of different containers"));
-        }
+                case 0x08:
+                {
+                    error_message = "invalid string: control character U+0008 (BS) must be escaped to \\u0008 or \\b";
+                    return token_type::parse_error;
+                }
 
-        assert(m_object != nullptr);
+                case 0x09:
+                {
+                    error_message = "invalid string: control character U+0009 (HT) must be escaped to \\u0009 or \\t";
+                    return token_type::parse_error;
+                }
 
-        switch (m_object->m_type)
-        {
-            case value_t::object:
-                JSON_THROW(invalid_iterator::create(213, "cannot compare order of object iterators"));
+                case 0x0A:
+                {
+                    error_message = "invalid string: control character U+000A (LF) must be escaped to \\u000A or \\n";
+                    return token_type::parse_error;
+                }
 
-            case value_t::array:
-                return (m_it.array_iterator < other.m_it.array_iterator);
+                case 0x0B:
+                {
+                    error_message = "invalid string: control character U+000B (VT) must be escaped to \\u000B";
+                    return token_type::parse_error;
+                }
 
-            default:
-                return (m_it.primitive_iterator < other.m_it.primitive_iterator);
-        }
-    }
+                case 0x0C:
+                {
+                    error_message = "invalid string: control character U+000C (FF) must be escaped to \\u000C or \\f";
+                    return token_type::parse_error;
+                }
 
-    /*!
-    @brief  comparison: less than or equal
-    @pre The iterator is initialized; i.e. `m_object != nullptr`.
-    */
-    bool operator<=(const iter_impl& other) const
-    {
-        return not other.operator < (*this);
-    }
+                case 0x0D:
+                {
+                    error_message = "invalid string: control character U+000D (CR) must be escaped to \\u000D or \\r";
+                    return token_type::parse_error;
+                }
 
-    /*!
-    @brief  comparison: greater than
-    @pre The iterator is initialized; i.e. `m_object != nullptr`.
-    */
-    bool operator>(const iter_impl& other) const
-    {
-        return not operator<=(other);
-    }
+                case 0x0E:
+                {
+                    error_message = "invalid string: control character U+000E (SO) must be escaped to \\u000E";
+                    return token_type::parse_error;
+                }
 
-    /*!
-    @brief  comparison: greater than or equal
-    @pre The iterator is initialized; i.e. `m_object != nullptr`.
-    */
-    bool operator>=(const iter_impl& other) const
-    {
-        return not operator<(other);
-    }
-
-    /*!
-    @brief  add to iterator
-    @pre The iterator is initialized; i.e. `m_object != nullptr`.
-    */
-    iter_impl& operator+=(difference_type i)
-    {
-        assert(m_object != nullptr);
-
-        switch (m_object->m_type)
-        {
-            case value_t::object:
-                JSON_THROW(invalid_iterator::create(209, "cannot use offsets with object iterators"));
-
-            case value_t::array:
-            {
-                std::advance(m_it.array_iterator, i);
-                break;
-            }
-
-            default:
-            {
-                m_it.primitive_iterator += i;
-                break;
-            }
-        }
-
-        return *this;
-    }
-
-    /*!
-    @brief  subtract from iterator
-    @pre The iterator is initialized; i.e. `m_object != nullptr`.
-    */
-    iter_impl& operator-=(difference_type i)
-    {
-        return operator+=(-i);
-    }
-
-    /*!
-    @brief  add to iterator
-    @pre The iterator is initialized; i.e. `m_object != nullptr`.
-    */
-    iter_impl operator+(difference_type i) const
-    {
-        auto result = *this;
-        result += i;
-        return result;
-    }
-
-    /*!
-    @brief  addition of distance and iterator
-    @pre The iterator is initialized; i.e. `m_object != nullptr`.
-    */
-    friend iter_impl operator+(difference_type i, const iter_impl& it)
-    {
-        auto result = it;
-        result += i;
-        return result;
-    }
-
-    /*!
-    @brief  subtract from iterator
-    @pre The iterator is initialized; i.e. `m_object != nullptr`.
-    */
-    iter_impl operator-(difference_type i) const
-    {
-        auto result = *this;
-        result -= i;
-        return result;
-    }
-
-    /*!
-    @brief  return difference
-    @pre The iterator is initialized; i.e. `m_object != nullptr`.
-    */
-    difference_type operator-(const iter_impl& other) const
-    {
-        assert(m_object != nullptr);
-
-        switch (m_object->m_type)
-        {
-            case value_t::object:
-                JSON_THROW(invalid_iterator::create(209, "cannot use offsets with object iterators"));
-
-            case value_t::array:
-                return m_it.array_iterator - other.m_it.array_iterator;
-
-            default:
-                return m_it.primitive_iterator - other.m_it.primitive_iterator;
-        }
-    }
-
-    /*!
-    @brief  access to successor
-    @pre The iterator is initialized; i.e. `m_object != nullptr`.
-    */
-    reference operator[](difference_type n) const
-    {
-        assert(m_object != nullptr);
-
-        switch (m_object->m_type)
-        {
-            case value_t::object:
-                JSON_THROW(invalid_iterator::create(208, "cannot use operator[] for object iterators"));
+                case 0x0F:
+                {
+                    error_message = "invalid string: control character U+000F (SI) must be escaped to \\u000F";
+                    return token_type::parse_error;
+                }
 
-            case value_t::array:
-                return *std::next(m_it.array_iterator, n);
+                case 0x10:
+                {
+                    error_message = "invalid string: control character U+0010 (DLE) must be escaped to \\u0010";
+                    return token_type::parse_error;
+                }
 
-            case value_t::null:
-                JSON_THROW(invalid_iterator::create(214, "cannot get value"));
+                case 0x11:
+                {
+                    error_message = "invalid string: control character U+0011 (DC1) must be escaped to \\u0011";
+                    return token_type::parse_error;
+                }
 
-            default:
-            {
-                if (JSON_LIKELY(m_it.primitive_iterator.get_value() == -n))
+                case 0x12:
                 {
-                    return *m_object;
+                    error_message = "invalid string: control character U+0012 (DC2) must be escaped to \\u0012";
+                    return token_type::parse_error;
                 }
 
-                JSON_THROW(invalid_iterator::create(214, "cannot get value"));
-            }
-        }
-    }
+                case 0x13:
+                {
+                    error_message = "invalid string: control character U+0013 (DC3) must be escaped to \\u0013";
+                    return token_type::parse_error;
+                }
 
-    /*!
-    @brief  return the key of an object iterator
-    @pre The iterator is initialized; i.e. `m_object != nullptr`.
-    */
-    const typename object_t::key_type& key() const
-    {
-        assert(m_object != nullptr);
+                case 0x14:
+                {
+                    error_message = "invalid string: control character U+0014 (DC4) must be escaped to \\u0014";
+                    return token_type::parse_error;
+                }
 
-        if (JSON_LIKELY(m_object->is_object()))
-        {
-            return m_it.object_iterator->first;
-        }
+                case 0x15:
+                {
+                    error_message = "invalid string: control character U+0015 (NAK) must be escaped to \\u0015";
+                    return token_type::parse_error;
+                }
 
-        JSON_THROW(invalid_iterator::create(207, "cannot use key() for non-object iterators"));
-    }
+                case 0x16:
+                {
+                    error_message = "invalid string: control character U+0016 (SYN) must be escaped to \\u0016";
+                    return token_type::parse_error;
+                }
 
-    /*!
-    @brief  return the value of an iterator
-    @pre The iterator is initialized; i.e. `m_object != nullptr`.
-    */
-    reference value() const
-    {
-        return operator*();
-    }
+                case 0x17:
+                {
+                    error_message = "invalid string: control character U+0017 (ETB) must be escaped to \\u0017";
+                    return token_type::parse_error;
+                }
 
-  private:
-    /// associated JSON instance
-    pointer m_object = nullptr;
-    /// the actual iterator of the associated instance
-    internal_iterator<typename std::remove_const<BasicJsonType>::type> m_it;
-};
-}  // namespace detail
-} // namespace nlohmann
-// #include <nlohmann/detail/iterators/iteration_proxy.hpp>
+                case 0x18:
+                {
+                    error_message = "invalid string: control character U+0018 (CAN) must be escaped to \\u0018";
+                    return token_type::parse_error;
+                }
 
-// #include <nlohmann/detail/iterators/json_reverse_iterator.hpp>
+                case 0x19:
+                {
+                    error_message = "invalid string: control character U+0019 (EM) must be escaped to \\u0019";
+                    return token_type::parse_error;
+                }
 
+                case 0x1A:
+                {
+                    error_message = "invalid string: control character U+001A (SUB) must be escaped to \\u001A";
+                    return token_type::parse_error;
+                }
 
-#include <cstddef> // ptrdiff_t
-#include <iterator> // reverse_iterator
-#include <utility> // declval
+                case 0x1B:
+                {
+                    error_message = "invalid string: control character U+001B (ESC) must be escaped to \\u001B";
+                    return token_type::parse_error;
+                }
 
-namespace nlohmann
-{
-namespace detail
-{
-//////////////////////
-// reverse_iterator //
-//////////////////////
+                case 0x1C:
+                {
+                    error_message = "invalid string: control character U+001C (FS) must be escaped to \\u001C";
+                    return token_type::parse_error;
+                }
 
-/*!
-@brief a template for a reverse iterator class
+                case 0x1D:
+                {
+                    error_message = "invalid string: control character U+001D (GS) must be escaped to \\u001D";
+                    return token_type::parse_error;
+                }
 
-@tparam Base the base iterator type to reverse. Valid types are @ref
-iterator (to create @ref reverse_iterator) and @ref const_iterator (to
-create @ref const_reverse_iterator).
+                case 0x1E:
+                {
+                    error_message = "invalid string: control character U+001E (RS) must be escaped to \\u001E";
+                    return token_type::parse_error;
+                }
 
-@requirement The class satisfies the following concept requirements:
--
-[BidirectionalIterator](https://en.cppreference.com/w/cpp/named_req/BidirectionalIterator):
-  The iterator that can be moved can be moved in both directions (i.e.
-  incremented and decremented).
-- [OutputIterator](https://en.cppreference.com/w/cpp/named_req/OutputIterator):
-  It is possible to write to the pointed-to element (only if @a Base is
-  @ref iterator).
+                case 0x1F:
+                {
+                    error_message = "invalid string: control character U+001F (US) must be escaped to \\u001F";
+                    return token_type::parse_error;
+                }
 
-@since version 1.0.0
-*/
-template<typename Base>
-class json_reverse_iterator : public std::reverse_iterator<Base>
-{
-  public:
-    using difference_type = std::ptrdiff_t;
-    /// shortcut to the reverse iterator adapter
-    using base_iterator = std::reverse_iterator<Base>;
-    /// the reference type for the pointed-to element
-    using reference = typename Base::reference;
+                // U+0020..U+007F (except U+0022 (quote) and U+005C (backspace))
+                case 0x20:
+                case 0x21:
+                case 0x23:
+                case 0x24:
+                case 0x25:
+                case 0x26:
+                case 0x27:
+                case 0x28:
+                case 0x29:
+                case 0x2A:
+                case 0x2B:
+                case 0x2C:
+                case 0x2D:
+                case 0x2E:
+                case 0x2F:
+                case 0x30:
+                case 0x31:
+                case 0x32:
+                case 0x33:
+                case 0x34:
+                case 0x35:
+                case 0x36:
+                case 0x37:
+                case 0x38:
+                case 0x39:
+                case 0x3A:
+                case 0x3B:
+                case 0x3C:
+                case 0x3D:
+                case 0x3E:
+                case 0x3F:
+                case 0x40:
+                case 0x41:
+                case 0x42:
+                case 0x43:
+                case 0x44:
+                case 0x45:
+                case 0x46:
+                case 0x47:
+                case 0x48:
+                case 0x49:
+                case 0x4A:
+                case 0x4B:
+                case 0x4C:
+                case 0x4D:
+                case 0x4E:
+                case 0x4F:
+                case 0x50:
+                case 0x51:
+                case 0x52:
+                case 0x53:
+                case 0x54:
+                case 0x55:
+                case 0x56:
+                case 0x57:
+                case 0x58:
+                case 0x59:
+                case 0x5A:
+                case 0x5B:
+                case 0x5D:
+                case 0x5E:
+                case 0x5F:
+                case 0x60:
+                case 0x61:
+                case 0x62:
+                case 0x63:
+                case 0x64:
+                case 0x65:
+                case 0x66:
+                case 0x67:
+                case 0x68:
+                case 0x69:
+                case 0x6A:
+                case 0x6B:
+                case 0x6C:
+                case 0x6D:
+                case 0x6E:
+                case 0x6F:
+                case 0x70:
+                case 0x71:
+                case 0x72:
+                case 0x73:
+                case 0x74:
+                case 0x75:
+                case 0x76:
+                case 0x77:
+                case 0x78:
+                case 0x79:
+                case 0x7A:
+                case 0x7B:
+                case 0x7C:
+                case 0x7D:
+                case 0x7E:
+                case 0x7F:
+                {
+                    add(current);
+                    break;
+                }
 
-    /// create reverse iterator from iterator
-    explicit json_reverse_iterator(const typename base_iterator::iterator_type& it) noexcept
-        : base_iterator(it) {}
+                // U+0080..U+07FF: bytes C2..DF 80..BF
+                case 0xC2:
+                case 0xC3:
+                case 0xC4:
+                case 0xC5:
+                case 0xC6:
+                case 0xC7:
+                case 0xC8:
+                case 0xC9:
+                case 0xCA:
+                case 0xCB:
+                case 0xCC:
+                case 0xCD:
+                case 0xCE:
+                case 0xCF:
+                case 0xD0:
+                case 0xD1:
+                case 0xD2:
+                case 0xD3:
+                case 0xD4:
+                case 0xD5:
+                case 0xD6:
+                case 0xD7:
+                case 0xD8:
+                case 0xD9:
+                case 0xDA:
+                case 0xDB:
+                case 0xDC:
+                case 0xDD:
+                case 0xDE:
+                case 0xDF:
+                {
+                    if (JSON_UNLIKELY(not next_byte_in_range({0x80, 0xBF})))
+                    {
+                        return token_type::parse_error;
+                    }
+                    break;
+                }
 
-    /// create reverse iterator from base class
-    explicit json_reverse_iterator(const base_iterator& it) noexcept : base_iterator(it) {}
+                // U+0800..U+0FFF: bytes E0 A0..BF 80..BF
+                case 0xE0:
+                {
+                    if (JSON_UNLIKELY(not (next_byte_in_range({0xA0, 0xBF, 0x80, 0xBF}))))
+                    {
+                        return token_type::parse_error;
+                    }
+                    break;
+                }
 
-    /// post-increment (it++)
-    json_reverse_iterator const operator++(int)
-    {
-        return static_cast<json_reverse_iterator>(base_iterator::operator++(1));
+                // U+1000..U+CFFF: bytes E1..EC 80..BF 80..BF
+                // U+E000..U+FFFF: bytes EE..EF 80..BF 80..BF
+                case 0xE1:
+                case 0xE2:
+                case 0xE3:
+                case 0xE4:
+                case 0xE5:
+                case 0xE6:
+                case 0xE7:
+                case 0xE8:
+                case 0xE9:
+                case 0xEA:
+                case 0xEB:
+                case 0xEC:
+                case 0xEE:
+                case 0xEF:
+                {
+                    if (JSON_UNLIKELY(not (next_byte_in_range({0x80, 0xBF, 0x80, 0xBF}))))
+                    {
+                        return token_type::parse_error;
+                    }
+                    break;
+                }
+
+                // U+D000..U+D7FF: bytes ED 80..9F 80..BF
+                case 0xED:
+                {
+                    if (JSON_UNLIKELY(not (next_byte_in_range({0x80, 0x9F, 0x80, 0xBF}))))
+                    {
+                        return token_type::parse_error;
+                    }
+                    break;
+                }
+
+                // U+10000..U+3FFFF F0 90..BF 80..BF 80..BF
+                case 0xF0:
+                {
+                    if (JSON_UNLIKELY(not (next_byte_in_range({0x90, 0xBF, 0x80, 0xBF, 0x80, 0xBF}))))
+                    {
+                        return token_type::parse_error;
+                    }
+                    break;
+                }
+
+                // U+40000..U+FFFFF F1..F3 80..BF 80..BF 80..BF
+                case 0xF1:
+                case 0xF2:
+                case 0xF3:
+                {
+                    if (JSON_UNLIKELY(not (next_byte_in_range({0x80, 0xBF, 0x80, 0xBF, 0x80, 0xBF}))))
+                    {
+                        return token_type::parse_error;
+                    }
+                    break;
+                }
+
+                // U+100000..U+10FFFF F4 80..8F 80..BF 80..BF
+                case 0xF4:
+                {
+                    if (JSON_UNLIKELY(not (next_byte_in_range({0x80, 0x8F, 0x80, 0xBF, 0x80, 0xBF}))))
+                    {
+                        return token_type::parse_error;
+                    }
+                    break;
+                }
+
+                // remaining bytes (80..C1 and F5..FF) are ill-formed
+                default:
+                {
+                    error_message = "invalid string: ill-formed UTF-8 byte";
+                    return token_type::parse_error;
+                }
+            }
+        }
     }
 
-    /// pre-increment (++it)
-    json_reverse_iterator& operator++()
+    static void strtof(float& f, const char* str, char** endptr) noexcept
     {
-        return static_cast<json_reverse_iterator&>(base_iterator::operator++());
+        f = std::strtof(str, endptr);
     }
 
-    /// post-decrement (it--)
-    json_reverse_iterator const operator--(int)
+    static void strtof(double& f, const char* str, char** endptr) noexcept
     {
-        return static_cast<json_reverse_iterator>(base_iterator::operator--(1));
+        f = std::strtod(str, endptr);
     }
 
-    /// pre-decrement (--it)
-    json_reverse_iterator& operator--()
+    static void strtof(long double& f, const char* str, char** endptr) noexcept
     {
-        return static_cast<json_reverse_iterator&>(base_iterator::operator--());
+        f = std::strtold(str, endptr);
     }
 
-    /// add to iterator
-    json_reverse_iterator& operator+=(difference_type i)
-    {
-        return static_cast<json_reverse_iterator&>(base_iterator::operator+=(i));
-    }
+    /*!
+    @brief scan a number literal
 
-    /// add to iterator
-    json_reverse_iterator operator+(difference_type i) const
-    {
-        return static_cast<json_reverse_iterator>(base_iterator::operator+(i));
-    }
+    This function scans a string according to Sect. 6 of RFC 7159.
 
-    /// subtract from iterator
-    json_reverse_iterator operator-(difference_type i) const
-    {
-        return static_cast<json_reverse_iterator>(base_iterator::operator-(i));
-    }
+    The function is realized with a deterministic finite state machine derived
+    from the grammar described in RFC 7159. Starting in state "init", the
+    input is read and used to determined the next state. Only state "done"
+    accepts the number. State "error" is a trap state to model errors. In the
+    table below, "anything" means any character but the ones listed before.
 
-    /// return difference
-    difference_type operator-(const json_reverse_iterator& other) const
-    {
-        return base_iterator(*this) - base_iterator(other);
-    }
+    state    | 0        | 1-9      | e E      | +       | -       | .        | anything
+    ---------|----------|----------|----------|---------|---------|----------|-----------
+    init     | zero     | any1     | [error]  | [error] | minus   | [error]  | [error]
+    minus    | zero     | any1     | [error]  | [error] | [error] | [error]  | [error]
+    zero     | done     | done     | exponent | done    | done    | decimal1 | done
+    any1     | any1     | any1     | exponent | done    | done    | decimal1 | done
+    decimal1 | decimal2 | [error]  | [error]  | [error] | [error] | [error]  | [error]
+    decimal2 | decimal2 | decimal2 | exponent | done    | done    | done     | done
+    exponent | any2     | any2     | [error]  | sign    | sign    | [error]  | [error]
+    sign     | any2     | any2     | [error]  | [error] | [error] | [error]  | [error]
+    any2     | any2     | any2     | done     | done    | done    | done     | done
 
-    /// access to successor
-    reference operator[](difference_type n) const
-    {
-        return *(this->operator+(n));
-    }
+    The state machine is realized with one label per state (prefixed with
+    "scan_number_") and `goto` statements between them. The state machine
+    contains cycles, but any cycle can be left when EOF is read. Therefore,
+    the function is guaranteed to terminate.
 
-    /// return the key of an object iterator
-    auto key() const -> decltype(std::declval<Base>().key())
-    {
-        auto it = --this->base();
-        return it.key();
-    }
+    During scanning, the read bytes are stored in token_buffer. This string is
+    then converted to a signed integer, an unsigned integer, or a
+    floating-point number.
 
-    /// return the value of an iterator
-    reference value() const
-    {
-        auto it = --this->base();
-        return it.operator * ();
-    }
-};
-}  // namespace detail
-}  // namespace nlohmann
+    @return token_type::value_unsigned, token_type::value_integer, or
+            token_type::value_float if number could be successfully scanned,
+            token_type::parse_error otherwise
 
-// #include <nlohmann/detail/output/output_adapters.hpp>
+    @note The scanner is independent of the current locale. Internally, the
+          locale's decimal point is used instead of `.` to work with the
+          locale-dependent converters.
+    */
+    token_type scan_number()  // lgtm [cpp/use-of-goto]
+    {
+        // reset token_buffer to store the number's bytes
+        reset();
 
+        // the type of the parsed number; initially set to unsigned; will be
+        // changed if minus sign, decimal point or exponent is read
+        token_type number_type = token_type::value_unsigned;
 
-#include <algorithm> // copy
-#include <cstddef> // size_t
-#include <ios> // streamsize
-#include <iterator> // back_inserter
-#include <memory> // shared_ptr, make_shared
-#include <ostream> // basic_ostream
-#include <string> // basic_string
-#include <vector> // vector
+        // state (init): we just found out we need to scan a number
+        switch (current)
+        {
+            case '-':
+            {
+                add(current);
+                goto scan_number_minus;
+            }
 
-namespace nlohmann
-{
-namespace detail
-{
-/// abstract output adapter interface
-template<typename CharType> struct output_adapter_protocol
-{
-    virtual void write_character(CharType c) = 0;
-    virtual void write_characters(const CharType* s, std::size_t length) = 0;
-    virtual ~output_adapter_protocol() = default;
-};
+            case '0':
+            {
+                add(current);
+                goto scan_number_zero;
+            }
 
-/// a type to simplify interfaces
-template<typename CharType>
-using output_adapter_t = std::shared_ptr<output_adapter_protocol<CharType>>;
+            case '1':
+            case '2':
+            case '3':
+            case '4':
+            case '5':
+            case '6':
+            case '7':
+            case '8':
+            case '9':
+            {
+                add(current);
+                goto scan_number_any1;
+            }
 
-/// output adapter for byte vectors
-template<typename CharType>
-class output_vector_adapter : public output_adapter_protocol<CharType>
-{
-  public:
-    explicit output_vector_adapter(std::vector<CharType>& vec) noexcept
-        : v(vec)
-    {}
+            // all other characters are rejected outside scan_number()
+            default:            // LCOV_EXCL_LINE
+                assert(false);  // LCOV_EXCL_LINE
+        }
 
-    void write_character(CharType c) override
-    {
-        v.push_back(c);
-    }
+scan_number_minus:
+        // state: we just parsed a leading minus sign
+        number_type = token_type::value_integer;
+        switch (get())
+        {
+            case '0':
+            {
+                add(current);
+                goto scan_number_zero;
+            }
 
-    void write_characters(const CharType* s, std::size_t length) override
-    {
-        std::copy(s, s + length, std::back_inserter(v));
-    }
+            case '1':
+            case '2':
+            case '3':
+            case '4':
+            case '5':
+            case '6':
+            case '7':
+            case '8':
+            case '9':
+            {
+                add(current);
+                goto scan_number_any1;
+            }
 
-  private:
-    std::vector<CharType>& v;
-};
+            default:
+            {
+                error_message = "invalid number; expected digit after '-'";
+                return token_type::parse_error;
+            }
+        }
 
-/// output adapter for output streams
-template<typename CharType>
-class output_stream_adapter : public output_adapter_protocol<CharType>
-{
-  public:
-    explicit output_stream_adapter(std::basic_ostream<CharType>& s) noexcept
-        : stream(s)
-    {}
+scan_number_zero:
+        // state: we just parse a zero (maybe with a leading minus sign)
+        switch (get())
+        {
+            case '.':
+            {
+                add(decimal_point_char);
+                goto scan_number_decimal1;
+            }
 
-    void write_character(CharType c) override
-    {
-        stream.put(c);
-    }
+            case 'e':
+            case 'E':
+            {
+                add(current);
+                goto scan_number_exponent;
+            }
 
-    void write_characters(const CharType* s, std::size_t length) override
-    {
-        stream.write(s, static_cast<std::streamsize>(length));
-    }
+            default:
+                goto scan_number_done;
+        }
 
-  private:
-    std::basic_ostream<CharType>& stream;
-};
+scan_number_any1:
+        // state: we just parsed a number 0-9 (maybe with a leading minus sign)
+        switch (get())
+        {
+            case '0':
+            case '1':
+            case '2':
+            case '3':
+            case '4':
+            case '5':
+            case '6':
+            case '7':
+            case '8':
+            case '9':
+            {
+                add(current);
+                goto scan_number_any1;
+            }
 
-/// output adapter for basic_string
-template<typename CharType, typename StringType = std::basic_string<CharType>>
-class output_string_adapter : public output_adapter_protocol<CharType>
-{
-  public:
-    explicit output_string_adapter(StringType& s) noexcept
-        : str(s)
-    {}
+            case '.':
+            {
+                add(decimal_point_char);
+                goto scan_number_decimal1;
+            }
 
-    void write_character(CharType c) override
-    {
-        str.push_back(c);
-    }
+            case 'e':
+            case 'E':
+            {
+                add(current);
+                goto scan_number_exponent;
+            }
 
-    void write_characters(const CharType* s, std::size_t length) override
-    {
-        str.append(s, length);
-    }
+            default:
+                goto scan_number_done;
+        }
 
-  private:
-    StringType& str;
-};
+scan_number_decimal1:
+        // state: we just parsed a decimal point
+        number_type = token_type::value_float;
+        switch (get())
+        {
+            case '0':
+            case '1':
+            case '2':
+            case '3':
+            case '4':
+            case '5':
+            case '6':
+            case '7':
+            case '8':
+            case '9':
+            {
+                add(current);
+                goto scan_number_decimal2;
+            }
 
-template<typename CharType, typename StringType = std::basic_string<CharType>>
-class output_adapter
-{
-  public:
-    output_adapter(std::vector<CharType>& vec)
-        : oa(std::make_shared<output_vector_adapter<CharType>>(vec)) {}
+            default:
+            {
+                error_message = "invalid number; expected digit after '.'";
+                return token_type::parse_error;
+            }
+        }
 
-    output_adapter(std::basic_ostream<CharType>& s)
-        : oa(std::make_shared<output_stream_adapter<CharType>>(s)) {}
+scan_number_decimal2:
+        // we just parsed at least one number after a decimal point
+        switch (get())
+        {
+            case '0':
+            case '1':
+            case '2':
+            case '3':
+            case '4':
+            case '5':
+            case '6':
+            case '7':
+            case '8':
+            case '9':
+            {
+                add(current);
+                goto scan_number_decimal2;
+            }
 
-    output_adapter(StringType& s)
-        : oa(std::make_shared<output_string_adapter<CharType, StringType>>(s)) {}
+            case 'e':
+            case 'E':
+            {
+                add(current);
+                goto scan_number_exponent;
+            }
 
-    operator output_adapter_t<CharType>()
-    {
-        return oa;
-    }
+            default:
+                goto scan_number_done;
+        }
 
-  private:
-    output_adapter_t<CharType> oa = nullptr;
-};
-}  // namespace detail
-}  // namespace nlohmann
+scan_number_exponent:
+        // we just parsed an exponent
+        number_type = token_type::value_float;
+        switch (get())
+        {
+            case '+':
+            case '-':
+            {
+                add(current);
+                goto scan_number_sign;
+            }
 
-// #include <nlohmann/detail/input/binary_reader.hpp>
+            case '0':
+            case '1':
+            case '2':
+            case '3':
+            case '4':
+            case '5':
+            case '6':
+            case '7':
+            case '8':
+            case '9':
+            {
+                add(current);
+                goto scan_number_any2;
+            }
 
+            default:
+            {
+                error_message =
+                    "invalid number; expected '+', '-', or digit after exponent";
+                return token_type::parse_error;
+            }
+        }
 
-#include <algorithm> // generate_n
-#include <array> // array
-#include <cassert> // assert
-#include <cmath> // ldexp
-#include <cstddef> // size_t
-#include <cstdint> // uint8_t, uint16_t, uint32_t, uint64_t
-#include <cstdio> // snprintf
-#include <cstring> // memcpy
-#include <iterator> // back_inserter
-#include <limits> // numeric_limits
-#include <string> // char_traits, string
-#include <utility> // make_pair, move
+scan_number_sign:
+        // we just parsed an exponent sign
+        switch (get())
+        {
+            case '0':
+            case '1':
+            case '2':
+            case '3':
+            case '4':
+            case '5':
+            case '6':
+            case '7':
+            case '8':
+            case '9':
+            {
+                add(current);
+                goto scan_number_any2;
+            }
 
-// #include <nlohmann/detail/input/input_adapters.hpp>
+            default:
+            {
+                error_message = "invalid number; expected digit after exponent sign";
+                return token_type::parse_error;
+            }
+        }
 
-// #include <nlohmann/detail/input/json_sax.hpp>
+scan_number_any2:
+        // we just parsed a number after the exponent or exponent sign
+        switch (get())
+        {
+            case '0':
+            case '1':
+            case '2':
+            case '3':
+            case '4':
+            case '5':
+            case '6':
+            case '7':
+            case '8':
+            case '9':
+            {
+                add(current);
+                goto scan_number_any2;
+            }
 
-// #include <nlohmann/detail/exceptions.hpp>
+            default:
+                goto scan_number_done;
+        }
 
-// #include <nlohmann/detail/macro_scope.hpp>
+scan_number_done:
+        // unget the character after the number (we only read it to know that
+        // we are done scanning a number)
+        unget();
 
-// #include <nlohmann/detail/meta/is_sax.hpp>
+        char* endptr = nullptr;
+        errno = 0;
 
-// #include <nlohmann/detail/value_t.hpp>
+        // try to parse integers first and fall back to floats
+        if (number_type == token_type::value_unsigned)
+        {
+            const auto x = std::strtoull(token_buffer.data(), &endptr, 10);
 
+            // we checked the number format before
+            assert(endptr == token_buffer.data() + token_buffer.size());
 
-namespace nlohmann
-{
-namespace detail
-{
-///////////////////
-// binary reader //
-///////////////////
+            if (errno == 0)
+            {
+                value_unsigned = static_cast<number_unsigned_t>(x);
+                if (value_unsigned == x)
+                {
+                    return token_type::value_unsigned;
+                }
+            }
+        }
+        else if (number_type == token_type::value_integer)
+        {
+            const auto x = std::strtoll(token_buffer.data(), &endptr, 10);
 
-/*!
-@brief deserialization of CBOR, MessagePack, and UBJSON values
-*/
-template<typename BasicJsonType, typename SAX = json_sax_dom_parser<BasicJsonType>>
-class binary_reader
-{
-    using number_integer_t = typename BasicJsonType::number_integer_t;
-    using number_unsigned_t = typename BasicJsonType::number_unsigned_t;
-    using number_float_t = typename BasicJsonType::number_float_t;
-    using string_t = typename BasicJsonType::string_t;
-    using json_sax_t = SAX;
+            // we checked the number format before
+            assert(endptr == token_buffer.data() + token_buffer.size());
 
-  public:
-    /*!
-    @brief create a binary reader
+            if (errno == 0)
+            {
+                value_integer = static_cast<number_integer_t>(x);
+                if (value_integer == x)
+                {
+                    return token_type::value_integer;
+                }
+            }
+        }
 
-    @param[in] adapter  input adapter to read from
-    */
-    explicit binary_reader(input_adapter_t adapter) : ia(std::move(adapter))
-    {
-        (void)detail::is_sax_static_asserts<SAX, BasicJsonType> {};
-        assert(ia);
+        // this code is reached if we parse a floating-point number or if an
+        // integer conversion above failed
+        strtof(value_float, token_buffer.data(), &endptr);
+
+        // we checked the number format before
+        assert(endptr == token_buffer.data() + token_buffer.size());
+
+        return token_type::value_float;
     }
 
     /*!
-    @param[in] format  the binary format to parse
-    @param[in] sax_    a SAX event processor
-    @param[in] strict  whether to expect the input to be consumed completed
-
-    @return
+    @param[in] literal_text  the literal text to expect
+    @param[in] length        the length of the passed literal text
+    @param[in] return_type   the token type to return on success
     */
-    bool sax_parse(const input_format_t format,
-                   json_sax_t* sax_,
-                   const bool strict = true)
+    token_type scan_literal(const char* literal_text, const std::size_t length,
+                            token_type return_type)
     {
-        sax = sax_;
-        bool result = false;
-
-        switch (format)
-        {
-            case input_format_t::bson:
-                result = parse_bson_internal();
-                break;
-
-            case input_format_t::cbor:
-                result = parse_cbor_internal();
-                break;
-
-            case input_format_t::msgpack:
-                result = parse_msgpack_internal();
-                break;
-
-            case input_format_t::ubjson:
-                result = parse_ubjson_internal();
-                break;
-
-            // LCOV_EXCL_START
-            default:
-                assert(false);
-                // LCOV_EXCL_STOP
-        }
-
-        // strict mode: next byte must be EOF
-        if (result and strict)
+        assert(current == literal_text[0]);
+        for (std::size_t i = 1; i < length; ++i)
         {
-            if (format == input_format_t::ubjson)
-            {
-                get_ignore_noop();
-            }
-            else
-            {
-                get();
-            }
-
-            if (JSON_UNLIKELY(current != std::char_traits<char>::eof()))
+            if (JSON_UNLIKELY(get() != literal_text[i]))
             {
-                return sax->parse_error(chars_read, get_token_string(),
-                                        parse_error::create(110, chars_read, exception_message(format, "expected end of input; last byte: 0x" + get_token_string(), "value")));
+                error_message = "invalid literal";
+                return token_type::parse_error;
             }
         }
-
-        return result;
+        return return_type;
     }
 
-    /*!
-    @brief determine system byte order
-
-    @return true if and only if system's byte order is little endian
+    /////////////////////
+    // input management
+    /////////////////////
 
-    @note from http://stackoverflow.com/a/1001328/266378
-    */
-    static constexpr bool little_endianess(int num = 1) noexcept
+    /// reset token_buffer; current character is beginning of token
+    void reset() noexcept
     {
-        return (*reinterpret_cast<char*>(&num) == 1);
+        token_buffer.clear();
+        token_string.clear();
+        token_string.push_back(std::char_traits<char>::to_char_type(current));
     }
 
-  private:
-    //////////
-    // BSON //
-    //////////
+    /*
+    @brief get next character from the input
 
-    /*!
-    @brief Reads in a BSON-object and passes it to the SAX-parser.
-    @return whether a valid BSON-value was passed to the SAX parser
+    This function provides the interface to the used input adapter. It does
+    not throw in case the input reached EOF, but returns a
+    `std::char_traits<char>::eof()` in that case.  Stores the scanned characters
+    for use in error messages.
+
+    @return character read from the input
     */
-    bool parse_bson_internal()
+    std::char_traits<char>::int_type get()
     {
-        std::int32_t document_size;
-        get_number<std::int32_t, true>(input_format_t::bson, document_size);
+        ++position.chars_read_total;
+        ++position.chars_read_current_line;
 
-        if (JSON_UNLIKELY(not sax->start_object(std::size_t(-1))))
+        if (next_unget)
         {
-            return false;
+            // just reset the next_unget variable and work with current
+            next_unget = false;
+        }
+        else
+        {
+            current = ia->get_character();
         }
 
-        if (JSON_UNLIKELY(not parse_bson_element_list(/*is_array*/false)))
+        if (JSON_LIKELY(current != std::char_traits<char>::eof()))
         {
-            return false;
+            token_string.push_back(std::char_traits<char>::to_char_type(current));
         }
 
-        return sax->end_object();
+        if (current == '\n')
+        {
+            ++position.lines_read;
+            position.chars_read_current_line = 0;
+        }
+
+        return current;
     }
 
     /*!
-    @brief Parses a C-style string from the BSON input.
-    @param[in, out] result  A reference to the string variable where the read
-                            string is to be stored.
-    @return `true` if the \x00-byte indicating the end of the string was
-             encountered before the EOF; false` indicates an unexpected EOF.
+    @brief unget current character (read it again on next get)
+
+    We implement unget by setting variable next_unget to true. The input is not
+    changed - we just simulate ungetting by modifying chars_read_total,
+    chars_read_current_line, and token_string. The next call to get() will
+    behave as if the unget character is read again.
     */
-    bool get_bson_cstr(string_t& result)
+    void unget()
     {
-        auto out = std::back_inserter(result);
-        while (true)
+        next_unget = true;
+
+        --position.chars_read_total;
+
+        // in case we "unget" a newline, we have to also decrement the lines_read
+        if (position.chars_read_current_line == 0)
         {
-            get();
-            if (JSON_UNLIKELY(not unexpect_eof(input_format_t::bson, "cstring")))
-            {
-                return false;
-            }
-            if (current == 0x00)
+            if (position.lines_read > 0)
             {
-                return true;
+                --position.lines_read;
             }
-            *out++ = static_cast<char>(current);
+        }
+        else
+        {
+            --position.chars_read_current_line;
         }
 
-        return true;
+        if (JSON_LIKELY(current != std::char_traits<char>::eof()))
+        {
+            assert(not token_string.empty());
+            token_string.pop_back();
+        }
     }
 
-    /*!
-    @brief Parses a zero-terminated string of length @a len from the BSON
-           input.
-    @param[in] len  The length (including the zero-byte at the end) of the
-                    string to be read.
-    @param[in, out] result  A reference to the string variable where the read
-                            string is to be stored.
-    @tparam NumberType The type of the length @a len
-    @pre len >= 1
-    @return `true` if the string was successfully parsed
-    */
-    template<typename NumberType>
-    bool get_bson_string(const NumberType len, string_t& result)
+    /// add a character to token_buffer
+    void add(int c)
     {
-        if (JSON_UNLIKELY(len < 1))
-        {
-            auto last_token = get_token_string();
-            return sax->parse_error(chars_read, last_token, parse_error::create(112, chars_read, exception_message(input_format_t::bson, "string length must be at least 1, is " + std::to_string(len), "string")));
-        }
+        token_buffer.push_back(std::char_traits<char>::to_char_type(c));
+    }
 
-        return get_string(input_format_t::bson, len - static_cast<NumberType>(1), result) and get() != std::char_traits<char>::eof();
+  public:
+    /////////////////////
+    // value getters
+    /////////////////////
+
+    /// return integer value
+    constexpr number_integer_t get_number_integer() const noexcept
+    {
+        return value_integer;
     }
 
-    /*!
-    @brief Read a BSON document element of the given @a element_type.
-    @param[in] element_type The BSON element type, c.f. http://bsonspec.org/spec.html
-    @param[in] element_type_parse_position The position in the input stream,
-               where the `element_type` was read.
-    @warning Not all BSON element types are supported yet. An unsupported
-             @a element_type will give rise to a parse_error.114:
-             Unsupported BSON record type 0x...
-    @return whether a valid BSON-object/array was passed to the SAX parser
-    */
-    bool parse_bson_element_internal(const int element_type,
-                                     const std::size_t element_type_parse_position)
+    /// return unsigned integer value
+    constexpr number_unsigned_t get_number_unsigned() const noexcept
     {
-        switch (element_type)
-        {
-            case 0x01: // double
-            {
-                double number;
-                return get_number<double, true>(input_format_t::bson, number) and sax->number_float(static_cast<number_float_t>(number), "");
-            }
+        return value_unsigned;
+    }
 
-            case 0x02: // string
-            {
-                std::int32_t len;
-                string_t value;
-                return get_number<std::int32_t, true>(input_format_t::bson, len) and get_bson_string(len, value) and sax->string(value);
-            }
+    /// return floating-point value
+    constexpr number_float_t get_number_float() const noexcept
+    {
+        return value_float;
+    }
 
-            case 0x03: // object
-            {
-                return parse_bson_internal();
-            }
+    /// return current string value (implicitly resets the token; useful only once)
+    string_t& get_string()
+    {
+        return token_buffer;
+    }
 
-            case 0x04: // array
-            {
-                return parse_bson_array();
-            }
+    /////////////////////
+    // diagnostics
+    /////////////////////
 
-            case 0x08: // boolean
+    /// return position of last read token
+    constexpr position_t get_position() const noexcept
+    {
+        return position;
+    }
+
+    /// return the last read token (for errors only).  Will never contain EOF
+    /// (an arbitrary value that is not a valid char value, often -1), because
+    /// 255 may legitimately occur.  May contain NUL, which should be escaped.
+    std::string get_token_string() const
+    {
+        // escape control characters
+        std::string result;
+        for (const auto c : token_string)
+        {
+            if ('\x00' <= c and c <= '\x1F')
             {
-                return sax->boolean(get() != 0);
+                // escape control characters
+                std::array<char, 9> cs{{}};
+                (std::snprintf)(cs.data(), cs.size(), "<U+%.4X>", static_cast<unsigned char>(c));
+                result += cs.data();
             }
-
-            case 0x0A: // null
+            else
             {
-                return sax->null();
+                // add character as is
+                result.push_back(c);
             }
+        }
 
-            case 0x10: // int32
-            {
-                std::int32_t value;
-                return get_number<std::int32_t, true>(input_format_t::bson, value) and sax->number_integer(value);
-            }
-
-            case 0x12: // int64
-            {
-                std::int64_t value;
-                return get_number<std::int64_t, true>(input_format_t::bson, value) and sax->number_integer(value);
-            }
-
-            default: // anything else not supported (yet)
-            {
-                char cr[3];
-                (std::snprintf)(cr, sizeof(cr), "%.2hhX", static_cast<unsigned char>(element_type));
-                return sax->parse_error(element_type_parse_position, std::string(cr), parse_error::create(114, element_type_parse_position, "Unsupported BSON record type 0x" + std::string(cr)));
-            }
-        }
+        return result;
     }
 
-    /*!
-    @brief Read a BSON element list (as specified in the BSON-spec)
+    /// return syntax error message
+    constexpr const char* get_error_message() const noexcept
+    {
+        return error_message;
+    }
 
-    The same binary layout is used for objects and arrays, hence it must be
-    indicated with the argument @a is_array which one is expected
-    (true --> array, false --> object).
+    /////////////////////
+    // actual scanner
+    /////////////////////
 
-    @param[in] is_array Determines if the element list being read is to be
-                        treated as an object (@a is_array == false), or as an
-                        array (@a is_array == true).
-    @return whether a valid BSON-object/array was passed to the SAX parser
+    /*!
+    @brief skip the UTF-8 byte order mark
+    @return true iff there is no BOM or the correct BOM has been skipped
     */
-    bool parse_bson_element_list(const bool is_array)
+    bool skip_bom()
     {
-        string_t key;
-        while (int element_type = get())
+        if (get() == 0xEF)
         {
-            if (JSON_UNLIKELY(not unexpect_eof(input_format_t::bson, "element list")))
-            {
-                return false;
-            }
-
-            const std::size_t element_type_parse_position = chars_read;
-            if (JSON_UNLIKELY(not get_bson_cstr(key)))
-            {
-                return false;
-            }
-
-            if (not is_array)
-            {
-                if (not sax->key(key))
-                {
-                    return false;
-                }
-            }
-
-            if (JSON_UNLIKELY(not parse_bson_element_internal(element_type, element_type_parse_position)))
-            {
-                return false;
-            }
-
-            // get_bson_cstr only appends
-            key.clear();
+            // check if we completely parse the BOM
+            return get() == 0xBB and get() == 0xBF;
         }
 
+        // the first character is not the beginning of the BOM; unget it to
+        // process is later
+        unget();
         return true;
     }
 
-    /*!
-    @brief Reads an array from the BSON input and passes it to the SAX-parser.
-    @return whether a valid BSON-array was passed to the SAX parser
-    */
-    bool parse_bson_array()
+    token_type scan()
     {
-        std::int32_t document_size;
-        get_number<std::int32_t, true>(input_format_t::bson, document_size);
-
-        if (JSON_UNLIKELY(not sax->start_array(std::size_t(-1))))
+        // initially, skip the BOM
+        if (position.chars_read_total == 0 and not skip_bom())
         {
-            return false;
+            error_message = "invalid BOM; must be 0xEF 0xBB 0xBF if given";
+            return token_type::parse_error;
         }
 
-        if (JSON_UNLIKELY(not parse_bson_element_list(/*is_array*/true)))
+        // read next character and ignore whitespace
+        do
         {
-            return false;
+            get();
         }
+        while (current == ' ' or current == '\t' or current == '\n' or current == '\r');
 
-        return sax->end_array();
-    }
+        switch (current)
+        {
+            // structural characters
+            case '[':
+                return token_type::begin_array;
+            case ']':
+                return token_type::end_array;
+            case '{':
+                return token_type::begin_object;
+            case '}':
+                return token_type::end_object;
+            case ':':
+                return token_type::name_separator;
+            case ',':
+                return token_type::value_separator;
 
-    //////////
-    // CBOR //
-    //////////
+            // literals
+            case 't':
+                return scan_literal("true", 4, token_type::literal_true);
+            case 'f':
+                return scan_literal("false", 5, token_type::literal_false);
+            case 'n':
+                return scan_literal("null", 4, token_type::literal_null);
 
-    /*!
-    @param[in] get_char  whether a new character should be retrieved from the
-                         input (true, default) or whether the last read
-                         character should be considered instead
+            // string
+            case '\"':
+                return scan_string();
 
-    @return whether a valid CBOR value was passed to the SAX parser
-    */
-    bool parse_cbor_internal(const bool get_char = true)
-    {
-        switch (get_char ? get() : current)
-        {
-            // EOF
+            // number
+            case '-':
+            case '0':
+            case '1':
+            case '2':
+            case '3':
+            case '4':
+            case '5':
+            case '6':
+            case '7':
+            case '8':
+            case '9':
+                return scan_number();
+
+            // end of input (the null byte is needed when parsing from
+            // string literals)
+            case '\0':
             case std::char_traits<char>::eof():
-                return unexpect_eof(input_format_t::cbor, "value");
+                return token_type::end_of_input;
 
-            // Integer 0x00..0x17 (0..23)
-            case 0x00:
-            case 0x01:
-            case 0x02:
-            case 0x03:
-            case 0x04:
-            case 0x05:
-            case 0x06:
-            case 0x07:
-            case 0x08:
-            case 0x09:
-            case 0x0A:
-            case 0x0B:
-            case 0x0C:
-            case 0x0D:
-            case 0x0E:
-            case 0x0F:
-            case 0x10:
-            case 0x11:
-            case 0x12:
-            case 0x13:
-            case 0x14:
-            case 0x15:
-            case 0x16:
-            case 0x17:
-                return sax->number_unsigned(static_cast<number_unsigned_t>(current));
+            // error
+            default:
+                error_message = "invalid literal";
+                return token_type::parse_error;
+        }
+    }
 
-            case 0x18: // Unsigned integer (one-byte uint8_t follows)
-            {
-                uint8_t number;
-                return get_number(input_format_t::cbor, number) and sax->number_unsigned(number);
-            }
+  private:
+    /// input adapter
+    detail::input_adapter_t ia = nullptr;
 
-            case 0x19: // Unsigned integer (two-byte uint16_t follows)
-            {
-                uint16_t number;
-                return get_number(input_format_t::cbor, number) and sax->number_unsigned(number);
-            }
+    /// the current character
+    std::char_traits<char>::int_type current = std::char_traits<char>::eof();
 
-            case 0x1A: // Unsigned integer (four-byte uint32_t follows)
-            {
-                uint32_t number;
-                return get_number(input_format_t::cbor, number) and sax->number_unsigned(number);
-            }
+    /// whether the next get() call should just return current
+    bool next_unget = false;
 
-            case 0x1B: // Unsigned integer (eight-byte uint64_t follows)
-            {
-                uint64_t number;
-                return get_number(input_format_t::cbor, number) and sax->number_unsigned(number);
-            }
+    /// the start position of the current token
+    position_t position {};
 
-            // Negative integer -1-0x00..-1-0x17 (-1..-24)
-            case 0x20:
-            case 0x21:
-            case 0x22:
-            case 0x23:
-            case 0x24:
-            case 0x25:
-            case 0x26:
-            case 0x27:
-            case 0x28:
-            case 0x29:
-            case 0x2A:
-            case 0x2B:
-            case 0x2C:
-            case 0x2D:
-            case 0x2E:
-            case 0x2F:
-            case 0x30:
-            case 0x31:
-            case 0x32:
-            case 0x33:
-            case 0x34:
-            case 0x35:
-            case 0x36:
-            case 0x37:
-                return sax->number_integer(static_cast<int8_t>(0x20 - 1 - current));
+    /// raw input token string (for error messages)
+    std::vector<char> token_string {};
 
-            case 0x38: // Negative integer (one-byte uint8_t follows)
-            {
-                uint8_t number;
-                return get_number(input_format_t::cbor, number) and sax->number_integer(static_cast<number_integer_t>(-1) - number);
-            }
+    /// buffer for variable-length tokens (numbers, strings)
+    string_t token_buffer {};
 
-            case 0x39: // Negative integer -1-n (two-byte uint16_t follows)
-            {
-                uint16_t number;
-                return get_number(input_format_t::cbor, number) and sax->number_integer(static_cast<number_integer_t>(-1) - number);
-            }
+    /// a description of occurred lexer errors
+    const char* error_message = "";
 
-            case 0x3A: // Negative integer -1-n (four-byte uint32_t follows)
-            {
-                uint32_t number;
-                return get_number(input_format_t::cbor, number) and sax->number_integer(static_cast<number_integer_t>(-1) - number);
-            }
+    // number values
+    number_integer_t value_integer = 0;
+    number_unsigned_t value_unsigned = 0;
+    number_float_t value_float = 0;
 
-            case 0x3B: // Negative integer -1-n (eight-byte uint64_t follows)
-            {
-                uint64_t number;
-                return get_number(input_format_t::cbor, number) and sax->number_integer(static_cast<number_integer_t>(-1)
-                        - static_cast<number_integer_t>(number));
-            }
+    /// the decimal point
+    const char decimal_point_char = '.';
+};
+}  // namespace detail
+}  // namespace nlohmann
 
-            // UTF-8 string (0x00..0x17 bytes follow)
-            case 0x60:
-            case 0x61:
-            case 0x62:
-            case 0x63:
-            case 0x64:
-            case 0x65:
-            case 0x66:
-            case 0x67:
-            case 0x68:
-            case 0x69:
-            case 0x6A:
-            case 0x6B:
-            case 0x6C:
-            case 0x6D:
-            case 0x6E:
-            case 0x6F:
-            case 0x70:
-            case 0x71:
-            case 0x72:
-            case 0x73:
-            case 0x74:
-            case 0x75:
-            case 0x76:
-            case 0x77:
-            case 0x78: // UTF-8 string (one-byte uint8_t for n follows)
-            case 0x79: // UTF-8 string (two-byte uint16_t for n follow)
-            case 0x7A: // UTF-8 string (four-byte uint32_t for n follow)
-            case 0x7B: // UTF-8 string (eight-byte uint64_t for n follow)
-            case 0x7F: // UTF-8 string (indefinite length)
-            {
-                string_t s;
-                return get_cbor_string(s) and sax->string(s);
-            }
+// #include <nlohmann/detail/input/parser.hpp>
 
-            // array (0x00..0x17 data items follow)
-            case 0x80:
-            case 0x81:
-            case 0x82:
-            case 0x83:
-            case 0x84:
-            case 0x85:
-            case 0x86:
-            case 0x87:
-            case 0x88:
-            case 0x89:
-            case 0x8A:
-            case 0x8B:
-            case 0x8C:
-            case 0x8D:
-            case 0x8E:
-            case 0x8F:
-            case 0x90:
-            case 0x91:
-            case 0x92:
-            case 0x93:
-            case 0x94:
-            case 0x95:
-            case 0x96:
-            case 0x97:
-                return get_cbor_array(static_cast<std::size_t>(current & 0x1F));
 
-            case 0x98: // array (one-byte uint8_t for n follows)
-            {
-                uint8_t len;
-                return get_number(input_format_t::cbor, len) and get_cbor_array(static_cast<std::size_t>(len));
-            }
+#include <cassert> // assert
+#include <cmath> // isfinite
+#include <cstdint> // uint8_t
+#include <functional> // function
+#include <string> // string
+#include <utility> // move
+#include <vector> // vector
 
-            case 0x99: // array (two-byte uint16_t for n follow)
-            {
-                uint16_t len;
-                return get_number(input_format_t::cbor, len) and get_cbor_array(static_cast<std::size_t>(len));
-            }
+// #include <nlohmann/detail/exceptions.hpp>
 
-            case 0x9A: // array (four-byte uint32_t for n follow)
-            {
-                uint32_t len;
-                return get_number(input_format_t::cbor, len) and get_cbor_array(static_cast<std::size_t>(len));
-            }
+// #include <nlohmann/detail/input/input_adapters.hpp>
 
-            case 0x9B: // array (eight-byte uint64_t for n follow)
-            {
-                uint64_t len;
-                return get_number(input_format_t::cbor, len) and get_cbor_array(static_cast<std::size_t>(len));
-            }
+// #include <nlohmann/detail/input/json_sax.hpp>
 
-            case 0x9F: // array (indefinite length)
-                return get_cbor_array(std::size_t(-1));
+// #include <nlohmann/detail/input/lexer.hpp>
 
-            // map (0x00..0x17 pairs of data items follow)
-            case 0xA0:
-            case 0xA1:
-            case 0xA2:
-            case 0xA3:
-            case 0xA4:
-            case 0xA5:
-            case 0xA6:
-            case 0xA7:
-            case 0xA8:
-            case 0xA9:
-            case 0xAA:
-            case 0xAB:
-            case 0xAC:
-            case 0xAD:
-            case 0xAE:
-            case 0xAF:
-            case 0xB0:
-            case 0xB1:
-            case 0xB2:
-            case 0xB3:
-            case 0xB4:
-            case 0xB5:
-            case 0xB6:
-            case 0xB7:
-                return get_cbor_object(static_cast<std::size_t>(current & 0x1F));
+// #include <nlohmann/detail/macro_scope.hpp>
 
-            case 0xB8: // map (one-byte uint8_t for n follows)
+// #include <nlohmann/detail/meta/is_sax.hpp>
+
+// #include <nlohmann/detail/value_t.hpp>
+
+
+namespace nlohmann
+{
+namespace detail
+{
+////////////
+// parser //
+////////////
+
+/*!
+@brief syntax analysis
+
+This class implements a recursive decent parser.
+*/
+template<typename BasicJsonType>
+class parser
+{
+    using number_integer_t = typename BasicJsonType::number_integer_t;
+    using number_unsigned_t = typename BasicJsonType::number_unsigned_t;
+    using number_float_t = typename BasicJsonType::number_float_t;
+    using string_t = typename BasicJsonType::string_t;
+    using lexer_t = lexer<BasicJsonType>;
+    using token_type = typename lexer_t::token_type;
+
+  public:
+    enum class parse_event_t : uint8_t
+    {
+        /// the parser read `{` and started to process a JSON object
+        object_start,
+        /// the parser read `}` and finished processing a JSON object
+        object_end,
+        /// the parser read `[` and started to process a JSON array
+        array_start,
+        /// the parser read `]` and finished processing a JSON array
+        array_end,
+        /// the parser read a key of a value in an object
+        key,
+        /// the parser finished reading a JSON value
+        value
+    };
+
+    using parser_callback_t =
+        std::function<bool(int depth, parse_event_t event, BasicJsonType& parsed)>;
+
+    /// a parser reading from an input adapter
+    explicit parser(detail::input_adapter_t&& adapter,
+                    const parser_callback_t cb = nullptr,
+                    const bool allow_exceptions_ = true)
+        : callback(cb), m_lexer(std::move(adapter)), allow_exceptions(allow_exceptions_)
+    {
+        // read first token
+        get_token();
+    }
+
+    /*!
+    @brief public parser interface
+
+    @param[in] strict      whether to expect the last token to be EOF
+    @param[in,out] result  parsed JSON value
+
+    @throw parse_error.101 in case of an unexpected token
+    @throw parse_error.102 if to_unicode fails or surrogate error
+    @throw parse_error.103 if to_unicode fails
+    */
+    void parse(const bool strict, BasicJsonType& result)
+    {
+        if (callback)
+        {
+            json_sax_dom_callback_parser<BasicJsonType> sdp(result, callback, allow_exceptions);
+            sax_parse_internal(&sdp);
+            result.assert_invariant();
+
+            // in strict mode, input must be completely read
+            if (strict and (get_token() != token_type::end_of_input))
             {
-                uint8_t len;
-                return get_number(input_format_t::cbor, len) and get_cbor_object(static_cast<std::size_t>(len));
+                sdp.parse_error(m_lexer.get_position(),
+                                m_lexer.get_token_string(),
+                                parse_error::create(101, m_lexer.get_position(),
+                                                    exception_message(token_type::end_of_input, "value")));
             }
 
-            case 0xB9: // map (two-byte uint16_t for n follow)
+            // in case of an error, return discarded value
+            if (sdp.is_errored())
             {
-                uint16_t len;
-                return get_number(input_format_t::cbor, len) and get_cbor_object(static_cast<std::size_t>(len));
+                result = value_t::discarded;
+                return;
             }
 
-            case 0xBA: // map (four-byte uint32_t for n follow)
+            // set top-level value to null if it was discarded by the callback
+            // function
+            if (result.is_discarded())
             {
-                uint32_t len;
-                return get_number(input_format_t::cbor, len) and get_cbor_object(static_cast<std::size_t>(len));
+                result = nullptr;
             }
+        }
+        else
+        {
+            json_sax_dom_parser<BasicJsonType> sdp(result, allow_exceptions);
+            sax_parse_internal(&sdp);
+            result.assert_invariant();
 
-            case 0xBB: // map (eight-byte uint64_t for n follow)
+            // in strict mode, input must be completely read
+            if (strict and (get_token() != token_type::end_of_input))
             {
-                uint64_t len;
-                return get_number(input_format_t::cbor, len) and get_cbor_object(static_cast<std::size_t>(len));
+                sdp.parse_error(m_lexer.get_position(),
+                                m_lexer.get_token_string(),
+                                parse_error::create(101, m_lexer.get_position(),
+                                                    exception_message(token_type::end_of_input, "value")));
             }
 
-            case 0xBF: // map (indefinite length)
-                return get_cbor_object(std::size_t(-1));
-
-            case 0xF4: // false
-                return sax->boolean(false);
-
-            case 0xF5: // true
-                return sax->boolean(true);
+            // in case of an error, return discarded value
+            if (sdp.is_errored())
+            {
+                result = value_t::discarded;
+                return;
+            }
+        }
+    }
 
-            case 0xF6: // null
-                return sax->null();
+    /*!
+    @brief public accept interface
 
-            case 0xF9: // Half-Precision Float (two-byte IEEE 754)
-            {
-                const int byte1_raw = get();
-                if (JSON_UNLIKELY(not unexpect_eof(input_format_t::cbor, "number")))
-                {
-                    return false;
-                }
-                const int byte2_raw = get();
-                if (JSON_UNLIKELY(not unexpect_eof(input_format_t::cbor, "number")))
-                {
-                    return false;
-                }
+    @param[in] strict  whether to expect the last token to be EOF
+    @return whether the input is a proper JSON text
+    */
+    bool accept(const bool strict = true)
+    {
+        json_sax_acceptor<BasicJsonType> sax_acceptor;
+        return sax_parse(&sax_acceptor, strict);
+    }
 
-                const auto byte1 = static_cast<unsigned char>(byte1_raw);
-                const auto byte2 = static_cast<unsigned char>(byte2_raw);
+    template <typename SAX>
+    bool sax_parse(SAX* sax, const bool strict = true)
+    {
+        (void)detail::is_sax_static_asserts<SAX, BasicJsonType> {};
+        const bool result = sax_parse_internal(sax);
 
-                // code from RFC 7049, Appendix D, Figure 3:
-                // As half-precision floating-point numbers were only added
-                // to IEEE 754 in 2008, today's programming platforms often
-                // still only have limited support for them. It is very
-                // easy to include at least decoding support for them even
-                // without such support. An example of a small decoder for
-                // half-precision floating-point numbers in the C language
-                // is shown in Fig. 3.
-                const int half = (byte1 << 8) + byte2;
-                const double val = [&half]
-                {
-                    const int exp = (half >> 10) & 0x1F;
-                    const int mant = half & 0x3FF;
-                    assert(0 <= exp and exp <= 32);
-                    assert(0 <= mant and mant <= 1024);
-                    switch (exp)
-                    {
-                        case 0:
-                            return std::ldexp(mant, -24);
-                        case 31:
-                            return (mant == 0)
-                            ? std::numeric_limits<double>::infinity()
-                            : std::numeric_limits<double>::quiet_NaN();
-                        default:
-                            return std::ldexp(mant + 1024, exp - 25);
-                    }
-                }();
-                return sax->number_float((half & 0x8000) != 0
-                                         ? static_cast<number_float_t>(-val)
-                                         : static_cast<number_float_t>(val), "");
-            }
+        // strict mode: next byte must be EOF
+        if (result and strict and (get_token() != token_type::end_of_input))
+        {
+            return sax->parse_error(m_lexer.get_position(),
+                                    m_lexer.get_token_string(),
+                                    parse_error::create(101, m_lexer.get_position(),
+                                            exception_message(token_type::end_of_input, "value")));
+        }
 
-            case 0xFA: // Single-Precision Float (four-byte IEEE 754)
-            {
-                float number;
-                return get_number(input_format_t::cbor, number) and sax->number_float(static_cast<number_float_t>(number), "");
-            }
+        return result;
+    }
 
-            case 0xFB: // Double-Precision Float (eight-byte IEEE 754)
-            {
-                double number;
-                return get_number(input_format_t::cbor, number) and sax->number_float(static_cast<number_float_t>(number), "");
-            }
+  private:
+    template <typename SAX>
+    bool sax_parse_internal(SAX* sax)
+    {
+        // stack to remember the hierarchy of structured values we are parsing
+        // true = array; false = object
+        std::vector<bool> states;
+        // value to avoid a goto (see comment where set to true)
+        bool skip_to_state_evaluation = false;
 
-            default: // anything else (0xFF is handled inside the other types)
+        while (true)
+        {
+            if (not skip_to_state_evaluation)
             {
-                auto last_token = get_token_string();
-                return sax->parse_error(chars_read, last_token, parse_error::create(112, chars_read, exception_message(input_format_t::cbor, "invalid byte: 0x" + last_token, "value")));
-            }
-        }
-    }
+                // invariant: get_token() was called before each iteration
+                switch (last_token)
+                {
+                    case token_type::begin_object:
+                    {
+                        if (JSON_UNLIKELY(not sax->start_object(std::size_t(-1))))
+                        {
+                            return false;
+                        }
 
-    /*!
-    @brief reads a CBOR string
+                        // closing } -> we are done
+                        if (get_token() == token_type::end_object)
+                        {
+                            if (JSON_UNLIKELY(not sax->end_object()))
+                            {
+                                return false;
+                            }
+                            break;
+                        }
 
-    This function first reads starting bytes to determine the expected
-    string length and then copies this number of bytes into a string.
-    Additionally, CBOR's strings with indefinite lengths are supported.
+                        // parse key
+                        if (JSON_UNLIKELY(last_token != token_type::value_string))
+                        {
+                            return sax->parse_error(m_lexer.get_position(),
+                                                    m_lexer.get_token_string(),
+                                                    parse_error::create(101, m_lexer.get_position(),
+                                                            exception_message(token_type::value_string, "object key")));
+                        }
+                        if (JSON_UNLIKELY(not sax->key(m_lexer.get_string())))
+                        {
+                            return false;
+                        }
 
-    @param[out] result  created string
+                        // parse separator (:)
+                        if (JSON_UNLIKELY(get_token() != token_type::name_separator))
+                        {
+                            return sax->parse_error(m_lexer.get_position(),
+                                                    m_lexer.get_token_string(),
+                                                    parse_error::create(101, m_lexer.get_position(),
+                                                            exception_message(token_type::name_separator, "object separator")));
+                        }
 
-    @return whether string creation completed
-    */
-    bool get_cbor_string(string_t& result)
-    {
-        if (JSON_UNLIKELY(not unexpect_eof(input_format_t::cbor, "string")))
-        {
-            return false;
-        }
+                        // remember we are now inside an object
+                        states.push_back(false);
 
-        switch (current)
-        {
-            // UTF-8 string (0x00..0x17 bytes follow)
-            case 0x60:
-            case 0x61:
-            case 0x62:
-            case 0x63:
-            case 0x64:
-            case 0x65:
-            case 0x66:
-            case 0x67:
-            case 0x68:
-            case 0x69:
-            case 0x6A:
-            case 0x6B:
-            case 0x6C:
-            case 0x6D:
-            case 0x6E:
-            case 0x6F:
-            case 0x70:
-            case 0x71:
-            case 0x72:
-            case 0x73:
-            case 0x74:
-            case 0x75:
-            case 0x76:
-            case 0x77:
-            {
-                return get_string(input_format_t::cbor, current & 0x1F, result);
-            }
+                        // parse values
+                        get_token();
+                        continue;
+                    }
 
-            case 0x78: // UTF-8 string (one-byte uint8_t for n follows)
-            {
-                uint8_t len;
-                return get_number(input_format_t::cbor, len) and get_string(input_format_t::cbor, len, result);
-            }
+                    case token_type::begin_array:
+                    {
+                        if (JSON_UNLIKELY(not sax->start_array(std::size_t(-1))))
+                        {
+                            return false;
+                        }
 
-            case 0x79: // UTF-8 string (two-byte uint16_t for n follow)
-            {
-                uint16_t len;
-                return get_number(input_format_t::cbor, len) and get_string(input_format_t::cbor, len, result);
-            }
+                        // closing ] -> we are done
+                        if (get_token() == token_type::end_array)
+                        {
+                            if (JSON_UNLIKELY(not sax->end_array()))
+                            {
+                                return false;
+                            }
+                            break;
+                        }
 
-            case 0x7A: // UTF-8 string (four-byte uint32_t for n follow)
-            {
-                uint32_t len;
-                return get_number(input_format_t::cbor, len) and get_string(input_format_t::cbor, len, result);
-            }
+                        // remember we are now inside an array
+                        states.push_back(true);
 
-            case 0x7B: // UTF-8 string (eight-byte uint64_t for n follow)
-            {
-                uint64_t len;
-                return get_number(input_format_t::cbor, len) and get_string(input_format_t::cbor, len, result);
-            }
+                        // parse values (no need to call get_token)
+                        continue;
+                    }
 
-            case 0x7F: // UTF-8 string (indefinite length)
-            {
-                while (get() != 0xFF)
-                {
-                    string_t chunk;
-                    if (not get_cbor_string(chunk))
+                    case token_type::value_float:
                     {
-                        return false;
-                    }
-                    result.append(chunk);
-                }
-                return true;
-            }
+                        const auto res = m_lexer.get_number_float();
 
-            default:
-            {
-                auto last_token = get_token_string();
-                return sax->parse_error(chars_read, last_token, parse_error::create(113, chars_read, exception_message(input_format_t::cbor, "expected length specification (0x60-0x7B) or indefinite string type (0x7F); last byte: 0x" + last_token, "string")));
-            }
-        }
-    }
+                        if (JSON_UNLIKELY(not std::isfinite(res)))
+                        {
+                            return sax->parse_error(m_lexer.get_position(),
+                                                    m_lexer.get_token_string(),
+                                                    out_of_range::create(406, "number overflow parsing '" + m_lexer.get_token_string() + "'"));
+                        }
 
-    /*!
-    @param[in] len  the length of the array or std::size_t(-1) for an
-                    array of indefinite size
-    @return whether array creation completed
-    */
-    bool get_cbor_array(const std::size_t len)
-    {
-        if (JSON_UNLIKELY(not sax->start_array(len)))
-        {
-            return false;
-        }
+                        if (JSON_UNLIKELY(not sax->number_float(res, m_lexer.get_string())))
+                        {
+                            return false;
+                        }
 
-        if (len != std::size_t(-1))
-        {
-            for (std::size_t i = 0; i < len; ++i)
+                        break;
+                    }
+
+                    case token_type::literal_false:
+                    {
+                        if (JSON_UNLIKELY(not sax->boolean(false)))
+                        {
+                            return false;
+                        }
+                        break;
+                    }
+
+                    case token_type::literal_null:
+                    {
+                        if (JSON_UNLIKELY(not sax->null()))
+                        {
+                            return false;
+                        }
+                        break;
+                    }
+
+                    case token_type::literal_true:
+                    {
+                        if (JSON_UNLIKELY(not sax->boolean(true)))
+                        {
+                            return false;
+                        }
+                        break;
+                    }
+
+                    case token_type::value_integer:
+                    {
+                        if (JSON_UNLIKELY(not sax->number_integer(m_lexer.get_number_integer())))
+                        {
+                            return false;
+                        }
+                        break;
+                    }
+
+                    case token_type::value_string:
+                    {
+                        if (JSON_UNLIKELY(not sax->string(m_lexer.get_string())))
+                        {
+                            return false;
+                        }
+                        break;
+                    }
+
+                    case token_type::value_unsigned:
+                    {
+                        if (JSON_UNLIKELY(not sax->number_unsigned(m_lexer.get_number_unsigned())))
+                        {
+                            return false;
+                        }
+                        break;
+                    }
+
+                    case token_type::parse_error:
+                    {
+                        // using "uninitialized" to avoid "expected" message
+                        return sax->parse_error(m_lexer.get_position(),
+                                                m_lexer.get_token_string(),
+                                                parse_error::create(101, m_lexer.get_position(),
+                                                        exception_message(token_type::uninitialized, "value")));
+                    }
+
+                    default: // the last token was unexpected
+                    {
+                        return sax->parse_error(m_lexer.get_position(),
+                                                m_lexer.get_token_string(),
+                                                parse_error::create(101, m_lexer.get_position(),
+                                                        exception_message(token_type::literal_or_value, "value")));
+                    }
+                }
+            }
+            else
             {
-                if (JSON_UNLIKELY(not parse_cbor_internal()))
+                skip_to_state_evaluation = false;
+            }
+
+            // we reached this line after we successfully parsed a value
+            if (states.empty())
+            {
+                // empty stack: we reached the end of the hierarchy: done
+                return true;
+            }
+
+            if (states.back())  // array
+            {
+                // comma -> next value
+                if (get_token() == token_type::value_separator)
                 {
-                    return false;
+                    // parse a new value
+                    get_token();
+                    continue;
+                }
+
+                // closing ]
+                if (JSON_LIKELY(last_token == token_type::end_array))
+                {
+                    if (JSON_UNLIKELY(not sax->end_array()))
+                    {
+                        return false;
+                    }
+
+                    // We are done with this array. Before we can parse a
+                    // new value, we need to evaluate the new state first.
+                    // By setting skip_to_state_evaluation to false, we
+                    // are effectively jumping to the beginning of this if.
+                    assert(not states.empty());
+                    states.pop_back();
+                    skip_to_state_evaluation = true;
+                    continue;
                 }
+
+                return sax->parse_error(m_lexer.get_position(),
+                                        m_lexer.get_token_string(),
+                                        parse_error::create(101, m_lexer.get_position(),
+                                                exception_message(token_type::end_array, "array")));
             }
-        }
-        else
-        {
-            while (get() != 0xFF)
+            else  // object
             {
-                if (JSON_UNLIKELY(not parse_cbor_internal(false)))
+                // comma -> next value
+                if (get_token() == token_type::value_separator)
                 {
-                    return false;
+                    // parse key
+                    if (JSON_UNLIKELY(get_token() != token_type::value_string))
+                    {
+                        return sax->parse_error(m_lexer.get_position(),
+                                                m_lexer.get_token_string(),
+                                                parse_error::create(101, m_lexer.get_position(),
+                                                        exception_message(token_type::value_string, "object key")));
+                    }
+
+                    if (JSON_UNLIKELY(not sax->key(m_lexer.get_string())))
+                    {
+                        return false;
+                    }
+
+                    // parse separator (:)
+                    if (JSON_UNLIKELY(get_token() != token_type::name_separator))
+                    {
+                        return sax->parse_error(m_lexer.get_position(),
+                                                m_lexer.get_token_string(),
+                                                parse_error::create(101, m_lexer.get_position(),
+                                                        exception_message(token_type::name_separator, "object separator")));
+                    }
+
+                    // parse values
+                    get_token();
+                    continue;
                 }
+
+                // closing }
+                if (JSON_LIKELY(last_token == token_type::end_object))
+                {
+                    if (JSON_UNLIKELY(not sax->end_object()))
+                    {
+                        return false;
+                    }
+
+                    // We are done with this object. Before we can parse a
+                    // new value, we need to evaluate the new state first.
+                    // By setting skip_to_state_evaluation to false, we
+                    // are effectively jumping to the beginning of this if.
+                    assert(not states.empty());
+                    states.pop_back();
+                    skip_to_state_evaluation = true;
+                    continue;
+                }
+
+                return sax->parse_error(m_lexer.get_position(),
+                                        m_lexer.get_token_string(),
+                                        parse_error::create(101, m_lexer.get_position(),
+                                                exception_message(token_type::end_object, "object")));
             }
         }
+    }
 
-        return sax->end_array();
+    /// get next token from lexer
+    token_type get_token()
+    {
+        return last_token = m_lexer.scan();
     }
 
-    /*!
-    @param[in] len  the length of the object or std::size_t(-1) for an
-                    object of indefinite size
-    @return whether object creation completed
-    */
-    bool get_cbor_object(const std::size_t len)
+    std::string exception_message(const token_type expected, const std::string& context)
     {
-        if (not JSON_UNLIKELY(sax->start_object(len)))
+        std::string error_msg = "syntax error ";
+
+        if (not context.empty())
         {
-            return false;
+            error_msg += "while parsing " + context + " ";
         }
 
-        string_t key;
-        if (len != std::size_t(-1))
-        {
-            for (std::size_t i = 0; i < len; ++i)
-            {
-                get();
-                if (JSON_UNLIKELY(not get_cbor_string(key) or not sax->key(key)))
-                {
-                    return false;
-                }
+        error_msg += "- ";
 
-                if (JSON_UNLIKELY(not parse_cbor_internal()))
-                {
-                    return false;
-                }
-                key.clear();
-            }
+        if (last_token == token_type::parse_error)
+        {
+            error_msg += std::string(m_lexer.get_error_message()) + "; last read: '" +
+                         m_lexer.get_token_string() + "'";
         }
         else
         {
-            while (get() != 0xFF)
-            {
-                if (JSON_UNLIKELY(not get_cbor_string(key) or not sax->key(key)))
-                {
-                    return false;
-                }
+            error_msg += "unexpected " + std::string(lexer_t::token_type_name(last_token));
+        }
 
-                if (JSON_UNLIKELY(not parse_cbor_internal()))
-                {
-                    return false;
-                }
-                key.clear();
-            }
+        if (expected != token_type::uninitialized)
+        {
+            error_msg += "; expected " + std::string(lexer_t::token_type_name(expected));
         }
 
-        return sax->end_object();
+        return error_msg;
     }
 
-    /////////////
-    // MsgPack //
-    /////////////
+  private:
+    /// callback function
+    const parser_callback_t callback = nullptr;
+    /// the type of the last read token
+    token_type last_token = token_type::uninitialized;
+    /// the lexer
+    lexer_t m_lexer;
+    /// whether to throw exceptions in case of errors
+    const bool allow_exceptions = true;
+};
+}  // namespace detail
+}  // namespace nlohmann
 
-    /*!
-    @return whether a valid MessagePack value was passed to the SAX parser
-    */
-    bool parse_msgpack_internal()
+// #include <nlohmann/detail/iterators/internal_iterator.hpp>
+
+
+// #include <nlohmann/detail/iterators/primitive_iterator.hpp>
+
+
+#include <cstddef> // ptrdiff_t
+#include <limits>  // numeric_limits
+
+namespace nlohmann
+{
+namespace detail
+{
+/*
+@brief an iterator for primitive JSON types
+
+This class models an iterator for primitive JSON types (boolean, number,
+string). It's only purpose is to allow the iterator/const_iterator classes
+to "iterate" over primitive values. Internally, the iterator is modeled by
+a `difference_type` variable. Value begin_value (`0`) models the begin,
+end_value (`1`) models past the end.
+*/
+class primitive_iterator_t
+{
+  private:
+    using difference_type = std::ptrdiff_t;
+    static constexpr difference_type begin_value = 0;
+    static constexpr difference_type end_value = begin_value + 1;
+
+    /// iterator as signed integer type
+    difference_type m_it = (std::numeric_limits<std::ptrdiff_t>::min)();
+
+  public:
+    constexpr difference_type get_value() const noexcept
     {
-        switch (get())
-        {
-            // EOF
-            case std::char_traits<char>::eof():
-                return unexpect_eof(input_format_t::msgpack, "value");
+        return m_it;
+    }
 
-            // positive fixint
-            case 0x00:
-            case 0x01:
-            case 0x02:
-            case 0x03:
-            case 0x04:
-            case 0x05:
-            case 0x06:
-            case 0x07:
-            case 0x08:
-            case 0x09:
-            case 0x0A:
-            case 0x0B:
-            case 0x0C:
-            case 0x0D:
-            case 0x0E:
-            case 0x0F:
-            case 0x10:
-            case 0x11:
-            case 0x12:
-            case 0x13:
-            case 0x14:
-            case 0x15:
-            case 0x16:
-            case 0x17:
-            case 0x18:
-            case 0x19:
-            case 0x1A:
-            case 0x1B:
-            case 0x1C:
-            case 0x1D:
-            case 0x1E:
-            case 0x1F:
-            case 0x20:
-            case 0x21:
-            case 0x22:
-            case 0x23:
-            case 0x24:
-            case 0x25:
-            case 0x26:
-            case 0x27:
-            case 0x28:
-            case 0x29:
-            case 0x2A:
-            case 0x2B:
-            case 0x2C:
-            case 0x2D:
-            case 0x2E:
-            case 0x2F:
-            case 0x30:
-            case 0x31:
-            case 0x32:
-            case 0x33:
-            case 0x34:
-            case 0x35:
-            case 0x36:
-            case 0x37:
-            case 0x38:
-            case 0x39:
-            case 0x3A:
-            case 0x3B:
-            case 0x3C:
-            case 0x3D:
-            case 0x3E:
-            case 0x3F:
-            case 0x40:
-            case 0x41:
-            case 0x42:
-            case 0x43:
-            case 0x44:
-            case 0x45:
-            case 0x46:
-            case 0x47:
-            case 0x48:
-            case 0x49:
-            case 0x4A:
-            case 0x4B:
-            case 0x4C:
-            case 0x4D:
-            case 0x4E:
-            case 0x4F:
-            case 0x50:
-            case 0x51:
-            case 0x52:
-            case 0x53:
-            case 0x54:
-            case 0x55:
-            case 0x56:
-            case 0x57:
-            case 0x58:
-            case 0x59:
-            case 0x5A:
-            case 0x5B:
-            case 0x5C:
-            case 0x5D:
-            case 0x5E:
-            case 0x5F:
-            case 0x60:
-            case 0x61:
-            case 0x62:
-            case 0x63:
-            case 0x64:
-            case 0x65:
-            case 0x66:
-            case 0x67:
-            case 0x68:
-            case 0x69:
-            case 0x6A:
-            case 0x6B:
-            case 0x6C:
-            case 0x6D:
-            case 0x6E:
-            case 0x6F:
-            case 0x70:
-            case 0x71:
-            case 0x72:
-            case 0x73:
-            case 0x74:
-            case 0x75:
-            case 0x76:
-            case 0x77:
-            case 0x78:
-            case 0x79:
-            case 0x7A:
-            case 0x7B:
-            case 0x7C:
-            case 0x7D:
-            case 0x7E:
-            case 0x7F:
-                return sax->number_unsigned(static_cast<number_unsigned_t>(current));
+    /// set iterator to a defined beginning
+    void set_begin() noexcept
+    {
+        m_it = begin_value;
+    }
 
-            // fixmap
-            case 0x80:
-            case 0x81:
-            case 0x82:
-            case 0x83:
-            case 0x84:
-            case 0x85:
-            case 0x86:
-            case 0x87:
-            case 0x88:
-            case 0x89:
-            case 0x8A:
-            case 0x8B:
-            case 0x8C:
-            case 0x8D:
-            case 0x8E:
-            case 0x8F:
-                return get_msgpack_object(static_cast<std::size_t>(current & 0x0F));
+    /// set iterator to a defined past the end
+    void set_end() noexcept
+    {
+        m_it = end_value;
+    }
 
-            // fixarray
-            case 0x90:
-            case 0x91:
-            case 0x92:
-            case 0x93:
-            case 0x94:
-            case 0x95:
-            case 0x96:
-            case 0x97:
-            case 0x98:
-            case 0x99:
-            case 0x9A:
-            case 0x9B:
-            case 0x9C:
-            case 0x9D:
-            case 0x9E:
-            case 0x9F:
-                return get_msgpack_array(static_cast<std::size_t>(current & 0x0F));
+    /// return whether the iterator can be dereferenced
+    constexpr bool is_begin() const noexcept
+    {
+        return m_it == begin_value;
+    }
 
-            // fixstr
-            case 0xA0:
-            case 0xA1:
-            case 0xA2:
-            case 0xA3:
-            case 0xA4:
-            case 0xA5:
-            case 0xA6:
-            case 0xA7:
-            case 0xA8:
-            case 0xA9:
-            case 0xAA:
-            case 0xAB:
-            case 0xAC:
-            case 0xAD:
-            case 0xAE:
-            case 0xAF:
-            case 0xB0:
-            case 0xB1:
-            case 0xB2:
-            case 0xB3:
-            case 0xB4:
-            case 0xB5:
-            case 0xB6:
-            case 0xB7:
-            case 0xB8:
-            case 0xB9:
-            case 0xBA:
-            case 0xBB:
-            case 0xBC:
-            case 0xBD:
-            case 0xBE:
-            case 0xBF:
-            {
-                string_t s;
-                return get_msgpack_string(s) and sax->string(s);
-            }
+    /// return whether the iterator is at end
+    constexpr bool is_end() const noexcept
+    {
+        return m_it == end_value;
+    }
 
-            case 0xC0: // nil
-                return sax->null();
+    friend constexpr bool operator==(primitive_iterator_t lhs, primitive_iterator_t rhs) noexcept
+    {
+        return lhs.m_it == rhs.m_it;
+    }
 
-            case 0xC2: // false
-                return sax->boolean(false);
+    friend constexpr bool operator<(primitive_iterator_t lhs, primitive_iterator_t rhs) noexcept
+    {
+        return lhs.m_it < rhs.m_it;
+    }
 
-            case 0xC3: // true
-                return sax->boolean(true);
+    primitive_iterator_t operator+(difference_type n) noexcept
+    {
+        auto result = *this;
+        result += n;
+        return result;
+    }
 
-            case 0xCA: // float 32
+    friend constexpr difference_type operator-(primitive_iterator_t lhs, primitive_iterator_t rhs) noexcept
+    {
+        return lhs.m_it - rhs.m_it;
+    }
+
+    primitive_iterator_t& operator++() noexcept
+    {
+        ++m_it;
+        return *this;
+    }
+
+    primitive_iterator_t const operator++(int) noexcept
+    {
+        auto result = *this;
+        ++m_it;
+        return result;
+    }
+
+    primitive_iterator_t& operator--() noexcept
+    {
+        --m_it;
+        return *this;
+    }
+
+    primitive_iterator_t const operator--(int) noexcept
+    {
+        auto result = *this;
+        --m_it;
+        return result;
+    }
+
+    primitive_iterator_t& operator+=(difference_type n) noexcept
+    {
+        m_it += n;
+        return *this;
+    }
+
+    primitive_iterator_t& operator-=(difference_type n) noexcept
+    {
+        m_it -= n;
+        return *this;
+    }
+};
+}  // namespace detail
+}  // namespace nlohmann
+
+
+namespace nlohmann
+{
+namespace detail
+{
+/*!
+@brief an iterator value
+
+@note This structure could easily be a union, but MSVC currently does not allow
+unions members with complex constructors, see https://github.com/nlohmann/json/pull/105.
+*/
+template<typename BasicJsonType> struct internal_iterator
+{
+    /// iterator for JSON objects
+    typename BasicJsonType::object_t::iterator object_iterator {};
+    /// iterator for JSON arrays
+    typename BasicJsonType::array_t::iterator array_iterator {};
+    /// generic iterator for all other types
+    primitive_iterator_t primitive_iterator {};
+};
+}  // namespace detail
+}  // namespace nlohmann
+
+// #include <nlohmann/detail/iterators/iter_impl.hpp>
+
+
+#include <ciso646> // not
+#include <iterator> // iterator, random_access_iterator_tag, bidirectional_iterator_tag, advance, next
+#include <type_traits> // conditional, is_const, remove_const
+
+// #include <nlohmann/detail/exceptions.hpp>
+
+// #include <nlohmann/detail/iterators/internal_iterator.hpp>
+
+// #include <nlohmann/detail/iterators/primitive_iterator.hpp>
+
+// #include <nlohmann/detail/macro_scope.hpp>
+
+// #include <nlohmann/detail/meta/cpp_future.hpp>
+
+// #include <nlohmann/detail/meta/type_traits.hpp>
+
+// #include <nlohmann/detail/value_t.hpp>
+
+
+namespace nlohmann
+{
+namespace detail
+{
+// forward declare, to be able to friend it later on
+template<typename IteratorType> class iteration_proxy;
+template<typename IteratorType> class iteration_proxy_value;
+
+/*!
+@brief a template for a bidirectional iterator for the @ref basic_json class
+This class implements a both iterators (iterator and const_iterator) for the
+@ref basic_json class.
+@note An iterator is called *initialized* when a pointer to a JSON value has
+      been set (e.g., by a constructor or a copy assignment). If the iterator is
+      default-constructed, it is *uninitialized* and most methods are undefined.
+      **The library uses assertions to detect calls on uninitialized iterators.**
+@requirement The class satisfies the following concept requirements:
+-
+[BidirectionalIterator](https://en.cppreference.com/w/cpp/named_req/BidirectionalIterator):
+  The iterator that can be moved can be moved in both directions (i.e.
+  incremented and decremented).
+@since version 1.0.0, simplified in version 2.0.9, change to bidirectional
+       iterators in version 3.0.0 (see https://github.com/nlohmann/json/issues/593)
+*/
+template<typename BasicJsonType>
+class iter_impl
+{
+    /// allow basic_json to access private members
+    friend iter_impl<typename std::conditional<std::is_const<BasicJsonType>::value, typename std::remove_const<BasicJsonType>::type, const BasicJsonType>::type>;
+    friend BasicJsonType;
+    friend iteration_proxy<iter_impl>;
+    friend iteration_proxy_value<iter_impl>;
+
+    using object_t = typename BasicJsonType::object_t;
+    using array_t = typename BasicJsonType::array_t;
+    // make sure BasicJsonType is basic_json or const basic_json
+    static_assert(is_basic_json<typename std::remove_const<BasicJsonType>::type>::value,
+                  "iter_impl only accepts (const) basic_json");
+
+  public:
+
+    /// The std::iterator class template (used as a base class to provide typedefs) is deprecated in C++17.
+    /// The C++ Standard has never required user-defined iterators to derive from std::iterator.
+    /// A user-defined iterator should provide publicly accessible typedefs named
+    /// iterator_category, value_type, difference_type, pointer, and reference.
+    /// Note that value_type is required to be non-const, even for constant iterators.
+    using iterator_category = std::bidirectional_iterator_tag;
+
+    /// the type of the values when the iterator is dereferenced
+    using value_type = typename BasicJsonType::value_type;
+    /// a type to represent differences between iterators
+    using difference_type = typename BasicJsonType::difference_type;
+    /// defines a pointer to the type iterated over (value_type)
+    using pointer = typename std::conditional<std::is_const<BasicJsonType>::value,
+          typename BasicJsonType::const_pointer,
+          typename BasicJsonType::pointer>::type;
+    /// defines a reference to the type iterated over (value_type)
+    using reference =
+        typename std::conditional<std::is_const<BasicJsonType>::value,
+        typename BasicJsonType::const_reference,
+        typename BasicJsonType::reference>::type;
+
+    /// default constructor
+    iter_impl() = default;
+
+    /*!
+    @brief constructor for a given JSON instance
+    @param[in] object  pointer to a JSON object for this iterator
+    @pre object != nullptr
+    @post The iterator is initialized; i.e. `m_object != nullptr`.
+    */
+    explicit iter_impl(pointer object) noexcept : m_object(object)
+    {
+        assert(m_object != nullptr);
+
+        switch (m_object->m_type)
+        {
+            case value_t::object:
             {
-                float number;
-                return get_number(input_format_t::msgpack, number) and sax->number_float(static_cast<number_float_t>(number), "");
+                m_it.object_iterator = typename object_t::iterator();
+                break;
+            }
+
+            case value_t::array:
+            {
+                m_it.array_iterator = typename array_t::iterator();
+                break;
+            }
+
+            default:
+            {
+                m_it.primitive_iterator = primitive_iterator_t();
+                break;
             }
+        }
+    }
+
+    /*!
+    @note The conventional copy constructor and copy assignment are implicitly
+          defined. Combined with the following converting constructor and
+          assignment, they support: (1) copy from iterator to iterator, (2)
+          copy from const iterator to const iterator, and (3) conversion from
+          iterator to const iterator. However conversion from const iterator
+          to iterator is not defined.
+    */
+
+    /*!
+    @brief converting constructor
+    @param[in] other  non-const iterator to copy from
+    @note It is not checked whether @a other is initialized.
+    */
+    iter_impl(const iter_impl<typename std::remove_const<BasicJsonType>::type>& other) noexcept
+        : m_object(other.m_object), m_it(other.m_it) {}
+
+    /*!
+    @brief converting assignment
+    @param[in,out] other  non-const iterator to copy from
+    @return const/non-const iterator
+    @note It is not checked whether @a other is initialized.
+    */
+    iter_impl& operator=(const iter_impl<typename std::remove_const<BasicJsonType>::type>& other) noexcept
+    {
+        m_object = other.m_object;
+        m_it = other.m_it;
+        return *this;
+    }
 
-            case 0xCB: // float 64
-            {
-                double number;
-                return get_number(input_format_t::msgpack, number) and sax->number_float(static_cast<number_float_t>(number), "");
-            }
+  private:
+    /*!
+    @brief set the iterator to the first value
+    @pre The iterator is initialized; i.e. `m_object != nullptr`.
+    */
+    void set_begin() noexcept
+    {
+        assert(m_object != nullptr);
 
-            case 0xCC: // uint 8
+        switch (m_object->m_type)
+        {
+            case value_t::object:
             {
-                uint8_t number;
-                return get_number(input_format_t::msgpack, number) and sax->number_unsigned(number);
+                m_it.object_iterator = m_object->m_value.object->begin();
+                break;
             }
 
-            case 0xCD: // uint 16
+            case value_t::array:
             {
-                uint16_t number;
-                return get_number(input_format_t::msgpack, number) and sax->number_unsigned(number);
+                m_it.array_iterator = m_object->m_value.array->begin();
+                break;
             }
 
-            case 0xCE: // uint 32
+            case value_t::null:
             {
-                uint32_t number;
-                return get_number(input_format_t::msgpack, number) and sax->number_unsigned(number);
+                // set to end so begin()==end() is true: null is empty
+                m_it.primitive_iterator.set_end();
+                break;
             }
 
-            case 0xCF: // uint 64
+            default:
             {
-                uint64_t number;
-                return get_number(input_format_t::msgpack, number) and sax->number_unsigned(number);
+                m_it.primitive_iterator.set_begin();
+                break;
             }
+        }
+    }
 
-            case 0xD0: // int 8
-            {
-                int8_t number;
-                return get_number(input_format_t::msgpack, number) and sax->number_integer(number);
-            }
+    /*!
+    @brief set the iterator past the last value
+    @pre The iterator is initialized; i.e. `m_object != nullptr`.
+    */
+    void set_end() noexcept
+    {
+        assert(m_object != nullptr);
 
-            case 0xD1: // int 16
+        switch (m_object->m_type)
+        {
+            case value_t::object:
             {
-                int16_t number;
-                return get_number(input_format_t::msgpack, number) and sax->number_integer(number);
+                m_it.object_iterator = m_object->m_value.object->end();
+                break;
             }
 
-            case 0xD2: // int 32
+            case value_t::array:
             {
-                int32_t number;
-                return get_number(input_format_t::msgpack, number) and sax->number_integer(number);
+                m_it.array_iterator = m_object->m_value.array->end();
+                break;
             }
 
-            case 0xD3: // int 64
+            default:
             {
-                int64_t number;
-                return get_number(input_format_t::msgpack, number) and sax->number_integer(number);
+                m_it.primitive_iterator.set_end();
+                break;
             }
+        }
+    }
 
-            case 0xD9: // str 8
-            case 0xDA: // str 16
-            case 0xDB: // str 32
-            {
-                string_t s;
-                return get_msgpack_string(s) and sax->string(s);
-            }
+  public:
+    /*!
+    @brief return a reference to the value pointed to by the iterator
+    @pre The iterator is initialized; i.e. `m_object != nullptr`.
+    */
+    reference operator*() const
+    {
+        assert(m_object != nullptr);
 
-            case 0xDC: // array 16
+        switch (m_object->m_type)
+        {
+            case value_t::object:
             {
-                uint16_t len;
-                return get_number(input_format_t::msgpack, len) and get_msgpack_array(static_cast<std::size_t>(len));
+                assert(m_it.object_iterator != m_object->m_value.object->end());
+                return m_it.object_iterator->second;
             }
 
-            case 0xDD: // array 32
+            case value_t::array:
             {
-                uint32_t len;
-                return get_number(input_format_t::msgpack, len) and get_msgpack_array(static_cast<std::size_t>(len));
+                assert(m_it.array_iterator != m_object->m_value.array->end());
+                return *m_it.array_iterator;
             }
 
-            case 0xDE: // map 16
-            {
-                uint16_t len;
-                return get_number(input_format_t::msgpack, len) and get_msgpack_object(static_cast<std::size_t>(len));
-            }
+            case value_t::null:
+                JSON_THROW(invalid_iterator::create(214, "cannot get value"));
 
-            case 0xDF: // map 32
+            default:
             {
-                uint32_t len;
-                return get_number(input_format_t::msgpack, len) and get_msgpack_object(static_cast<std::size_t>(len));
-            }
-
-            // negative fixint
-            case 0xE0:
-            case 0xE1:
-            case 0xE2:
-            case 0xE3:
-            case 0xE4:
-            case 0xE5:
-            case 0xE6:
-            case 0xE7:
-            case 0xE8:
-            case 0xE9:
-            case 0xEA:
-            case 0xEB:
-            case 0xEC:
-            case 0xED:
-            case 0xEE:
-            case 0xEF:
-            case 0xF0:
-            case 0xF1:
-            case 0xF2:
-            case 0xF3:
-            case 0xF4:
-            case 0xF5:
-            case 0xF6:
-            case 0xF7:
-            case 0xF8:
-            case 0xF9:
-            case 0xFA:
-            case 0xFB:
-            case 0xFC:
-            case 0xFD:
-            case 0xFE:
-            case 0xFF:
-                return sax->number_integer(static_cast<int8_t>(current));
+                if (JSON_LIKELY(m_it.primitive_iterator.is_begin()))
+                {
+                    return *m_object;
+                }
 
-            default: // anything else
-            {
-                auto last_token = get_token_string();
-                return sax->parse_error(chars_read, last_token, parse_error::create(112, chars_read, exception_message(input_format_t::msgpack, "invalid byte: 0x" + last_token, "value")));
+                JSON_THROW(invalid_iterator::create(214, "cannot get value"));
             }
         }
     }
 
     /*!
-    @brief reads a MessagePack string
-
-    This function first reads starting bytes to determine the expected
-    string length and then copies this number of bytes into a string.
-
-    @param[out] result  created string
-
-    @return whether string creation completed
+    @brief dereference the iterator
+    @pre The iterator is initialized; i.e. `m_object != nullptr`.
     */
-    bool get_msgpack_string(string_t& result)
+    pointer operator->() const
     {
-        if (JSON_UNLIKELY(not unexpect_eof(input_format_t::msgpack, "string")))
-        {
-            return false;
-        }
+        assert(m_object != nullptr);
 
-        switch (current)
+        switch (m_object->m_type)
         {
-            // fixstr
-            case 0xA0:
-            case 0xA1:
-            case 0xA2:
-            case 0xA3:
-            case 0xA4:
-            case 0xA5:
-            case 0xA6:
-            case 0xA7:
-            case 0xA8:
-            case 0xA9:
-            case 0xAA:
-            case 0xAB:
-            case 0xAC:
-            case 0xAD:
-            case 0xAE:
-            case 0xAF:
-            case 0xB0:
-            case 0xB1:
-            case 0xB2:
-            case 0xB3:
-            case 0xB4:
-            case 0xB5:
-            case 0xB6:
-            case 0xB7:
-            case 0xB8:
-            case 0xB9:
-            case 0xBA:
-            case 0xBB:
-            case 0xBC:
-            case 0xBD:
-            case 0xBE:
-            case 0xBF:
-            {
-                return get_string(input_format_t::msgpack, current & 0x1F, result);
-            }
-
-            case 0xD9: // str 8
-            {
-                uint8_t len;
-                return get_number(input_format_t::msgpack, len) and get_string(input_format_t::msgpack, len, result);
-            }
-
-            case 0xDA: // str 16
+            case value_t::object:
             {
-                uint16_t len;
-                return get_number(input_format_t::msgpack, len) and get_string(input_format_t::msgpack, len, result);
+                assert(m_it.object_iterator != m_object->m_value.object->end());
+                return &(m_it.object_iterator->second);
             }
 
-            case 0xDB: // str 32
+            case value_t::array:
             {
-                uint32_t len;
-                return get_number(input_format_t::msgpack, len) and get_string(input_format_t::msgpack, len, result);
+                assert(m_it.array_iterator != m_object->m_value.array->end());
+                return &*m_it.array_iterator;
             }
 
             default:
             {
-                auto last_token = get_token_string();
-                return sax->parse_error(chars_read, last_token, parse_error::create(113, chars_read, exception_message(input_format_t::msgpack, "expected length specification (0xA0-0xBF, 0xD9-0xDB); last byte: 0x" + last_token, "string")));
+                if (JSON_LIKELY(m_it.primitive_iterator.is_begin()))
+                {
+                    return m_object;
+                }
+
+                JSON_THROW(invalid_iterator::create(214, "cannot get value"));
             }
         }
     }
 
     /*!
-    @param[in] len  the length of the array
-    @return whether array creation completed
+    @brief post-increment (it++)
+    @pre The iterator is initialized; i.e. `m_object != nullptr`.
     */
-    bool get_msgpack_array(const std::size_t len)
+    iter_impl const operator++(int)
     {
-        if (JSON_UNLIKELY(not sax->start_array(len)))
-        {
-            return false;
-        }
-
-        for (std::size_t i = 0; i < len; ++i)
-        {
-            if (JSON_UNLIKELY(not parse_msgpack_internal()))
-            {
-                return false;
-            }
-        }
-
-        return sax->end_array();
+        auto result = *this;
+        ++(*this);
+        return result;
     }
 
     /*!
-    @param[in] len  the length of the object
-    @return whether object creation completed
+    @brief pre-increment (++it)
+    @pre The iterator is initialized; i.e. `m_object != nullptr`.
     */
-    bool get_msgpack_object(const std::size_t len)
+    iter_impl& operator++()
     {
-        if (JSON_UNLIKELY(not sax->start_object(len)))
-        {
-            return false;
-        }
+        assert(m_object != nullptr);
 
-        string_t key;
-        for (std::size_t i = 0; i < len; ++i)
+        switch (m_object->m_type)
         {
-            get();
-            if (JSON_UNLIKELY(not get_msgpack_string(key) or not sax->key(key)))
+            case value_t::object:
             {
-                return false;
+                std::advance(m_it.object_iterator, 1);
+                break;
             }
 
-            if (JSON_UNLIKELY(not parse_msgpack_internal()))
+            case value_t::array:
             {
-                return false;
+                std::advance(m_it.array_iterator, 1);
+                break;
+            }
+
+            default:
+            {
+                ++m_it.primitive_iterator;
+                break;
             }
-            key.clear();
         }
 
-        return sax->end_object();
+        return *this;
     }
 
-    ////////////
-    // UBJSON //
-    ////////////
-
     /*!
-    @param[in] get_char  whether a new character should be retrieved from the
-                         input (true, default) or whether the last read
-                         character should be considered instead
-
-    @return whether a valid UBJSON value was passed to the SAX parser
+    @brief post-decrement (it--)
+    @pre The iterator is initialized; i.e. `m_object != nullptr`.
     */
-    bool parse_ubjson_internal(const bool get_char = true)
+    iter_impl const operator--(int)
     {
-        return get_ubjson_value(get_char ? get_ignore_noop() : current);
+        auto result = *this;
+        --(*this);
+        return result;
     }
 
     /*!
-    @brief reads a UBJSON string
-
-    This function is either called after reading the 'S' byte explicitly
-    indicating a string, or in case of an object key where the 'S' byte can be
-    left out.
-
-    @param[out] result   created string
-    @param[in] get_char  whether a new character should be retrieved from the
-                         input (true, default) or whether the last read
-                         character should be considered instead
-
-    @return whether string creation completed
+    @brief pre-decrement (--it)
+    @pre The iterator is initialized; i.e. `m_object != nullptr`.
     */
-    bool get_ubjson_string(string_t& result, const bool get_char = true)
+    iter_impl& operator--()
     {
-        if (get_char)
-        {
-            get();  // TODO: may we ignore N here?
-        }
-
-        if (JSON_UNLIKELY(not unexpect_eof(input_format_t::ubjson, "value")))
-        {
-            return false;
-        }
+        assert(m_object != nullptr);
 
-        switch (current)
+        switch (m_object->m_type)
         {
-            case 'U':
-            {
-                uint8_t len;
-                return get_number(input_format_t::ubjson, len) and get_string(input_format_t::ubjson, len, result);
-            }
-
-            case 'i':
-            {
-                int8_t len;
-                return get_number(input_format_t::ubjson, len) and get_string(input_format_t::ubjson, len, result);
-            }
-
-            case 'I':
+            case value_t::object:
             {
-                int16_t len;
-                return get_number(input_format_t::ubjson, len) and get_string(input_format_t::ubjson, len, result);
+                std::advance(m_it.object_iterator, -1);
+                break;
             }
 
-            case 'l':
+            case value_t::array:
             {
-                int32_t len;
-                return get_number(input_format_t::ubjson, len) and get_string(input_format_t::ubjson, len, result);
+                std::advance(m_it.array_iterator, -1);
+                break;
             }
 
-            case 'L':
+            default:
             {
-                int64_t len;
-                return get_number(input_format_t::ubjson, len) and get_string(input_format_t::ubjson, len, result);
+                --m_it.primitive_iterator;
+                break;
             }
-
-            default:
-                auto last_token = get_token_string();
-                return sax->parse_error(chars_read, last_token, parse_error::create(113, chars_read, exception_message(input_format_t::ubjson, "expected length type specification (U, i, I, l, L); last byte: 0x" + last_token, "string")));
         }
+
+        return *this;
     }
 
     /*!
-    @param[out] result  determined size
-    @return whether size determination completed
+    @brief  comparison: equal
+    @pre The iterator is initialized; i.e. `m_object != nullptr`.
     */
-    bool get_ubjson_size_value(std::size_t& result)
+    bool operator==(const iter_impl& other) const
     {
-        switch (get_ignore_noop())
+        // if objects are not the same, the comparison is undefined
+        if (JSON_UNLIKELY(m_object != other.m_object))
         {
-            case 'U':
-            {
-                uint8_t number;
-                if (JSON_UNLIKELY(not get_number(input_format_t::ubjson, number)))
-                {
-                    return false;
-                }
-                result = static_cast<std::size_t>(number);
-                return true;
-            }
-
-            case 'i':
-            {
-                int8_t number;
-                if (JSON_UNLIKELY(not get_number(input_format_t::ubjson, number)))
-                {
-                    return false;
-                }
-                result = static_cast<std::size_t>(number);
-                return true;
-            }
+            JSON_THROW(invalid_iterator::create(212, "cannot compare iterators of different containers"));
+        }
 
-            case 'I':
-            {
-                int16_t number;
-                if (JSON_UNLIKELY(not get_number(input_format_t::ubjson, number)))
-                {
-                    return false;
-                }
-                result = static_cast<std::size_t>(number);
-                return true;
-            }
+        assert(m_object != nullptr);
 
-            case 'l':
-            {
-                int32_t number;
-                if (JSON_UNLIKELY(not get_number(input_format_t::ubjson, number)))
-                {
-                    return false;
-                }
-                result = static_cast<std::size_t>(number);
-                return true;
-            }
+        switch (m_object->m_type)
+        {
+            case value_t::object:
+                return (m_it.object_iterator == other.m_it.object_iterator);
 
-            case 'L':
-            {
-                int64_t number;
-                if (JSON_UNLIKELY(not get_number(input_format_t::ubjson, number)))
-                {
-                    return false;
-                }
-                result = static_cast<std::size_t>(number);
-                return true;
-            }
+            case value_t::array:
+                return (m_it.array_iterator == other.m_it.array_iterator);
 
             default:
-            {
-                auto last_token = get_token_string();
-                return sax->parse_error(chars_read, last_token, parse_error::create(113, chars_read, exception_message(input_format_t::ubjson, "expected length type specification (U, i, I, l, L) after '#'; last byte: 0x" + last_token, "size")));
-            }
+                return (m_it.primitive_iterator == other.m_it.primitive_iterator);
         }
     }
 
     /*!
-    @brief determine the type and size for a container
-
-    In the optimized UBJSON format, a type and a size can be provided to allow
-    for a more compact representation.
-
-    @param[out] result  pair of the size and the type
+    @brief  comparison: not equal
+    @pre The iterator is initialized; i.e. `m_object != nullptr`.
+    */
+    bool operator!=(const iter_impl& other) const
+    {
+        return not operator==(other);
+    }
 
-    @return whether pair creation completed
+    /*!
+    @brief  comparison: smaller
+    @pre The iterator is initialized; i.e. `m_object != nullptr`.
     */
-    bool get_ubjson_size_type(std::pair<std::size_t, int>& result)
+    bool operator<(const iter_impl& other) const
     {
-        result.first = string_t::npos; // size
-        result.second = 0; // type
+        // if objects are not the same, the comparison is undefined
+        if (JSON_UNLIKELY(m_object != other.m_object))
+        {
+            JSON_THROW(invalid_iterator::create(212, "cannot compare iterators of different containers"));
+        }
 
-        get_ignore_noop();
+        assert(m_object != nullptr);
 
-        if (current == '$')
+        switch (m_object->m_type)
         {
-            result.second = get();  // must not ignore 'N', because 'N' maybe the type
-            if (JSON_UNLIKELY(not unexpect_eof(input_format_t::ubjson, "type")))
-            {
-                return false;
-            }
+            case value_t::object:
+                JSON_THROW(invalid_iterator::create(213, "cannot compare order of object iterators"));
 
-            get_ignore_noop();
-            if (JSON_UNLIKELY(current != '#'))
-            {
-                if (JSON_UNLIKELY(not unexpect_eof(input_format_t::ubjson, "value")))
-                {
-                    return false;
-                }
-                auto last_token = get_token_string();
-                return sax->parse_error(chars_read, last_token, parse_error::create(112, chars_read, exception_message(input_format_t::ubjson, "expected '#' after type information; last byte: 0x" + last_token, "size")));
-            }
+            case value_t::array:
+                return (m_it.array_iterator < other.m_it.array_iterator);
 
-            return get_ubjson_size_value(result.first);
-        }
-        else if (current == '#')
-        {
-            return get_ubjson_size_value(result.first);
+            default:
+                return (m_it.primitive_iterator < other.m_it.primitive_iterator);
         }
-        return true;
     }
 
     /*!
-    @param prefix  the previously read or set type prefix
-    @return whether value creation completed
+    @brief  comparison: less than or equal
+    @pre The iterator is initialized; i.e. `m_object != nullptr`.
+    */
+    bool operator<=(const iter_impl& other) const
+    {
+        return not other.operator < (*this);
+    }
+
+    /*!
+    @brief  comparison: greater than
+    @pre The iterator is initialized; i.e. `m_object != nullptr`.
+    */
+    bool operator>(const iter_impl& other) const
+    {
+        return not operator<=(other);
+    }
+
+    /*!
+    @brief  comparison: greater than or equal
+    @pre The iterator is initialized; i.e. `m_object != nullptr`.
+    */
+    bool operator>=(const iter_impl& other) const
+    {
+        return not operator<(other);
+    }
+
+    /*!
+    @brief  add to iterator
+    @pre The iterator is initialized; i.e. `m_object != nullptr`.
     */
-    bool get_ubjson_value(const int prefix)
+    iter_impl& operator+=(difference_type i)
     {
-        switch (prefix)
-        {
-            case std::char_traits<char>::eof():  // EOF
-                return unexpect_eof(input_format_t::ubjson, "value");
-
-            case 'T':  // true
-                return sax->boolean(true);
-            case 'F':  // false
-                return sax->boolean(false);
-
-            case 'Z':  // null
-                return sax->null();
-
-            case 'U':
-            {
-                uint8_t number;
-                return get_number(input_format_t::ubjson, number) and sax->number_unsigned(number);
-            }
-
-            case 'i':
-            {
-                int8_t number;
-                return get_number(input_format_t::ubjson, number) and sax->number_integer(number);
-            }
-
-            case 'I':
-            {
-                int16_t number;
-                return get_number(input_format_t::ubjson, number) and sax->number_integer(number);
-            }
-
-            case 'l':
-            {
-                int32_t number;
-                return get_number(input_format_t::ubjson, number) and sax->number_integer(number);
-            }
+        assert(m_object != nullptr);
 
-            case 'L':
-            {
-                int64_t number;
-                return get_number(input_format_t::ubjson, number) and sax->number_integer(number);
-            }
+        switch (m_object->m_type)
+        {
+            case value_t::object:
+                JSON_THROW(invalid_iterator::create(209, "cannot use offsets with object iterators"));
 
-            case 'd':
+            case value_t::array:
             {
-                float number;
-                return get_number(input_format_t::ubjson, number) and sax->number_float(static_cast<number_float_t>(number), "");
+                std::advance(m_it.array_iterator, i);
+                break;
             }
 
-            case 'D':
+            default:
             {
-                double number;
-                return get_number(input_format_t::ubjson, number) and sax->number_float(static_cast<number_float_t>(number), "");
+                m_it.primitive_iterator += i;
+                break;
             }
+        }
 
-            case 'C':  // char
-            {
-                get();
-                if (JSON_UNLIKELY(not unexpect_eof(input_format_t::ubjson, "char")))
-                {
-                    return false;
-                }
-                if (JSON_UNLIKELY(current > 127))
-                {
-                    auto last_token = get_token_string();
-                    return sax->parse_error(chars_read, last_token, parse_error::create(113, chars_read, exception_message(input_format_t::ubjson, "byte after 'C' must be in range 0x00..0x7F; last byte: 0x" + last_token, "char")));
-                }
-                string_t s(1, static_cast<char>(current));
-                return sax->string(s);
-            }
+        return *this;
+    }
 
-            case 'S':  // string
-            {
-                string_t s;
-                return get_ubjson_string(s) and sax->string(s);
-            }
+    /*!
+    @brief  subtract from iterator
+    @pre The iterator is initialized; i.e. `m_object != nullptr`.
+    */
+    iter_impl& operator-=(difference_type i)
+    {
+        return operator+=(-i);
+    }
 
-            case '[':  // array
-                return get_ubjson_array();
+    /*!
+    @brief  add to iterator
+    @pre The iterator is initialized; i.e. `m_object != nullptr`.
+    */
+    iter_impl operator+(difference_type i) const
+    {
+        auto result = *this;
+        result += i;
+        return result;
+    }
 
-            case '{':  // object
-                return get_ubjson_object();
+    /*!
+    @brief  addition of distance and iterator
+    @pre The iterator is initialized; i.e. `m_object != nullptr`.
+    */
+    friend iter_impl operator+(difference_type i, const iter_impl& it)
+    {
+        auto result = it;
+        result += i;
+        return result;
+    }
 
-            default: // anything else
-            {
-                auto last_token = get_token_string();
-                return sax->parse_error(chars_read, last_token, parse_error::create(112, chars_read, exception_message(input_format_t::ubjson, "invalid byte: 0x" + last_token, "value")));
-            }
-        }
+    /*!
+    @brief  subtract from iterator
+    @pre The iterator is initialized; i.e. `m_object != nullptr`.
+    */
+    iter_impl operator-(difference_type i) const
+    {
+        auto result = *this;
+        result -= i;
+        return result;
     }
 
     /*!
-    @return whether array creation completed
+    @brief  return difference
+    @pre The iterator is initialized; i.e. `m_object != nullptr`.
     */
-    bool get_ubjson_array()
+    difference_type operator-(const iter_impl& other) const
     {
-        std::pair<std::size_t, int> size_and_type;
-        if (JSON_UNLIKELY(not get_ubjson_size_type(size_and_type)))
-        {
-            return false;
-        }
+        assert(m_object != nullptr);
 
-        if (size_and_type.first != string_t::npos)
+        switch (m_object->m_type)
         {
-            if (JSON_UNLIKELY(not sax->start_array(size_and_type.first)))
-            {
-                return false;
-            }
+            case value_t::object:
+                JSON_THROW(invalid_iterator::create(209, "cannot use offsets with object iterators"));
 
-            if (size_and_type.second != 0)
-            {
-                if (size_and_type.second != 'N')
-                {
-                    for (std::size_t i = 0; i < size_and_type.first; ++i)
-                    {
-                        if (JSON_UNLIKELY(not get_ubjson_value(size_and_type.second)))
-                        {
-                            return false;
-                        }
-                    }
-                }
-            }
-            else
-            {
-                for (std::size_t i = 0; i < size_and_type.first; ++i)
-                {
-                    if (JSON_UNLIKELY(not parse_ubjson_internal()))
-                    {
-                        return false;
-                    }
-                }
-            }
-        }
-        else
-        {
-            if (JSON_UNLIKELY(not sax->start_array(std::size_t(-1))))
-            {
-                return false;
-            }
+            case value_t::array:
+                return m_it.array_iterator - other.m_it.array_iterator;
 
-            while (current != ']')
-            {
-                if (JSON_UNLIKELY(not parse_ubjson_internal(false)))
-                {
-                    return false;
-                }
-                get_ignore_noop();
-            }
+            default:
+                return m_it.primitive_iterator - other.m_it.primitive_iterator;
         }
-
-        return sax->end_array();
     }
 
     /*!
-    @return whether object creation completed
+    @brief  access to successor
+    @pre The iterator is initialized; i.e. `m_object != nullptr`.
     */
-    bool get_ubjson_object()
+    reference operator[](difference_type n) const
     {
-        std::pair<std::size_t, int> size_and_type;
-        if (JSON_UNLIKELY(not get_ubjson_size_type(size_and_type)))
-        {
-            return false;
-        }
+        assert(m_object != nullptr);
 
-        string_t key;
-        if (size_and_type.first != string_t::npos)
+        switch (m_object->m_type)
         {
-            if (JSON_UNLIKELY(not sax->start_object(size_and_type.first)))
-            {
-                return false;
-            }
+            case value_t::object:
+                JSON_THROW(invalid_iterator::create(208, "cannot use operator[] for object iterators"));
 
-            if (size_and_type.second != 0)
-            {
-                for (std::size_t i = 0; i < size_and_type.first; ++i)
-                {
-                    if (JSON_UNLIKELY(not get_ubjson_string(key) or not sax->key(key)))
-                    {
-                        return false;
-                    }
-                    if (JSON_UNLIKELY(not get_ubjson_value(size_and_type.second)))
-                    {
-                        return false;
-                    }
-                    key.clear();
-                }
-            }
-            else
-            {
-                for (std::size_t i = 0; i < size_and_type.first; ++i)
-                {
-                    if (JSON_UNLIKELY(not get_ubjson_string(key) or not sax->key(key)))
-                    {
-                        return false;
-                    }
-                    if (JSON_UNLIKELY(not parse_ubjson_internal()))
-                    {
-                        return false;
-                    }
-                    key.clear();
-                }
-            }
-        }
-        else
-        {
-            if (JSON_UNLIKELY(not sax->start_object(std::size_t(-1))))
-            {
-                return false;
-            }
+            case value_t::array:
+                return *std::next(m_it.array_iterator, n);
+
+            case value_t::null:
+                JSON_THROW(invalid_iterator::create(214, "cannot get value"));
 
-            while (current != '}')
+            default:
             {
-                if (JSON_UNLIKELY(not get_ubjson_string(key, false) or not sax->key(key)))
-                {
-                    return false;
-                }
-                if (JSON_UNLIKELY(not parse_ubjson_internal()))
+                if (JSON_LIKELY(m_it.primitive_iterator.get_value() == -n))
                 {
-                    return false;
+                    return *m_object;
                 }
-                get_ignore_noop();
-                key.clear();
+
+                JSON_THROW(invalid_iterator::create(214, "cannot get value"));
             }
         }
-
-        return sax->end_object();
     }
 
-    ///////////////////////
-    // Utility functions //
-    ///////////////////////
-
     /*!
-    @brief get next character from the input
-
-    This function provides the interface to the used input adapter. It does
-    not throw in case the input reached EOF, but returns a -'ve valued
-    `std::char_traits<char>::eof()` in that case.
-
-    @return character read from the input
+    @brief  return the key of an object iterator
+    @pre The iterator is initialized; i.e. `m_object != nullptr`.
     */
-    int get()
+    const typename object_t::key_type& key() const
     {
-        ++chars_read;
-        return (current = ia->get_character());
+        assert(m_object != nullptr);
+
+        if (JSON_LIKELY(m_object->is_object()))
+        {
+            return m_it.object_iterator->first;
+        }
+
+        JSON_THROW(invalid_iterator::create(207, "cannot use key() for non-object iterators"));
     }
 
     /*!
-    @return character read from the input after ignoring all 'N' entries
+    @brief  return the value of an iterator
+    @pre The iterator is initialized; i.e. `m_object != nullptr`.
     */
-    int get_ignore_noop()
+    reference value() const
     {
-        do
-        {
-            get();
-        }
-        while (current == 'N');
+        return operator*();
+    }
 
-        return current;
+  private:
+    /// associated JSON instance
+    pointer m_object = nullptr;
+    /// the actual iterator of the associated instance
+    internal_iterator<typename std::remove_const<BasicJsonType>::type> m_it {};
+};
+}  // namespace detail
+} // namespace nlohmann
+
+// #include <nlohmann/detail/iterators/iteration_proxy.hpp>
+
+// #include <nlohmann/detail/iterators/json_reverse_iterator.hpp>
+
+
+#include <cstddef> // ptrdiff_t
+#include <iterator> // reverse_iterator
+#include <utility> // declval
+
+namespace nlohmann
+{
+namespace detail
+{
+//////////////////////
+// reverse_iterator //
+//////////////////////
+
+/*!
+@brief a template for a reverse iterator class
+
+@tparam Base the base iterator type to reverse. Valid types are @ref
+iterator (to create @ref reverse_iterator) and @ref const_iterator (to
+create @ref const_reverse_iterator).
+
+@requirement The class satisfies the following concept requirements:
+-
+[BidirectionalIterator](https://en.cppreference.com/w/cpp/named_req/BidirectionalIterator):
+  The iterator that can be moved can be moved in both directions (i.e.
+  incremented and decremented).
+- [OutputIterator](https://en.cppreference.com/w/cpp/named_req/OutputIterator):
+  It is possible to write to the pointed-to element (only if @a Base is
+  @ref iterator).
+
+@since version 1.0.0
+*/
+template<typename Base>
+class json_reverse_iterator : public std::reverse_iterator<Base>
+{
+  public:
+    using difference_type = std::ptrdiff_t;
+    /// shortcut to the reverse iterator adapter
+    using base_iterator = std::reverse_iterator<Base>;
+    /// the reference type for the pointed-to element
+    using reference = typename Base::reference;
+
+    /// create reverse iterator from iterator
+    explicit json_reverse_iterator(const typename base_iterator::iterator_type& it) noexcept
+        : base_iterator(it) {}
+
+    /// create reverse iterator from base class
+    explicit json_reverse_iterator(const base_iterator& it) noexcept : base_iterator(it) {}
+
+    /// post-increment (it++)
+    json_reverse_iterator const operator++(int)
+    {
+        return static_cast<json_reverse_iterator>(base_iterator::operator++(1));
     }
 
-    /*
-    @brief read a number from the input
+    /// pre-increment (++it)
+    json_reverse_iterator& operator++()
+    {
+        return static_cast<json_reverse_iterator&>(base_iterator::operator++());
+    }
 
-    @tparam NumberType the type of the number
-    @param[in] format   the current format (for diagnostics)
-    @param[out] result  number of type @a NumberType
+    /// post-decrement (it--)
+    json_reverse_iterator const operator--(int)
+    {
+        return static_cast<json_reverse_iterator>(base_iterator::operator--(1));
+    }
 
-    @return whether conversion completed
+    /// pre-decrement (--it)
+    json_reverse_iterator& operator--()
+    {
+        return static_cast<json_reverse_iterator&>(base_iterator::operator--());
+    }
 
-    @note This function needs to respect the system's endianess, because
-          bytes in CBOR, MessagePack, and UBJSON are stored in network order
-          (big endian) and therefore need reordering on little endian systems.
-    */
-    template<typename NumberType, bool InputIsLittleEndian = false>
-    bool get_number(const input_format_t format, NumberType& result)
+    /// add to iterator
+    json_reverse_iterator& operator+=(difference_type i)
     {
-        // step 1: read input into array with system's byte order
-        std::array<uint8_t, sizeof(NumberType)> vec;
-        for (std::size_t i = 0; i < sizeof(NumberType); ++i)
-        {
-            get();
-            if (JSON_UNLIKELY(not unexpect_eof(format, "number")))
-            {
-                return false;
-            }
+        return static_cast<json_reverse_iterator&>(base_iterator::operator+=(i));
+    }
 
-            // reverse byte order prior to conversion if necessary
-            if (is_little_endian && !InputIsLittleEndian)
-            {
-                vec[sizeof(NumberType) - i - 1] = static_cast<uint8_t>(current);
-            }
-            else
-            {
-                vec[i] = static_cast<uint8_t>(current); // LCOV_EXCL_LINE
-            }
-        }
+    /// add to iterator
+    json_reverse_iterator operator+(difference_type i) const
+    {
+        return static_cast<json_reverse_iterator>(base_iterator::operator+(i));
+    }
 
-        // step 2: convert array into number of type T and return
-        std::memcpy(&result, vec.data(), sizeof(NumberType));
-        return true;
+    /// subtract from iterator
+    json_reverse_iterator operator-(difference_type i) const
+    {
+        return static_cast<json_reverse_iterator>(base_iterator::operator-(i));
+    }
+
+    /// return difference
+    difference_type operator-(const json_reverse_iterator& other) const
+    {
+        return base_iterator(*this) - base_iterator(other);
+    }
+
+    /// access to successor
+    reference operator[](difference_type n) const
+    {
+        return *(this->operator+(n));
+    }
+
+    /// return the key of an object iterator
+    auto key() const -> decltype(std::declval<Base>().key())
+    {
+        auto it = --this->base();
+        return it.key();
+    }
+
+    /// return the value of an iterator
+    reference value() const
+    {
+        auto it = --this->base();
+        return it.operator * ();
     }
+};
+}  // namespace detail
+}  // namespace nlohmann
+
+// #include <nlohmann/detail/iterators/primitive_iterator.hpp>
+
+// #include <nlohmann/detail/json_pointer.hpp>
+
+
+#include <algorithm> // all_of
+#include <cassert> // assert
+#include <numeric> // accumulate
+#include <string> // string
+#include <utility> // move
+#include <vector> // vector
+
+// #include <nlohmann/detail/exceptions.hpp>
+
+// #include <nlohmann/detail/macro_scope.hpp>
+
+// #include <nlohmann/detail/value_t.hpp>
+
+
+namespace nlohmann
+{
+template<typename BasicJsonType>
+class json_pointer
+{
+    // allow basic_json to access private members
+    NLOHMANN_BASIC_JSON_TPL_DECLARATION
+    friend class basic_json;
+
+  public:
+    /*!
+    @brief create JSON pointer
+
+    Create a JSON pointer according to the syntax described in
+    [Section 3 of RFC6901](https://tools.ietf.org/html/rfc6901#section-3).
+
+    @param[in] s  string representing the JSON pointer; if omitted, the empty
+                  string is assumed which references the whole JSON value
+
+    @throw parse_error.107 if the given JSON pointer @a s is nonempty and does
+                           not begin with a slash (`/`); see example below
+
+    @throw parse_error.108 if a tilde (`~`) in the given JSON pointer @a s is
+    not followed by `0` (representing `~`) or `1` (representing `/`); see
+    example below
+
+    @liveexample{The example shows the construction several valid JSON pointers
+    as well as the exceptional behavior.,json_pointer}
+
+    @since version 2.0.0
+    */
+    explicit json_pointer(const std::string& s = "")
+        : reference_tokens(split(s))
+    {}
 
     /*!
-    @brief create a string by reading characters from the input
+    @brief return a string representation of the JSON pointer
 
-    @tparam NumberType the type of the number
-    @param[in] format the current format (for diagnostics)
-    @param[in] len number of characters to read
-    @param[out] result string created by reading @a len bytes
+    @invariant For each JSON pointer `ptr`, it holds:
+    @code {.cpp}
+    ptr == json_pointer(ptr.to_string());
+    @endcode
 
-    @return whether string creation completed
+    @return a string representation of the JSON pointer
 
-    @note We can not reserve @a len bytes for the result, because @a len
-          may be too large. Usually, @ref unexpect_eof() detects the end of
-          the input before we run out of string memory.
+    @liveexample{The example shows the result of `to_string`.,json_pointer__to_string}
+
+    @since version 2.0.0
     */
-    template<typename NumberType>
-    bool get_string(const input_format_t format,
-                    const NumberType len,
-                    string_t& result)
+    std::string to_string() const
     {
-        bool success = true;
-        std::generate_n(std::back_inserter(result), len, [this, &success, &format]()
+        return std::accumulate(reference_tokens.begin(), reference_tokens.end(),
+                               std::string{},
+                               [](const std::string & a, const std::string & b)
         {
-            get();
-            if (JSON_UNLIKELY(not unexpect_eof(format, "string")))
-            {
-                success = false;
-            }
-            return static_cast<char>(current);
+            return a + "/" + escape(b);
         });
-        return success;
     }
 
-    /*!
-    @param[in] format   the current format (for diagnostics)
-    @param[in] context  further context information (for diagnostics)
-    @return whether the last read character is not EOF
-    */
-    bool unexpect_eof(const input_format_t format, const char* context) const
+    /// @copydoc to_string()
+    operator std::string() const
     {
-        if (JSON_UNLIKELY(current == std::char_traits<char>::eof()))
-        {
-            return sax->parse_error(chars_read, "<end of file>",
-                                    parse_error::create(110, chars_read, exception_message(format, "unexpected end of input", context)));
-        }
-        return true;
+        return to_string();
     }
 
     /*!
-    @return a string representation of the last read byte
+    @brief append another JSON pointer at the end of this JSON pointer
+
+    @param[in] ptr  JSON pointer to append
+    @return JSON pointer with @a ptr appended
+
+    @liveexample{The example shows the usage of `operator/=`.,json_pointer__operator_add}
+
+    @complexity Linear in the length of @a ptr.
+
+    @sa @ref operator/=(std::string) to append a reference token
+    @sa @ref operator/=(std::size_t) to append an array index
+    @sa @ref operator/(const json_pointer&, const json_pointer&) for a binary operator
+
+    @since version 3.6.0
     */
-    std::string get_token_string() const
+    json_pointer& operator/=(const json_pointer& ptr)
     {
-        char cr[3];
-        (std::snprintf)(cr, 3, "%.2hhX", static_cast<unsigned char>(current));
-        return std::string{cr};
+        reference_tokens.insert(reference_tokens.end(),
+                                ptr.reference_tokens.begin(),
+                                ptr.reference_tokens.end());
+        return *this;
     }
 
     /*!
-    @param[in] format   the current format
-    @param[in] detail   a detailed error message
-    @param[in] context  further contect information
-    @return a message string to use in the parse_error exceptions
-    */
-    std::string exception_message(const input_format_t format,
-                                  const std::string& detail,
-                                  const std::string& context) const
-    {
-        std::string error_msg = "syntax error while parsing ";
-
-        switch (format)
-        {
-            case input_format_t::cbor:
-                error_msg += "CBOR";
-                break;
+    @brief append an unescaped reference token at the end of this JSON pointer
 
-            case input_format_t::msgpack:
-                error_msg += "MessagePack";
-                break;
+    @param[in] token  reference token to append
+    @return JSON pointer with @a token appended without escaping @a token
 
-            case input_format_t::ubjson:
-                error_msg += "UBJSON";
-                break;
+    @liveexample{The example shows the usage of `operator/=`.,json_pointer__operator_add}
 
-            case input_format_t::bson:
-                error_msg += "BSON";
-                break;
+    @complexity Amortized constant.
 
-            // LCOV_EXCL_START
-            default:
-                assert(false);
-                // LCOV_EXCL_STOP
-        }
+    @sa @ref operator/=(const json_pointer&) to append a JSON pointer
+    @sa @ref operator/=(std::size_t) to append an array index
+    @sa @ref operator/(const json_pointer&, std::size_t) for a binary operator
 
-        return error_msg + " " + context + ": " + detail;
+    @since version 3.6.0
+    */
+    json_pointer& operator/=(std::string token)
+    {
+        push_back(std::move(token));
+        return *this;
     }
 
-  private:
-    /// input adapter
-    input_adapter_t ia = nullptr;
-
-    /// the current character
-    int current = std::char_traits<char>::eof();
-
-    /// the number of characters read
-    std::size_t chars_read = 0;
-
-    /// whether we can assume little endianess
-    const bool is_little_endian = little_endianess();
+    /*!
+    @brief append an array index at the end of this JSON pointer
 
-    /// the SAX parser
-    json_sax_t* sax = nullptr;
-};
-}  // namespace detail
-}  // namespace nlohmann
+    @param[in] array_index  array index ot append
+    @return JSON pointer with @a array_index appended
 
-// #include <nlohmann/detail/output/binary_writer.hpp>
+    @liveexample{The example shows the usage of `operator/=`.,json_pointer__operator_add}
 
+    @complexity Amortized constant.
 
-#include <algorithm> // reverse
-#include <array> // array
-#include <cstdint> // uint8_t, uint16_t, uint32_t, uint64_t
-#include <cstring> // memcpy
-#include <limits> // numeric_limits
+    @sa @ref operator/=(const json_pointer&) to append a JSON pointer
+    @sa @ref operator/=(std::string) to append a reference token
+    @sa @ref operator/(const json_pointer&, std::string) for a binary operator
 
-// #include <nlohmann/detail/input/binary_reader.hpp>
+    @since version 3.6.0
+    */
+    json_pointer& operator/=(std::size_t array_index)
+    {
+        return *this /= std::to_string(array_index);
+    }
 
-// #include <nlohmann/detail/output/output_adapters.hpp>
+    /*!
+    @brief create a new JSON pointer by appending the right JSON pointer at the end of the left JSON pointer
 
+    @param[in] lhs  JSON pointer
+    @param[in] rhs  JSON pointer
+    @return a new JSON pointer with @a rhs appended to @a lhs
 
-namespace nlohmann
-{
-namespace detail
-{
-///////////////////
-// binary writer //
-///////////////////
+    @liveexample{The example shows the usage of `operator/`.,json_pointer__operator_add_binary}
 
-/*!
-@brief serialization to CBOR and MessagePack values
-*/
-template<typename BasicJsonType, typename CharType>
-class binary_writer
-{
-    using string_t = typename BasicJsonType::string_t;
+    @complexity Linear in the length of @a lhs and @a rhs.
 
-  public:
-    /*!
-    @brief create a binary writer
+    @sa @ref operator/=(const json_pointer&) to append a JSON pointer
 
-    @param[in] adapter  output adapter to write to
+    @since version 3.6.0
     */
-    explicit binary_writer(output_adapter_t<CharType> adapter) : oa(adapter)
+    friend json_pointer operator/(const json_pointer& lhs,
+                                  const json_pointer& rhs)
     {
-        assert(oa);
+        return json_pointer(lhs) /= rhs;
     }
 
     /*!
-    @param[in] j  JSON value to serialize
-    @pre       j.type() == value_t::object
+    @brief create a new JSON pointer by appending the unescaped token at the end of the JSON pointer
+
+    @param[in] ptr  JSON pointer
+    @param[in] token  reference token
+    @return a new JSON pointer with unescaped @a token appended to @a ptr
+
+    @liveexample{The example shows the usage of `operator/`.,json_pointer__operator_add_binary}
+
+    @complexity Linear in the length of @a ptr.
+
+    @sa @ref operator/=(std::string) to append a reference token
+
+    @since version 3.6.0
     */
-    void write_bson(const BasicJsonType& j)
+    friend json_pointer operator/(const json_pointer& ptr, std::string token)
     {
-        switch (j.type())
-        {
-            case value_t::object:
-            {
-                write_bson_object(*j.m_value.object);
-                break;
-            }
-
-            default:
-            {
-                JSON_THROW(type_error::create(317, "to serialize to BSON, top-level type must be object, but is " + std::string(j.type_name())));
-            }
-        }
+        return json_pointer(ptr) /= std::move(token);
     }
 
     /*!
-    @param[in] j  JSON value to serialize
-    */
-    void write_cbor(const BasicJsonType& j)
-    {
-        switch (j.type())
-        {
-            case value_t::null:
-            {
-                oa->write_character(to_char_type(0xF6));
-                break;
-            }
+    @brief create a new JSON pointer by appending the array-index-token at the end of the JSON pointer
 
-            case value_t::boolean:
-            {
-                oa->write_character(j.m_value.boolean
-                                    ? to_char_type(0xF5)
-                                    : to_char_type(0xF4));
-                break;
-            }
+    @param[in] ptr  JSON pointer
+    @param[in] array_index  array index
+    @return a new JSON pointer with @a array_index appended to @a ptr
 
-            case value_t::number_integer:
-            {
-                if (j.m_value.number_integer >= 0)
-                {
-                    // CBOR does not differentiate between positive signed
-                    // integers and unsigned integers. Therefore, we used the
-                    // code from the value_t::number_unsigned case here.
-                    if (j.m_value.number_integer <= 0x17)
-                    {
-                        write_number(static_cast<uint8_t>(j.m_value.number_integer));
-                    }
-                    else if (j.m_value.number_integer <= (std::numeric_limits<uint8_t>::max)())
-                    {
-                        oa->write_character(to_char_type(0x18));
-                        write_number(static_cast<uint8_t>(j.m_value.number_integer));
-                    }
-                    else if (j.m_value.number_integer <= (std::numeric_limits<uint16_t>::max)())
-                    {
-                        oa->write_character(to_char_type(0x19));
-                        write_number(static_cast<uint16_t>(j.m_value.number_integer));
-                    }
-                    else if (j.m_value.number_integer <= (std::numeric_limits<uint32_t>::max)())
-                    {
-                        oa->write_character(to_char_type(0x1A));
-                        write_number(static_cast<uint32_t>(j.m_value.number_integer));
-                    }
-                    else
-                    {
-                        oa->write_character(to_char_type(0x1B));
-                        write_number(static_cast<uint64_t>(j.m_value.number_integer));
-                    }
-                }
-                else
-                {
-                    // The conversions below encode the sign in the first
-                    // byte, and the value is converted to a positive number.
-                    const auto positive_number = -1 - j.m_value.number_integer;
-                    if (j.m_value.number_integer >= -24)
-                    {
-                        write_number(static_cast<uint8_t>(0x20 + positive_number));
-                    }
-                    else if (positive_number <= (std::numeric_limits<uint8_t>::max)())
-                    {
-                        oa->write_character(to_char_type(0x38));
-                        write_number(static_cast<uint8_t>(positive_number));
-                    }
-                    else if (positive_number <= (std::numeric_limits<uint16_t>::max)())
-                    {
-                        oa->write_character(to_char_type(0x39));
-                        write_number(static_cast<uint16_t>(positive_number));
-                    }
-                    else if (positive_number <= (std::numeric_limits<uint32_t>::max)())
-                    {
-                        oa->write_character(to_char_type(0x3A));
-                        write_number(static_cast<uint32_t>(positive_number));
-                    }
-                    else
-                    {
-                        oa->write_character(to_char_type(0x3B));
-                        write_number(static_cast<uint64_t>(positive_number));
-                    }
-                }
-                break;
-            }
+    @liveexample{The example shows the usage of `operator/`.,json_pointer__operator_add_binary}
 
-            case value_t::number_unsigned:
-            {
-                if (j.m_value.number_unsigned <= 0x17)
-                {
-                    write_number(static_cast<uint8_t>(j.m_value.number_unsigned));
-                }
-                else if (j.m_value.number_unsigned <= (std::numeric_limits<uint8_t>::max)())
-                {
-                    oa->write_character(to_char_type(0x18));
-                    write_number(static_cast<uint8_t>(j.m_value.number_unsigned));
-                }
-                else if (j.m_value.number_unsigned <= (std::numeric_limits<uint16_t>::max)())
-                {
-                    oa->write_character(to_char_type(0x19));
-                    write_number(static_cast<uint16_t>(j.m_value.number_unsigned));
-                }
-                else if (j.m_value.number_unsigned <= (std::numeric_limits<uint32_t>::max)())
-                {
-                    oa->write_character(to_char_type(0x1A));
-                    write_number(static_cast<uint32_t>(j.m_value.number_unsigned));
-                }
-                else
-                {
-                    oa->write_character(to_char_type(0x1B));
-                    write_number(static_cast<uint64_t>(j.m_value.number_unsigned));
-                }
-                break;
-            }
+    @complexity Linear in the length of @a ptr.
+
+    @sa @ref operator/=(std::size_t) to append an array index
+
+    @since version 3.6.0
+    */
+    friend json_pointer operator/(const json_pointer& ptr, std::size_t array_index)
+    {
+        return json_pointer(ptr) /= array_index;
+    }
 
-            case value_t::number_float:
-            {
-                oa->write_character(get_cbor_float_prefix(j.m_value.number_float));
-                write_number(j.m_value.number_float);
-                break;
-            }
+    /*!
+    @brief returns the parent of this JSON pointer
 
-            case value_t::string:
-            {
-                // step 1: write control byte and the string length
-                const auto N = j.m_value.string->size();
-                if (N <= 0x17)
-                {
-                    write_number(static_cast<uint8_t>(0x60 + N));
-                }
-                else if (N <= (std::numeric_limits<uint8_t>::max)())
-                {
-                    oa->write_character(to_char_type(0x78));
-                    write_number(static_cast<uint8_t>(N));
-                }
-                else if (N <= (std::numeric_limits<uint16_t>::max)())
-                {
-                    oa->write_character(to_char_type(0x79));
-                    write_number(static_cast<uint16_t>(N));
-                }
-                else if (N <= (std::numeric_limits<uint32_t>::max)())
-                {
-                    oa->write_character(to_char_type(0x7A));
-                    write_number(static_cast<uint32_t>(N));
-                }
-                // LCOV_EXCL_START
-                else if (N <= (std::numeric_limits<uint64_t>::max)())
-                {
-                    oa->write_character(to_char_type(0x7B));
-                    write_number(static_cast<uint64_t>(N));
-                }
-                // LCOV_EXCL_STOP
+    @return parent of this JSON pointer; in case this JSON pointer is the root,
+            the root itself is returned
 
-                // step 2: write the string
-                oa->write_characters(
-                    reinterpret_cast<const CharType*>(j.m_value.string->c_str()),
-                    j.m_value.string->size());
-                break;
-            }
+    @complexity Linear in the length of the JSON pointer.
 
-            case value_t::array:
-            {
-                // step 1: write control byte and the array size
-                const auto N = j.m_value.array->size();
-                if (N <= 0x17)
-                {
-                    write_number(static_cast<uint8_t>(0x80 + N));
-                }
-                else if (N <= (std::numeric_limits<uint8_t>::max)())
-                {
-                    oa->write_character(to_char_type(0x98));
-                    write_number(static_cast<uint8_t>(N));
-                }
-                else if (N <= (std::numeric_limits<uint16_t>::max)())
-                {
-                    oa->write_character(to_char_type(0x99));
-                    write_number(static_cast<uint16_t>(N));
-                }
-                else if (N <= (std::numeric_limits<uint32_t>::max)())
-                {
-                    oa->write_character(to_char_type(0x9A));
-                    write_number(static_cast<uint32_t>(N));
-                }
-                // LCOV_EXCL_START
-                else if (N <= (std::numeric_limits<uint64_t>::max)())
-                {
-                    oa->write_character(to_char_type(0x9B));
-                    write_number(static_cast<uint64_t>(N));
-                }
-                // LCOV_EXCL_STOP
+    @liveexample{The example shows the result of `parent_pointer` for different
+    JSON Pointers.,json_pointer__parent_pointer}
 
-                // step 2: write each element
-                for (const auto& el : *j.m_value.array)
-                {
-                    write_cbor(el);
-                }
-                break;
-            }
+    @since version 3.6.0
+    */
+    json_pointer parent_pointer() const
+    {
+        if (empty())
+        {
+            return *this;
+        }
 
-            case value_t::object:
-            {
-                // step 1: write control byte and the object size
-                const auto N = j.m_value.object->size();
-                if (N <= 0x17)
-                {
-                    write_number(static_cast<uint8_t>(0xA0 + N));
-                }
-                else if (N <= (std::numeric_limits<uint8_t>::max)())
-                {
-                    oa->write_character(to_char_type(0xB8));
-                    write_number(static_cast<uint8_t>(N));
-                }
-                else if (N <= (std::numeric_limits<uint16_t>::max)())
-                {
-                    oa->write_character(to_char_type(0xB9));
-                    write_number(static_cast<uint16_t>(N));
-                }
-                else if (N <= (std::numeric_limits<uint32_t>::max)())
-                {
-                    oa->write_character(to_char_type(0xBA));
-                    write_number(static_cast<uint32_t>(N));
-                }
-                // LCOV_EXCL_START
-                else if (N <= (std::numeric_limits<uint64_t>::max)())
-                {
-                    oa->write_character(to_char_type(0xBB));
-                    write_number(static_cast<uint64_t>(N));
-                }
-                // LCOV_EXCL_STOP
+        json_pointer res = *this;
+        res.pop_back();
+        return res;
+    }
 
-                // step 2: write each element
-                for (const auto& el : *j.m_value.object)
-                {
-                    write_cbor(el.first);
-                    write_cbor(el.second);
-                }
-                break;
-            }
+    /*!
+    @brief remove last reference token
 
-            default:
-                break;
+    @pre not `empty()`
+
+    @liveexample{The example shows the usage of `pop_back`.,json_pointer__pop_back}
+
+    @complexity Constant.
+
+    @throw out_of_range.405 if JSON pointer has no parent
+
+    @since version 3.6.0
+    */
+    void pop_back()
+    {
+        if (JSON_UNLIKELY(empty()))
+        {
+            JSON_THROW(detail::out_of_range::create(405, "JSON pointer has no parent"));
         }
+
+        reference_tokens.pop_back();
     }
 
     /*!
-    @param[in] j  JSON value to serialize
+    @brief return last reference token
+
+    @pre not `empty()`
+    @return last reference token
+
+    @liveexample{The example shows the usage of `back`.,json_pointer__back}
+
+    @complexity Constant.
+
+    @throw out_of_range.405 if JSON pointer has no parent
+
+    @since version 3.6.0
     */
-    void write_msgpack(const BasicJsonType& j)
+    const std::string& back()
     {
-        switch (j.type())
+        if (JSON_UNLIKELY(empty()))
         {
-            case value_t::null: // nil
-            {
-                oa->write_character(to_char_type(0xC0));
-                break;
-            }
+            JSON_THROW(detail::out_of_range::create(405, "JSON pointer has no parent"));
+        }
 
-            case value_t::boolean: // true and false
-            {
-                oa->write_character(j.m_value.boolean
-                                    ? to_char_type(0xC3)
-                                    : to_char_type(0xC2));
-                break;
-            }
+        return reference_tokens.back();
+    }
 
-            case value_t::number_integer:
-            {
-                if (j.m_value.number_integer >= 0)
-                {
-                    // MessagePack does not differentiate between positive
-                    // signed integers and unsigned integers. Therefore, we used
-                    // the code from the value_t::number_unsigned case here.
-                    if (j.m_value.number_unsigned < 128)
-                    {
-                        // positive fixnum
-                        write_number(static_cast<uint8_t>(j.m_value.number_integer));
-                    }
-                    else if (j.m_value.number_unsigned <= (std::numeric_limits<uint8_t>::max)())
-                    {
-                        // uint 8
-                        oa->write_character(to_char_type(0xCC));
-                        write_number(static_cast<uint8_t>(j.m_value.number_integer));
-                    }
-                    else if (j.m_value.number_unsigned <= (std::numeric_limits<uint16_t>::max)())
-                    {
-                        // uint 16
-                        oa->write_character(to_char_type(0xCD));
-                        write_number(static_cast<uint16_t>(j.m_value.number_integer));
-                    }
-                    else if (j.m_value.number_unsigned <= (std::numeric_limits<uint32_t>::max)())
-                    {
-                        // uint 32
-                        oa->write_character(to_char_type(0xCE));
-                        write_number(static_cast<uint32_t>(j.m_value.number_integer));
-                    }
-                    else if (j.m_value.number_unsigned <= (std::numeric_limits<uint64_t>::max)())
-                    {
-                        // uint 64
-                        oa->write_character(to_char_type(0xCF));
-                        write_number(static_cast<uint64_t>(j.m_value.number_integer));
-                    }
-                }
-                else
-                {
-                    if (j.m_value.number_integer >= -32)
-                    {
-                        // negative fixnum
-                        write_number(static_cast<int8_t>(j.m_value.number_integer));
-                    }
-                    else if (j.m_value.number_integer >= (std::numeric_limits<int8_t>::min)() and
-                             j.m_value.number_integer <= (std::numeric_limits<int8_t>::max)())
-                    {
-                        // int 8
-                        oa->write_character(to_char_type(0xD0));
-                        write_number(static_cast<int8_t>(j.m_value.number_integer));
-                    }
-                    else if (j.m_value.number_integer >= (std::numeric_limits<int16_t>::min)() and
-                             j.m_value.number_integer <= (std::numeric_limits<int16_t>::max)())
-                    {
-                        // int 16
-                        oa->write_character(to_char_type(0xD1));
-                        write_number(static_cast<int16_t>(j.m_value.number_integer));
-                    }
-                    else if (j.m_value.number_integer >= (std::numeric_limits<int32_t>::min)() and
-                             j.m_value.number_integer <= (std::numeric_limits<int32_t>::max)())
-                    {
-                        // int 32
-                        oa->write_character(to_char_type(0xD2));
-                        write_number(static_cast<int32_t>(j.m_value.number_integer));
-                    }
-                    else if (j.m_value.number_integer >= (std::numeric_limits<int64_t>::min)() and
-                             j.m_value.number_integer <= (std::numeric_limits<int64_t>::max)())
-                    {
-                        // int 64
-                        oa->write_character(to_char_type(0xD3));
-                        write_number(static_cast<int64_t>(j.m_value.number_integer));
-                    }
-                }
-                break;
-            }
+    /*!
+    @brief append an unescaped token at the end of the reference pointer
 
-            case value_t::number_unsigned:
-            {
-                if (j.m_value.number_unsigned < 128)
-                {
-                    // positive fixnum
-                    write_number(static_cast<uint8_t>(j.m_value.number_integer));
-                }
-                else if (j.m_value.number_unsigned <= (std::numeric_limits<uint8_t>::max)())
-                {
-                    // uint 8
-                    oa->write_character(to_char_type(0xCC));
-                    write_number(static_cast<uint8_t>(j.m_value.number_integer));
-                }
-                else if (j.m_value.number_unsigned <= (std::numeric_limits<uint16_t>::max)())
-                {
-                    // uint 16
-                    oa->write_character(to_char_type(0xCD));
-                    write_number(static_cast<uint16_t>(j.m_value.number_integer));
-                }
-                else if (j.m_value.number_unsigned <= (std::numeric_limits<uint32_t>::max)())
-                {
-                    // uint 32
-                    oa->write_character(to_char_type(0xCE));
-                    write_number(static_cast<uint32_t>(j.m_value.number_integer));
-                }
-                else if (j.m_value.number_unsigned <= (std::numeric_limits<uint64_t>::max)())
-                {
-                    // uint 64
-                    oa->write_character(to_char_type(0xCF));
-                    write_number(static_cast<uint64_t>(j.m_value.number_integer));
-                }
-                break;
-            }
+    @param[in] token  token to add
+
+    @complexity Amortized constant.
+
+    @liveexample{The example shows the result of `push_back` for different
+    JSON Pointers.,json_pointer__push_back}
+
+    @since version 3.6.0
+    */
+    void push_back(const std::string& token)
+    {
+        reference_tokens.push_back(token);
+    }
+
+    /// @copydoc push_back(const std::string&)
+    void push_back(std::string&& token)
+    {
+        reference_tokens.push_back(std::move(token));
+    }
+
+    /*!
+    @brief return whether pointer points to the root document
+
+    @return true iff the JSON pointer points to the root document
+
+    @complexity Constant.
+
+    @exceptionsafety No-throw guarantee: this function never throws exceptions.
+
+    @liveexample{The example shows the result of `empty` for different JSON
+    Pointers.,json_pointer__empty}
+
+    @since version 3.6.0
+    */
+    bool empty() const noexcept
+    {
+        return reference_tokens.empty();
+    }
+
+  private:
+    /*!
+    @param[in] s  reference token to be converted into an array index
+
+    @return integer representation of @a s
+
+    @throw out_of_range.404 if string @a s could not be converted to an integer
+    */
+    static int array_index(const std::string& s)
+    {
+        std::size_t processed_chars = 0;
+        const int res = std::stoi(s, &processed_chars);
+
+        // check if the string was completely read
+        if (JSON_UNLIKELY(processed_chars != s.size()))
+        {
+            JSON_THROW(detail::out_of_range::create(404, "unresolved reference token '" + s + "'"));
+        }
 
-            case value_t::number_float:
-            {
-                oa->write_character(get_msgpack_float_prefix(j.m_value.number_float));
-                write_number(j.m_value.number_float);
-                break;
-            }
+        return res;
+    }
 
-            case value_t::string:
-            {
-                // step 1: write control byte and the string length
-                const auto N = j.m_value.string->size();
-                if (N <= 31)
-                {
-                    // fixstr
-                    write_number(static_cast<uint8_t>(0xA0 | N));
-                }
-                else if (N <= (std::numeric_limits<uint8_t>::max)())
-                {
-                    // str 8
-                    oa->write_character(to_char_type(0xD9));
-                    write_number(static_cast<uint8_t>(N));
-                }
-                else if (N <= (std::numeric_limits<uint16_t>::max)())
-                {
-                    // str 16
-                    oa->write_character(to_char_type(0xDA));
-                    write_number(static_cast<uint16_t>(N));
-                }
-                else if (N <= (std::numeric_limits<uint32_t>::max)())
-                {
-                    // str 32
-                    oa->write_character(to_char_type(0xDB));
-                    write_number(static_cast<uint32_t>(N));
-                }
+    json_pointer top() const
+    {
+        if (JSON_UNLIKELY(empty()))
+        {
+            JSON_THROW(detail::out_of_range::create(405, "JSON pointer has no parent"));
+        }
 
-                // step 2: write the string
-                oa->write_characters(
-                    reinterpret_cast<const CharType*>(j.m_value.string->c_str()),
-                    j.m_value.string->size());
-                break;
-            }
+        json_pointer result = *this;
+        result.reference_tokens = {reference_tokens[0]};
+        return result;
+    }
 
-            case value_t::array:
-            {
-                // step 1: write control byte and the array size
-                const auto N = j.m_value.array->size();
-                if (N <= 15)
-                {
-                    // fixarray
-                    write_number(static_cast<uint8_t>(0x90 | N));
-                }
-                else if (N <= (std::numeric_limits<uint16_t>::max)())
-                {
-                    // array 16
-                    oa->write_character(to_char_type(0xDC));
-                    write_number(static_cast<uint16_t>(N));
-                }
-                else if (N <= (std::numeric_limits<uint32_t>::max)())
-                {
-                    // array 32
-                    oa->write_character(to_char_type(0xDD));
-                    write_number(static_cast<uint32_t>(N));
-                }
+    /*!
+    @brief create and return a reference to the pointed to value
 
-                // step 2: write each element
-                for (const auto& el : *j.m_value.array)
-                {
-                    write_msgpack(el);
-                }
-                break;
-            }
+    @complexity Linear in the number of reference tokens.
 
-            case value_t::object:
+    @throw parse_error.109 if array index is not a number
+    @throw type_error.313 if value cannot be unflattened
+    */
+    BasicJsonType& get_and_create(BasicJsonType& j) const
+    {
+        using size_type = typename BasicJsonType::size_type;
+        auto result = &j;
+
+        // in case no reference tokens exist, return a reference to the JSON value
+        // j which will be overwritten by a primitive value
+        for (const auto& reference_token : reference_tokens)
+        {
+            switch (result->m_type)
             {
-                // step 1: write control byte and the object size
-                const auto N = j.m_value.object->size();
-                if (N <= 15)
-                {
-                    // fixmap
-                    write_number(static_cast<uint8_t>(0x80 | (N & 0xF)));
-                }
-                else if (N <= (std::numeric_limits<uint16_t>::max)())
+                case detail::value_t::null:
                 {
-                    // map 16
-                    oa->write_character(to_char_type(0xDE));
-                    write_number(static_cast<uint16_t>(N));
+                    if (reference_token == "0")
+                    {
+                        // start a new array if reference token is 0
+                        result = &result->operator[](0);
+                    }
+                    else
+                    {
+                        // start a new object otherwise
+                        result = &result->operator[](reference_token);
+                    }
+                    break;
                 }
-                else if (N <= (std::numeric_limits<uint32_t>::max)())
+
+                case detail::value_t::object:
                 {
-                    // map 32
-                    oa->write_character(to_char_type(0xDF));
-                    write_number(static_cast<uint32_t>(N));
+                    // create an entry in the object
+                    result = &result->operator[](reference_token);
+                    break;
                 }
 
-                // step 2: write each element
-                for (const auto& el : *j.m_value.object)
+                case detail::value_t::array:
                 {
-                    write_msgpack(el.first);
-                    write_msgpack(el.second);
+                    // create an entry in the array
+                    JSON_TRY
+                    {
+                        result = &result->operator[](static_cast<size_type>(array_index(reference_token)));
+                    }
+                    JSON_CATCH(std::invalid_argument&)
+                    {
+                        JSON_THROW(detail::parse_error::create(109, 0, "array index '" + reference_token + "' is not a number"));
+                    }
+                    break;
                 }
-                break;
-            }
 
-            default:
-                break;
+                /*
+                The following code is only reached if there exists a reference
+                token _and_ the current value is primitive. In this case, we have
+                an error situation, because primitive values may only occur as
+                single value; that is, with an empty list of reference tokens.
+                */
+                default:
+                    JSON_THROW(detail::type_error::create(313, "invalid value to unflatten"));
+            }
         }
+
+        return *result;
     }
 
     /*!
-    @param[in] j  JSON value to serialize
-    @param[in] use_count   whether to use '#' prefixes (optimized format)
-    @param[in] use_type    whether to use '$' prefixes (optimized format)
-    @param[in] add_prefix  whether prefixes need to be used for this value
+    @brief return a reference to the pointed to value
+
+    @note This version does not throw if a value is not present, but tries to
+          create nested values instead. For instance, calling this function
+          with pointer `"/this/that"` on a null value is equivalent to calling
+          `operator[]("this").operator[]("that")` on that value, effectively
+          changing the null value to an object.
+
+    @param[in] ptr  a JSON value
+
+    @return reference to the JSON value pointed to by the JSON pointer
+
+    @complexity Linear in the length of the JSON pointer.
+
+    @throw parse_error.106   if an array index begins with '0'
+    @throw parse_error.109   if an array index was not a number
+    @throw out_of_range.404  if the JSON pointer can not be resolved
     */
-    void write_ubjson(const BasicJsonType& j, const bool use_count,
-                      const bool use_type, const bool add_prefix = true)
+    BasicJsonType& get_unchecked(BasicJsonType* ptr) const
     {
-        switch (j.type())
+        using size_type = typename BasicJsonType::size_type;
+        for (const auto& reference_token : reference_tokens)
         {
-            case value_t::null:
+            // convert null values to arrays or objects before continuing
+            if (ptr->m_type == detail::value_t::null)
             {
-                if (add_prefix)
+                // check if reference token is a number
+                const bool nums =
+                    std::all_of(reference_token.begin(), reference_token.end(),
+                                [](const char x)
                 {
-                    oa->write_character(to_char_type('Z'));
-                }
-                break;
+                    return x >= '0' and x <= '9';
+                });
+
+                // change value to array for numbers or "-" or to object otherwise
+                *ptr = (nums or reference_token == "-")
+                       ? detail::value_t::array
+                       : detail::value_t::object;
             }
 
-            case value_t::boolean:
+            switch (ptr->m_type)
             {
-                if (add_prefix)
+                case detail::value_t::object:
                 {
-                    oa->write_character(j.m_value.boolean
-                                        ? to_char_type('T')
-                                        : to_char_type('F'));
+                    // use unchecked object access
+                    ptr = &ptr->operator[](reference_token);
+                    break;
                 }
-                break;
-            }
-
-            case value_t::number_integer:
-            {
-                write_number_with_ubjson_prefix(j.m_value.number_integer, add_prefix);
-                break;
-            }
-
-            case value_t::number_unsigned:
-            {
-                write_number_with_ubjson_prefix(j.m_value.number_unsigned, add_prefix);
-                break;
-            }
-
-            case value_t::number_float:
-            {
-                write_number_with_ubjson_prefix(j.m_value.number_float, add_prefix);
-                break;
-            }
 
-            case value_t::string:
-            {
-                if (add_prefix)
+                case detail::value_t::array:
                 {
-                    oa->write_character(to_char_type('S'));
-                }
-                write_number_with_ubjson_prefix(j.m_value.string->size(), true);
-                oa->write_characters(
-                    reinterpret_cast<const CharType*>(j.m_value.string->c_str()),
-                    j.m_value.string->size());
-                break;
+                    // error condition (cf. RFC 6901, Sect. 4)
+                    if (JSON_UNLIKELY(reference_token.size() > 1 and reference_token[0] == '0'))
+                    {
+                        JSON_THROW(detail::parse_error::create(106, 0,
+                                                               "array index '" + reference_token +
+                                                               "' must not begin with '0'"));
+                    }
+
+                    if (reference_token == "-")
+                    {
+                        // explicitly treat "-" as index beyond the end
+                        ptr = &ptr->operator[](ptr->m_value.array->size());
+                    }
+                    else
+                    {
+                        // convert array index to number; unchecked access
+                        JSON_TRY
+                        {
+                            ptr = &ptr->operator[](
+                                static_cast<size_type>(array_index(reference_token)));
+                        }
+                        JSON_CATCH(std::invalid_argument&)
+                        {
+                            JSON_THROW(detail::parse_error::create(109, 0, "array index '" + reference_token + "' is not a number"));
+                        }
+                    }
+                    break;
+                }
+
+                default:
+                    JSON_THROW(detail::out_of_range::create(404, "unresolved reference token '" + reference_token + "'"));
             }
+        }
 
-            case value_t::array:
+        return *ptr;
+    }
+
+    /*!
+    @throw parse_error.106   if an array index begins with '0'
+    @throw parse_error.109   if an array index was not a number
+    @throw out_of_range.402  if the array index '-' is used
+    @throw out_of_range.404  if the JSON pointer can not be resolved
+    */
+    BasicJsonType& get_checked(BasicJsonType* ptr) const
+    {
+        using size_type = typename BasicJsonType::size_type;
+        for (const auto& reference_token : reference_tokens)
+        {
+            switch (ptr->m_type)
             {
-                if (add_prefix)
+                case detail::value_t::object:
                 {
-                    oa->write_character(to_char_type('['));
+                    // note: at performs range check
+                    ptr = &ptr->at(reference_token);
+                    break;
                 }
 
-                bool prefix_required = true;
-                if (use_type and not j.m_value.array->empty())
+                case detail::value_t::array:
                 {
-                    assert(use_count);
-                    const CharType first_prefix = ubjson_prefix(j.front());
-                    const bool same_prefix = std::all_of(j.begin() + 1, j.end(),
-                                                         [this, first_prefix](const BasicJsonType & v)
+                    if (JSON_UNLIKELY(reference_token == "-"))
                     {
-                        return ubjson_prefix(v) == first_prefix;
-                    });
+                        // "-" always fails the range check
+                        JSON_THROW(detail::out_of_range::create(402,
+                                                                "array index '-' (" + std::to_string(ptr->m_value.array->size()) +
+                                                                ") is out of range"));
+                    }
 
-                    if (same_prefix)
+                    // error condition (cf. RFC 6901, Sect. 4)
+                    if (JSON_UNLIKELY(reference_token.size() > 1 and reference_token[0] == '0'))
                     {
-                        prefix_required = false;
-                        oa->write_character(to_char_type('$'));
-                        oa->write_character(first_prefix);
+                        JSON_THROW(detail::parse_error::create(106, 0,
+                                                               "array index '" + reference_token +
+                                                               "' must not begin with '0'"));
                     }
-                }
 
-                if (use_count)
-                {
-                    oa->write_character(to_char_type('#'));
-                    write_number_with_ubjson_prefix(j.m_value.array->size(), true);
+                    // note: at performs range check
+                    JSON_TRY
+                    {
+                        ptr = &ptr->at(static_cast<size_type>(array_index(reference_token)));
+                    }
+                    JSON_CATCH(std::invalid_argument&)
+                    {
+                        JSON_THROW(detail::parse_error::create(109, 0, "array index '" + reference_token + "' is not a number"));
+                    }
+                    break;
                 }
 
-                for (const auto& el : *j.m_value.array)
-                {
-                    write_ubjson(el, use_count, use_type, prefix_required);
-                }
+                default:
+                    JSON_THROW(detail::out_of_range::create(404, "unresolved reference token '" + reference_token + "'"));
+            }
+        }
 
-                if (not use_count)
-                {
-                    oa->write_character(to_char_type(']'));
-                }
+        return *ptr;
+    }
 
-                break;
-            }
+    /*!
+    @brief return a const reference to the pointed to value
 
-            case value_t::object:
+    @param[in] ptr  a JSON value
+
+    @return const reference to the JSON value pointed to by the JSON
+    pointer
+
+    @throw parse_error.106   if an array index begins with '0'
+    @throw parse_error.109   if an array index was not a number
+    @throw out_of_range.402  if the array index '-' is used
+    @throw out_of_range.404  if the JSON pointer can not be resolved
+    */
+    const BasicJsonType& get_unchecked(const BasicJsonType* ptr) const
+    {
+        using size_type = typename BasicJsonType::size_type;
+        for (const auto& reference_token : reference_tokens)
+        {
+            switch (ptr->m_type)
             {
-                if (add_prefix)
+                case detail::value_t::object:
                 {
-                    oa->write_character(to_char_type('{'));
+                    // use unchecked object access
+                    ptr = &ptr->operator[](reference_token);
+                    break;
                 }
 
-                bool prefix_required = true;
-                if (use_type and not j.m_value.object->empty())
+                case detail::value_t::array:
                 {
-                    assert(use_count);
-                    const CharType first_prefix = ubjson_prefix(j.front());
-                    const bool same_prefix = std::all_of(j.begin(), j.end(),
-                                                         [this, first_prefix](const BasicJsonType & v)
+                    if (JSON_UNLIKELY(reference_token == "-"))
                     {
-                        return ubjson_prefix(v) == first_prefix;
-                    });
+                        // "-" cannot be used for const access
+                        JSON_THROW(detail::out_of_range::create(402,
+                                                                "array index '-' (" + std::to_string(ptr->m_value.array->size()) +
+                                                                ") is out of range"));
+                    }
 
-                    if (same_prefix)
+                    // error condition (cf. RFC 6901, Sect. 4)
+                    if (JSON_UNLIKELY(reference_token.size() > 1 and reference_token[0] == '0'))
                     {
-                        prefix_required = false;
-                        oa->write_character(to_char_type('$'));
-                        oa->write_character(first_prefix);
+                        JSON_THROW(detail::parse_error::create(106, 0,
+                                                               "array index '" + reference_token +
+                                                               "' must not begin with '0'"));
                     }
-                }
-
-                if (use_count)
-                {
-                    oa->write_character(to_char_type('#'));
-                    write_number_with_ubjson_prefix(j.m_value.object->size(), true);
-                }
-
-                for (const auto& el : *j.m_value.object)
-                {
-                    write_number_with_ubjson_prefix(el.first.size(), true);
-                    oa->write_characters(
-                        reinterpret_cast<const CharType*>(el.first.c_str()),
-                        el.first.size());
-                    write_ubjson(el.second, use_count, use_type, prefix_required);
-                }
 
-                if (not use_count)
-                {
-                    oa->write_character(to_char_type('}'));
+                    // use unchecked array access
+                    JSON_TRY
+                    {
+                        ptr = &ptr->operator[](
+                            static_cast<size_type>(array_index(reference_token)));
+                    }
+                    JSON_CATCH(std::invalid_argument&)
+                    {
+                        JSON_THROW(detail::parse_error::create(109, 0, "array index '" + reference_token + "' is not a number"));
+                    }
+                    break;
                 }
 
-                break;
+                default:
+                    JSON_THROW(detail::out_of_range::create(404, "unresolved reference token '" + reference_token + "'"));
             }
-
-            default:
-                break;
         }
-    }
 
-  private:
-    //////////
-    // BSON //
-    //////////
+        return *ptr;
+    }
 
     /*!
-    @return The size of a BSON document entry header, including the id marker
-            and the entry name size (and its null-terminator).
+    @throw parse_error.106   if an array index begins with '0'
+    @throw parse_error.109   if an array index was not a number
+    @throw out_of_range.402  if the array index '-' is used
+    @throw out_of_range.404  if the JSON pointer can not be resolved
     */
-    static std::size_t calc_bson_entry_header_size(const string_t& name)
+    const BasicJsonType& get_checked(const BasicJsonType* ptr) const
     {
-        const auto it = name.find(static_cast<typename string_t::value_type>(0));
-        if (JSON_UNLIKELY(it != BasicJsonType::string_t::npos))
+        using size_type = typename BasicJsonType::size_type;
+        for (const auto& reference_token : reference_tokens)
         {
-            JSON_THROW(out_of_range::create(409,
-                                            "BSON key cannot contain code point U+0000 (at byte " + std::to_string(it) + ")"));
-        }
+            switch (ptr->m_type)
+            {
+                case detail::value_t::object:
+                {
+                    // note: at performs range check
+                    ptr = &ptr->at(reference_token);
+                    break;
+                }
 
-        return /*id*/ 1ul + name.size() + /*zero-terminator*/1u;
-    }
+                case detail::value_t::array:
+                {
+                    if (JSON_UNLIKELY(reference_token == "-"))
+                    {
+                        // "-" always fails the range check
+                        JSON_THROW(detail::out_of_range::create(402,
+                                                                "array index '-' (" + std::to_string(ptr->m_value.array->size()) +
+                                                                ") is out of range"));
+                    }
 
-    /*!
-    @brief Writes the given @a element_type and @a name to the output adapter
-    */
-    void write_bson_entry_header(const string_t& name,
-                                 const std::uint8_t element_type)
-    {
-        oa->write_character(to_char_type(element_type)); // boolean
-        oa->write_characters(
-            reinterpret_cast<const CharType*>(name.c_str()),
-            name.size() + 1u);
-    }
+                    // error condition (cf. RFC 6901, Sect. 4)
+                    if (JSON_UNLIKELY(reference_token.size() > 1 and reference_token[0] == '0'))
+                    {
+                        JSON_THROW(detail::parse_error::create(106, 0,
+                                                               "array index '" + reference_token +
+                                                               "' must not begin with '0'"));
+                    }
 
-    /*!
-    @brief Writes a BSON element with key @a name and boolean value @a value
-    */
-    void write_bson_boolean(const string_t& name,
-                            const bool value)
-    {
-        write_bson_entry_header(name, 0x08);
-        oa->write_character(value ? to_char_type(0x01) : to_char_type(0x00));
-    }
+                    // note: at performs range check
+                    JSON_TRY
+                    {
+                        ptr = &ptr->at(static_cast<size_type>(array_index(reference_token)));
+                    }
+                    JSON_CATCH(std::invalid_argument&)
+                    {
+                        JSON_THROW(detail::parse_error::create(109, 0, "array index '" + reference_token + "' is not a number"));
+                    }
+                    break;
+                }
 
-    /*!
-    @brief Writes a BSON element with key @a name and double value @a value
-    */
-    void write_bson_double(const string_t& name,
-                           const double value)
-    {
-        write_bson_entry_header(name, 0x01);
-        write_number<double, true>(value);
-    }
+                default:
+                    JSON_THROW(detail::out_of_range::create(404, "unresolved reference token '" + reference_token + "'"));
+            }
+        }
 
-    /*!
-    @return The size of the BSON-encoded string in @a value
-    */
-    static std::size_t calc_bson_string_size(const string_t& value)
-    {
-        return sizeof(std::int32_t) + value.size() + 1ul;
+        return *ptr;
     }
 
     /*!
-    @brief Writes a BSON element with key @a name and string value @a value
-    */
-    void write_bson_string(const string_t& name,
-                           const string_t& value)
-    {
-        write_bson_entry_header(name, 0x02);
+    @brief split the string input to reference tokens
 
-        write_number<std::int32_t, true>(static_cast<std::int32_t>(value.size() + 1ul));
-        oa->write_characters(
-            reinterpret_cast<const CharType*>(value.c_str()),
-            value.size() + 1);
-    }
+    @note This function is only called by the json_pointer constructor.
+          All exceptions below are documented there.
 
-    /*!
-    @brief Writes a BSON element with key @a name and null value
+    @throw parse_error.107  if the pointer is not empty or begins with '/'
+    @throw parse_error.108  if character '~' is not followed by '0' or '1'
     */
-    void write_bson_null(const string_t& name)
+    static std::vector<std::string> split(const std::string& reference_string)
     {
-        write_bson_entry_header(name, 0x0A);
-    }
+        std::vector<std::string> result;
 
-    /*!
-    @return The size of the BSON-encoded integer @a value
-    */
-    static std::size_t calc_bson_integer_size(const std::int64_t value)
-    {
-        if ((std::numeric_limits<std::int32_t>::min)() <= value and value <= (std::numeric_limits<std::int32_t>::max)())
-        {
-            return sizeof(std::int32_t);
-        }
-        else
+        // special case: empty reference string -> no reference tokens
+        if (reference_string.empty())
         {
-            return sizeof(std::int64_t);
+            return result;
         }
-    }
 
-    /*!
-    @brief Writes a BSON element with key @a name and integer @a value
-    */
-    void write_bson_integer(const string_t& name,
-                            const std::int64_t value)
-    {
-        if ((std::numeric_limits<std::int32_t>::min)() <= value and value <= (std::numeric_limits<std::int32_t>::max)())
+        // check if nonempty reference string begins with slash
+        if (JSON_UNLIKELY(reference_string[0] != '/'))
         {
-            write_bson_entry_header(name, 0x10); // int32
-            write_number<std::int32_t, true>(static_cast<std::int32_t>(value));
+            JSON_THROW(detail::parse_error::create(107, 1,
+                                                   "JSON pointer must be empty or begin with '/' - was: '" +
+                                                   reference_string + "'"));
         }
-        else
+
+        // extract the reference tokens:
+        // - slash: position of the last read slash (or end of string)
+        // - start: position after the previous slash
+        for (
+            // search for the first slash after the first character
+            std::size_t slash = reference_string.find_first_of('/', 1),
+            // set the beginning of the first reference token
+            start = 1;
+            // we can stop if start == 0 (if slash == std::string::npos)
+            start != 0;
+            // set the beginning of the next reference token
+            // (will eventually be 0 if slash == std::string::npos)
+            start = (slash == std::string::npos) ? 0 : slash + 1,
+            // find next slash
+            slash = reference_string.find_first_of('/', start))
         {
-            write_bson_entry_header(name, 0x12); // int64
-            write_number<std::int64_t, true>(static_cast<std::int64_t>(value));
-        }
-    }
+            // use the text between the beginning of the reference token
+            // (start) and the last slash (slash).
+            auto reference_token = reference_string.substr(start, slash - start);
 
-    /*!
-    @return The size of the BSON-encoded unsigned integer in @a j
-    */
-    static constexpr std::size_t calc_bson_unsigned_size(const std::uint64_t value) noexcept
-    {
-        return (value <= static_cast<std::uint64_t>((std::numeric_limits<std::int32_t>::max)()))
-               ? sizeof(std::int32_t)
-               : sizeof(std::int64_t);
-    }
+            // check reference tokens are properly escaped
+            for (std::size_t pos = reference_token.find_first_of('~');
+                    pos != std::string::npos;
+                    pos = reference_token.find_first_of('~', pos + 1))
+            {
+                assert(reference_token[pos] == '~');
 
-    /*!
-    @brief Writes a BSON element with key @a name and unsigned @a value
-    */
-    void write_bson_unsigned(const string_t& name,
-                             const std::uint64_t value)
-    {
-        if (value <= static_cast<std::uint64_t>((std::numeric_limits<std::int32_t>::max)()))
-        {
-            write_bson_entry_header(name, 0x10 /* int32 */);
-            write_number<std::int32_t, true>(static_cast<std::int32_t>(value));
-        }
-        else if (value <= static_cast<std::uint64_t>((std::numeric_limits<std::int64_t>::max)()))
-        {
-            write_bson_entry_header(name, 0x12 /* int64 */);
-            write_number<std::int64_t, true>(static_cast<std::int64_t>(value));
-        }
-        else
-        {
-            JSON_THROW(out_of_range::create(407, "integer number " + std::to_string(value) + " cannot be represented by BSON as it does not fit int64"));
+                // ~ must be followed by 0 or 1
+                if (JSON_UNLIKELY(pos == reference_token.size() - 1 or
+                                  (reference_token[pos + 1] != '0' and
+                                   reference_token[pos + 1] != '1')))
+                {
+                    JSON_THROW(detail::parse_error::create(108, 0, "escape character '~' must be followed with '0' or '1'"));
+                }
+            }
+
+            // finally, store the reference token
+            unescape(reference_token);
+            result.push_back(reference_token);
         }
-    }
 
-    /*!
-    @brief Writes a BSON element with key @a name and object @a value
-    */
-    void write_bson_object_entry(const string_t& name,
-                                 const typename BasicJsonType::object_t& value)
-    {
-        write_bson_entry_header(name, 0x03); // object
-        write_bson_object(value);
+        return result;
     }
 
     /*!
-    @return The size of the BSON-encoded array @a value
-    */
-    static std::size_t calc_bson_array_size(const typename BasicJsonType::array_t& value)
-    {
-        std::size_t embedded_document_size = 0ul;
-        std::size_t array_index = 0ul;
+    @brief replace all occurrences of a substring by another string
 
-        for (const auto& el : value)
-        {
-            embedded_document_size += calc_bson_element_size(std::to_string(array_index++), el);
-        }
+    @param[in,out] s  the string to manipulate; changed so that all
+                   occurrences of @a f are replaced with @a t
+    @param[in]     f  the substring to replace with @a t
+    @param[in]     t  the string to replace @a f
 
-        return sizeof(std::int32_t) + embedded_document_size + 1ul;
-    }
+    @pre The search string @a f must not be empty. **This precondition is
+    enforced with an assertion.**
 
-    /*!
-    @brief Writes a BSON element with key @a name and array @a value
+    @since version 2.0.0
     */
-    void write_bson_array(const string_t& name,
-                          const typename BasicJsonType::array_t& value)
+    static void replace_substring(std::string& s, const std::string& f,
+                                  const std::string& t)
     {
-        write_bson_entry_header(name, 0x04); // array
-        write_number<std::int32_t, true>(static_cast<std::int32_t>(calc_bson_array_size(value)));
-
-        std::size_t array_index = 0ul;
+        assert(not f.empty());
+        for (auto pos = s.find(f);                // find first occurrence of f
+                pos != std::string::npos;         // make sure f was found
+                s.replace(pos, f.size(), t),      // replace with t, and
+                pos = s.find(f, pos + t.size()))  // find next occurrence of f
+        {}
+    }
 
-        for (const auto& el : value)
-        {
-            write_bson_element(std::to_string(array_index++), el);
-        }
+    /// escape "~" to "~0" and "/" to "~1"
+    static std::string escape(std::string s)
+    {
+        replace_substring(s, "~", "~0");
+        replace_substring(s, "/", "~1");
+        return s;
+    }
 
-        oa->write_character(to_char_type(0x00));
+    /// unescape "~1" to tilde and "~0" to slash (order is important!)
+    static void unescape(std::string& s)
+    {
+        replace_substring(s, "~1", "/");
+        replace_substring(s, "~0", "~");
     }
 
     /*!
-    @brief Calculates the size necessary to serialize the JSON value @a j with its @a name
-    @return The calculated size for the BSON document entry for @a j with the given @a name.
+    @param[in] reference_string  the reference string to the current value
+    @param[in] value             the value to consider
+    @param[in,out] result        the result object to insert values to
+
+    @note Empty objects or arrays are flattened to `null`.
     */
-    static std::size_t calc_bson_element_size(const string_t& name,
-            const BasicJsonType& j)
+    static void flatten(const std::string& reference_string,
+                        const BasicJsonType& value,
+                        BasicJsonType& result)
     {
-        const auto header_size = calc_bson_entry_header_size(name);
-        switch (j.type())
+        switch (value.m_type)
         {
-            case value_t::object:
-                return header_size + calc_bson_object_size(*j.m_value.object);
-
-            case value_t::array:
-                return header_size + calc_bson_array_size(*j.m_value.array);
-
-            case value_t::boolean:
-                return header_size + 1ul;
-
-            case value_t::number_float:
-                return header_size + 8ul;
-
-            case value_t::number_integer:
-                return header_size + calc_bson_integer_size(j.m_value.number_integer);
-
-            case value_t::number_unsigned:
-                return header_size + calc_bson_unsigned_size(j.m_value.number_unsigned);
-
-            case value_t::string:
-                return header_size + calc_bson_string_size(*j.m_value.string);
+            case detail::value_t::array:
+            {
+                if (value.m_value.array->empty())
+                {
+                    // flatten empty array as null
+                    result[reference_string] = nullptr;
+                }
+                else
+                {
+                    // iterate array and use index as reference string
+                    for (std::size_t i = 0; i < value.m_value.array->size(); ++i)
+                    {
+                        flatten(reference_string + "/" + std::to_string(i),
+                                value.m_value.array->operator[](i), result);
+                    }
+                }
+                break;
+            }
 
-            case value_t::null:
-                return header_size + 0ul;
+            case detail::value_t::object:
+            {
+                if (value.m_value.object->empty())
+                {
+                    // flatten empty object as null
+                    result[reference_string] = nullptr;
+                }
+                else
+                {
+                    // iterate object and use keys as reference string
+                    for (const auto& element : *value.m_value.object)
+                    {
+                        flatten(reference_string + "/" + escape(element.first), element.second, result);
+                    }
+                }
+                break;
+            }
 
-            // LCOV_EXCL_START
             default:
-                assert(false);
-                return 0ul;
-                // LCOV_EXCL_STOP
-        };
+            {
+                // add primitive value with its reference string
+                result[reference_string] = value;
+                break;
+            }
+        }
     }
 
     /*!
-    @brief Serializes the JSON value @a j to BSON and associates it with the
-           key @a name.
-    @param name The name to associate with the JSON entity @a j within the
-                current BSON document
-    @return The size of the BSON entry
+    @param[in] value  flattened JSON
+
+    @return unflattened JSON
+
+    @throw parse_error.109 if array index is not a number
+    @throw type_error.314  if value is not an object
+    @throw type_error.315  if object values are not primitive
+    @throw type_error.313  if value cannot be unflattened
     */
-    void write_bson_element(const string_t& name,
-                            const BasicJsonType& j)
+    static BasicJsonType
+    unflatten(const BasicJsonType& value)
     {
-        switch (j.type())
+        if (JSON_UNLIKELY(not value.is_object()))
         {
-            case value_t::object:
-                return write_bson_object_entry(name, *j.m_value.object);
-
-            case value_t::array:
-                return write_bson_array(name, *j.m_value.array);
+            JSON_THROW(detail::type_error::create(314, "only objects can be unflattened"));
+        }
 
-            case value_t::boolean:
-                return write_bson_boolean(name, j.m_value.boolean);
+        BasicJsonType result;
 
-            case value_t::number_float:
-                return write_bson_double(name, j.m_value.number_float);
+        // iterate the JSON object values
+        for (const auto& element : *value.m_value.object)
+        {
+            if (JSON_UNLIKELY(not element.second.is_primitive()))
+            {
+                JSON_THROW(detail::type_error::create(315, "values in object must be primitive"));
+            }
 
-            case value_t::number_integer:
-                return write_bson_integer(name, j.m_value.number_integer);
+            // assign value to reference pointed to by JSON pointer; Note that if
+            // the JSON pointer is "" (i.e., points to the whole value), function
+            // get_and_create returns a reference to result itself. An assignment
+            // will then create a primitive value.
+            json_pointer(element.first).get_and_create(result) = element.second;
+        }
 
-            case value_t::number_unsigned:
-                return write_bson_unsigned(name, j.m_value.number_unsigned);
+        return result;
+    }
 
-            case value_t::string:
-                return write_bson_string(name, *j.m_value.string);
+    /*!
+    @brief compares two JSON pointers for equality
 
-            case value_t::null:
-                return write_bson_null(name);
+    @param[in] lhs  JSON pointer to compare
+    @param[in] rhs  JSON pointer to compare
+    @return whether @a lhs is equal to @a rhs
 
-            // LCOV_EXCL_START
-            default:
-                assert(false);
-                return;
-                // LCOV_EXCL_STOP
-        };
-    }
+    @complexity Linear in the length of the JSON pointer
 
-    /*!
-    @brief Calculates the size of the BSON serialization of the given
-           JSON-object @a j.
-    @param[in] j  JSON value to serialize
-    @pre       j.type() == value_t::object
+    @exceptionsafety No-throw guarantee: this function never throws exceptions.
     */
-    static std::size_t calc_bson_object_size(const typename BasicJsonType::object_t& value)
+    friend bool operator==(json_pointer const& lhs,
+                           json_pointer const& rhs) noexcept
     {
-        std::size_t document_size = std::accumulate(value.begin(), value.end(), 0ul,
-                                    [](size_t result, const typename BasicJsonType::object_t::value_type & el)
-        {
-            return result += calc_bson_element_size(el.first, el.second);
-        });
-
-        return sizeof(std::int32_t) + document_size + 1ul;
+        return lhs.reference_tokens == rhs.reference_tokens;
     }
 
     /*!
-    @param[in] j  JSON value to serialize
-    @pre       j.type() == value_t::object
-    */
-    void write_bson_object(const typename BasicJsonType::object_t& value)
-    {
-        write_number<std::int32_t, true>(static_cast<std::int32_t>(calc_bson_object_size(value)));
-
-        for (const auto& el : value)
-        {
-            write_bson_element(el.first, el.second);
-        }
+    @brief compares two JSON pointers for inequality
 
-        oa->write_character(to_char_type(0x00));
-    }
+    @param[in] lhs  JSON pointer to compare
+    @param[in] rhs  JSON pointer to compare
+    @return whether @a lhs is not equal @a rhs
 
-    //////////
-    // CBOR //
-    //////////
+    @complexity Linear in the length of the JSON pointer
 
-    static constexpr CharType get_cbor_float_prefix(float /*unused*/)
+    @exceptionsafety No-throw guarantee: this function never throws exceptions.
+    */
+    friend bool operator!=(json_pointer const& lhs,
+                           json_pointer const& rhs) noexcept
     {
-        return to_char_type(0xFA);  // Single-Precision Float
+        return not (lhs == rhs);
     }
 
-    static constexpr CharType get_cbor_float_prefix(double /*unused*/)
-    {
-        return to_char_type(0xFB);  // Double-Precision Float
-    }
+    /// the reference tokens
+    std::vector<std::string> reference_tokens;
+};
+}  // namespace nlohmann
 
-    /////////////
-    // MsgPack //
-    /////////////
+// #include <nlohmann/detail/json_ref.hpp>
 
-    static constexpr CharType get_msgpack_float_prefix(float /*unused*/)
-    {
-        return to_char_type(0xCA);  // float 32
-    }
 
-    static constexpr CharType get_msgpack_float_prefix(double /*unused*/)
-    {
-        return to_char_type(0xCB);  // float 64
-    }
+#include <initializer_list>
+#include <utility>
 
-    ////////////
-    // UBJSON //
-    ////////////
+// #include <nlohmann/detail/meta/type_traits.hpp>
 
-    // UBJSON: write number (floating point)
-    template<typename NumberType, typename std::enable_if<
-                 std::is_floating_point<NumberType>::value, int>::type = 0>
-    void write_number_with_ubjson_prefix(const NumberType n,
-                                         const bool add_prefix)
-    {
-        if (add_prefix)
-        {
-            oa->write_character(get_ubjson_float_prefix(n));
-        }
-        write_number(n);
-    }
 
-    // UBJSON: write number (unsigned integer)
-    template<typename NumberType, typename std::enable_if<
-                 std::is_unsigned<NumberType>::value, int>::type = 0>
-    void write_number_with_ubjson_prefix(const NumberType n,
-                                         const bool add_prefix)
-    {
-        if (n <= static_cast<uint64_t>((std::numeric_limits<int8_t>::max)()))
-        {
-            if (add_prefix)
-            {
-                oa->write_character(to_char_type('i'));  // int8
-            }
-            write_number(static_cast<uint8_t>(n));
-        }
-        else if (n <= (std::numeric_limits<uint8_t>::max)())
-        {
-            if (add_prefix)
-            {
-                oa->write_character(to_char_type('U'));  // uint8
-            }
-            write_number(static_cast<uint8_t>(n));
-        }
-        else if (n <= static_cast<uint64_t>((std::numeric_limits<int16_t>::max)()))
-        {
-            if (add_prefix)
-            {
-                oa->write_character(to_char_type('I'));  // int16
-            }
-            write_number(static_cast<int16_t>(n));
-        }
-        else if (n <= static_cast<uint64_t>((std::numeric_limits<int32_t>::max)()))
-        {
-            if (add_prefix)
-            {
-                oa->write_character(to_char_type('l'));  // int32
-            }
-            write_number(static_cast<int32_t>(n));
-        }
-        else if (n <= static_cast<uint64_t>((std::numeric_limits<int64_t>::max)()))
-        {
-            if (add_prefix)
-            {
-                oa->write_character(to_char_type('L'));  // int64
-            }
-            write_number(static_cast<int64_t>(n));
-        }
-        else
-        {
-            JSON_THROW(out_of_range::create(407, "integer number " + std::to_string(n) + " cannot be represented by UBJSON as it does not fit int64"));
-        }
-    }
+namespace nlohmann
+{
+namespace detail
+{
+template<typename BasicJsonType>
+class json_ref
+{
+  public:
+    using value_type = BasicJsonType;
 
-    // UBJSON: write number (signed integer)
-    template<typename NumberType, typename std::enable_if<
-                 std::is_signed<NumberType>::value and
-                 not std::is_floating_point<NumberType>::value, int>::type = 0>
-    void write_number_with_ubjson_prefix(const NumberType n,
-                                         const bool add_prefix)
-    {
-        if ((std::numeric_limits<int8_t>::min)() <= n and n <= (std::numeric_limits<int8_t>::max)())
-        {
-            if (add_prefix)
-            {
-                oa->write_character(to_char_type('i'));  // int8
-            }
-            write_number(static_cast<int8_t>(n));
-        }
-        else if (static_cast<int64_t>((std::numeric_limits<uint8_t>::min)()) <= n and n <= static_cast<int64_t>((std::numeric_limits<uint8_t>::max)()))
-        {
-            if (add_prefix)
-            {
-                oa->write_character(to_char_type('U'));  // uint8
-            }
-            write_number(static_cast<uint8_t>(n));
-        }
-        else if ((std::numeric_limits<int16_t>::min)() <= n and n <= (std::numeric_limits<int16_t>::max)())
-        {
-            if (add_prefix)
-            {
-                oa->write_character(to_char_type('I'));  // int16
-            }
-            write_number(static_cast<int16_t>(n));
-        }
-        else if ((std::numeric_limits<int32_t>::min)() <= n and n <= (std::numeric_limits<int32_t>::max)())
-        {
-            if (add_prefix)
-            {
-                oa->write_character(to_char_type('l'));  // int32
-            }
-            write_number(static_cast<int32_t>(n));
-        }
-        else if ((std::numeric_limits<int64_t>::min)() <= n and n <= (std::numeric_limits<int64_t>::max)())
-        {
-            if (add_prefix)
-            {
-                oa->write_character(to_char_type('L'));  // int64
-            }
-            write_number(static_cast<int64_t>(n));
-        }
-        // LCOV_EXCL_START
-        else
+    json_ref(value_type&& value)
+        : owned_value(std::move(value)), value_ref(&owned_value), is_rvalue(true)
+    {}
+
+    json_ref(const value_type& value)
+        : value_ref(const_cast<value_type*>(&value)), is_rvalue(false)
+    {}
+
+    json_ref(std::initializer_list<json_ref> init)
+        : owned_value(init), value_ref(&owned_value), is_rvalue(true)
+    {}
+
+    template <
+        class... Args,
+        enable_if_t<std::is_constructible<value_type, Args...>::value, int> = 0 >
+    json_ref(Args && ... args)
+        : owned_value(std::forward<Args>(args)...), value_ref(&owned_value),
+          is_rvalue(true) {}
+
+    // class should be movable only
+    json_ref(json_ref&&) = default;
+    json_ref(const json_ref&) = delete;
+    json_ref& operator=(const json_ref&) = delete;
+    json_ref& operator=(json_ref&&) = delete;
+    ~json_ref() = default;
+
+    value_type moved_or_copied() const
+    {
+        if (is_rvalue)
         {
-            JSON_THROW(out_of_range::create(407, "integer number " + std::to_string(n) + " cannot be represented by UBJSON as it does not fit int64"));
+            return std::move(*value_ref);
         }
-        // LCOV_EXCL_STOP
+        return *value_ref;
     }
 
-    /*!
-    @brief determine the type prefix of container values
+    value_type const& operator*() const
+    {
+        return *static_cast<value_type const*>(value_ref);
+    }
 
-    @note This function does not need to be 100% accurate when it comes to
-          integer limits. In case a number exceeds the limits of int64_t,
-          this will be detected by a later call to function
-          write_number_with_ubjson_prefix. Therefore, we return 'L' for any
-          value that does not fit the previous limits.
-    */
-    CharType ubjson_prefix(const BasicJsonType& j) const noexcept
+    value_type const* operator->() const
     {
-        switch (j.type())
-        {
-            case value_t::null:
-                return 'Z';
+        return static_cast<value_type const*>(value_ref);
+    }
 
-            case value_t::boolean:
-                return j.m_value.boolean ? 'T' : 'F';
+  private:
+    mutable value_type owned_value = nullptr;
+    value_type* value_ref = nullptr;
+    const bool is_rvalue;
+};
+}  // namespace detail
+}  // namespace nlohmann
 
-            case value_t::number_integer:
-            {
-                if ((std::numeric_limits<int8_t>::min)() <= j.m_value.number_integer and j.m_value.number_integer <= (std::numeric_limits<int8_t>::max)())
-                {
-                    return 'i';
-                }
-                if ((std::numeric_limits<uint8_t>::min)() <= j.m_value.number_integer and j.m_value.number_integer <= (std::numeric_limits<uint8_t>::max)())
-                {
-                    return 'U';
-                }
-                if ((std::numeric_limits<int16_t>::min)() <= j.m_value.number_integer and j.m_value.number_integer <= (std::numeric_limits<int16_t>::max)())
-                {
-                    return 'I';
-                }
-                if ((std::numeric_limits<int32_t>::min)() <= j.m_value.number_integer and j.m_value.number_integer <= (std::numeric_limits<int32_t>::max)())
-                {
-                    return 'l';
-                }
-                // no check and assume int64_t (see note above)
-                return 'L';
-            }
+// #include <nlohmann/detail/macro_scope.hpp>
 
-            case value_t::number_unsigned:
-            {
-                if (j.m_value.number_unsigned <= (std::numeric_limits<int8_t>::max)())
-                {
-                    return 'i';
-                }
-                if (j.m_value.number_unsigned <= (std::numeric_limits<uint8_t>::max)())
-                {
-                    return 'U';
-                }
-                if (j.m_value.number_unsigned <= (std::numeric_limits<int16_t>::max)())
-                {
-                    return 'I';
-                }
-                if (j.m_value.number_unsigned <= (std::numeric_limits<int32_t>::max)())
-                {
-                    return 'l';
-                }
-                // no check and assume int64_t (see note above)
-                return 'L';
-            }
+// #include <nlohmann/detail/meta/cpp_future.hpp>
 
-            case value_t::number_float:
-                return get_ubjson_float_prefix(j.m_value.number_float);
+// #include <nlohmann/detail/meta/type_traits.hpp>
 
-            case value_t::string:
-                return 'S';
+// #include <nlohmann/detail/output/binary_writer.hpp>
 
-            case value_t::array:
-                return '[';
 
-            case value_t::object:
-                return '{';
+#include <algorithm> // reverse
+#include <array> // array
+#include <cstdint> // uint8_t, uint16_t, uint32_t, uint64_t
+#include <cstring> // memcpy
+#include <limits> // numeric_limits
+#include <string> // string
 
-            default:  // discarded values
-                return 'N';
-        }
-    }
+// #include <nlohmann/detail/input/binary_reader.hpp>
 
-    static constexpr CharType get_ubjson_float_prefix(float /*unused*/)
+// #include <nlohmann/detail/output/output_adapters.hpp>
+
+
+#include <algorithm> // copy
+#include <cstddef> // size_t
+#include <ios> // streamsize
+#include <iterator> // back_inserter
+#include <memory> // shared_ptr, make_shared
+#include <ostream> // basic_ostream
+#include <string> // basic_string
+#include <vector> // vector
+
+namespace nlohmann
+{
+namespace detail
+{
+/// abstract output adapter interface
+template<typename CharType> struct output_adapter_protocol
+{
+    virtual void write_character(CharType c) = 0;
+    virtual void write_characters(const CharType* s, std::size_t length) = 0;
+    virtual ~output_adapter_protocol() = default;
+};
+
+/// a type to simplify interfaces
+template<typename CharType>
+using output_adapter_t = std::shared_ptr<output_adapter_protocol<CharType>>;
+
+/// output adapter for byte vectors
+template<typename CharType>
+class output_vector_adapter : public output_adapter_protocol<CharType>
+{
+  public:
+    explicit output_vector_adapter(std::vector<CharType>& vec) noexcept
+        : v(vec)
+    {}
+
+    void write_character(CharType c) override
     {
-        return 'd';  // float 32
+        v.push_back(c);
     }
 
-    static constexpr CharType get_ubjson_float_prefix(double /*unused*/)
+    void write_characters(const CharType* s, std::size_t length) override
     {
-        return 'D';  // float 64
+        std::copy(s, s + length, std::back_inserter(v));
     }
 
-    ///////////////////////
-    // Utility functions //
-    ///////////////////////
+  private:
+    std::vector<CharType>& v;
+};
 
-    /*
-    @brief write a number to output input
-    @param[in] n number of type @a NumberType
-    @tparam NumberType the type of the number
-    @tparam OutputIsLittleEndian Set to true if output data is
-                                 required to be little endian
+/// output adapter for output streams
+template<typename CharType>
+class output_stream_adapter : public output_adapter_protocol<CharType>
+{
+  public:
+    explicit output_stream_adapter(std::basic_ostream<CharType>& s) noexcept
+        : stream(s)
+    {}
 
-    @note This function needs to respect the system's endianess, because bytes
-          in CBOR, MessagePack, and UBJSON are stored in network order (big
-          endian) and therefore need reordering on little endian systems.
-    */
-    template<typename NumberType, bool OutputIsLittleEndian = false>
-    void write_number(const NumberType n)
+    void write_character(CharType c) override
     {
-        // step 1: write number to array of length NumberType
-        std::array<CharType, sizeof(NumberType)> vec;
-        std::memcpy(vec.data(), &n, sizeof(NumberType));
-
-        // step 2: write array to output (with possible reordering)
-        if (is_little_endian and not OutputIsLittleEndian)
-        {
-            // reverse byte order prior to conversion if necessary
-            std::reverse(vec.begin(), vec.end());
-        }
-
-        oa->write_characters(vec.data(), sizeof(NumberType));
+        stream.put(c);
     }
 
-  public:
-    // The following to_char_type functions are implement the conversion
-    // between uint8_t and CharType. In case CharType is not unsigned,
-    // such a conversion is required to allow values greater than 128.
-    // See <https://github.com/nlohmann/json/issues/1286> for a discussion.
-    template < typename C = CharType,
-               enable_if_t < std::is_signed<C>::value and std::is_signed<char>::value > * = nullptr >
-    static constexpr CharType to_char_type(std::uint8_t x) noexcept
+    void write_characters(const CharType* s, std::size_t length) override
     {
-        return *reinterpret_cast<char*>(&x);
+        stream.write(s, static_cast<std::streamsize>(length));
     }
 
-    template < typename C = CharType,
-               enable_if_t < std::is_signed<C>::value and std::is_unsigned<char>::value > * = nullptr >
-    static CharType to_char_type(std::uint8_t x) noexcept
+  private:
+    std::basic_ostream<CharType>& stream;
+};
+
+/// output adapter for basic_string
+template<typename CharType, typename StringType = std::basic_string<CharType>>
+class output_string_adapter : public output_adapter_protocol<CharType>
+{
+  public:
+    explicit output_string_adapter(StringType& s) noexcept
+        : str(s)
+    {}
+
+    void write_character(CharType c) override
     {
-        static_assert(sizeof(std::uint8_t) == sizeof(CharType), "size of CharType must be equal to std::uint8_t");
-        static_assert(std::is_pod<CharType>::value, "CharType must be POD");
-        CharType result;
-        std::memcpy(&result, &x, sizeof(x));
-        return result;
+        str.push_back(c);
     }
 
-    template<typename C = CharType,
-             enable_if_t<std::is_unsigned<C>::value>* = nullptr>
-    static constexpr CharType to_char_type(std::uint8_t x) noexcept
+    void write_characters(const CharType* s, std::size_t length) override
     {
-        return x;
+        str.append(s, length);
     }
 
-    template < typename InputCharType, typename C = CharType,
-               enable_if_t <
-                   std::is_signed<C>::value and
-                   std::is_signed<char>::value and
-                   std::is_same<char, typename std::remove_cv<InputCharType>::type>::value
-                   > * = nullptr >
-    static constexpr CharType to_char_type(InputCharType x) noexcept
+  private:
+    StringType& str;
+};
+
+template<typename CharType, typename StringType = std::basic_string<CharType>>
+class output_adapter
+{
+  public:
+    output_adapter(std::vector<CharType>& vec)
+        : oa(std::make_shared<output_vector_adapter<CharType>>(vec)) {}
+
+    output_adapter(std::basic_ostream<CharType>& s)
+        : oa(std::make_shared<output_stream_adapter<CharType>>(s)) {}
+
+    output_adapter(StringType& s)
+        : oa(std::make_shared<output_string_adapter<CharType, StringType>>(s)) {}
+
+    operator output_adapter_t<CharType>()
     {
-        return x;
+        return oa;
     }
 
   private:
-    /// whether we can assume little endianess
-    const bool is_little_endian = binary_reader<BasicJsonType>::little_endianess();
-
-    /// the output
     output_adapter_t<CharType> oa = nullptr;
 };
 }  // namespace detail
 }  // namespace nlohmann
 
-// #include <nlohmann/detail/output/serializer.hpp>
-
-
-#include <algorithm> // reverse, remove, fill, find, none_of
-#include <array> // array
-#include <cassert> // assert
-#include <ciso646> // and, or
-#include <clocale> // localeconv, lconv
-#include <cmath> // labs, isfinite, isnan, signbit
-#include <cstddef> // size_t, ptrdiff_t
-#include <cstdint> // uint8_t
-#include <cstdio> // snprintf
-#include <limits> // numeric_limits
-#include <string> // string
-#include <type_traits> // is_same
-
-// #include <nlohmann/detail/exceptions.hpp>
-
-// #include <nlohmann/detail/conversions/to_chars.hpp>
-
-
-#include <cassert> // assert
-#include <ciso646> // or, and, not
-#include <cmath>   // signbit, isfinite
-#include <cstdint> // intN_t, uintN_t
-#include <cstring> // memcpy, memmove
 
 namespace nlohmann
 {
 namespace detail
 {
+///////////////////
+// binary writer //
+///////////////////
 
 /*!
-@brief implements the Grisu2 algorithm for binary to decimal floating-point
-conversion.
-
-This implementation is a slightly modified version of the reference
-implementation which may be obtained from
-http://florian.loitsch.com/publications (bench.tar.gz).
-
-The code is distributed under the MIT license, Copyright (c) 2009 Florian Loitsch.
-
-For a detailed description of the algorithm see:
-
-[1] Loitsch, "Printing Floating-Point Numbers Quickly and Accurately with
-    Integers", Proceedings of the ACM SIGPLAN 2010 Conference on Programming
-    Language Design and Implementation, PLDI 2010
-[2] Burger, Dybvig, "Printing Floating-Point Numbers Quickly and Accurately",
-    Proceedings of the ACM SIGPLAN 1996 Conference on Programming Language
-    Design and Implementation, PLDI 1996
+@brief serialization to CBOR and MessagePack values
 */
-namespace dtoa_impl
-{
-
-template <typename Target, typename Source>
-Target reinterpret_bits(const Source source)
-{
-    static_assert(sizeof(Target) == sizeof(Source), "size mismatch");
-
-    Target target;
-    std::memcpy(&target, &source, sizeof(Source));
-    return target;
-}
-
-struct diyfp // f * 2^e
+template<typename BasicJsonType, typename CharType>
+class binary_writer
 {
-    static constexpr int kPrecision = 64; // = q
+    using string_t = typename BasicJsonType::string_t;
 
-    uint64_t f = 0;
-    int e = 0;
+  public:
+    /*!
+    @brief create a binary writer
 
-    constexpr diyfp(uint64_t f_, int e_) noexcept : f(f_), e(e_) {}
+    @param[in] adapter  output adapter to write to
+    */
+    explicit binary_writer(output_adapter_t<CharType> adapter) : oa(adapter)
+    {
+        assert(oa);
+    }
 
     /*!
-    @brief returns x - y
-    @pre x.e == y.e and x.f >= y.f
+    @param[in] j  JSON value to serialize
+    @pre       j.type() == value_t::object
     */
-    static diyfp sub(const diyfp& x, const diyfp& y) noexcept
+    void write_bson(const BasicJsonType& j)
     {
-        assert(x.e == y.e);
-        assert(x.f >= y.f);
+        switch (j.type())
+        {
+            case value_t::object:
+            {
+                write_bson_object(*j.m_value.object);
+                break;
+            }
 
-        return {x.f - y.f, x.e};
+            default:
+            {
+                JSON_THROW(type_error::create(317, "to serialize to BSON, top-level type must be object, but is " + std::string(j.type_name())));
+            }
+        }
     }
 
     /*!
-    @brief returns x * y
-    @note The result is rounded. (Only the upper q bits are returned.)
+    @param[in] j  JSON value to serialize
     */
-    static diyfp mul(const diyfp& x, const diyfp& y) noexcept
+    void write_cbor(const BasicJsonType& j)
     {
-        static_assert(kPrecision == 64, "internal error");
-
-        // Computes:
-        //  f = round((x.f * y.f) / 2^q)
-        //  e = x.e + y.e + q
+        switch (j.type())
+        {
+            case value_t::null:
+            {
+                oa->write_character(to_char_type(0xF6));
+                break;
+            }
 
-        // Emulate the 64-bit * 64-bit multiplication:
-        //
-        // p = u * v
-        //   = (u_lo + 2^32 u_hi) (v_lo + 2^32 v_hi)
-        //   = (u_lo v_lo         ) + 2^32 ((u_lo v_hi         ) + (u_hi v_lo         )) + 2^64 (u_hi v_hi         )
-        //   = (p0                ) + 2^32 ((p1                ) + (p2                )) + 2^64 (p3                )
-        //   = (p0_lo + 2^32 p0_hi) + 2^32 ((p1_lo + 2^32 p1_hi) + (p2_lo + 2^32 p2_hi)) + 2^64 (p3                )
-        //   = (p0_lo             ) + 2^32 (p0_hi + p1_lo + p2_lo                      ) + 2^64 (p1_hi + p2_hi + p3)
-        //   = (p0_lo             ) + 2^32 (Q                                          ) + 2^64 (H                 )
-        //   = (p0_lo             ) + 2^32 (Q_lo + 2^32 Q_hi                           ) + 2^64 (H                 )
-        //
-        // (Since Q might be larger than 2^32 - 1)
-        //
-        //   = (p0_lo + 2^32 Q_lo) + 2^64 (Q_hi + H)
-        //
-        // (Q_hi + H does not overflow a 64-bit int)
-        //
-        //   = p_lo + 2^64 p_hi
+            case value_t::boolean:
+            {
+                oa->write_character(j.m_value.boolean
+                                    ? to_char_type(0xF5)
+                                    : to_char_type(0xF4));
+                break;
+            }
 
-        const uint64_t u_lo = x.f & 0xFFFFFFFF;
-        const uint64_t u_hi = x.f >> 32;
-        const uint64_t v_lo = y.f & 0xFFFFFFFF;
-        const uint64_t v_hi = y.f >> 32;
+            case value_t::number_integer:
+            {
+                if (j.m_value.number_integer >= 0)
+                {
+                    // CBOR does not differentiate between positive signed
+                    // integers and unsigned integers. Therefore, we used the
+                    // code from the value_t::number_unsigned case here.
+                    if (j.m_value.number_integer <= 0x17)
+                    {
+                        write_number(static_cast<std::uint8_t>(j.m_value.number_integer));
+                    }
+                    else if (j.m_value.number_integer <= (std::numeric_limits<std::uint8_t>::max)())
+                    {
+                        oa->write_character(to_char_type(0x18));
+                        write_number(static_cast<std::uint8_t>(j.m_value.number_integer));
+                    }
+                    else if (j.m_value.number_integer <= (std::numeric_limits<std::uint16_t>::max)())
+                    {
+                        oa->write_character(to_char_type(0x19));
+                        write_number(static_cast<std::uint16_t>(j.m_value.number_integer));
+                    }
+                    else if (j.m_value.number_integer <= (std::numeric_limits<std::uint32_t>::max)())
+                    {
+                        oa->write_character(to_char_type(0x1A));
+                        write_number(static_cast<std::uint32_t>(j.m_value.number_integer));
+                    }
+                    else
+                    {
+                        oa->write_character(to_char_type(0x1B));
+                        write_number(static_cast<std::uint64_t>(j.m_value.number_integer));
+                    }
+                }
+                else
+                {
+                    // The conversions below encode the sign in the first
+                    // byte, and the value is converted to a positive number.
+                    const auto positive_number = -1 - j.m_value.number_integer;
+                    if (j.m_value.number_integer >= -24)
+                    {
+                        write_number(static_cast<std::uint8_t>(0x20 + positive_number));
+                    }
+                    else if (positive_number <= (std::numeric_limits<std::uint8_t>::max)())
+                    {
+                        oa->write_character(to_char_type(0x38));
+                        write_number(static_cast<std::uint8_t>(positive_number));
+                    }
+                    else if (positive_number <= (std::numeric_limits<std::uint16_t>::max)())
+                    {
+                        oa->write_character(to_char_type(0x39));
+                        write_number(static_cast<std::uint16_t>(positive_number));
+                    }
+                    else if (positive_number <= (std::numeric_limits<std::uint32_t>::max)())
+                    {
+                        oa->write_character(to_char_type(0x3A));
+                        write_number(static_cast<std::uint32_t>(positive_number));
+                    }
+                    else
+                    {
+                        oa->write_character(to_char_type(0x3B));
+                        write_number(static_cast<std::uint64_t>(positive_number));
+                    }
+                }
+                break;
+            }
 
-        const uint64_t p0 = u_lo * v_lo;
-        const uint64_t p1 = u_lo * v_hi;
-        const uint64_t p2 = u_hi * v_lo;
-        const uint64_t p3 = u_hi * v_hi;
+            case value_t::number_unsigned:
+            {
+                if (j.m_value.number_unsigned <= 0x17)
+                {
+                    write_number(static_cast<std::uint8_t>(j.m_value.number_unsigned));
+                }
+                else if (j.m_value.number_unsigned <= (std::numeric_limits<std::uint8_t>::max)())
+                {
+                    oa->write_character(to_char_type(0x18));
+                    write_number(static_cast<std::uint8_t>(j.m_value.number_unsigned));
+                }
+                else if (j.m_value.number_unsigned <= (std::numeric_limits<std::uint16_t>::max)())
+                {
+                    oa->write_character(to_char_type(0x19));
+                    write_number(static_cast<std::uint16_t>(j.m_value.number_unsigned));
+                }
+                else if (j.m_value.number_unsigned <= (std::numeric_limits<std::uint32_t>::max)())
+                {
+                    oa->write_character(to_char_type(0x1A));
+                    write_number(static_cast<std::uint32_t>(j.m_value.number_unsigned));
+                }
+                else
+                {
+                    oa->write_character(to_char_type(0x1B));
+                    write_number(static_cast<std::uint64_t>(j.m_value.number_unsigned));
+                }
+                break;
+            }
 
-        const uint64_t p0_hi = p0 >> 32;
-        const uint64_t p1_lo = p1 & 0xFFFFFFFF;
-        const uint64_t p1_hi = p1 >> 32;
-        const uint64_t p2_lo = p2 & 0xFFFFFFFF;
-        const uint64_t p2_hi = p2 >> 32;
+            case value_t::number_float:
+            {
+                oa->write_character(get_cbor_float_prefix(j.m_value.number_float));
+                write_number(j.m_value.number_float);
+                break;
+            }
 
-        uint64_t Q = p0_hi + p1_lo + p2_lo;
+            case value_t::string:
+            {
+                // step 1: write control byte and the string length
+                const auto N = j.m_value.string->size();
+                if (N <= 0x17)
+                {
+                    write_number(static_cast<std::uint8_t>(0x60 + N));
+                }
+                else if (N <= (std::numeric_limits<std::uint8_t>::max)())
+                {
+                    oa->write_character(to_char_type(0x78));
+                    write_number(static_cast<std::uint8_t>(N));
+                }
+                else if (N <= (std::numeric_limits<std::uint16_t>::max)())
+                {
+                    oa->write_character(to_char_type(0x79));
+                    write_number(static_cast<std::uint16_t>(N));
+                }
+                else if (N <= (std::numeric_limits<std::uint32_t>::max)())
+                {
+                    oa->write_character(to_char_type(0x7A));
+                    write_number(static_cast<std::uint32_t>(N));
+                }
+                // LCOV_EXCL_START
+                else if (N <= (std::numeric_limits<std::uint64_t>::max)())
+                {
+                    oa->write_character(to_char_type(0x7B));
+                    write_number(static_cast<std::uint64_t>(N));
+                }
+                // LCOV_EXCL_STOP
 
-        // The full product might now be computed as
-        //
-        // p_hi = p3 + p2_hi + p1_hi + (Q >> 32)
-        // p_lo = p0_lo + (Q << 32)
-        //
-        // But in this particular case here, the full p_lo is not required.
-        // Effectively we only need to add the highest bit in p_lo to p_hi (and
-        // Q_hi + 1 does not overflow).
+                // step 2: write the string
+                oa->write_characters(
+                    reinterpret_cast<const CharType*>(j.m_value.string->c_str()),
+                    j.m_value.string->size());
+                break;
+            }
 
-        Q += uint64_t{1} << (64 - 32 - 1); // round, ties up
+            case value_t::array:
+            {
+                // step 1: write control byte and the array size
+                const auto N = j.m_value.array->size();
+                if (N <= 0x17)
+                {
+                    write_number(static_cast<std::uint8_t>(0x80 + N));
+                }
+                else if (N <= (std::numeric_limits<std::uint8_t>::max)())
+                {
+                    oa->write_character(to_char_type(0x98));
+                    write_number(static_cast<std::uint8_t>(N));
+                }
+                else if (N <= (std::numeric_limits<std::uint16_t>::max)())
+                {
+                    oa->write_character(to_char_type(0x99));
+                    write_number(static_cast<std::uint16_t>(N));
+                }
+                else if (N <= (std::numeric_limits<std::uint32_t>::max)())
+                {
+                    oa->write_character(to_char_type(0x9A));
+                    write_number(static_cast<std::uint32_t>(N));
+                }
+                // LCOV_EXCL_START
+                else if (N <= (std::numeric_limits<std::uint64_t>::max)())
+                {
+                    oa->write_character(to_char_type(0x9B));
+                    write_number(static_cast<std::uint64_t>(N));
+                }
+                // LCOV_EXCL_STOP
 
-        const uint64_t h = p3 + p2_hi + p1_hi + (Q >> 32);
+                // step 2: write each element
+                for (const auto& el : *j.m_value.array)
+                {
+                    write_cbor(el);
+                }
+                break;
+            }
 
-        return {h, x.e + y.e + 64};
-    }
+            case value_t::object:
+            {
+                // step 1: write control byte and the object size
+                const auto N = j.m_value.object->size();
+                if (N <= 0x17)
+                {
+                    write_number(static_cast<std::uint8_t>(0xA0 + N));
+                }
+                else if (N <= (std::numeric_limits<std::uint8_t>::max)())
+                {
+                    oa->write_character(to_char_type(0xB8));
+                    write_number(static_cast<std::uint8_t>(N));
+                }
+                else if (N <= (std::numeric_limits<std::uint16_t>::max)())
+                {
+                    oa->write_character(to_char_type(0xB9));
+                    write_number(static_cast<std::uint16_t>(N));
+                }
+                else if (N <= (std::numeric_limits<std::uint32_t>::max)())
+                {
+                    oa->write_character(to_char_type(0xBA));
+                    write_number(static_cast<std::uint32_t>(N));
+                }
+                // LCOV_EXCL_START
+                else if (N <= (std::numeric_limits<std::uint64_t>::max)())
+                {
+                    oa->write_character(to_char_type(0xBB));
+                    write_number(static_cast<std::uint64_t>(N));
+                }
+                // LCOV_EXCL_STOP
 
-    /*!
-    @brief normalize x such that the significand is >= 2^(q-1)
-    @pre x.f != 0
-    */
-    static diyfp normalize(diyfp x) noexcept
-    {
-        assert(x.f != 0);
+                // step 2: write each element
+                for (const auto& el : *j.m_value.object)
+                {
+                    write_cbor(el.first);
+                    write_cbor(el.second);
+                }
+                break;
+            }
 
-        while ((x.f >> 63) == 0)
-        {
-            x.f <<= 1;
-            x.e--;
+            default:
+                break;
         }
-
-        return x;
     }
 
     /*!
-    @brief normalize x such that the result has the exponent E
-    @pre e >= x.e and the upper e - x.e bits of x.f must be zero.
+    @param[in] j  JSON value to serialize
     */
-    static diyfp normalize_to(const diyfp& x, const int target_exponent) noexcept
+    void write_msgpack(const BasicJsonType& j)
     {
-        const int delta = x.e - target_exponent;
-
-        assert(delta >= 0);
-        assert(((x.f << delta) >> delta) == x.f);
+        switch (j.type())
+        {
+            case value_t::null: // nil
+            {
+                oa->write_character(to_char_type(0xC0));
+                break;
+            }
 
-        return {x.f << delta, target_exponent};
-    }
-};
+            case value_t::boolean: // true and false
+            {
+                oa->write_character(j.m_value.boolean
+                                    ? to_char_type(0xC3)
+                                    : to_char_type(0xC2));
+                break;
+            }
 
-struct boundaries
-{
-    diyfp w;
-    diyfp minus;
-    diyfp plus;
-};
+            case value_t::number_integer:
+            {
+                if (j.m_value.number_integer >= 0)
+                {
+                    // MessagePack does not differentiate between positive
+                    // signed integers and unsigned integers. Therefore, we used
+                    // the code from the value_t::number_unsigned case here.
+                    if (j.m_value.number_unsigned < 128)
+                    {
+                        // positive fixnum
+                        write_number(static_cast<std::uint8_t>(j.m_value.number_integer));
+                    }
+                    else if (j.m_value.number_unsigned <= (std::numeric_limits<std::uint8_t>::max)())
+                    {
+                        // uint 8
+                        oa->write_character(to_char_type(0xCC));
+                        write_number(static_cast<std::uint8_t>(j.m_value.number_integer));
+                    }
+                    else if (j.m_value.number_unsigned <= (std::numeric_limits<std::uint16_t>::max)())
+                    {
+                        // uint 16
+                        oa->write_character(to_char_type(0xCD));
+                        write_number(static_cast<std::uint16_t>(j.m_value.number_integer));
+                    }
+                    else if (j.m_value.number_unsigned <= (std::numeric_limits<std::uint32_t>::max)())
+                    {
+                        // uint 32
+                        oa->write_character(to_char_type(0xCE));
+                        write_number(static_cast<std::uint32_t>(j.m_value.number_integer));
+                    }
+                    else if (j.m_value.number_unsigned <= (std::numeric_limits<std::uint64_t>::max)())
+                    {
+                        // uint 64
+                        oa->write_character(to_char_type(0xCF));
+                        write_number(static_cast<std::uint64_t>(j.m_value.number_integer));
+                    }
+                }
+                else
+                {
+                    if (j.m_value.number_integer >= -32)
+                    {
+                        // negative fixnum
+                        write_number(static_cast<std::int8_t>(j.m_value.number_integer));
+                    }
+                    else if (j.m_value.number_integer >= (std::numeric_limits<std::int8_t>::min)() and
+                             j.m_value.number_integer <= (std::numeric_limits<std::int8_t>::max)())
+                    {
+                        // int 8
+                        oa->write_character(to_char_type(0xD0));
+                        write_number(static_cast<std::int8_t>(j.m_value.number_integer));
+                    }
+                    else if (j.m_value.number_integer >= (std::numeric_limits<std::int16_t>::min)() and
+                             j.m_value.number_integer <= (std::numeric_limits<std::int16_t>::max)())
+                    {
+                        // int 16
+                        oa->write_character(to_char_type(0xD1));
+                        write_number(static_cast<std::int16_t>(j.m_value.number_integer));
+                    }
+                    else if (j.m_value.number_integer >= (std::numeric_limits<std::int32_t>::min)() and
+                             j.m_value.number_integer <= (std::numeric_limits<std::int32_t>::max)())
+                    {
+                        // int 32
+                        oa->write_character(to_char_type(0xD2));
+                        write_number(static_cast<std::int32_t>(j.m_value.number_integer));
+                    }
+                    else if (j.m_value.number_integer >= (std::numeric_limits<std::int64_t>::min)() and
+                             j.m_value.number_integer <= (std::numeric_limits<std::int64_t>::max)())
+                    {
+                        // int 64
+                        oa->write_character(to_char_type(0xD3));
+                        write_number(static_cast<std::int64_t>(j.m_value.number_integer));
+                    }
+                }
+                break;
+            }
 
-/*!
-Compute the (normalized) diyfp representing the input number 'value' and its
-boundaries.
+            case value_t::number_unsigned:
+            {
+                if (j.m_value.number_unsigned < 128)
+                {
+                    // positive fixnum
+                    write_number(static_cast<std::uint8_t>(j.m_value.number_integer));
+                }
+                else if (j.m_value.number_unsigned <= (std::numeric_limits<std::uint8_t>::max)())
+                {
+                    // uint 8
+                    oa->write_character(to_char_type(0xCC));
+                    write_number(static_cast<std::uint8_t>(j.m_value.number_integer));
+                }
+                else if (j.m_value.number_unsigned <= (std::numeric_limits<std::uint16_t>::max)())
+                {
+                    // uint 16
+                    oa->write_character(to_char_type(0xCD));
+                    write_number(static_cast<std::uint16_t>(j.m_value.number_integer));
+                }
+                else if (j.m_value.number_unsigned <= (std::numeric_limits<std::uint32_t>::max)())
+                {
+                    // uint 32
+                    oa->write_character(to_char_type(0xCE));
+                    write_number(static_cast<std::uint32_t>(j.m_value.number_integer));
+                }
+                else if (j.m_value.number_unsigned <= (std::numeric_limits<std::uint64_t>::max)())
+                {
+                    // uint 64
+                    oa->write_character(to_char_type(0xCF));
+                    write_number(static_cast<std::uint64_t>(j.m_value.number_integer));
+                }
+                break;
+            }
 
-@pre value must be finite and positive
-*/
-template <typename FloatType>
-boundaries compute_boundaries(FloatType value)
-{
-    assert(std::isfinite(value));
-    assert(value > 0);
+            case value_t::number_float:
+            {
+                oa->write_character(get_msgpack_float_prefix(j.m_value.number_float));
+                write_number(j.m_value.number_float);
+                break;
+            }
 
-    // Convert the IEEE representation into a diyfp.
-    //
-    // If v is denormal:
-    //      value = 0.F * 2^(1 - bias) = (          F) * 2^(1 - bias - (p-1))
-    // If v is normalized:
-    //      value = 1.F * 2^(E - bias) = (2^(p-1) + F) * 2^(E - bias - (p-1))
+            case value_t::string:
+            {
+                // step 1: write control byte and the string length
+                const auto N = j.m_value.string->size();
+                if (N <= 31)
+                {
+                    // fixstr
+                    write_number(static_cast<std::uint8_t>(0xA0 | N));
+                }
+                else if (N <= (std::numeric_limits<std::uint8_t>::max)())
+                {
+                    // str 8
+                    oa->write_character(to_char_type(0xD9));
+                    write_number(static_cast<std::uint8_t>(N));
+                }
+                else if (N <= (std::numeric_limits<std::uint16_t>::max)())
+                {
+                    // str 16
+                    oa->write_character(to_char_type(0xDA));
+                    write_number(static_cast<std::uint16_t>(N));
+                }
+                else if (N <= (std::numeric_limits<std::uint32_t>::max)())
+                {
+                    // str 32
+                    oa->write_character(to_char_type(0xDB));
+                    write_number(static_cast<std::uint32_t>(N));
+                }
 
-    static_assert(std::numeric_limits<FloatType>::is_iec559,
-                  "internal error: dtoa_short requires an IEEE-754 floating-point implementation");
+                // step 2: write the string
+                oa->write_characters(
+                    reinterpret_cast<const CharType*>(j.m_value.string->c_str()),
+                    j.m_value.string->size());
+                break;
+            }
 
-    constexpr int      kPrecision = std::numeric_limits<FloatType>::digits; // = p (includes the hidden bit)
-    constexpr int      kBias      = std::numeric_limits<FloatType>::max_exponent - 1 + (kPrecision - 1);
-    constexpr int      kMinExp    = 1 - kBias;
-    constexpr uint64_t kHiddenBit = uint64_t{1} << (kPrecision - 1); // = 2^(p-1)
+            case value_t::array:
+            {
+                // step 1: write control byte and the array size
+                const auto N = j.m_value.array->size();
+                if (N <= 15)
+                {
+                    // fixarray
+                    write_number(static_cast<std::uint8_t>(0x90 | N));
+                }
+                else if (N <= (std::numeric_limits<std::uint16_t>::max)())
+                {
+                    // array 16
+                    oa->write_character(to_char_type(0xDC));
+                    write_number(static_cast<std::uint16_t>(N));
+                }
+                else if (N <= (std::numeric_limits<std::uint32_t>::max)())
+                {
+                    // array 32
+                    oa->write_character(to_char_type(0xDD));
+                    write_number(static_cast<std::uint32_t>(N));
+                }
 
-    using bits_type = typename std::conditional< kPrecision == 24, uint32_t, uint64_t >::type;
+                // step 2: write each element
+                for (const auto& el : *j.m_value.array)
+                {
+                    write_msgpack(el);
+                }
+                break;
+            }
 
-    const uint64_t bits = reinterpret_bits<bits_type>(value);
-    const uint64_t E = bits >> (kPrecision - 1);
-    const uint64_t F = bits & (kHiddenBit - 1);
+            case value_t::object:
+            {
+                // step 1: write control byte and the object size
+                const auto N = j.m_value.object->size();
+                if (N <= 15)
+                {
+                    // fixmap
+                    write_number(static_cast<std::uint8_t>(0x80 | (N & 0xF)));
+                }
+                else if (N <= (std::numeric_limits<std::uint16_t>::max)())
+                {
+                    // map 16
+                    oa->write_character(to_char_type(0xDE));
+                    write_number(static_cast<std::uint16_t>(N));
+                }
+                else if (N <= (std::numeric_limits<std::uint32_t>::max)())
+                {
+                    // map 32
+                    oa->write_character(to_char_type(0xDF));
+                    write_number(static_cast<std::uint32_t>(N));
+                }
 
-    const bool is_denormal = (E == 0);
-    const diyfp v = is_denormal
-                    ? diyfp(F, kMinExp)
-                    : diyfp(F + kHiddenBit, static_cast<int>(E) - kBias);
+                // step 2: write each element
+                for (const auto& el : *j.m_value.object)
+                {
+                    write_msgpack(el.first);
+                    write_msgpack(el.second);
+                }
+                break;
+            }
 
-    // Compute the boundaries m- and m+ of the floating-point value
-    // v = f * 2^e.
-    //
-    // Determine v- and v+, the floating-point predecessor and successor if v,
-    // respectively.
-    //
-    //      v- = v - 2^e        if f != 2^(p-1) or e == e_min                (A)
-    //         = v - 2^(e-1)    if f == 2^(p-1) and e > e_min                (B)
-    //
-    //      v+ = v + 2^e
-    //
-    // Let m- = (v- + v) / 2 and m+ = (v + v+) / 2. All real numbers _strictly_
-    // between m- and m+ round to v, regardless of how the input rounding
-    // algorithm breaks ties.
-    //
-    //      ---+-------------+-------------+-------------+-------------+---  (A)
-    //         v-            m-            v             m+            v+
-    //
-    //      -----------------+------+------+-------------+-------------+---  (B)
-    //                       v-     m-     v             m+            v+
+            default:
+                break;
+        }
+    }
 
-    const bool lower_boundary_is_closer = (F == 0 and E > 1);
-    const diyfp m_plus = diyfp(2 * v.f + 1, v.e - 1);
-    const diyfp m_minus = lower_boundary_is_closer
-                          ? diyfp(4 * v.f - 1, v.e - 2)  // (B)
-                          : diyfp(2 * v.f - 1, v.e - 1); // (A)
+    /*!
+    @param[in] j  JSON value to serialize
+    @param[in] use_count   whether to use '#' prefixes (optimized format)
+    @param[in] use_type    whether to use '$' prefixes (optimized format)
+    @param[in] add_prefix  whether prefixes need to be used for this value
+    */
+    void write_ubjson(const BasicJsonType& j, const bool use_count,
+                      const bool use_type, const bool add_prefix = true)
+    {
+        switch (j.type())
+        {
+            case value_t::null:
+            {
+                if (add_prefix)
+                {
+                    oa->write_character(to_char_type('Z'));
+                }
+                break;
+            }
 
-    // Determine the normalized w+ = m+.
-    const diyfp w_plus = diyfp::normalize(m_plus);
+            case value_t::boolean:
+            {
+                if (add_prefix)
+                {
+                    oa->write_character(j.m_value.boolean
+                                        ? to_char_type('T')
+                                        : to_char_type('F'));
+                }
+                break;
+            }
 
-    // Determine w- = m- such that e_(w-) = e_(w+).
-    const diyfp w_minus = diyfp::normalize_to(m_minus, w_plus.e);
+            case value_t::number_integer:
+            {
+                write_number_with_ubjson_prefix(j.m_value.number_integer, add_prefix);
+                break;
+            }
 
-    return {diyfp::normalize(v), w_minus, w_plus};
-}
+            case value_t::number_unsigned:
+            {
+                write_number_with_ubjson_prefix(j.m_value.number_unsigned, add_prefix);
+                break;
+            }
 
-// Given normalized diyfp w, Grisu needs to find a (normalized) cached
-// power-of-ten c, such that the exponent of the product c * w = f * 2^e lies
-// within a certain range [alpha, gamma] (Definition 3.2 from [1])
-//
-//      alpha <= e = e_c + e_w + q <= gamma
-//
-// or
-//
-//      f_c * f_w * 2^alpha <= f_c 2^(e_c) * f_w 2^(e_w) * 2^q
-//                          <= f_c * f_w * 2^gamma
-//
-// Since c and w are normalized, i.e. 2^(q-1) <= f < 2^q, this implies
-//
-//      2^(q-1) * 2^(q-1) * 2^alpha <= c * w * 2^q < 2^q * 2^q * 2^gamma
-//
-// or
-//
-//      2^(q - 2 + alpha) <= c * w < 2^(q + gamma)
-//
-// The choice of (alpha,gamma) determines the size of the table and the form of
-// the digit generation procedure. Using (alpha,gamma)=(-60,-32) works out well
-// in practice:
-//
-// The idea is to cut the number c * w = f * 2^e into two parts, which can be
-// processed independently: An integral part p1, and a fractional part p2:
-//
-//      f * 2^e = ( (f div 2^-e) * 2^-e + (f mod 2^-e) ) * 2^e
-//              = (f div 2^-e) + (f mod 2^-e) * 2^e
-//              = p1 + p2 * 2^e
-//
-// The conversion of p1 into decimal form requires a series of divisions and
-// modulos by (a power of) 10. These operations are faster for 32-bit than for
-// 64-bit integers, so p1 should ideally fit into a 32-bit integer. This can be
-// achieved by choosing
-//
-//      -e >= 32   or   e <= -32 := gamma
-//
-// In order to convert the fractional part
-//
-//      p2 * 2^e = p2 / 2^-e = d[-1] / 10^1 + d[-2] / 10^2 + ...
-//
-// into decimal form, the fraction is repeatedly multiplied by 10 and the digits
-// d[-i] are extracted in order:
-//
-//      (10 * p2) div 2^-e = d[-1]
-//      (10 * p2) mod 2^-e = d[-2] / 10^1 + ...
-//
-// The multiplication by 10 must not overflow. It is sufficient to choose
-//
-//      10 * p2 < 16 * p2 = 2^4 * p2 <= 2^64.
-//
-// Since p2 = f mod 2^-e < 2^-e,
-//
-//      -e <= 60   or   e >= -60 := alpha
+            case value_t::number_float:
+            {
+                write_number_with_ubjson_prefix(j.m_value.number_float, add_prefix);
+                break;
+            }
 
-constexpr int kAlpha = -60;
-constexpr int kGamma = -32;
+            case value_t::string:
+            {
+                if (add_prefix)
+                {
+                    oa->write_character(to_char_type('S'));
+                }
+                write_number_with_ubjson_prefix(j.m_value.string->size(), true);
+                oa->write_characters(
+                    reinterpret_cast<const CharType*>(j.m_value.string->c_str()),
+                    j.m_value.string->size());
+                break;
+            }
 
-struct cached_power // c = f * 2^e ~= 10^k
-{
-    uint64_t f;
-    int e;
-    int k;
-};
+            case value_t::array:
+            {
+                if (add_prefix)
+                {
+                    oa->write_character(to_char_type('['));
+                }
 
-/*!
-For a normalized diyfp w = f * 2^e, this function returns a (normalized) cached
-power-of-ten c = f_c * 2^e_c, such that the exponent of the product w * c
-satisfies (Definition 3.2 from [1])
+                bool prefix_required = true;
+                if (use_type and not j.m_value.array->empty())
+                {
+                    assert(use_count);
+                    const CharType first_prefix = ubjson_prefix(j.front());
+                    const bool same_prefix = std::all_of(j.begin() + 1, j.end(),
+                                                         [this, first_prefix](const BasicJsonType & v)
+                    {
+                        return ubjson_prefix(v) == first_prefix;
+                    });
 
-     alpha <= e_c + e + q <= gamma.
-*/
-inline cached_power get_cached_power_for_binary_exponent(int e)
-{
-    // Now
-    //
-    //      alpha <= e_c + e + q <= gamma                                    (1)
-    //      ==> f_c * 2^alpha <= c * 2^e * 2^q
-    //
-    // and since the c's are normalized, 2^(q-1) <= f_c,
-    //
-    //      ==> 2^(q - 1 + alpha) <= c * 2^(e + q)
-    //      ==> 2^(alpha - e - 1) <= c
-    //
-    // If c were an exakt power of ten, i.e. c = 10^k, one may determine k as
-    //
-    //      k = ceil( log_10( 2^(alpha - e - 1) ) )
-    //        = ceil( (alpha - e - 1) * log_10(2) )
-    //
-    // From the paper:
-    // "In theory the result of the procedure could be wrong since c is rounded,
-    //  and the computation itself is approximated [...]. In practice, however,
-    //  this simple function is sufficient."
-    //
-    // For IEEE double precision floating-point numbers converted into
-    // normalized diyfp's w = f * 2^e, with q = 64,
-    //
-    //      e >= -1022      (min IEEE exponent)
-    //           -52        (p - 1)
-    //           -52        (p - 1, possibly normalize denormal IEEE numbers)
-    //           -11        (normalize the diyfp)
-    //         = -1137
-    //
-    // and
-    //
-    //      e <= +1023      (max IEEE exponent)
-    //           -52        (p - 1)
-    //           -11        (normalize the diyfp)
-    //         = 960
-    //
-    // This binary exponent range [-1137,960] results in a decimal exponent
-    // range [-307,324]. One does not need to store a cached power for each
-    // k in this range. For each such k it suffices to find a cached power
-    // such that the exponent of the product lies in [alpha,gamma].
-    // This implies that the difference of the decimal exponents of adjacent
-    // table entries must be less than or equal to
-    //
-    //      floor( (gamma - alpha) * log_10(2) ) = 8.
-    //
-    // (A smaller distance gamma-alpha would require a larger table.)
+                    if (same_prefix)
+                    {
+                        prefix_required = false;
+                        oa->write_character(to_char_type('$'));
+                        oa->write_character(first_prefix);
+                    }
+                }
 
-    // NB:
-    // Actually this function returns c, such that -60 <= e_c + e + 64 <= -34.
+                if (use_count)
+                {
+                    oa->write_character(to_char_type('#'));
+                    write_number_with_ubjson_prefix(j.m_value.array->size(), true);
+                }
 
-    constexpr int kCachedPowersSize = 79;
-    constexpr int kCachedPowersMinDecExp = -300;
-    constexpr int kCachedPowersDecStep = 8;
+                for (const auto& el : *j.m_value.array)
+                {
+                    write_ubjson(el, use_count, use_type, prefix_required);
+                }
 
-    static constexpr cached_power kCachedPowers[] =
-    {
-        { 0xAB70FE17C79AC6CA, -1060, -300 },
-        { 0xFF77B1FCBEBCDC4F, -1034, -292 },
-        { 0xBE5691EF416BD60C, -1007, -284 },
-        { 0x8DD01FAD907FFC3C,  -980, -276 },
-        { 0xD3515C2831559A83,  -954, -268 },
-        { 0x9D71AC8FADA6C9B5,  -927, -260 },
-        { 0xEA9C227723EE8BCB,  -901, -252 },
-        { 0xAECC49914078536D,  -874, -244 },
-        { 0x823C12795DB6CE57,  -847, -236 },
-        { 0xC21094364DFB5637,  -821, -228 },
-        { 0x9096EA6F3848984F,  -794, -220 },
-        { 0xD77485CB25823AC7,  -768, -212 },
-        { 0xA086CFCD97BF97F4,  -741, -204 },
-        { 0xEF340A98172AACE5,  -715, -196 },
-        { 0xB23867FB2A35B28E,  -688, -188 },
-        { 0x84C8D4DFD2C63F3B,  -661, -180 },
-        { 0xC5DD44271AD3CDBA,  -635, -172 },
-        { 0x936B9FCEBB25C996,  -608, -164 },
-        { 0xDBAC6C247D62A584,  -582, -156 },
-        { 0xA3AB66580D5FDAF6,  -555, -148 },
-        { 0xF3E2F893DEC3F126,  -529, -140 },
-        { 0xB5B5ADA8AAFF80B8,  -502, -132 },
-        { 0x87625F056C7C4A8B,  -475, -124 },
-        { 0xC9BCFF6034C13053,  -449, -116 },
-        { 0x964E858C91BA2655,  -422, -108 },
-        { 0xDFF9772470297EBD,  -396, -100 },
-        { 0xA6DFBD9FB8E5B88F,  -369,  -92 },
-        { 0xF8A95FCF88747D94,  -343,  -84 },
-        { 0xB94470938FA89BCF,  -316,  -76 },
-        { 0x8A08F0F8BF0F156B,  -289,  -68 },
-        { 0xCDB02555653131B6,  -263,  -60 },
-        { 0x993FE2C6D07B7FAC,  -236,  -52 },
-        { 0xE45C10C42A2B3B06,  -210,  -44 },
-        { 0xAA242499697392D3,  -183,  -36 },
-        { 0xFD87B5F28300CA0E,  -157,  -28 },
-        { 0xBCE5086492111AEB,  -130,  -20 },
-        { 0x8CBCCC096F5088CC,  -103,  -12 },
-        { 0xD1B71758E219652C,   -77,   -4 },
-        { 0x9C40000000000000,   -50,    4 },
-        { 0xE8D4A51000000000,   -24,   12 },
-        { 0xAD78EBC5AC620000,     3,   20 },
-        { 0x813F3978F8940984,    30,   28 },
-        { 0xC097CE7BC90715B3,    56,   36 },
-        { 0x8F7E32CE7BEA5C70,    83,   44 },
-        { 0xD5D238A4ABE98068,   109,   52 },
-        { 0x9F4F2726179A2245,   136,   60 },
-        { 0xED63A231D4C4FB27,   162,   68 },
-        { 0xB0DE65388CC8ADA8,   189,   76 },
-        { 0x83C7088E1AAB65DB,   216,   84 },
-        { 0xC45D1DF942711D9A,   242,   92 },
-        { 0x924D692CA61BE758,   269,  100 },
-        { 0xDA01EE641A708DEA,   295,  108 },
-        { 0xA26DA3999AEF774A,   322,  116 },
-        { 0xF209787BB47D6B85,   348,  124 },
-        { 0xB454E4A179DD1877,   375,  132 },
-        { 0x865B86925B9BC5C2,   402,  140 },
-        { 0xC83553C5C8965D3D,   428,  148 },
-        { 0x952AB45CFA97A0B3,   455,  156 },
-        { 0xDE469FBD99A05FE3,   481,  164 },
-        { 0xA59BC234DB398C25,   508,  172 },
-        { 0xF6C69A72A3989F5C,   534,  180 },
-        { 0xB7DCBF5354E9BECE,   561,  188 },
-        { 0x88FCF317F22241E2,   588,  196 },
-        { 0xCC20CE9BD35C78A5,   614,  204 },
-        { 0x98165AF37B2153DF,   641,  212 },
-        { 0xE2A0B5DC971F303A,   667,  220 },
-        { 0xA8D9D1535CE3B396,   694,  228 },
-        { 0xFB9B7CD9A4A7443C,   720,  236 },
-        { 0xBB764C4CA7A44410,   747,  244 },
-        { 0x8BAB8EEFB6409C1A,   774,  252 },
-        { 0xD01FEF10A657842C,   800,  260 },
-        { 0x9B10A4E5E9913129,   827,  268 },
-        { 0xE7109BFBA19C0C9D,   853,  276 },
-        { 0xAC2820D9623BF429,   880,  284 },
-        { 0x80444B5E7AA7CF85,   907,  292 },
-        { 0xBF21E44003ACDD2D,   933,  300 },
-        { 0x8E679C2F5E44FF8F,   960,  308 },
-        { 0xD433179D9C8CB841,   986,  316 },
-        { 0x9E19DB92B4E31BA9,  1013,  324 },
-    };
+                if (not use_count)
+                {
+                    oa->write_character(to_char_type(']'));
+                }
 
-    // This computation gives exactly the same results for k as
-    //      k = ceil((kAlpha - e - 1) * 0.30102999566398114)
-    // for |e| <= 1500, but doesn't require floating-point operations.
-    // NB: log_10(2) ~= 78913 / 2^18
-    assert(e >= -1500);
-    assert(e <=  1500);
-    const int f = kAlpha - e - 1;
-    const int k = (f * 78913) / (1 << 18) + static_cast<int>(f > 0);
+                break;
+            }
 
-    const int index = (-kCachedPowersMinDecExp + k + (kCachedPowersDecStep - 1)) / kCachedPowersDecStep;
-    assert(index >= 0);
-    assert(index < kCachedPowersSize);
-    static_cast<void>(kCachedPowersSize); // Fix warning.
+            case value_t::object:
+            {
+                if (add_prefix)
+                {
+                    oa->write_character(to_char_type('{'));
+                }
 
-    const cached_power cached = kCachedPowers[index];
-    assert(kAlpha <= cached.e + e + 64);
-    assert(kGamma >= cached.e + e + 64);
+                bool prefix_required = true;
+                if (use_type and not j.m_value.object->empty())
+                {
+                    assert(use_count);
+                    const CharType first_prefix = ubjson_prefix(j.front());
+                    const bool same_prefix = std::all_of(j.begin(), j.end(),
+                                                         [this, first_prefix](const BasicJsonType & v)
+                    {
+                        return ubjson_prefix(v) == first_prefix;
+                    });
 
-    return cached;
-}
+                    if (same_prefix)
+                    {
+                        prefix_required = false;
+                        oa->write_character(to_char_type('$'));
+                        oa->write_character(first_prefix);
+                    }
+                }
 
-/*!
-For n != 0, returns k, such that pow10 := 10^(k-1) <= n < 10^k.
-For n == 0, returns 1 and sets pow10 := 1.
-*/
-inline int find_largest_pow10(const uint32_t n, uint32_t& pow10)
-{
-    // LCOV_EXCL_START
-    if (n >= 1000000000)
-    {
-        pow10 = 1000000000;
-        return 10;
-    }
-    // LCOV_EXCL_STOP
-    else if (n >= 100000000)
-    {
-        pow10 = 100000000;
-        return  9;
-    }
-    else if (n >= 10000000)
-    {
-        pow10 = 10000000;
-        return  8;
-    }
-    else if (n >= 1000000)
-    {
-        pow10 = 1000000;
-        return  7;
-    }
-    else if (n >= 100000)
-    {
-        pow10 = 100000;
-        return  6;
-    }
-    else if (n >= 10000)
-    {
-        pow10 = 10000;
-        return  5;
+                if (use_count)
+                {
+                    oa->write_character(to_char_type('#'));
+                    write_number_with_ubjson_prefix(j.m_value.object->size(), true);
+                }
+
+                for (const auto& el : *j.m_value.object)
+                {
+                    write_number_with_ubjson_prefix(el.first.size(), true);
+                    oa->write_characters(
+                        reinterpret_cast<const CharType*>(el.first.c_str()),
+                        el.first.size());
+                    write_ubjson(el.second, use_count, use_type, prefix_required);
+                }
+
+                if (not use_count)
+                {
+                    oa->write_character(to_char_type('}'));
+                }
+
+                break;
+            }
+
+            default:
+                break;
+        }
     }
-    else if (n >= 1000)
+
+  private:
+    //////////
+    // BSON //
+    //////////
+
+    /*!
+    @return The size of a BSON document entry header, including the id marker
+            and the entry name size (and its null-terminator).
+    */
+    static std::size_t calc_bson_entry_header_size(const string_t& name)
     {
-        pow10 = 1000;
-        return  4;
+        const auto it = name.find(static_cast<typename string_t::value_type>(0));
+        if (JSON_UNLIKELY(it != BasicJsonType::string_t::npos))
+        {
+            JSON_THROW(out_of_range::create(409,
+                                            "BSON key cannot contain code point U+0000 (at byte " + std::to_string(it) + ")"));
+        }
+
+        return /*id*/ 1ul + name.size() + /*zero-terminator*/1u;
     }
-    else if (n >= 100)
+
+    /*!
+    @brief Writes the given @a element_type and @a name to the output adapter
+    */
+    void write_bson_entry_header(const string_t& name,
+                                 const std::uint8_t element_type)
     {
-        pow10 = 100;
-        return  3;
+        oa->write_character(to_char_type(element_type)); // boolean
+        oa->write_characters(
+            reinterpret_cast<const CharType*>(name.c_str()),
+            name.size() + 1u);
     }
-    else if (n >= 10)
+
+    /*!
+    @brief Writes a BSON element with key @a name and boolean value @a value
+    */
+    void write_bson_boolean(const string_t& name,
+                            const bool value)
     {
-        pow10 = 10;
-        return  2;
+        write_bson_entry_header(name, 0x08);
+        oa->write_character(value ? to_char_type(0x01) : to_char_type(0x00));
     }
-    else
+
+    /*!
+    @brief Writes a BSON element with key @a name and double value @a value
+    */
+    void write_bson_double(const string_t& name,
+                           const double value)
     {
-        pow10 = 1;
-        return 1;
+        write_bson_entry_header(name, 0x01);
+        write_number<double, true>(value);
     }
-}
-
-inline void grisu2_round(char* buf, int len, uint64_t dist, uint64_t delta,
-                         uint64_t rest, uint64_t ten_k)
-{
-    assert(len >= 1);
-    assert(dist <= delta);
-    assert(rest <= delta);
-    assert(ten_k > 0);
-
-    //               <--------------------------- delta ---->
-    //                                  <---- dist --------->
-    // --------------[------------------+-------------------]--------------
-    //               M-                 w                   M+
-    //
-    //                                  ten_k
-    //                                <------>
-    //                                       <---- rest ---->
-    // --------------[------------------+----+--------------]--------------
-    //                                  w    V
-    //                                       = buf * 10^k
-    //
-    // ten_k represents a unit-in-the-last-place in the decimal representation
-    // stored in buf.
-    // Decrement buf by ten_k while this takes buf closer to w.
-
-    // The tests are written in this order to avoid overflow in unsigned
-    // integer arithmetic.
 
-    while (rest < dist
-            and delta - rest >= ten_k
-            and (rest + ten_k < dist or dist - rest > rest + ten_k - dist))
+    /*!
+    @return The size of the BSON-encoded string in @a value
+    */
+    static std::size_t calc_bson_string_size(const string_t& value)
     {
-        assert(buf[len - 1] != '0');
-        buf[len - 1]--;
-        rest += ten_k;
+        return sizeof(std::int32_t) + value.size() + 1ul;
     }
-}
-
-/*!
-Generates V = buffer * 10^decimal_exponent, such that M- <= V <= M+.
-M- and M+ must be normalized and share the same exponent -60 <= e <= -32.
-*/
-inline void grisu2_digit_gen(char* buffer, int& length, int& decimal_exponent,
-                             diyfp M_minus, diyfp w, diyfp M_plus)
-{
-    static_assert(kAlpha >= -60, "internal error");
-    static_assert(kGamma <= -32, "internal error");
-
-    // Generates the digits (and the exponent) of a decimal floating-point
-    // number V = buffer * 10^decimal_exponent in the range [M-, M+]. The diyfp's
-    // w, M- and M+ share the same exponent e, which satisfies alpha <= e <= gamma.
-    //
-    //               <--------------------------- delta ---->
-    //                                  <---- dist --------->
-    // --------------[------------------+-------------------]--------------
-    //               M-                 w                   M+
-    //
-    // Grisu2 generates the digits of M+ from left to right and stops as soon as
-    // V is in [M-,M+].
-
-    assert(M_plus.e >= kAlpha);
-    assert(M_plus.e <= kGamma);
 
-    uint64_t delta = diyfp::sub(M_plus, M_minus).f; // (significand of (M+ - M-), implicit exponent is e)
-    uint64_t dist  = diyfp::sub(M_plus, w      ).f; // (significand of (M+ - w ), implicit exponent is e)
-
-    // Split M+ = f * 2^e into two parts p1 and p2 (note: e < 0):
-    //
-    //      M+ = f * 2^e
-    //         = ((f div 2^-e) * 2^-e + (f mod 2^-e)) * 2^e
-    //         = ((p1        ) * 2^-e + (p2        )) * 2^e
-    //         = p1 + p2 * 2^e
+    /*!
+    @brief Writes a BSON element with key @a name and string value @a value
+    */
+    void write_bson_string(const string_t& name,
+                           const string_t& value)
+    {
+        write_bson_entry_header(name, 0x02);
 
-    const diyfp one(uint64_t{1} << -M_plus.e, M_plus.e);
+        write_number<std::int32_t, true>(static_cast<std::int32_t>(value.size() + 1ul));
+        oa->write_characters(
+            reinterpret_cast<const CharType*>(value.c_str()),
+            value.size() + 1);
+    }
 
-    auto p1 = static_cast<uint32_t>(M_plus.f >> -one.e); // p1 = f div 2^-e (Since -e >= 32, p1 fits into a 32-bit int.)
-    uint64_t p2 = M_plus.f & (one.f - 1);                    // p2 = f mod 2^-e
+    /*!
+    @brief Writes a BSON element with key @a name and null value
+    */
+    void write_bson_null(const string_t& name)
+    {
+        write_bson_entry_header(name, 0x0A);
+    }
 
-    // 1)
-    //
-    // Generate the digits of the integral part p1 = d[n-1]...d[1]d[0]
+    /*!
+    @return The size of the BSON-encoded integer @a value
+    */
+    static std::size_t calc_bson_integer_size(const std::int64_t value)
+    {
+        return (std::numeric_limits<std::int32_t>::min)() <= value and value <= (std::numeric_limits<std::int32_t>::max)()
+               ? sizeof(std::int32_t)
+               : sizeof(std::int64_t);
+    }
 
-    assert(p1 > 0);
+    /*!
+    @brief Writes a BSON element with key @a name and integer @a value
+    */
+    void write_bson_integer(const string_t& name,
+                            const std::int64_t value)
+    {
+        if ((std::numeric_limits<std::int32_t>::min)() <= value and value <= (std::numeric_limits<std::int32_t>::max)())
+        {
+            write_bson_entry_header(name, 0x10); // int32
+            write_number<std::int32_t, true>(static_cast<std::int32_t>(value));
+        }
+        else
+        {
+            write_bson_entry_header(name, 0x12); // int64
+            write_number<std::int64_t, true>(static_cast<std::int64_t>(value));
+        }
+    }
 
-    uint32_t pow10;
-    const int k = find_largest_pow10(p1, pow10);
+    /*!
+    @return The size of the BSON-encoded unsigned integer in @a j
+    */
+    static constexpr std::size_t calc_bson_unsigned_size(const std::uint64_t value) noexcept
+    {
+        return (value <= static_cast<std::uint64_t>((std::numeric_limits<std::int32_t>::max)()))
+               ? sizeof(std::int32_t)
+               : sizeof(std::int64_t);
+    }
 
-    //      10^(k-1) <= p1 < 10^k, pow10 = 10^(k-1)
-    //
-    //      p1 = (p1 div 10^(k-1)) * 10^(k-1) + (p1 mod 10^(k-1))
-    //         = (d[k-1]         ) * 10^(k-1) + (p1 mod 10^(k-1))
-    //
-    //      M+ = p1                                             + p2 * 2^e
-    //         = d[k-1] * 10^(k-1) + (p1 mod 10^(k-1))          + p2 * 2^e
-    //         = d[k-1] * 10^(k-1) + ((p1 mod 10^(k-1)) * 2^-e + p2) * 2^e
-    //         = d[k-1] * 10^(k-1) + (                         rest) * 2^e
-    //
-    // Now generate the digits d[n] of p1 from left to right (n = k-1,...,0)
-    //
-    //      p1 = d[k-1]...d[n] * 10^n + d[n-1]...d[0]
-    //
-    // but stop as soon as
-    //
-    //      rest * 2^e = (d[n-1]...d[0] * 2^-e + p2) * 2^e <= delta * 2^e
+    /*!
+    @brief Writes a BSON element with key @a name and unsigned @a value
+    */
+    void write_bson_unsigned(const string_t& name,
+                             const std::uint64_t value)
+    {
+        if (value <= static_cast<std::uint64_t>((std::numeric_limits<std::int32_t>::max)()))
+        {
+            write_bson_entry_header(name, 0x10 /* int32 */);
+            write_number<std::int32_t, true>(static_cast<std::int32_t>(value));
+        }
+        else if (value <= static_cast<std::uint64_t>((std::numeric_limits<std::int64_t>::max)()))
+        {
+            write_bson_entry_header(name, 0x12 /* int64 */);
+            write_number<std::int64_t, true>(static_cast<std::int64_t>(value));
+        }
+        else
+        {
+            JSON_THROW(out_of_range::create(407, "integer number " + std::to_string(value) + " cannot be represented by BSON as it does not fit int64"));
+        }
+    }
 
-    int n = k;
-    while (n > 0)
+    /*!
+    @brief Writes a BSON element with key @a name and object @a value
+    */
+    void write_bson_object_entry(const string_t& name,
+                                 const typename BasicJsonType::object_t& value)
     {
-        // Invariants:
-        //      M+ = buffer * 10^n + (p1 + p2 * 2^e)    (buffer = 0 for n = k)
-        //      pow10 = 10^(n-1) <= p1 < 10^n
-        //
-        const uint32_t d = p1 / pow10;  // d = p1 div 10^(n-1)
-        const uint32_t r = p1 % pow10;  // r = p1 mod 10^(n-1)
-        //
-        //      M+ = buffer * 10^n + (d * 10^(n-1) + r) + p2 * 2^e
-        //         = (buffer * 10 + d) * 10^(n-1) + (r + p2 * 2^e)
-        //
-        assert(d <= 9);
-        buffer[length++] = static_cast<char>('0' + d); // buffer := buffer * 10 + d
-        //
-        //      M+ = buffer * 10^(n-1) + (r + p2 * 2^e)
-        //
-        p1 = r;
-        n--;
-        //
-        //      M+ = buffer * 10^n + (p1 + p2 * 2^e)
-        //      pow10 = 10^n
-        //
+        write_bson_entry_header(name, 0x03); // object
+        write_bson_object(value);
+    }
 
-        // Now check if enough digits have been generated.
-        // Compute
-        //
-        //      p1 + p2 * 2^e = (p1 * 2^-e + p2) * 2^e = rest * 2^e
-        //
-        // Note:
-        // Since rest and delta share the same exponent e, it suffices to
-        // compare the significands.
-        const uint64_t rest = (uint64_t{p1} << -one.e) + p2;
-        if (rest <= delta)
+    /*!
+    @return The size of the BSON-encoded array @a value
+    */
+    static std::size_t calc_bson_array_size(const typename BasicJsonType::array_t& value)
+    {
+        std::size_t embedded_document_size = 0ul;
+        std::size_t array_index = 0ul;
+
+        for (const auto& el : value)
         {
-            // V = buffer * 10^n, with M- <= V <= M+.
+            embedded_document_size += calc_bson_element_size(std::to_string(array_index++), el);
+        }
 
-            decimal_exponent += n;
+        return sizeof(std::int32_t) + embedded_document_size + 1ul;
+    }
 
-            // We may now just stop. But instead look if the buffer could be
-            // decremented to bring V closer to w.
-            //
-            // pow10 = 10^n is now 1 ulp in the decimal representation V.
-            // The rounding procedure works with diyfp's with an implicit
-            // exponent of e.
-            //
-            //      10^n = (10^n * 2^-e) * 2^e = ulp * 2^e
-            //
-            const uint64_t ten_n = uint64_t{pow10} << -one.e;
-            grisu2_round(buffer, length, dist, delta, rest, ten_n);
+    /*!
+    @brief Writes a BSON element with key @a name and array @a value
+    */
+    void write_bson_array(const string_t& name,
+                          const typename BasicJsonType::array_t& value)
+    {
+        write_bson_entry_header(name, 0x04); // array
+        write_number<std::int32_t, true>(static_cast<std::int32_t>(calc_bson_array_size(value)));
 
-            return;
+        std::size_t array_index = 0ul;
+
+        for (const auto& el : value)
+        {
+            write_bson_element(std::to_string(array_index++), el);
         }
 
-        pow10 /= 10;
-        //
-        //      pow10 = 10^(n-1) <= p1 < 10^n
-        // Invariants restored.
+        oa->write_character(to_char_type(0x00));
     }
 
-    // 2)
-    //
-    // The digits of the integral part have been generated:
-    //
-    //      M+ = d[k-1]...d[1]d[0] + p2 * 2^e
-    //         = buffer            + p2 * 2^e
-    //
-    // Now generate the digits of the fractional part p2 * 2^e.
-    //
-    // Note:
-    // No decimal point is generated: the exponent is adjusted instead.
-    //
-    // p2 actually represents the fraction
-    //
-    //      p2 * 2^e
-    //          = p2 / 2^-e
-    //          = d[-1] / 10^1 + d[-2] / 10^2 + ...
-    //
-    // Now generate the digits d[-m] of p1 from left to right (m = 1,2,...)
-    //
-    //      p2 * 2^e = d[-1]d[-2]...d[-m] * 10^-m
-    //                      + 10^-m * (d[-m-1] / 10^1 + d[-m-2] / 10^2 + ...)
-    //
-    // using
-    //
-    //      10^m * p2 = ((10^m * p2) div 2^-e) * 2^-e + ((10^m * p2) mod 2^-e)
-    //                = (                   d) * 2^-e + (                   r)
-    //
-    // or
-    //      10^m * p2 * 2^e = d + r * 2^e
-    //
-    // i.e.
-    //
-    //      M+ = buffer + p2 * 2^e
-    //         = buffer + 10^-m * (d + r * 2^e)
-    //         = (buffer * 10^m + d) * 10^-m + 10^-m * r * 2^e
-    //
-    // and stop as soon as 10^-m * r * 2^e <= delta * 2^e
+    /*!
+    @brief Calculates the size necessary to serialize the JSON value @a j with its @a name
+    @return The calculated size for the BSON document entry for @a j with the given @a name.
+    */
+    static std::size_t calc_bson_element_size(const string_t& name,
+            const BasicJsonType& j)
+    {
+        const auto header_size = calc_bson_entry_header_size(name);
+        switch (j.type())
+        {
+            case value_t::object:
+                return header_size + calc_bson_object_size(*j.m_value.object);
 
-    assert(p2 > delta);
+            case value_t::array:
+                return header_size + calc_bson_array_size(*j.m_value.array);
 
-    int m = 0;
-    for (;;)
-    {
-        // Invariant:
-        //      M+ = buffer * 10^-m + 10^-m * (d[-m-1] / 10 + d[-m-2] / 10^2 + ...) * 2^e
-        //         = buffer * 10^-m + 10^-m * (p2                                 ) * 2^e
-        //         = buffer * 10^-m + 10^-m * (1/10 * (10 * p2)                   ) * 2^e
-        //         = buffer * 10^-m + 10^-m * (1/10 * ((10*p2 div 2^-e) * 2^-e + (10*p2 mod 2^-e)) * 2^e
-        //
-        assert(p2 <= UINT64_MAX / 10);
-        p2 *= 10;
-        const uint64_t d = p2 >> -one.e;     // d = (10 * p2) div 2^-e
-        const uint64_t r = p2 & (one.f - 1); // r = (10 * p2) mod 2^-e
-        //
-        //      M+ = buffer * 10^-m + 10^-m * (1/10 * (d * 2^-e + r) * 2^e
-        //         = buffer * 10^-m + 10^-m * (1/10 * (d + r * 2^e))
-        //         = (buffer * 10 + d) * 10^(-m-1) + 10^(-m-1) * r * 2^e
-        //
-        assert(d <= 9);
-        buffer[length++] = static_cast<char>('0' + d); // buffer := buffer * 10 + d
-        //
-        //      M+ = buffer * 10^(-m-1) + 10^(-m-1) * r * 2^e
-        //
-        p2 = r;
-        m++;
-        //
-        //      M+ = buffer * 10^-m + 10^-m * p2 * 2^e
-        // Invariant restored.
+            case value_t::boolean:
+                return header_size + 1ul;
+
+            case value_t::number_float:
+                return header_size + 8ul;
+
+            case value_t::number_integer:
+                return header_size + calc_bson_integer_size(j.m_value.number_integer);
 
-        // Check if enough digits have been generated.
-        //
-        //      10^-m * p2 * 2^e <= delta * 2^e
-        //              p2 * 2^e <= 10^m * delta * 2^e
-        //                    p2 <= 10^m * delta
-        delta *= 10;
-        dist  *= 10;
-        if (p2 <= delta)
-        {
-            break;
+            case value_t::number_unsigned:
+                return header_size + calc_bson_unsigned_size(j.m_value.number_unsigned);
+
+            case value_t::string:
+                return header_size + calc_bson_string_size(*j.m_value.string);
+
+            case value_t::null:
+                return header_size + 0ul;
+
+            // LCOV_EXCL_START
+            default:
+                assert(false);
+                return 0ul;
+                // LCOV_EXCL_STOP
         }
     }
 
-    // V = buffer * 10^-m, with M- <= V <= M+.
+    /*!
+    @brief Serializes the JSON value @a j to BSON and associates it with the
+           key @a name.
+    @param name The name to associate with the JSON entity @a j within the
+                current BSON document
+    @return The size of the BSON entry
+    */
+    void write_bson_element(const string_t& name,
+                            const BasicJsonType& j)
+    {
+        switch (j.type())
+        {
+            case value_t::object:
+                return write_bson_object_entry(name, *j.m_value.object);
 
-    decimal_exponent -= m;
+            case value_t::array:
+                return write_bson_array(name, *j.m_value.array);
 
-    // 1 ulp in the decimal representation is now 10^-m.
-    // Since delta and dist are now scaled by 10^m, we need to do the
-    // same with ulp in order to keep the units in sync.
-    //
-    //      10^m * 10^-m = 1 = 2^-e * 2^e = ten_m * 2^e
-    //
-    const uint64_t ten_m = one.f;
-    grisu2_round(buffer, length, dist, delta, p2, ten_m);
+            case value_t::boolean:
+                return write_bson_boolean(name, j.m_value.boolean);
 
-    // By construction this algorithm generates the shortest possible decimal
-    // number (Loitsch, Theorem 6.2) which rounds back to w.
-    // For an input number of precision p, at least
-    //
-    //      N = 1 + ceil(p * log_10(2))
-    //
-    // decimal digits are sufficient to identify all binary floating-point
-    // numbers (Matula, "In-and-Out conversions").
-    // This implies that the algorithm does not produce more than N decimal
-    // digits.
-    //
-    //      N = 17 for p = 53 (IEEE double precision)
-    //      N = 9  for p = 24 (IEEE single precision)
-}
+            case value_t::number_float:
+                return write_bson_double(name, j.m_value.number_float);
 
-/*!
-v = buf * 10^decimal_exponent
-len is the length of the buffer (number of decimal digits)
-The buffer must be large enough, i.e. >= max_digits10.
-*/
-inline void grisu2(char* buf, int& len, int& decimal_exponent,
-                   diyfp m_minus, diyfp v, diyfp m_plus)
-{
-    assert(m_plus.e == m_minus.e);
-    assert(m_plus.e == v.e);
+            case value_t::number_integer:
+                return write_bson_integer(name, j.m_value.number_integer);
 
-    //  --------(-----------------------+-----------------------)--------    (A)
-    //          m-                      v                       m+
-    //
-    //  --------------------(-----------+-----------------------)--------    (B)
-    //                      m-          v                       m+
-    //
-    // First scale v (and m- and m+) such that the exponent is in the range
-    // [alpha, gamma].
+            case value_t::number_unsigned:
+                return write_bson_unsigned(name, j.m_value.number_unsigned);
 
-    const cached_power cached = get_cached_power_for_binary_exponent(m_plus.e);
+            case value_t::string:
+                return write_bson_string(name, *j.m_value.string);
 
-    const diyfp c_minus_k(cached.f, cached.e); // = c ~= 10^-k
+            case value_t::null:
+                return write_bson_null(name);
 
-    // The exponent of the products is = v.e + c_minus_k.e + q and is in the range [alpha,gamma]
-    const diyfp w       = diyfp::mul(v,       c_minus_k);
-    const diyfp w_minus = diyfp::mul(m_minus, c_minus_k);
-    const diyfp w_plus  = diyfp::mul(m_plus,  c_minus_k);
+            // LCOV_EXCL_START
+            default:
+                assert(false);
+                return;
+                // LCOV_EXCL_STOP
+        }
+    }
 
-    //  ----(---+---)---------------(---+---)---------------(---+---)----
-    //          w-                      w                       w+
-    //          = c*m-                  = c*v                   = c*m+
-    //
-    // diyfp::mul rounds its result and c_minus_k is approximated too. w, w- and
-    // w+ are now off by a small amount.
-    // In fact:
-    //
-    //      w - v * 10^k < 1 ulp
-    //
-    // To account for this inaccuracy, add resp. subtract 1 ulp.
-    //
-    //  --------+---[---------------(---+---)---------------]---+--------
-    //          w-  M-                  w                   M+  w+
-    //
-    // Now any number in [M-, M+] (bounds included) will round to w when input,
-    // regardless of how the input rounding algorithm breaks ties.
-    //
-    // And digit_gen generates the shortest possible such number in [M-, M+].
-    // Note that this does not mean that Grisu2 always generates the shortest
-    // possible number in the interval (m-, m+).
-    const diyfp M_minus(w_minus.f + 1, w_minus.e);
-    const diyfp M_plus (w_plus.f  - 1, w_plus.e );
+    /*!
+    @brief Calculates the size of the BSON serialization of the given
+           JSON-object @a j.
+    @param[in] j  JSON value to serialize
+    @pre       j.type() == value_t::object
+    */
+    static std::size_t calc_bson_object_size(const typename BasicJsonType::object_t& value)
+    {
+        std::size_t document_size = std::accumulate(value.begin(), value.end(), 0ul,
+                                    [](size_t result, const typename BasicJsonType::object_t::value_type & el)
+        {
+            return result += calc_bson_element_size(el.first, el.second);
+        });
 
-    decimal_exponent = -cached.k; // = -(-k) = k
+        return sizeof(std::int32_t) + document_size + 1ul;
+    }
 
-    grisu2_digit_gen(buf, len, decimal_exponent, M_minus, w, M_plus);
-}
+    /*!
+    @param[in] j  JSON value to serialize
+    @pre       j.type() == value_t::object
+    */
+    void write_bson_object(const typename BasicJsonType::object_t& value)
+    {
+        write_number<std::int32_t, true>(static_cast<std::int32_t>(calc_bson_object_size(value)));
 
-/*!
-v = buf * 10^decimal_exponent
-len is the length of the buffer (number of decimal digits)
-The buffer must be large enough, i.e. >= max_digits10.
-*/
-template <typename FloatType>
-void grisu2(char* buf, int& len, int& decimal_exponent, FloatType value)
-{
-    static_assert(diyfp::kPrecision >= std::numeric_limits<FloatType>::digits + 3,
-                  "internal error: not enough precision");
+        for (const auto& el : value)
+        {
+            write_bson_element(el.first, el.second);
+        }
 
-    assert(std::isfinite(value));
-    assert(value > 0);
+        oa->write_character(to_char_type(0x00));
+    }
 
-    // If the neighbors (and boundaries) of 'value' are always computed for double-precision
-    // numbers, all float's can be recovered using strtod (and strtof). However, the resulting
-    // decimal representations are not exactly "short".
-    //
-    // The documentation for 'std::to_chars' (https://en.cppreference.com/w/cpp/utility/to_chars)
-    // says "value is converted to a string as if by std::sprintf in the default ("C") locale"
-    // and since sprintf promotes float's to double's, I think this is exactly what 'std::to_chars'
-    // does.
-    // On the other hand, the documentation for 'std::to_chars' requires that "parsing the
-    // representation using the corresponding std::from_chars function recovers value exactly". That
-    // indicates that single precision floating-point numbers should be recovered using
-    // 'std::strtof'.
-    //
-    // NB: If the neighbors are computed for single-precision numbers, there is a single float
-    //     (7.0385307e-26f) which can't be recovered using strtod. The resulting double precision
-    //     value is off by 1 ulp.
-#if 0
-    const boundaries w = compute_boundaries(static_cast<double>(value));
-#else
-    const boundaries w = compute_boundaries(value);
-#endif
+    //////////
+    // CBOR //
+    //////////
 
-    grisu2(buf, len, decimal_exponent, w.minus, w.w, w.plus);
-}
+    static constexpr CharType get_cbor_float_prefix(float /*unused*/)
+    {
+        return to_char_type(0xFA);  // Single-Precision Float
+    }
 
-/*!
-@brief appends a decimal representation of e to buf
-@return a pointer to the element following the exponent.
-@pre -1000 < e < 1000
-*/
-inline char* append_exponent(char* buf, int e)
-{
-    assert(e > -1000);
-    assert(e <  1000);
+    static constexpr CharType get_cbor_float_prefix(double /*unused*/)
+    {
+        return to_char_type(0xFB);  // Double-Precision Float
+    }
 
-    if (e < 0)
+    /////////////
+    // MsgPack //
+    /////////////
+
+    static constexpr CharType get_msgpack_float_prefix(float /*unused*/)
     {
-        e = -e;
-        *buf++ = '-';
+        return to_char_type(0xCA);  // float 32
     }
-    else
+
+    static constexpr CharType get_msgpack_float_prefix(double /*unused*/)
     {
-        *buf++ = '+';
+        return to_char_type(0xCB);  // float 64
     }
 
-    auto k = static_cast<uint32_t>(e);
-    if (k < 10)
+    ////////////
+    // UBJSON //
+    ////////////
+
+    // UBJSON: write number (floating point)
+    template<typename NumberType, typename std::enable_if<
+                 std::is_floating_point<NumberType>::value, int>::type = 0>
+    void write_number_with_ubjson_prefix(const NumberType n,
+                                         const bool add_prefix)
     {
-        // Always print at least two digits in the exponent.
-        // This is for compatibility with printf("%g").
-        *buf++ = '0';
-        *buf++ = static_cast<char>('0' + k);
+        if (add_prefix)
+        {
+            oa->write_character(get_ubjson_float_prefix(n));
+        }
+        write_number(n);
     }
-    else if (k < 100)
+
+    // UBJSON: write number (unsigned integer)
+    template<typename NumberType, typename std::enable_if<
+                 std::is_unsigned<NumberType>::value, int>::type = 0>
+    void write_number_with_ubjson_prefix(const NumberType n,
+                                         const bool add_prefix)
     {
-        *buf++ = static_cast<char>('0' + k / 10);
-        k %= 10;
-        *buf++ = static_cast<char>('0' + k);
+        if (n <= static_cast<std::uint64_t>((std::numeric_limits<std::int8_t>::max)()))
+        {
+            if (add_prefix)
+            {
+                oa->write_character(to_char_type('i'));  // int8
+            }
+            write_number(static_cast<std::uint8_t>(n));
+        }
+        else if (n <= (std::numeric_limits<std::uint8_t>::max)())
+        {
+            if (add_prefix)
+            {
+                oa->write_character(to_char_type('U'));  // uint8
+            }
+            write_number(static_cast<std::uint8_t>(n));
+        }
+        else if (n <= static_cast<std::uint64_t>((std::numeric_limits<std::int16_t>::max)()))
+        {
+            if (add_prefix)
+            {
+                oa->write_character(to_char_type('I'));  // int16
+            }
+            write_number(static_cast<std::int16_t>(n));
+        }
+        else if (n <= static_cast<std::uint64_t>((std::numeric_limits<std::int32_t>::max)()))
+        {
+            if (add_prefix)
+            {
+                oa->write_character(to_char_type('l'));  // int32
+            }
+            write_number(static_cast<std::int32_t>(n));
+        }
+        else if (n <= static_cast<std::uint64_t>((std::numeric_limits<std::int64_t>::max)()))
+        {
+            if (add_prefix)
+            {
+                oa->write_character(to_char_type('L'));  // int64
+            }
+            write_number(static_cast<std::int64_t>(n));
+        }
+        else
+        {
+            JSON_THROW(out_of_range::create(407, "integer number " + std::to_string(n) + " cannot be represented by UBJSON as it does not fit int64"));
+        }
     }
-    else
+
+    // UBJSON: write number (signed integer)
+    template<typename NumberType, typename std::enable_if<
+                 std::is_signed<NumberType>::value and
+                 not std::is_floating_point<NumberType>::value, int>::type = 0>
+    void write_number_with_ubjson_prefix(const NumberType n,
+                                         const bool add_prefix)
     {
-        *buf++ = static_cast<char>('0' + k / 100);
-        k %= 100;
-        *buf++ = static_cast<char>('0' + k / 10);
-        k %= 10;
-        *buf++ = static_cast<char>('0' + k);
+        if ((std::numeric_limits<std::int8_t>::min)() <= n and n <= (std::numeric_limits<std::int8_t>::max)())
+        {
+            if (add_prefix)
+            {
+                oa->write_character(to_char_type('i'));  // int8
+            }
+            write_number(static_cast<std::int8_t>(n));
+        }
+        else if (static_cast<std::int64_t>((std::numeric_limits<std::uint8_t>::min)()) <= n and n <= static_cast<std::int64_t>((std::numeric_limits<std::uint8_t>::max)()))
+        {
+            if (add_prefix)
+            {
+                oa->write_character(to_char_type('U'));  // uint8
+            }
+            write_number(static_cast<std::uint8_t>(n));
+        }
+        else if ((std::numeric_limits<std::int16_t>::min)() <= n and n <= (std::numeric_limits<std::int16_t>::max)())
+        {
+            if (add_prefix)
+            {
+                oa->write_character(to_char_type('I'));  // int16
+            }
+            write_number(static_cast<std::int16_t>(n));
+        }
+        else if ((std::numeric_limits<std::int32_t>::min)() <= n and n <= (std::numeric_limits<std::int32_t>::max)())
+        {
+            if (add_prefix)
+            {
+                oa->write_character(to_char_type('l'));  // int32
+            }
+            write_number(static_cast<std::int32_t>(n));
+        }
+        else if ((std::numeric_limits<std::int64_t>::min)() <= n and n <= (std::numeric_limits<std::int64_t>::max)())
+        {
+            if (add_prefix)
+            {
+                oa->write_character(to_char_type('L'));  // int64
+            }
+            write_number(static_cast<std::int64_t>(n));
+        }
+        // LCOV_EXCL_START
+        else
+        {
+            JSON_THROW(out_of_range::create(407, "integer number " + std::to_string(n) + " cannot be represented by UBJSON as it does not fit int64"));
+        }
+        // LCOV_EXCL_STOP
     }
 
-    return buf;
-}
-
-/*!
-@brief prettify v = buf * 10^decimal_exponent
+    /*!
+    @brief determine the type prefix of container values
 
-If v is in the range [10^min_exp, 10^max_exp) it will be printed in fixed-point
-notation. Otherwise it will be printed in exponential notation.
+    @note This function does not need to be 100% accurate when it comes to
+          integer limits. In case a number exceeds the limits of int64_t,
+          this will be detected by a later call to function
+          write_number_with_ubjson_prefix. Therefore, we return 'L' for any
+          value that does not fit the previous limits.
+    */
+    CharType ubjson_prefix(const BasicJsonType& j) const noexcept
+    {
+        switch (j.type())
+        {
+            case value_t::null:
+                return 'Z';
 
-@pre min_exp < 0
-@pre max_exp > 0
-*/
-inline char* format_buffer(char* buf, int len, int decimal_exponent,
-                           int min_exp, int max_exp)
-{
-    assert(min_exp < 0);
-    assert(max_exp > 0);
+            case value_t::boolean:
+                return j.m_value.boolean ? 'T' : 'F';
 
-    const int k = len;
-    const int n = len + decimal_exponent;
+            case value_t::number_integer:
+            {
+                if ((std::numeric_limits<std::int8_t>::min)() <= j.m_value.number_integer and j.m_value.number_integer <= (std::numeric_limits<std::int8_t>::max)())
+                {
+                    return 'i';
+                }
+                if ((std::numeric_limits<std::uint8_t>::min)() <= j.m_value.number_integer and j.m_value.number_integer <= (std::numeric_limits<std::uint8_t>::max)())
+                {
+                    return 'U';
+                }
+                if ((std::numeric_limits<std::int16_t>::min)() <= j.m_value.number_integer and j.m_value.number_integer <= (std::numeric_limits<std::int16_t>::max)())
+                {
+                    return 'I';
+                }
+                if ((std::numeric_limits<std::int32_t>::min)() <= j.m_value.number_integer and j.m_value.number_integer <= (std::numeric_limits<std::int32_t>::max)())
+                {
+                    return 'l';
+                }
+                // no check and assume int64_t (see note above)
+                return 'L';
+            }
 
-    // v = buf * 10^(n-k)
-    // k is the length of the buffer (number of decimal digits)
-    // n is the position of the decimal point relative to the start of the buffer.
+            case value_t::number_unsigned:
+            {
+                if (j.m_value.number_unsigned <= (std::numeric_limits<std::int8_t>::max)())
+                {
+                    return 'i';
+                }
+                if (j.m_value.number_unsigned <= (std::numeric_limits<std::uint8_t>::max)())
+                {
+                    return 'U';
+                }
+                if (j.m_value.number_unsigned <= (std::numeric_limits<std::int16_t>::max)())
+                {
+                    return 'I';
+                }
+                if (j.m_value.number_unsigned <= (std::numeric_limits<std::int32_t>::max)())
+                {
+                    return 'l';
+                }
+                // no check and assume int64_t (see note above)
+                return 'L';
+            }
 
-    if (k <= n and n <= max_exp)
-    {
-        // digits[000]
-        // len <= max_exp + 2
+            case value_t::number_float:
+                return get_ubjson_float_prefix(j.m_value.number_float);
 
-        std::memset(buf + k, '0', static_cast<size_t>(n - k));
-        // Make it look like a floating-point number (#362, #378)
-        buf[n + 0] = '.';
-        buf[n + 1] = '0';
-        return buf + (n + 2);
-    }
+            case value_t::string:
+                return 'S';
 
-    if (0 < n and n <= max_exp)
-    {
-        // dig.its
-        // len <= max_digits10 + 1
+            case value_t::array:
+                return '[';
 
-        assert(k > n);
+            case value_t::object:
+                return '{';
 
-        std::memmove(buf + (n + 1), buf + n, static_cast<size_t>(k - n));
-        buf[n] = '.';
-        return buf + (k + 1);
+            default:  // discarded values
+                return 'N';
+        }
     }
 
-    if (min_exp < n and n <= 0)
+    static constexpr CharType get_ubjson_float_prefix(float /*unused*/)
     {
-        // 0.[000]digits
-        // len <= 2 + (-min_exp - 1) + max_digits10
-
-        std::memmove(buf + (2 + -n), buf, static_cast<size_t>(k));
-        buf[0] = '0';
-        buf[1] = '.';
-        std::memset(buf + 2, '0', static_cast<size_t>(-n));
-        return buf + (2 + (-n) + k);
+        return 'd';  // float 32
     }
 
-    if (k == 1)
+    static constexpr CharType get_ubjson_float_prefix(double /*unused*/)
     {
-        // dE+123
-        // len <= 1 + 5
-
-        buf += 1;
+        return 'D';  // float 64
     }
-    else
-    {
-        // d.igitsE+123
-        // len <= max_digits10 + 1 + 5
 
-        std::memmove(buf + 2, buf + 1, static_cast<size_t>(k - 1));
-        buf[1] = '.';
-        buf += 1 + k;
-    }
+    ///////////////////////
+    // Utility functions //
+    ///////////////////////
 
-    *buf++ = 'e';
-    return append_exponent(buf, n - 1);
-}
+    /*
+    @brief write a number to output input
+    @param[in] n number of type @a NumberType
+    @tparam NumberType the type of the number
+    @tparam OutputIsLittleEndian Set to true if output data is
+                                 required to be little endian
 
-} // namespace dtoa_impl
+    @note This function needs to respect the system's endianess, because bytes
+          in CBOR, MessagePack, and UBJSON are stored in network order (big
+          endian) and therefore need reordering on little endian systems.
+    */
+    template<typename NumberType, bool OutputIsLittleEndian = false>
+    void write_number(const NumberType n)
+    {
+        // step 1: write number to array of length NumberType
+        std::array<CharType, sizeof(NumberType)> vec;
+        std::memcpy(vec.data(), &n, sizeof(NumberType));
 
-/*!
-@brief generates a decimal representation of the floating-point number value in [first, last).
+        // step 2: write array to output (with possible reordering)
+        if (is_little_endian != OutputIsLittleEndian)
+        {
+            // reverse byte order prior to conversion if necessary
+            std::reverse(vec.begin(), vec.end());
+        }
 
-The format of the resulting decimal representation is similar to printf's %g
-format. Returns an iterator pointing past-the-end of the decimal representation.
+        oa->write_characters(vec.data(), sizeof(NumberType));
+    }
+
+  public:
+    // The following to_char_type functions are implement the conversion
+    // between uint8_t and CharType. In case CharType is not unsigned,
+    // such a conversion is required to allow values greater than 128.
+    // See <https://github.com/nlohmann/json/issues/1286> for a discussion.
+    template < typename C = CharType,
+               enable_if_t < std::is_signed<C>::value and std::is_signed<char>::value > * = nullptr >
+    static constexpr CharType to_char_type(std::uint8_t x) noexcept
+    {
+        return *reinterpret_cast<char*>(&x);
+    }
 
-@note The input number must be finite, i.e. NaN's and Inf's are not supported.
-@note The buffer must be large enough.
-@note The result is NOT null-terminated.
-*/
-template <typename FloatType>
-char* to_chars(char* first, const char* last, FloatType value)
-{
-    static_cast<void>(last); // maybe unused - fix warning
-    assert(std::isfinite(value));
+    template < typename C = CharType,
+               enable_if_t < std::is_signed<C>::value and std::is_unsigned<char>::value > * = nullptr >
+    static CharType to_char_type(std::uint8_t x) noexcept
+    {
+        static_assert(sizeof(std::uint8_t) == sizeof(CharType), "size of CharType must be equal to std::uint8_t");
+        static_assert(std::is_pod<CharType>::value, "CharType must be POD");
+        CharType result;
+        std::memcpy(&result, &x, sizeof(x));
+        return result;
+    }
 
-    // Use signbit(value) instead of (value < 0) since signbit works for -0.
-    if (std::signbit(value))
+    template<typename C = CharType,
+             enable_if_t<std::is_unsigned<C>::value>* = nullptr>
+    static constexpr CharType to_char_type(std::uint8_t x) noexcept
     {
-        value = -value;
-        *first++ = '-';
+        return x;
     }
 
-    if (value == 0) // +-0
+    template < typename InputCharType, typename C = CharType,
+               enable_if_t <
+                   std::is_signed<C>::value and
+                   std::is_signed<char>::value and
+                   std::is_same<char, typename std::remove_cv<InputCharType>::type>::value
+                   > * = nullptr >
+    static constexpr CharType to_char_type(InputCharType x) noexcept
     {
-        *first++ = '0';
-        // Make it look like a floating-point number (#362, #378)
-        *first++ = '.';
-        *first++ = '0';
-        return first;
+        return x;
     }
 
-    assert(last - first >= std::numeric_limits<FloatType>::max_digits10);
+  private:
+    /// whether we can assume little endianess
+    const bool is_little_endian = binary_reader<BasicJsonType>::little_endianess();
 
-    // Compute v = buffer * 10^decimal_exponent.
-    // The decimal digits are stored in the buffer, which needs to be interpreted
-    // as an unsigned decimal integer.
-    // len is the length of the buffer, i.e. the number of decimal digits.
-    int len = 0;
-    int decimal_exponent = 0;
-    dtoa_impl::grisu2(first, len, decimal_exponent, value);
+    /// the output
+    output_adapter_t<CharType> oa = nullptr;
+};
+}  // namespace detail
+}  // namespace nlohmann
 
-    assert(len <= std::numeric_limits<FloatType>::max_digits10);
+// #include <nlohmann/detail/output/output_adapters.hpp>
 
-    // Format the buffer like printf("%.*g", prec, value)
-    constexpr int kMinExp = -4;
-    // Use digits10 here to increase compatibility with version 2.
-    constexpr int kMaxExp = std::numeric_limits<FloatType>::digits10;
+// #include <nlohmann/detail/output/serializer.hpp>
 
-    assert(last - first >= kMaxExp + 2);
-    assert(last - first >= 2 + (-kMinExp - 1) + std::numeric_limits<FloatType>::max_digits10);
-    assert(last - first >= std::numeric_limits<FloatType>::max_digits10 + 6);
 
-    return dtoa_impl::format_buffer(first, len, decimal_exponent, kMinExp, kMaxExp);
-}
+#include <algorithm> // reverse, remove, fill, find, none_of
+#include <array> // array
+#include <cassert> // assert
+#include <ciso646> // and, or
+#include <clocale> // localeconv, lconv
+#include <cmath> // labs, isfinite, isnan, signbit
+#include <cstddef> // size_t, ptrdiff_t
+#include <cstdint> // uint8_t
+#include <cstdio> // snprintf
+#include <limits> // numeric_limits
+#include <string> // string
+#include <type_traits> // is_same
+#include <utility> // move
 
-} // namespace detail
-} // namespace nlohmann
+// #include <nlohmann/detail/conversions/to_chars.hpp>
 
-// #include <nlohmann/detail/macro_scope.hpp>
 
-// #include <nlohmann/detail/meta/cpp_future.hpp>
+#include <array> // array
+#include <cassert> // assert
+#include <ciso646> // or, and, not
+#include <cmath>   // signbit, isfinite
+#include <cstdint> // intN_t, uintN_t
+#include <cstring> // memcpy, memmove
+#include <limits> // numeric_limits
+#include <type_traits> // conditional
 
-// #include <nlohmann/detail/output/binary_writer.hpp>
+namespace nlohmann
+{
+namespace detail
+{
 
-// #include <nlohmann/detail/output/output_adapters.hpp>
+/*!
+@brief implements the Grisu2 algorithm for binary to decimal floating-point
+conversion.
 
-// #include <nlohmann/detail/value_t.hpp>
+This implementation is a slightly modified version of the reference
+implementation which may be obtained from
+http://florian.loitsch.com/publications (bench.tar.gz).
 
+The code is distributed under the MIT license, Copyright (c) 2009 Florian Loitsch.
 
-namespace nlohmann
-{
-namespace detail
+For a detailed description of the algorithm see:
+
+[1] Loitsch, "Printing Floating-Point Numbers Quickly and Accurately with
+    Integers", Proceedings of the ACM SIGPLAN 2010 Conference on Programming
+    Language Design and Implementation, PLDI 2010
+[2] Burger, Dybvig, "Printing Floating-Point Numbers Quickly and Accurately",
+    Proceedings of the ACM SIGPLAN 1996 Conference on Programming Language
+    Design and Implementation, PLDI 1996
+*/
+namespace dtoa_impl
 {
-///////////////////
-// serialization //
-///////////////////
 
-/// how to treat decoding errors
-enum class error_handler_t
+template <typename Target, typename Source>
+Target reinterpret_bits(const Source source)
 {
-    strict,  ///< throw a type_error exception in case of invalid UTF-8
-    replace, ///< replace invalid UTF-8 sequences with U+FFFD
-    ignore   ///< ignore invalid UTF-8 sequences
-};
+    static_assert(sizeof(Target) == sizeof(Source), "size mismatch");
 
-template<typename BasicJsonType>
-class serializer
+    Target target;
+    std::memcpy(&target, &source, sizeof(Source));
+    return target;
+}
+
+struct diyfp // f * 2^e
 {
-    using string_t = typename BasicJsonType::string_t;
-    using number_float_t = typename BasicJsonType::number_float_t;
-    using number_integer_t = typename BasicJsonType::number_integer_t;
-    using number_unsigned_t = typename BasicJsonType::number_unsigned_t;
-    static constexpr uint8_t UTF8_ACCEPT = 0;
-    static constexpr uint8_t UTF8_REJECT = 1;
+    static constexpr int kPrecision = 64; // = q
+
+    std::uint64_t f = 0;
+    int e = 0;
+
+    constexpr diyfp(std::uint64_t f_, int e_) noexcept : f(f_), e(e_) {}
 
-  public:
     /*!
-    @param[in] s  output stream to serialize to
-    @param[in] ichar  indentation character to use
-    @param[in] error_handler_  how to react on decoding errors
+    @brief returns x - y
+    @pre x.e == y.e and x.f >= y.f
     */
-    serializer(output_adapter_t<char> s, const char ichar,
-               error_handler_t error_handler_ = error_handler_t::strict)
-        : o(std::move(s))
-        , loc(std::localeconv())
-        , thousands_sep(loc->thousands_sep == nullptr ? '\0' : * (loc->thousands_sep))
-        , decimal_point(loc->decimal_point == nullptr ? '\0' : * (loc->decimal_point))
-        , indent_char(ichar)
-        , indent_string(512, indent_char)
-        , error_handler(error_handler_)
-    {}
+    static diyfp sub(const diyfp& x, const diyfp& y) noexcept
+    {
+        assert(x.e == y.e);
+        assert(x.f >= y.f);
 
-    // delete because of pointer members
-    serializer(const serializer&) = delete;
-    serializer& operator=(const serializer&) = delete;
-    serializer(serializer&&) = delete;
-    serializer& operator=(serializer&&) = delete;
-    ~serializer() = default;
+        return {x.f - y.f, x.e};
+    }
 
     /*!
-    @brief internal implementation of the serialization function
+    @brief returns x * y
+    @note The result is rounded. (Only the upper q bits are returned.)
+    */
+    static diyfp mul(const diyfp& x, const diyfp& y) noexcept
+    {
+        static_assert(kPrecision == 64, "internal error");
 
-    This function is called by the public member function dump and organizes
-    the serialization internally. The indentation level is propagated as
-    additional parameter. In case of arrays and objects, the function is
-    called recursively.
+        // Computes:
+        //  f = round((x.f * y.f) / 2^q)
+        //  e = x.e + y.e + q
 
-    - strings and object keys are escaped using `escape_string()`
-    - integer numbers are converted implicitly via `operator<<`
-    - floating-point numbers are converted to a string using `"%g"` format
+        // Emulate the 64-bit * 64-bit multiplication:
+        //
+        // p = u * v
+        //   = (u_lo + 2^32 u_hi) (v_lo + 2^32 v_hi)
+        //   = (u_lo v_lo         ) + 2^32 ((u_lo v_hi         ) + (u_hi v_lo         )) + 2^64 (u_hi v_hi         )
+        //   = (p0                ) + 2^32 ((p1                ) + (p2                )) + 2^64 (p3                )
+        //   = (p0_lo + 2^32 p0_hi) + 2^32 ((p1_lo + 2^32 p1_hi) + (p2_lo + 2^32 p2_hi)) + 2^64 (p3                )
+        //   = (p0_lo             ) + 2^32 (p0_hi + p1_lo + p2_lo                      ) + 2^64 (p1_hi + p2_hi + p3)
+        //   = (p0_lo             ) + 2^32 (Q                                          ) + 2^64 (H                 )
+        //   = (p0_lo             ) + 2^32 (Q_lo + 2^32 Q_hi                           ) + 2^64 (H                 )
+        //
+        // (Since Q might be larger than 2^32 - 1)
+        //
+        //   = (p0_lo + 2^32 Q_lo) + 2^64 (Q_hi + H)
+        //
+        // (Q_hi + H does not overflow a 64-bit int)
+        //
+        //   = p_lo + 2^64 p_hi
 
-    @param[in] val             value to serialize
-    @param[in] pretty_print    whether the output shall be pretty-printed
-    @param[in] indent_step     the indent level
-    @param[in] current_indent  the current indent level (only used internally)
-    */
-    void dump(const BasicJsonType& val, const bool pretty_print,
-              const bool ensure_ascii,
-              const unsigned int indent_step,
-              const unsigned int current_indent = 0)
-    {
-        switch (val.m_type)
-        {
-            case value_t::object:
-            {
-                if (val.m_value.object->empty())
-                {
-                    o->write_characters("{}", 2);
-                    return;
-                }
+        const std::uint64_t u_lo = x.f & 0xFFFFFFFFu;
+        const std::uint64_t u_hi = x.f >> 32u;
+        const std::uint64_t v_lo = y.f & 0xFFFFFFFFu;
+        const std::uint64_t v_hi = y.f >> 32u;
 
-                if (pretty_print)
-                {
-                    o->write_characters("{\n", 2);
+        const std::uint64_t p0 = u_lo * v_lo;
+        const std::uint64_t p1 = u_lo * v_hi;
+        const std::uint64_t p2 = u_hi * v_lo;
+        const std::uint64_t p3 = u_hi * v_hi;
 
-                    // variable to hold indentation for recursive calls
-                    const auto new_indent = current_indent + indent_step;
-                    if (JSON_UNLIKELY(indent_string.size() < new_indent))
-                    {
-                        indent_string.resize(indent_string.size() * 2, ' ');
-                    }
+        const std::uint64_t p0_hi = p0 >> 32u;
+        const std::uint64_t p1_lo = p1 & 0xFFFFFFFFu;
+        const std::uint64_t p1_hi = p1 >> 32u;
+        const std::uint64_t p2_lo = p2 & 0xFFFFFFFFu;
+        const std::uint64_t p2_hi = p2 >> 32u;
 
-                    // first n-1 elements
-                    auto i = val.m_value.object->cbegin();
-                    for (std::size_t cnt = 0; cnt < val.m_value.object->size() - 1; ++cnt, ++i)
-                    {
-                        o->write_characters(indent_string.c_str(), new_indent);
-                        o->write_character('\"');
-                        dump_escaped(i->first, ensure_ascii);
-                        o->write_characters("\": ", 3);
-                        dump(i->second, true, ensure_ascii, indent_step, new_indent);
-                        o->write_characters(",\n", 2);
-                    }
+        std::uint64_t Q = p0_hi + p1_lo + p2_lo;
+
+        // The full product might now be computed as
+        //
+        // p_hi = p3 + p2_hi + p1_hi + (Q >> 32)
+        // p_lo = p0_lo + (Q << 32)
+        //
+        // But in this particular case here, the full p_lo is not required.
+        // Effectively we only need to add the highest bit in p_lo to p_hi (and
+        // Q_hi + 1 does not overflow).
 
-                    // last element
-                    assert(i != val.m_value.object->cend());
-                    assert(std::next(i) == val.m_value.object->cend());
-                    o->write_characters(indent_string.c_str(), new_indent);
-                    o->write_character('\"');
-                    dump_escaped(i->first, ensure_ascii);
-                    o->write_characters("\": ", 3);
-                    dump(i->second, true, ensure_ascii, indent_step, new_indent);
+        Q += std::uint64_t{1} << (64u - 32u - 1u); // round, ties up
 
-                    o->write_character('\n');
-                    o->write_characters(indent_string.c_str(), current_indent);
-                    o->write_character('}');
-                }
-                else
-                {
-                    o->write_character('{');
+        const std::uint64_t h = p3 + p2_hi + p1_hi + (Q >> 32u);
 
-                    // first n-1 elements
-                    auto i = val.m_value.object->cbegin();
-                    for (std::size_t cnt = 0; cnt < val.m_value.object->size() - 1; ++cnt, ++i)
-                    {
-                        o->write_character('\"');
-                        dump_escaped(i->first, ensure_ascii);
-                        o->write_characters("\":", 2);
-                        dump(i->second, false, ensure_ascii, indent_step, current_indent);
-                        o->write_character(',');
-                    }
+        return {h, x.e + y.e + 64};
+    }
 
-                    // last element
-                    assert(i != val.m_value.object->cend());
-                    assert(std::next(i) == val.m_value.object->cend());
-                    o->write_character('\"');
-                    dump_escaped(i->first, ensure_ascii);
-                    o->write_characters("\":", 2);
-                    dump(i->second, false, ensure_ascii, indent_step, current_indent);
+    /*!
+    @brief normalize x such that the significand is >= 2^(q-1)
+    @pre x.f != 0
+    */
+    static diyfp normalize(diyfp x) noexcept
+    {
+        assert(x.f != 0);
 
-                    o->write_character('}');
-                }
+        while ((x.f >> 63u) == 0)
+        {
+            x.f <<= 1u;
+            x.e--;
+        }
 
-                return;
-            }
+        return x;
+    }
 
-            case value_t::array:
-            {
-                if (val.m_value.array->empty())
-                {
-                    o->write_characters("[]", 2);
-                    return;
-                }
+    /*!
+    @brief normalize x such that the result has the exponent E
+    @pre e >= x.e and the upper e - x.e bits of x.f must be zero.
+    */
+    static diyfp normalize_to(const diyfp& x, const int target_exponent) noexcept
+    {
+        const int delta = x.e - target_exponent;
 
-                if (pretty_print)
-                {
-                    o->write_characters("[\n", 2);
+        assert(delta >= 0);
+        assert(((x.f << delta) >> delta) == x.f);
 
-                    // variable to hold indentation for recursive calls
-                    const auto new_indent = current_indent + indent_step;
-                    if (JSON_UNLIKELY(indent_string.size() < new_indent))
-                    {
-                        indent_string.resize(indent_string.size() * 2, ' ');
-                    }
+        return {x.f << delta, target_exponent};
+    }
+};
 
-                    // first n-1 elements
-                    for (auto i = val.m_value.array->cbegin();
-                            i != val.m_value.array->cend() - 1; ++i)
-                    {
-                        o->write_characters(indent_string.c_str(), new_indent);
-                        dump(*i, true, ensure_ascii, indent_step, new_indent);
-                        o->write_characters(",\n", 2);
-                    }
+struct boundaries
+{
+    diyfp w;
+    diyfp minus;
+    diyfp plus;
+};
 
-                    // last element
-                    assert(not val.m_value.array->empty());
-                    o->write_characters(indent_string.c_str(), new_indent);
-                    dump(val.m_value.array->back(), true, ensure_ascii, indent_step, new_indent);
+/*!
+Compute the (normalized) diyfp representing the input number 'value' and its
+boundaries.
 
-                    o->write_character('\n');
-                    o->write_characters(indent_string.c_str(), current_indent);
-                    o->write_character(']');
-                }
-                else
-                {
-                    o->write_character('[');
+@pre value must be finite and positive
+*/
+template <typename FloatType>
+boundaries compute_boundaries(FloatType value)
+{
+    assert(std::isfinite(value));
+    assert(value > 0);
 
-                    // first n-1 elements
-                    for (auto i = val.m_value.array->cbegin();
-                            i != val.m_value.array->cend() - 1; ++i)
-                    {
-                        dump(*i, false, ensure_ascii, indent_step, current_indent);
-                        o->write_character(',');
-                    }
+    // Convert the IEEE representation into a diyfp.
+    //
+    // If v is denormal:
+    //      value = 0.F * 2^(1 - bias) = (          F) * 2^(1 - bias - (p-1))
+    // If v is normalized:
+    //      value = 1.F * 2^(E - bias) = (2^(p-1) + F) * 2^(E - bias - (p-1))
 
-                    // last element
-                    assert(not val.m_value.array->empty());
-                    dump(val.m_value.array->back(), false, ensure_ascii, indent_step, current_indent);
+    static_assert(std::numeric_limits<FloatType>::is_iec559,
+                  "internal error: dtoa_short requires an IEEE-754 floating-point implementation");
 
-                    o->write_character(']');
-                }
+    constexpr int      kPrecision = std::numeric_limits<FloatType>::digits; // = p (includes the hidden bit)
+    constexpr int      kBias      = std::numeric_limits<FloatType>::max_exponent - 1 + (kPrecision - 1);
+    constexpr int      kMinExp    = 1 - kBias;
+    constexpr std::uint64_t kHiddenBit = std::uint64_t{1} << (kPrecision - 1); // = 2^(p-1)
 
-                return;
-            }
+    using bits_type = typename std::conditional<kPrecision == 24, std::uint32_t, std::uint64_t >::type;
 
-            case value_t::string:
-            {
-                o->write_character('\"');
-                dump_escaped(*val.m_value.string, ensure_ascii);
-                o->write_character('\"');
-                return;
-            }
+    const std::uint64_t bits = reinterpret_bits<bits_type>(value);
+    const std::uint64_t E = bits >> (kPrecision - 1);
+    const std::uint64_t F = bits & (kHiddenBit - 1);
 
-            case value_t::boolean:
-            {
-                if (val.m_value.boolean)
-                {
-                    o->write_characters("true", 4);
-                }
-                else
-                {
-                    o->write_characters("false", 5);
-                }
-                return;
-            }
+    const bool is_denormal = E == 0;
+    const diyfp v = is_denormal
+                    ? diyfp(F, kMinExp)
+                    : diyfp(F + kHiddenBit, static_cast<int>(E) - kBias);
 
-            case value_t::number_integer:
-            {
-                dump_integer(val.m_value.number_integer);
-                return;
-            }
+    // Compute the boundaries m- and m+ of the floating-point value
+    // v = f * 2^e.
+    //
+    // Determine v- and v+, the floating-point predecessor and successor if v,
+    // respectively.
+    //
+    //      v- = v - 2^e        if f != 2^(p-1) or e == e_min                (A)
+    //         = v - 2^(e-1)    if f == 2^(p-1) and e > e_min                (B)
+    //
+    //      v+ = v + 2^e
+    //
+    // Let m- = (v- + v) / 2 and m+ = (v + v+) / 2. All real numbers _strictly_
+    // between m- and m+ round to v, regardless of how the input rounding
+    // algorithm breaks ties.
+    //
+    //      ---+-------------+-------------+-------------+-------------+---  (A)
+    //         v-            m-            v             m+            v+
+    //
+    //      -----------------+------+------+-------------+-------------+---  (B)
+    //                       v-     m-     v             m+            v+
 
-            case value_t::number_unsigned:
-            {
-                dump_integer(val.m_value.number_unsigned);
-                return;
-            }
+    const bool lower_boundary_is_closer = F == 0 and E > 1;
+    const diyfp m_plus = diyfp(2 * v.f + 1, v.e - 1);
+    const diyfp m_minus = lower_boundary_is_closer
+                          ? diyfp(4 * v.f - 1, v.e - 2)  // (B)
+                          : diyfp(2 * v.f - 1, v.e - 1); // (A)
 
-            case value_t::number_float:
-            {
-                dump_float(val.m_value.number_float);
-                return;
-            }
+    // Determine the normalized w+ = m+.
+    const diyfp w_plus = diyfp::normalize(m_plus);
 
-            case value_t::discarded:
-            {
-                o->write_characters("<discarded>", 11);
-                return;
-            }
+    // Determine w- = m- such that e_(w-) = e_(w+).
+    const diyfp w_minus = diyfp::normalize_to(m_minus, w_plus.e);
 
-            case value_t::null:
-            {
-                o->write_characters("null", 4);
-                return;
-            }
-        }
-    }
+    return {diyfp::normalize(v), w_minus, w_plus};
+}
 
-  private:
-    /*!
-    @brief dump escaped string
+// Given normalized diyfp w, Grisu needs to find a (normalized) cached
+// power-of-ten c, such that the exponent of the product c * w = f * 2^e lies
+// within a certain range [alpha, gamma] (Definition 3.2 from [1])
+//
+//      alpha <= e = e_c + e_w + q <= gamma
+//
+// or
+//
+//      f_c * f_w * 2^alpha <= f_c 2^(e_c) * f_w 2^(e_w) * 2^q
+//                          <= f_c * f_w * 2^gamma
+//
+// Since c and w are normalized, i.e. 2^(q-1) <= f < 2^q, this implies
+//
+//      2^(q-1) * 2^(q-1) * 2^alpha <= c * w * 2^q < 2^q * 2^q * 2^gamma
+//
+// or
+//
+//      2^(q - 2 + alpha) <= c * w < 2^(q + gamma)
+//
+// The choice of (alpha,gamma) determines the size of the table and the form of
+// the digit generation procedure. Using (alpha,gamma)=(-60,-32) works out well
+// in practice:
+//
+// The idea is to cut the number c * w = f * 2^e into two parts, which can be
+// processed independently: An integral part p1, and a fractional part p2:
+//
+//      f * 2^e = ( (f div 2^-e) * 2^-e + (f mod 2^-e) ) * 2^e
+//              = (f div 2^-e) + (f mod 2^-e) * 2^e
+//              = p1 + p2 * 2^e
+//
+// The conversion of p1 into decimal form requires a series of divisions and
+// modulos by (a power of) 10. These operations are faster for 32-bit than for
+// 64-bit integers, so p1 should ideally fit into a 32-bit integer. This can be
+// achieved by choosing
+//
+//      -e >= 32   or   e <= -32 := gamma
+//
+// In order to convert the fractional part
+//
+//      p2 * 2^e = p2 / 2^-e = d[-1] / 10^1 + d[-2] / 10^2 + ...
+//
+// into decimal form, the fraction is repeatedly multiplied by 10 and the digits
+// d[-i] are extracted in order:
+//
+//      (10 * p2) div 2^-e = d[-1]
+//      (10 * p2) mod 2^-e = d[-2] / 10^1 + ...
+//
+// The multiplication by 10 must not overflow. It is sufficient to choose
+//
+//      10 * p2 < 16 * p2 = 2^4 * p2 <= 2^64.
+//
+// Since p2 = f mod 2^-e < 2^-e,
+//
+//      -e <= 60   or   e >= -60 := alpha
 
-    Escape a string by replacing certain special characters by a sequence of an
-    escape character (backslash) and another character and other control
-    characters by a sequence of "\u" followed by a four-digit hex
-    representation. The escaped string is written to output stream @a o.
+constexpr int kAlpha = -60;
+constexpr int kGamma = -32;
 
-    @param[in] s  the string to escape
-    @param[in] ensure_ascii  whether to escape non-ASCII characters with
-                             \uXXXX sequences
+struct cached_power // c = f * 2^e ~= 10^k
+{
+    std::uint64_t f;
+    int e;
+    int k;
+};
 
-    @complexity Linear in the length of string @a s.
-    */
-    void dump_escaped(const string_t& s, const bool ensure_ascii)
-    {
-        uint32_t codepoint;
-        uint8_t state = UTF8_ACCEPT;
-        std::size_t bytes = 0;  // number of bytes written to string_buffer
+/*!
+For a normalized diyfp w = f * 2^e, this function returns a (normalized) cached
+power-of-ten c = f_c * 2^e_c, such that the exponent of the product w * c
+satisfies (Definition 3.2 from [1])
 
-        // number of bytes written at the point of the last valid byte
-        std::size_t bytes_after_last_accept = 0;
-        std::size_t undumped_chars = 0;
+     alpha <= e_c + e + q <= gamma.
+*/
+inline cached_power get_cached_power_for_binary_exponent(int e)
+{
+    // Now
+    //
+    //      alpha <= e_c + e + q <= gamma                                    (1)
+    //      ==> f_c * 2^alpha <= c * 2^e * 2^q
+    //
+    // and since the c's are normalized, 2^(q-1) <= f_c,
+    //
+    //      ==> 2^(q - 1 + alpha) <= c * 2^(e + q)
+    //      ==> 2^(alpha - e - 1) <= c
+    //
+    // If c were an exakt power of ten, i.e. c = 10^k, one may determine k as
+    //
+    //      k = ceil( log_10( 2^(alpha - e - 1) ) )
+    //        = ceil( (alpha - e - 1) * log_10(2) )
+    //
+    // From the paper:
+    // "In theory the result of the procedure could be wrong since c is rounded,
+    //  and the computation itself is approximated [...]. In practice, however,
+    //  this simple function is sufficient."
+    //
+    // For IEEE double precision floating-point numbers converted into
+    // normalized diyfp's w = f * 2^e, with q = 64,
+    //
+    //      e >= -1022      (min IEEE exponent)
+    //           -52        (p - 1)
+    //           -52        (p - 1, possibly normalize denormal IEEE numbers)
+    //           -11        (normalize the diyfp)
+    //         = -1137
+    //
+    // and
+    //
+    //      e <= +1023      (max IEEE exponent)
+    //           -52        (p - 1)
+    //           -11        (normalize the diyfp)
+    //         = 960
+    //
+    // This binary exponent range [-1137,960] results in a decimal exponent
+    // range [-307,324]. One does not need to store a cached power for each
+    // k in this range. For each such k it suffices to find a cached power
+    // such that the exponent of the product lies in [alpha,gamma].
+    // This implies that the difference of the decimal exponents of adjacent
+    // table entries must be less than or equal to
+    //
+    //      floor( (gamma - alpha) * log_10(2) ) = 8.
+    //
+    // (A smaller distance gamma-alpha would require a larger table.)
 
-        for (std::size_t i = 0; i < s.size(); ++i)
-        {
-            const auto byte = static_cast<uint8_t>(s[i]);
+    // NB:
+    // Actually this function returns c, such that -60 <= e_c + e + 64 <= -34.
 
-            switch (decode(state, codepoint, byte))
-            {
-                case UTF8_ACCEPT:  // decode found a new code point
-                {
-                    switch (codepoint)
-                    {
-                        case 0x08: // backspace
-                        {
-                            string_buffer[bytes++] = '\\';
-                            string_buffer[bytes++] = 'b';
-                            break;
-                        }
+    constexpr int kCachedPowersMinDecExp = -300;
+    constexpr int kCachedPowersDecStep = 8;
 
-                        case 0x09: // horizontal tab
-                        {
-                            string_buffer[bytes++] = '\\';
-                            string_buffer[bytes++] = 't';
-                            break;
-                        }
+    static constexpr std::array<cached_power, 79> kCachedPowers =
+    {
+        {
+            { 0xAB70FE17C79AC6CA, -1060, -300 },
+            { 0xFF77B1FCBEBCDC4F, -1034, -292 },
+            { 0xBE5691EF416BD60C, -1007, -284 },
+            { 0x8DD01FAD907FFC3C,  -980, -276 },
+            { 0xD3515C2831559A83,  -954, -268 },
+            { 0x9D71AC8FADA6C9B5,  -927, -260 },
+            { 0xEA9C227723EE8BCB,  -901, -252 },
+            { 0xAECC49914078536D,  -874, -244 },
+            { 0x823C12795DB6CE57,  -847, -236 },
+            { 0xC21094364DFB5637,  -821, -228 },
+            { 0x9096EA6F3848984F,  -794, -220 },
+            { 0xD77485CB25823AC7,  -768, -212 },
+            { 0xA086CFCD97BF97F4,  -741, -204 },
+            { 0xEF340A98172AACE5,  -715, -196 },
+            { 0xB23867FB2A35B28E,  -688, -188 },
+            { 0x84C8D4DFD2C63F3B,  -661, -180 },
+            { 0xC5DD44271AD3CDBA,  -635, -172 },
+            { 0x936B9FCEBB25C996,  -608, -164 },
+            { 0xDBAC6C247D62A584,  -582, -156 },
+            { 0xA3AB66580D5FDAF6,  -555, -148 },
+            { 0xF3E2F893DEC3F126,  -529, -140 },
+            { 0xB5B5ADA8AAFF80B8,  -502, -132 },
+            { 0x87625F056C7C4A8B,  -475, -124 },
+            { 0xC9BCFF6034C13053,  -449, -116 },
+            { 0x964E858C91BA2655,  -422, -108 },
+            { 0xDFF9772470297EBD,  -396, -100 },
+            { 0xA6DFBD9FB8E5B88F,  -369,  -92 },
+            { 0xF8A95FCF88747D94,  -343,  -84 },
+            { 0xB94470938FA89BCF,  -316,  -76 },
+            { 0x8A08F0F8BF0F156B,  -289,  -68 },
+            { 0xCDB02555653131B6,  -263,  -60 },
+            { 0x993FE2C6D07B7FAC,  -236,  -52 },
+            { 0xE45C10C42A2B3B06,  -210,  -44 },
+            { 0xAA242499697392D3,  -183,  -36 },
+            { 0xFD87B5F28300CA0E,  -157,  -28 },
+            { 0xBCE5086492111AEB,  -130,  -20 },
+            { 0x8CBCCC096F5088CC,  -103,  -12 },
+            { 0xD1B71758E219652C,   -77,   -4 },
+            { 0x9C40000000000000,   -50,    4 },
+            { 0xE8D4A51000000000,   -24,   12 },
+            { 0xAD78EBC5AC620000,     3,   20 },
+            { 0x813F3978F8940984,    30,   28 },
+            { 0xC097CE7BC90715B3,    56,   36 },
+            { 0x8F7E32CE7BEA5C70,    83,   44 },
+            { 0xD5D238A4ABE98068,   109,   52 },
+            { 0x9F4F2726179A2245,   136,   60 },
+            { 0xED63A231D4C4FB27,   162,   68 },
+            { 0xB0DE65388CC8ADA8,   189,   76 },
+            { 0x83C7088E1AAB65DB,   216,   84 },
+            { 0xC45D1DF942711D9A,   242,   92 },
+            { 0x924D692CA61BE758,   269,  100 },
+            { 0xDA01EE641A708DEA,   295,  108 },
+            { 0xA26DA3999AEF774A,   322,  116 },
+            { 0xF209787BB47D6B85,   348,  124 },
+            { 0xB454E4A179DD1877,   375,  132 },
+            { 0x865B86925B9BC5C2,   402,  140 },
+            { 0xC83553C5C8965D3D,   428,  148 },
+            { 0x952AB45CFA97A0B3,   455,  156 },
+            { 0xDE469FBD99A05FE3,   481,  164 },
+            { 0xA59BC234DB398C25,   508,  172 },
+            { 0xF6C69A72A3989F5C,   534,  180 },
+            { 0xB7DCBF5354E9BECE,   561,  188 },
+            { 0x88FCF317F22241E2,   588,  196 },
+            { 0xCC20CE9BD35C78A5,   614,  204 },
+            { 0x98165AF37B2153DF,   641,  212 },
+            { 0xE2A0B5DC971F303A,   667,  220 },
+            { 0xA8D9D1535CE3B396,   694,  228 },
+            { 0xFB9B7CD9A4A7443C,   720,  236 },
+            { 0xBB764C4CA7A44410,   747,  244 },
+            { 0x8BAB8EEFB6409C1A,   774,  252 },
+            { 0xD01FEF10A657842C,   800,  260 },
+            { 0x9B10A4E5E9913129,   827,  268 },
+            { 0xE7109BFBA19C0C9D,   853,  276 },
+            { 0xAC2820D9623BF429,   880,  284 },
+            { 0x80444B5E7AA7CF85,   907,  292 },
+            { 0xBF21E44003ACDD2D,   933,  300 },
+            { 0x8E679C2F5E44FF8F,   960,  308 },
+            { 0xD433179D9C8CB841,   986,  316 },
+            { 0x9E19DB92B4E31BA9,  1013,  324 },
+        }
+    };
 
-                        case 0x0A: // newline
-                        {
-                            string_buffer[bytes++] = '\\';
-                            string_buffer[bytes++] = 'n';
-                            break;
-                        }
+    // This computation gives exactly the same results for k as
+    //      k = ceil((kAlpha - e - 1) * 0.30102999566398114)
+    // for |e| <= 1500, but doesn't require floating-point operations.
+    // NB: log_10(2) ~= 78913 / 2^18
+    assert(e >= -1500);
+    assert(e <=  1500);
+    const int f = kAlpha - e - 1;
+    const int k = (f * 78913) / (1 << 18) + static_cast<int>(f > 0);
 
-                        case 0x0C: // formfeed
-                        {
-                            string_buffer[bytes++] = '\\';
-                            string_buffer[bytes++] = 'f';
-                            break;
-                        }
+    const int index = (-kCachedPowersMinDecExp + k + (kCachedPowersDecStep - 1)) / kCachedPowersDecStep;
+    assert(index >= 0);
+    assert(static_cast<std::size_t>(index) < kCachedPowers.size());
 
-                        case 0x0D: // carriage return
-                        {
-                            string_buffer[bytes++] = '\\';
-                            string_buffer[bytes++] = 'r';
-                            break;
-                        }
+    const cached_power cached = kCachedPowers[static_cast<std::size_t>(index)];
+    assert(kAlpha <= cached.e + e + 64);
+    assert(kGamma >= cached.e + e + 64);
 
-                        case 0x22: // quotation mark
-                        {
-                            string_buffer[bytes++] = '\\';
-                            string_buffer[bytes++] = '\"';
-                            break;
-                        }
+    return cached;
+}
 
-                        case 0x5C: // reverse solidus
-                        {
-                            string_buffer[bytes++] = '\\';
-                            string_buffer[bytes++] = '\\';
-                            break;
-                        }
+/*!
+For n != 0, returns k, such that pow10 := 10^(k-1) <= n < 10^k.
+For n == 0, returns 1 and sets pow10 := 1.
+*/
+inline int find_largest_pow10(const std::uint32_t n, std::uint32_t& pow10)
+{
+    // LCOV_EXCL_START
+    if (n >= 1000000000)
+    {
+        pow10 = 1000000000;
+        return 10;
+    }
+    // LCOV_EXCL_STOP
+    else if (n >= 100000000)
+    {
+        pow10 = 100000000;
+        return  9;
+    }
+    else if (n >= 10000000)
+    {
+        pow10 = 10000000;
+        return  8;
+    }
+    else if (n >= 1000000)
+    {
+        pow10 = 1000000;
+        return  7;
+    }
+    else if (n >= 100000)
+    {
+        pow10 = 100000;
+        return  6;
+    }
+    else if (n >= 10000)
+    {
+        pow10 = 10000;
+        return  5;
+    }
+    else if (n >= 1000)
+    {
+        pow10 = 1000;
+        return  4;
+    }
+    else if (n >= 100)
+    {
+        pow10 = 100;
+        return  3;
+    }
+    else if (n >= 10)
+    {
+        pow10 = 10;
+        return  2;
+    }
+    else
+    {
+        pow10 = 1;
+        return 1;
+    }
+}
 
-                        default:
-                        {
-                            // escape control characters (0x00..0x1F) or, if
-                            // ensure_ascii parameter is used, non-ASCII characters
-                            if ((codepoint <= 0x1F) or (ensure_ascii and (codepoint >= 0x7F)))
-                            {
-                                if (codepoint <= 0xFFFF)
-                                {
-                                    (std::snprintf)(string_buffer.data() + bytes, 7, "\\u%04x",
-                                                    static_cast<uint16_t>(codepoint));
-                                    bytes += 6;
-                                }
-                                else
-                                {
-                                    (std::snprintf)(string_buffer.data() + bytes, 13, "\\u%04x\\u%04x",
-                                                    static_cast<uint16_t>(0xD7C0 + (codepoint >> 10)),
-                                                    static_cast<uint16_t>(0xDC00 + (codepoint & 0x3FF)));
-                                    bytes += 12;
-                                }
-                            }
-                            else
-                            {
-                                // copy byte to buffer (all previous bytes
-                                // been copied have in default case above)
-                                string_buffer[bytes++] = s[i];
-                            }
-                            break;
-                        }
-                    }
+inline void grisu2_round(char* buf, int len, std::uint64_t dist, std::uint64_t delta,
+                         std::uint64_t rest, std::uint64_t ten_k)
+{
+    assert(len >= 1);
+    assert(dist <= delta);
+    assert(rest <= delta);
+    assert(ten_k > 0);
 
-                    // write buffer and reset index; there must be 13 bytes
-                    // left, as this is the maximal number of bytes to be
-                    // written ("\uxxxx\uxxxx\0") for one code point
-                    if (string_buffer.size() - bytes < 13)
-                    {
-                        o->write_characters(string_buffer.data(), bytes);
-                        bytes = 0;
-                    }
+    //               <--------------------------- delta ---->
+    //                                  <---- dist --------->
+    // --------------[------------------+-------------------]--------------
+    //               M-                 w                   M+
+    //
+    //                                  ten_k
+    //                                <------>
+    //                                       <---- rest ---->
+    // --------------[------------------+----+--------------]--------------
+    //                                  w    V
+    //                                       = buf * 10^k
+    //
+    // ten_k represents a unit-in-the-last-place in the decimal representation
+    // stored in buf.
+    // Decrement buf by ten_k while this takes buf closer to w.
 
-                    // remember the byte position of this accept
-                    bytes_after_last_accept = bytes;
-                    undumped_chars = 0;
-                    break;
-                }
+    // The tests are written in this order to avoid overflow in unsigned
+    // integer arithmetic.
 
-                case UTF8_REJECT:  // decode found invalid UTF-8 byte
-                {
-                    switch (error_handler)
-                    {
-                        case error_handler_t::strict:
-                        {
-                            std::string sn(3, '\0');
-                            (std::snprintf)(&sn[0], sn.size(), "%.2X", byte);
-                            JSON_THROW(type_error::create(316, "invalid UTF-8 byte at index " + std::to_string(i) + ": 0x" + sn));
-                        }
+    while (rest < dist
+            and delta - rest >= ten_k
+            and (rest + ten_k < dist or dist - rest > rest + ten_k - dist))
+    {
+        assert(buf[len - 1] != '0');
+        buf[len - 1]--;
+        rest += ten_k;
+    }
+}
 
-                        case error_handler_t::ignore:
-                        case error_handler_t::replace:
-                        {
-                            // in case we saw this character the first time, we
-                            // would like to read it again, because the byte
-                            // may be OK for itself, but just not OK for the
-                            // previous sequence
-                            if (undumped_chars > 0)
-                            {
-                                --i;
-                            }
+/*!
+Generates V = buffer * 10^decimal_exponent, such that M- <= V <= M+.
+M- and M+ must be normalized and share the same exponent -60 <= e <= -32.
+*/
+inline void grisu2_digit_gen(char* buffer, int& length, int& decimal_exponent,
+                             diyfp M_minus, diyfp w, diyfp M_plus)
+{
+    static_assert(kAlpha >= -60, "internal error");
+    static_assert(kGamma <= -32, "internal error");
 
-                            // reset length buffer to the last accepted index;
-                            // thus removing/ignoring the invalid characters
-                            bytes = bytes_after_last_accept;
+    // Generates the digits (and the exponent) of a decimal floating-point
+    // number V = buffer * 10^decimal_exponent in the range [M-, M+]. The diyfp's
+    // w, M- and M+ share the same exponent e, which satisfies alpha <= e <= gamma.
+    //
+    //               <--------------------------- delta ---->
+    //                                  <---- dist --------->
+    // --------------[------------------+-------------------]--------------
+    //               M-                 w                   M+
+    //
+    // Grisu2 generates the digits of M+ from left to right and stops as soon as
+    // V is in [M-,M+].
 
-                            if (error_handler == error_handler_t::replace)
-                            {
-                                // add a replacement character
-                                if (ensure_ascii)
-                                {
-                                    string_buffer[bytes++] = '\\';
-                                    string_buffer[bytes++] = 'u';
-                                    string_buffer[bytes++] = 'f';
-                                    string_buffer[bytes++] = 'f';
-                                    string_buffer[bytes++] = 'f';
-                                    string_buffer[bytes++] = 'd';
-                                }
-                                else
-                                {
-                                    string_buffer[bytes++] = detail::binary_writer<BasicJsonType, char>::to_char_type('\xEF');
-                                    string_buffer[bytes++] = detail::binary_writer<BasicJsonType, char>::to_char_type('\xBF');
-                                    string_buffer[bytes++] = detail::binary_writer<BasicJsonType, char>::to_char_type('\xBD');
-                                }
-                                bytes_after_last_accept = bytes;
-                            }
+    assert(M_plus.e >= kAlpha);
+    assert(M_plus.e <= kGamma);
 
-                            undumped_chars = 0;
+    std::uint64_t delta = diyfp::sub(M_plus, M_minus).f; // (significand of (M+ - M-), implicit exponent is e)
+    std::uint64_t dist  = diyfp::sub(M_plus, w      ).f; // (significand of (M+ - w ), implicit exponent is e)
 
-                            // continue processing the string
-                            state = UTF8_ACCEPT;
-                            break;
-                        }
-                    }
-                    break;
-                }
+    // Split M+ = f * 2^e into two parts p1 and p2 (note: e < 0):
+    //
+    //      M+ = f * 2^e
+    //         = ((f div 2^-e) * 2^-e + (f mod 2^-e)) * 2^e
+    //         = ((p1        ) * 2^-e + (p2        )) * 2^e
+    //         = p1 + p2 * 2^e
 
-                default:  // decode found yet incomplete multi-byte code point
-                {
-                    if (not ensure_ascii)
-                    {
-                        // code point will not be escaped - copy byte to buffer
-                        string_buffer[bytes++] = s[i];
-                    }
-                    ++undumped_chars;
-                    break;
-                }
-            }
-        }
+    const diyfp one(std::uint64_t{1} << -M_plus.e, M_plus.e);
 
-        // we finished processing the string
-        if (JSON_LIKELY(state == UTF8_ACCEPT))
-        {
-            // write buffer
-            if (bytes > 0)
-            {
-                o->write_characters(string_buffer.data(), bytes);
-            }
-        }
-        else
-        {
-            // we finish reading, but do not accept: string was incomplete
-            switch (error_handler)
-            {
-                case error_handler_t::strict:
-                {
-                    std::string sn(3, '\0');
-                    (std::snprintf)(&sn[0], sn.size(), "%.2X", static_cast<uint8_t>(s.back()));
-                    JSON_THROW(type_error::create(316, "incomplete UTF-8 string; last byte: 0x" + sn));
-                }
+    auto p1 = static_cast<std::uint32_t>(M_plus.f >> -one.e); // p1 = f div 2^-e (Since -e >= 32, p1 fits into a 32-bit int.)
+    std::uint64_t p2 = M_plus.f & (one.f - 1);                    // p2 = f mod 2^-e
 
-                case error_handler_t::ignore:
-                {
-                    // write all accepted bytes
-                    o->write_characters(string_buffer.data(), bytes_after_last_accept);
-                    break;
-                }
+    // 1)
+    //
+    // Generate the digits of the integral part p1 = d[n-1]...d[1]d[0]
 
-                case error_handler_t::replace:
-                {
-                    // write all accepted bytes
-                    o->write_characters(string_buffer.data(), bytes_after_last_accept);
-                    // add a replacement character
-                    if (ensure_ascii)
-                    {
-                        o->write_characters("\\ufffd", 6);
-                    }
-                    else
-                    {
-                        o->write_characters("\xEF\xBF\xBD", 3);
-                    }
-                    break;
-                }
-            }
-        }
-    }
+    assert(p1 > 0);
 
-    /*!
-    @brief dump an integer
+    std::uint32_t pow10;
+    const int k = find_largest_pow10(p1, pow10);
 
-    Dump a given integer to output stream @a o. Works internally with
-    @a number_buffer.
+    //      10^(k-1) <= p1 < 10^k, pow10 = 10^(k-1)
+    //
+    //      p1 = (p1 div 10^(k-1)) * 10^(k-1) + (p1 mod 10^(k-1))
+    //         = (d[k-1]         ) * 10^(k-1) + (p1 mod 10^(k-1))
+    //
+    //      M+ = p1                                             + p2 * 2^e
+    //         = d[k-1] * 10^(k-1) + (p1 mod 10^(k-1))          + p2 * 2^e
+    //         = d[k-1] * 10^(k-1) + ((p1 mod 10^(k-1)) * 2^-e + p2) * 2^e
+    //         = d[k-1] * 10^(k-1) + (                         rest) * 2^e
+    //
+    // Now generate the digits d[n] of p1 from left to right (n = k-1,...,0)
+    //
+    //      p1 = d[k-1]...d[n] * 10^n + d[n-1]...d[0]
+    //
+    // but stop as soon as
+    //
+    //      rest * 2^e = (d[n-1]...d[0] * 2^-e + p2) * 2^e <= delta * 2^e
 
-    @param[in] x  integer number (signed or unsigned) to dump
-    @tparam NumberType either @a number_integer_t or @a number_unsigned_t
-    */
-    template<typename NumberType, detail::enable_if_t<
-                 std::is_same<NumberType, number_unsigned_t>::value or
-                 std::is_same<NumberType, number_integer_t>::value,
-                 int> = 0>
-    void dump_integer(NumberType x)
+    int n = k;
+    while (n > 0)
     {
-        // special case for "0"
-        if (x == 0)
+        // Invariants:
+        //      M+ = buffer * 10^n + (p1 + p2 * 2^e)    (buffer = 0 for n = k)
+        //      pow10 = 10^(n-1) <= p1 < 10^n
+        //
+        const std::uint32_t d = p1 / pow10;  // d = p1 div 10^(n-1)
+        const std::uint32_t r = p1 % pow10;  // r = p1 mod 10^(n-1)
+        //
+        //      M+ = buffer * 10^n + (d * 10^(n-1) + r) + p2 * 2^e
+        //         = (buffer * 10 + d) * 10^(n-1) + (r + p2 * 2^e)
+        //
+        assert(d <= 9);
+        buffer[length++] = static_cast<char>('0' + d); // buffer := buffer * 10 + d
+        //
+        //      M+ = buffer * 10^(n-1) + (r + p2 * 2^e)
+        //
+        p1 = r;
+        n--;
+        //
+        //      M+ = buffer * 10^n + (p1 + p2 * 2^e)
+        //      pow10 = 10^n
+        //
+
+        // Now check if enough digits have been generated.
+        // Compute
+        //
+        //      p1 + p2 * 2^e = (p1 * 2^-e + p2) * 2^e = rest * 2^e
+        //
+        // Note:
+        // Since rest and delta share the same exponent e, it suffices to
+        // compare the significands.
+        const std::uint64_t rest = (std::uint64_t{p1} << -one.e) + p2;
+        if (rest <= delta)
         {
-            o->write_character('0');
+            // V = buffer * 10^n, with M- <= V <= M+.
+
+            decimal_exponent += n;
+
+            // We may now just stop. But instead look if the buffer could be
+            // decremented to bring V closer to w.
+            //
+            // pow10 = 10^n is now 1 ulp in the decimal representation V.
+            // The rounding procedure works with diyfp's with an implicit
+            // exponent of e.
+            //
+            //      10^n = (10^n * 2^-e) * 2^e = ulp * 2^e
+            //
+            const std::uint64_t ten_n = std::uint64_t{pow10} << -one.e;
+            grisu2_round(buffer, length, dist, delta, rest, ten_n);
+
             return;
         }
 
-        const bool is_negative = std::is_same<NumberType, number_integer_t>::value and not (x >= 0);  // see issue #755
-        std::size_t i = 0;
+        pow10 /= 10;
+        //
+        //      pow10 = 10^(n-1) <= p1 < 10^n
+        // Invariants restored.
+    }
 
-        while (x != 0)
-        {
-            // spare 1 byte for '\0'
-            assert(i < number_buffer.size() - 1);
+    // 2)
+    //
+    // The digits of the integral part have been generated:
+    //
+    //      M+ = d[k-1]...d[1]d[0] + p2 * 2^e
+    //         = buffer            + p2 * 2^e
+    //
+    // Now generate the digits of the fractional part p2 * 2^e.
+    //
+    // Note:
+    // No decimal point is generated: the exponent is adjusted instead.
+    //
+    // p2 actually represents the fraction
+    //
+    //      p2 * 2^e
+    //          = p2 / 2^-e
+    //          = d[-1] / 10^1 + d[-2] / 10^2 + ...
+    //
+    // Now generate the digits d[-m] of p1 from left to right (m = 1,2,...)
+    //
+    //      p2 * 2^e = d[-1]d[-2]...d[-m] * 10^-m
+    //                      + 10^-m * (d[-m-1] / 10^1 + d[-m-2] / 10^2 + ...)
+    //
+    // using
+    //
+    //      10^m * p2 = ((10^m * p2) div 2^-e) * 2^-e + ((10^m * p2) mod 2^-e)
+    //                = (                   d) * 2^-e + (                   r)
+    //
+    // or
+    //      10^m * p2 * 2^e = d + r * 2^e
+    //
+    // i.e.
+    //
+    //      M+ = buffer + p2 * 2^e
+    //         = buffer + 10^-m * (d + r * 2^e)
+    //         = (buffer * 10^m + d) * 10^-m + 10^-m * r * 2^e
+    //
+    // and stop as soon as 10^-m * r * 2^e <= delta * 2^e
 
-            const auto digit = std::labs(static_cast<long>(x % 10));
-            number_buffer[i++] = static_cast<char>('0' + digit);
-            x /= 10;
-        }
+    assert(p2 > delta);
 
-        if (is_negative)
+    int m = 0;
+    for (;;)
+    {
+        // Invariant:
+        //      M+ = buffer * 10^-m + 10^-m * (d[-m-1] / 10 + d[-m-2] / 10^2 + ...) * 2^e
+        //         = buffer * 10^-m + 10^-m * (p2                                 ) * 2^e
+        //         = buffer * 10^-m + 10^-m * (1/10 * (10 * p2)                   ) * 2^e
+        //         = buffer * 10^-m + 10^-m * (1/10 * ((10*p2 div 2^-e) * 2^-e + (10*p2 mod 2^-e)) * 2^e
+        //
+        assert(p2 <= (std::numeric_limits<std::uint64_t>::max)() / 10);
+        p2 *= 10;
+        const std::uint64_t d = p2 >> -one.e;     // d = (10 * p2) div 2^-e
+        const std::uint64_t r = p2 & (one.f - 1); // r = (10 * p2) mod 2^-e
+        //
+        //      M+ = buffer * 10^-m + 10^-m * (1/10 * (d * 2^-e + r) * 2^e
+        //         = buffer * 10^-m + 10^-m * (1/10 * (d + r * 2^e))
+        //         = (buffer * 10 + d) * 10^(-m-1) + 10^(-m-1) * r * 2^e
+        //
+        assert(d <= 9);
+        buffer[length++] = static_cast<char>('0' + d); // buffer := buffer * 10 + d
+        //
+        //      M+ = buffer * 10^(-m-1) + 10^(-m-1) * r * 2^e
+        //
+        p2 = r;
+        m++;
+        //
+        //      M+ = buffer * 10^-m + 10^-m * p2 * 2^e
+        // Invariant restored.
+
+        // Check if enough digits have been generated.
+        //
+        //      10^-m * p2 * 2^e <= delta * 2^e
+        //              p2 * 2^e <= 10^m * delta * 2^e
+        //                    p2 <= 10^m * delta
+        delta *= 10;
+        dist  *= 10;
+        if (p2 <= delta)
         {
-            // make sure there is capacity for the '-'
-            assert(i < number_buffer.size() - 2);
-            number_buffer[i++] = '-';
+            break;
         }
-
-        std::reverse(number_buffer.begin(), number_buffer.begin() + i);
-        o->write_characters(number_buffer.data(), i);
     }
 
-    /*!
-    @brief dump a floating-point number
+    // V = buffer * 10^-m, with M- <= V <= M+.
 
-    Dump a given floating-point number to output stream @a o. Works internally
-    with @a number_buffer.
+    decimal_exponent -= m;
 
-    @param[in] x  floating-point number to dump
-    */
-    void dump_float(number_float_t x)
-    {
-        // NaN / inf
-        if (not std::isfinite(x))
-        {
-            o->write_characters("null", 4);
-            return;
-        }
+    // 1 ulp in the decimal representation is now 10^-m.
+    // Since delta and dist are now scaled by 10^m, we need to do the
+    // same with ulp in order to keep the units in sync.
+    //
+    //      10^m * 10^-m = 1 = 2^-e * 2^e = ten_m * 2^e
+    //
+    const std::uint64_t ten_m = one.f;
+    grisu2_round(buffer, length, dist, delta, p2, ten_m);
 
-        // If number_float_t is an IEEE-754 single or double precision number,
-        // use the Grisu2 algorithm to produce short numbers which are
-        // guaranteed to round-trip, using strtof and strtod, resp.
-        //
-        // NB: The test below works if <long double> == <double>.
-        static constexpr bool is_ieee_single_or_double
-            = (std::numeric_limits<number_float_t>::is_iec559 and std::numeric_limits<number_float_t>::digits == 24 and std::numeric_limits<number_float_t>::max_exponent == 128) or
-              (std::numeric_limits<number_float_t>::is_iec559 and std::numeric_limits<number_float_t>::digits == 53 and std::numeric_limits<number_float_t>::max_exponent == 1024);
+    // By construction this algorithm generates the shortest possible decimal
+    // number (Loitsch, Theorem 6.2) which rounds back to w.
+    // For an input number of precision p, at least
+    //
+    //      N = 1 + ceil(p * log_10(2))
+    //
+    // decimal digits are sufficient to identify all binary floating-point
+    // numbers (Matula, "In-and-Out conversions").
+    // This implies that the algorithm does not produce more than N decimal
+    // digits.
+    //
+    //      N = 17 for p = 53 (IEEE double precision)
+    //      N = 9  for p = 24 (IEEE single precision)
+}
 
-        dump_float(x, std::integral_constant<bool, is_ieee_single_or_double>());
-    }
+/*!
+v = buf * 10^decimal_exponent
+len is the length of the buffer (number of decimal digits)
+The buffer must be large enough, i.e. >= max_digits10.
+*/
+inline void grisu2(char* buf, int& len, int& decimal_exponent,
+                   diyfp m_minus, diyfp v, diyfp m_plus)
+{
+    assert(m_plus.e == m_minus.e);
+    assert(m_plus.e == v.e);
 
-    void dump_float(number_float_t x, std::true_type /*is_ieee_single_or_double*/)
-    {
-        char* begin = number_buffer.data();
-        char* end = ::nlohmann::detail::to_chars(begin, begin + number_buffer.size(), x);
+    //  --------(-----------------------+-----------------------)--------    (A)
+    //          m-                      v                       m+
+    //
+    //  --------------------(-----------+-----------------------)--------    (B)
+    //                      m-          v                       m+
+    //
+    // First scale v (and m- and m+) such that the exponent is in the range
+    // [alpha, gamma].
 
-        o->write_characters(begin, static_cast<size_t>(end - begin));
-    }
+    const cached_power cached = get_cached_power_for_binary_exponent(m_plus.e);
 
-    void dump_float(number_float_t x, std::false_type /*is_ieee_single_or_double*/)
-    {
-        // get number of digits for a float -> text -> float round-trip
-        static constexpr auto d = std::numeric_limits<number_float_t>::max_digits10;
+    const diyfp c_minus_k(cached.f, cached.e); // = c ~= 10^-k
 
-        // the actual conversion
-        std::ptrdiff_t len = (std::snprintf)(number_buffer.data(), number_buffer.size(), "%.*g", d, x);
+    // The exponent of the products is = v.e + c_minus_k.e + q and is in the range [alpha,gamma]
+    const diyfp w       = diyfp::mul(v,       c_minus_k);
+    const diyfp w_minus = diyfp::mul(m_minus, c_minus_k);
+    const diyfp w_plus  = diyfp::mul(m_plus,  c_minus_k);
 
-        // negative value indicates an error
-        assert(len > 0);
-        // check if buffer was large enough
-        assert(static_cast<std::size_t>(len) < number_buffer.size());
+    //  ----(---+---)---------------(---+---)---------------(---+---)----
+    //          w-                      w                       w+
+    //          = c*m-                  = c*v                   = c*m+
+    //
+    // diyfp::mul rounds its result and c_minus_k is approximated too. w, w- and
+    // w+ are now off by a small amount.
+    // In fact:
+    //
+    //      w - v * 10^k < 1 ulp
+    //
+    // To account for this inaccuracy, add resp. subtract 1 ulp.
+    //
+    //  --------+---[---------------(---+---)---------------]---+--------
+    //          w-  M-                  w                   M+  w+
+    //
+    // Now any number in [M-, M+] (bounds included) will round to w when input,
+    // regardless of how the input rounding algorithm breaks ties.
+    //
+    // And digit_gen generates the shortest possible such number in [M-, M+].
+    // Note that this does not mean that Grisu2 always generates the shortest
+    // possible number in the interval (m-, m+).
+    const diyfp M_minus(w_minus.f + 1, w_minus.e);
+    const diyfp M_plus (w_plus.f  - 1, w_plus.e );
 
-        // erase thousands separator
-        if (thousands_sep != '\0')
-        {
-            const auto end = std::remove(number_buffer.begin(),
-                                         number_buffer.begin() + len, thousands_sep);
-            std::fill(end, number_buffer.end(), '\0');
-            assert((end - number_buffer.begin()) <= len);
-            len = (end - number_buffer.begin());
-        }
+    decimal_exponent = -cached.k; // = -(-k) = k
 
-        // convert decimal point to '.'
-        if (decimal_point != '\0' and decimal_point != '.')
-        {
-            const auto dec_pos = std::find(number_buffer.begin(), number_buffer.end(), decimal_point);
-            if (dec_pos != number_buffer.end())
-            {
-                *dec_pos = '.';
-            }
-        }
+    grisu2_digit_gen(buf, len, decimal_exponent, M_minus, w, M_plus);
+}
+
+/*!
+v = buf * 10^decimal_exponent
+len is the length of the buffer (number of decimal digits)
+The buffer must be large enough, i.e. >= max_digits10.
+*/
+template <typename FloatType>
+void grisu2(char* buf, int& len, int& decimal_exponent, FloatType value)
+{
+    static_assert(diyfp::kPrecision >= std::numeric_limits<FloatType>::digits + 3,
+                  "internal error: not enough precision");
+
+    assert(std::isfinite(value));
+    assert(value > 0);
+
+    // If the neighbors (and boundaries) of 'value' are always computed for double-precision
+    // numbers, all float's can be recovered using strtod (and strtof). However, the resulting
+    // decimal representations are not exactly "short".
+    //
+    // The documentation for 'std::to_chars' (https://en.cppreference.com/w/cpp/utility/to_chars)
+    // says "value is converted to a string as if by std::sprintf in the default ("C") locale"
+    // and since sprintf promotes float's to double's, I think this is exactly what 'std::to_chars'
+    // does.
+    // On the other hand, the documentation for 'std::to_chars' requires that "parsing the
+    // representation using the corresponding std::from_chars function recovers value exactly". That
+    // indicates that single precision floating-point numbers should be recovered using
+    // 'std::strtof'.
+    //
+    // NB: If the neighbors are computed for single-precision numbers, there is a single float
+    //     (7.0385307e-26f) which can't be recovered using strtod. The resulting double precision
+    //     value is off by 1 ulp.
+#if 0
+    const boundaries w = compute_boundaries(static_cast<double>(value));
+#else
+    const boundaries w = compute_boundaries(value);
+#endif
+
+    grisu2(buf, len, decimal_exponent, w.minus, w.w, w.plus);
+}
 
-        o->write_characters(number_buffer.data(), static_cast<std::size_t>(len));
+/*!
+@brief appends a decimal representation of e to buf
+@return a pointer to the element following the exponent.
+@pre -1000 < e < 1000
+*/
+inline char* append_exponent(char* buf, int e)
+{
+    assert(e > -1000);
+    assert(e <  1000);
 
-        // determine if need to append ".0"
-        const bool value_is_int_like =
-            std::none_of(number_buffer.begin(), number_buffer.begin() + len + 1,
-                         [](char c)
-        {
-            return (c == '.' or c == 'e');
-        });
+    if (e < 0)
+    {
+        e = -e;
+        *buf++ = '-';
+    }
+    else
+    {
+        *buf++ = '+';
+    }
 
-        if (value_is_int_like)
-        {
-            o->write_characters(".0", 2);
-        }
+    auto k = static_cast<std::uint32_t>(e);
+    if (k < 10)
+    {
+        // Always print at least two digits in the exponent.
+        // This is for compatibility with printf("%g").
+        *buf++ = '0';
+        *buf++ = static_cast<char>('0' + k);
+    }
+    else if (k < 100)
+    {
+        *buf++ = static_cast<char>('0' + k / 10);
+        k %= 10;
+        *buf++ = static_cast<char>('0' + k);
+    }
+    else
+    {
+        *buf++ = static_cast<char>('0' + k / 100);
+        k %= 100;
+        *buf++ = static_cast<char>('0' + k / 10);
+        k %= 10;
+        *buf++ = static_cast<char>('0' + k);
     }
 
-    /*!
-    @brief check whether a string is UTF-8 encoded
+    return buf;
+}
 
-    The function checks each byte of a string whether it is UTF-8 encoded. The
-    result of the check is stored in the @a state parameter. The function must
-    be called initially with state 0 (accept). State 1 means the string must
-    be rejected, because the current byte is not allowed. If the string is
-    completely processed, but the state is non-zero, the string ended
-    prematurely; that is, the last byte indicated more bytes should have
-    followed.
+/*!
+@brief prettify v = buf * 10^decimal_exponent
 
-    @param[in,out] state  the state of the decoding
-    @param[in,out] codep  codepoint (valid only if resulting state is UTF8_ACCEPT)
-    @param[in] byte       next byte to decode
-    @return               new state
+If v is in the range [10^min_exp, 10^max_exp) it will be printed in fixed-point
+notation. Otherwise it will be printed in exponential notation.
 
-    @note The function has been edited: a std::array is used.
+@pre min_exp < 0
+@pre max_exp > 0
+*/
+inline char* format_buffer(char* buf, int len, int decimal_exponent,
+                           int min_exp, int max_exp)
+{
+    assert(min_exp < 0);
+    assert(max_exp > 0);
 
-    @copyright Copyright (c) 2008-2009 Bjoern Hoehrmann <bjoern@hoehrmann.de>
-    @sa http://bjoern.hoehrmann.de/utf-8/decoder/dfa/
-    */
-    static uint8_t decode(uint8_t& state, uint32_t& codep, const uint8_t byte) noexcept
-    {
-        static const std::array<uint8_t, 400> utf8d =
-        {
-            {
-                0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, // 00..1F
-                0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, // 20..3F
-                0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, // 40..5F
-                0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, // 60..7F
-                1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, // 80..9F
-                7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, // A0..BF
-                8, 8, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, // C0..DF
-                0xA, 0x3, 0x3, 0x3, 0x3, 0x3, 0x3, 0x3, 0x3, 0x3, 0x3, 0x3, 0x3, 0x4, 0x3, 0x3, // E0..EF
-                0xB, 0x6, 0x6, 0x6, 0x5, 0x8, 0x8, 0x8, 0x8, 0x8, 0x8, 0x8, 0x8, 0x8, 0x8, 0x8, // F0..FF
-                0x0, 0x1, 0x2, 0x3, 0x5, 0x8, 0x7, 0x1, 0x1, 0x1, 0x4, 0x6, 0x1, 0x1, 0x1, 0x1, // s0..s0
-                1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 0, 1, 1, 1, 1, 1, 0, 1, 0, 1, 1, 1, 1, 1, 1, // s1..s2
-                1, 2, 1, 1, 1, 1, 1, 2, 1, 2, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 2, 1, 1, 1, 1, 1, 1, 1, 1, // s3..s4
-                1, 2, 1, 1, 1, 1, 1, 1, 1, 2, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 3, 1, 3, 1, 1, 1, 1, 1, 1, // s5..s6
-                1, 3, 1, 1, 1, 1, 1, 3, 1, 3, 1, 1, 1, 1, 1, 1, 1, 3, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1 // s7..s8
-            }
-        };
+    const int k = len;
+    const int n = len + decimal_exponent;
 
-        const uint8_t type = utf8d[byte];
+    // v = buf * 10^(n-k)
+    // k is the length of the buffer (number of decimal digits)
+    // n is the position of the decimal point relative to the start of the buffer.
 
-        codep = (state != UTF8_ACCEPT)
-                ? (byte & 0x3fu) | (codep << 6)
-                : static_cast<uint32_t>(0xff >> type) & (byte);
+    if (k <= n and n <= max_exp)
+    {
+        // digits[000]
+        // len <= max_exp + 2
 
-        state = utf8d[256u + state * 16u + type];
-        return state;
+        std::memset(buf + k, '0', static_cast<size_t>(n - k));
+        // Make it look like a floating-point number (#362, #378)
+        buf[n + 0] = '.';
+        buf[n + 1] = '0';
+        return buf + (n + 2);
     }
 
-  private:
-    /// the output of the serializer
-    output_adapter_t<char> o = nullptr;
-
-    /// a (hopefully) large enough character buffer
-    std::array<char, 64> number_buffer{{}};
-
-    /// the locale
-    const std::lconv* loc = nullptr;
-    /// the locale's thousand separator character
-    const char thousands_sep = '\0';
-    /// the locale's decimal point character
-    const char decimal_point = '\0';
-
-    /// string buffer
-    std::array<char, 512> string_buffer{{}};
-
-    /// the indentation character
-    const char indent_char;
-    /// the indentation string
-    string_t indent_string;
+    if (0 < n and n <= max_exp)
+    {
+        // dig.its
+        // len <= max_digits10 + 1
 
-    /// error_handler how to react on decoding errors
-    const error_handler_t error_handler;
-};
-}  // namespace detail
-}  // namespace nlohmann
+        assert(k > n);
 
-// #include <nlohmann/detail/json_ref.hpp>
+        std::memmove(buf + (n + 1), buf + n, static_cast<size_t>(k - n));
+        buf[n] = '.';
+        return buf + (k + 1);
+    }
 
+    if (min_exp < n and n <= 0)
+    {
+        // 0.[000]digits
+        // len <= 2 + (-min_exp - 1) + max_digits10
 
-#include <initializer_list>
-#include <utility>
+        std::memmove(buf + (2 + -n), buf, static_cast<size_t>(k));
+        buf[0] = '0';
+        buf[1] = '.';
+        std::memset(buf + 2, '0', static_cast<size_t>(-n));
+        return buf + (2 + (-n) + k);
+    }
 
-// #include <nlohmann/detail/meta/type_traits.hpp>
+    if (k == 1)
+    {
+        // dE+123
+        // len <= 1 + 5
 
+        buf += 1;
+    }
+    else
+    {
+        // d.igitsE+123
+        // len <= max_digits10 + 1 + 5
 
-namespace nlohmann
-{
-namespace detail
-{
-template<typename BasicJsonType>
-class json_ref
-{
-  public:
-    using value_type = BasicJsonType;
+        std::memmove(buf + 2, buf + 1, static_cast<size_t>(k - 1));
+        buf[1] = '.';
+        buf += 1 + k;
+    }
 
-    json_ref(value_type&& value)
-        : owned_value(std::move(value)), value_ref(&owned_value), is_rvalue(true)
-    {}
+    *buf++ = 'e';
+    return append_exponent(buf, n - 1);
+}
 
-    json_ref(const value_type& value)
-        : value_ref(const_cast<value_type*>(&value)), is_rvalue(false)
-    {}
+} // namespace dtoa_impl
 
-    json_ref(std::initializer_list<json_ref> init)
-        : owned_value(init), value_ref(&owned_value), is_rvalue(true)
-    {}
+/*!
+@brief generates a decimal representation of the floating-point number value in [first, last).
 
-    template <
-        class... Args,
-        enable_if_t<std::is_constructible<value_type, Args...>::value, int> = 0 >
-    json_ref(Args && ... args)
-        : owned_value(std::forward<Args>(args)...), value_ref(&owned_value),
-          is_rvalue(true) {}
+The format of the resulting decimal representation is similar to printf's %g
+format. Returns an iterator pointing past-the-end of the decimal representation.
 
-    // class should be movable only
-    json_ref(json_ref&&) = default;
-    json_ref(const json_ref&) = delete;
-    json_ref& operator=(const json_ref&) = delete;
-    json_ref& operator=(json_ref&&) = delete;
-    ~json_ref() = default;
+@note The input number must be finite, i.e. NaN's and Inf's are not supported.
+@note The buffer must be large enough.
+@note The result is NOT null-terminated.
+*/
+template <typename FloatType>
+char* to_chars(char* first, const char* last, FloatType value)
+{
+    static_cast<void>(last); // maybe unused - fix warning
+    assert(std::isfinite(value));
 
-    value_type moved_or_copied() const
+    // Use signbit(value) instead of (value < 0) since signbit works for -0.
+    if (std::signbit(value))
     {
-        if (is_rvalue)
-        {
-            return std::move(*value_ref);
-        }
-        return *value_ref;
+        value = -value;
+        *first++ = '-';
     }
 
-    value_type const& operator*() const
+    if (value == 0) // +-0
     {
-        return *static_cast<value_type const*>(value_ref);
+        *first++ = '0';
+        // Make it look like a floating-point number (#362, #378)
+        *first++ = '.';
+        *first++ = '0';
+        return first;
     }
 
-    value_type const* operator->() const
-    {
-        return static_cast<value_type const*>(value_ref);
-    }
+    assert(last - first >= std::numeric_limits<FloatType>::max_digits10);
+
+    // Compute v = buffer * 10^decimal_exponent.
+    // The decimal digits are stored in the buffer, which needs to be interpreted
+    // as an unsigned decimal integer.
+    // len is the length of the buffer, i.e. the number of decimal digits.
+    int len = 0;
+    int decimal_exponent = 0;
+    dtoa_impl::grisu2(first, len, decimal_exponent, value);
+
+    assert(len <= std::numeric_limits<FloatType>::max_digits10);
+
+    // Format the buffer like printf("%.*g", prec, value)
+    constexpr int kMinExp = -4;
+    // Use digits10 here to increase compatibility with version 2.
+    constexpr int kMaxExp = std::numeric_limits<FloatType>::digits10;
 
-  private:
-    mutable value_type owned_value = nullptr;
-    value_type* value_ref = nullptr;
-    const bool is_rvalue;
-};
-}  // namespace detail
-}  // namespace nlohmann
+    assert(last - first >= kMaxExp + 2);
+    assert(last - first >= 2 + (-kMinExp - 1) + std::numeric_limits<FloatType>::max_digits10);
+    assert(last - first >= std::numeric_limits<FloatType>::max_digits10 + 6);
 
-// #include <nlohmann/detail/json_pointer.hpp>
+    return dtoa_impl::format_buffer(first, len, decimal_exponent, kMinExp, kMaxExp);
+}
 
+} // namespace detail
+} // namespace nlohmann
 
-#include <cassert> // assert
-#include <numeric> // accumulate
-#include <string> // string
-#include <vector> // vector
+// #include <nlohmann/detail/exceptions.hpp>
 
 // #include <nlohmann/detail/macro_scope.hpp>
 
-// #include <nlohmann/detail/exceptions.hpp>
+// #include <nlohmann/detail/meta/cpp_future.hpp>
+
+// #include <nlohmann/detail/output/binary_writer.hpp>
+
+// #include <nlohmann/detail/output/output_adapters.hpp>
 
 // #include <nlohmann/detail/value_t.hpp>
 
 
 namespace nlohmann
 {
+namespace detail
+{
+///////////////////
+// serialization //
+///////////////////
+
+/// how to treat decoding errors
+enum class error_handler_t
+{
+    strict,  ///< throw a type_error exception in case of invalid UTF-8
+    replace, ///< replace invalid UTF-8 sequences with U+FFFD
+    ignore   ///< ignore invalid UTF-8 sequences
+};
+
 template<typename BasicJsonType>
-class json_pointer
+class serializer
 {
-    // allow basic_json to access private members
-    NLOHMANN_BASIC_JSON_TPL_DECLARATION
-    friend class basic_json;
+    using string_t = typename BasicJsonType::string_t;
+    using number_float_t = typename BasicJsonType::number_float_t;
+    using number_integer_t = typename BasicJsonType::number_integer_t;
+    using number_unsigned_t = typename BasicJsonType::number_unsigned_t;
+    static constexpr std::uint8_t UTF8_ACCEPT = 0;
+    static constexpr std::uint8_t UTF8_REJECT = 1;
 
   public:
     /*!
-    @brief create JSON pointer
-
-    Create a JSON pointer according to the syntax described in
-    [Section 3 of RFC6901](https://tools.ietf.org/html/rfc6901#section-3).
+    @param[in] s  output stream to serialize to
+    @param[in] ichar  indentation character to use
+    @param[in] error_handler_  how to react on decoding errors
+    */
+    serializer(output_adapter_t<char> s, const char ichar,
+               error_handler_t error_handler_ = error_handler_t::strict)
+        : o(std::move(s))
+        , loc(std::localeconv())
+        , thousands_sep(loc->thousands_sep == nullptr ? '\0' : * (loc->thousands_sep))
+        , decimal_point(loc->decimal_point == nullptr ? '\0' : * (loc->decimal_point))
+        , indent_char(ichar)
+        , indent_string(512, indent_char)
+        , error_handler(error_handler_)
+    {}
 
-    @param[in] s  string representing the JSON pointer; if omitted, the empty
-                  string is assumed which references the whole JSON value
+    // delete because of pointer members
+    serializer(const serializer&) = delete;
+    serializer& operator=(const serializer&) = delete;
+    serializer(serializer&&) = delete;
+    serializer& operator=(serializer&&) = delete;
+    ~serializer() = default;
 
-    @throw parse_error.107 if the given JSON pointer @a s is nonempty and does
-                           not begin with a slash (`/`); see example below
+    /*!
+    @brief internal implementation of the serialization function
 
-    @throw parse_error.108 if a tilde (`~`) in the given JSON pointer @a s is
-    not followed by `0` (representing `~`) or `1` (representing `/`); see
-    example below
+    This function is called by the public member function dump and organizes
+    the serialization internally. The indentation level is propagated as
+    additional parameter. In case of arrays and objects, the function is
+    called recursively.
 
-    @liveexample{The example shows the construction several valid JSON pointers
-    as well as the exceptional behavior.,json_pointer}
+    - strings and object keys are escaped using `escape_string()`
+    - integer numbers are converted implicitly via `operator<<`
+    - floating-point numbers are converted to a string using `"%g"` format
 
-    @since version 2.0.0
+    @param[in] val             value to serialize
+    @param[in] pretty_print    whether the output shall be pretty-printed
+    @param[in] indent_step     the indent level
+    @param[in] current_indent  the current indent level (only used internally)
     */
-    explicit json_pointer(const std::string& s = "")
-        : reference_tokens(split(s))
-    {}
+    void dump(const BasicJsonType& val, const bool pretty_print,
+              const bool ensure_ascii,
+              const unsigned int indent_step,
+              const unsigned int current_indent = 0)
+    {
+        switch (val.m_type)
+        {
+            case value_t::object:
+            {
+                if (val.m_value.object->empty())
+                {
+                    o->write_characters("{}", 2);
+                    return;
+                }
 
-    /*!
-    @brief return a string representation of the JSON pointer
+                if (pretty_print)
+                {
+                    o->write_characters("{\n", 2);
 
-    @invariant For each JSON pointer `ptr`, it holds:
-    @code {.cpp}
-    ptr == json_pointer(ptr.to_string());
-    @endcode
+                    // variable to hold indentation for recursive calls
+                    const auto new_indent = current_indent + indent_step;
+                    if (JSON_UNLIKELY(indent_string.size() < new_indent))
+                    {
+                        indent_string.resize(indent_string.size() * 2, ' ');
+                    }
 
-    @return a string representation of the JSON pointer
+                    // first n-1 elements
+                    auto i = val.m_value.object->cbegin();
+                    for (std::size_t cnt = 0; cnt < val.m_value.object->size() - 1; ++cnt, ++i)
+                    {
+                        o->write_characters(indent_string.c_str(), new_indent);
+                        o->write_character('\"');
+                        dump_escaped(i->first, ensure_ascii);
+                        o->write_characters("\": ", 3);
+                        dump(i->second, true, ensure_ascii, indent_step, new_indent);
+                        o->write_characters(",\n", 2);
+                    }
 
-    @liveexample{The example shows the result of `to_string`.,
-    json_pointer__to_string}
+                    // last element
+                    assert(i != val.m_value.object->cend());
+                    assert(std::next(i) == val.m_value.object->cend());
+                    o->write_characters(indent_string.c_str(), new_indent);
+                    o->write_character('\"');
+                    dump_escaped(i->first, ensure_ascii);
+                    o->write_characters("\": ", 3);
+                    dump(i->second, true, ensure_ascii, indent_step, new_indent);
 
-    @since version 2.0.0
-    */
-    std::string to_string() const
-    {
-        return std::accumulate(reference_tokens.begin(), reference_tokens.end(),
-                               std::string{},
-                               [](const std::string & a, const std::string & b)
-        {
-            return a + "/" + escape(b);
-        });
-    }
+                    o->write_character('\n');
+                    o->write_characters(indent_string.c_str(), current_indent);
+                    o->write_character('}');
+                }
+                else
+                {
+                    o->write_character('{');
 
-    /// @copydoc to_string()
-    operator std::string() const
-    {
-        return to_string();
-    }
+                    // first n-1 elements
+                    auto i = val.m_value.object->cbegin();
+                    for (std::size_t cnt = 0; cnt < val.m_value.object->size() - 1; ++cnt, ++i)
+                    {
+                        o->write_character('\"');
+                        dump_escaped(i->first, ensure_ascii);
+                        o->write_characters("\":", 2);
+                        dump(i->second, false, ensure_ascii, indent_step, current_indent);
+                        o->write_character(',');
+                    }
 
-    /*!
-    @param[in] s  reference token to be converted into an array index
+                    // last element
+                    assert(i != val.m_value.object->cend());
+                    assert(std::next(i) == val.m_value.object->cend());
+                    o->write_character('\"');
+                    dump_escaped(i->first, ensure_ascii);
+                    o->write_characters("\":", 2);
+                    dump(i->second, false, ensure_ascii, indent_step, current_indent);
 
-    @return integer representation of @a s
+                    o->write_character('}');
+                }
 
-    @throw out_of_range.404 if string @a s could not be converted to an integer
-    */
-    static int array_index(const std::string& s)
-    {
-        std::size_t processed_chars = 0;
-        const int res = std::stoi(s, &processed_chars);
+                return;
+            }
 
-        // check if the string was completely read
-        if (JSON_UNLIKELY(processed_chars != s.size()))
-        {
-            JSON_THROW(detail::out_of_range::create(404, "unresolved reference token '" + s + "'"));
-        }
+            case value_t::array:
+            {
+                if (val.m_value.array->empty())
+                {
+                    o->write_characters("[]", 2);
+                    return;
+                }
 
-        return res;
-    }
+                if (pretty_print)
+                {
+                    o->write_characters("[\n", 2);
 
-  private:
-    /*!
-    @brief remove and return last reference pointer
-    @throw out_of_range.405 if JSON pointer has no parent
-    */
-    std::string pop_back()
-    {
-        if (JSON_UNLIKELY(is_root()))
-        {
-            JSON_THROW(detail::out_of_range::create(405, "JSON pointer has no parent"));
-        }
+                    // variable to hold indentation for recursive calls
+                    const auto new_indent = current_indent + indent_step;
+                    if (JSON_UNLIKELY(indent_string.size() < new_indent))
+                    {
+                        indent_string.resize(indent_string.size() * 2, ' ');
+                    }
 
-        auto last = reference_tokens.back();
-        reference_tokens.pop_back();
-        return last;
-    }
+                    // first n-1 elements
+                    for (auto i = val.m_value.array->cbegin();
+                            i != val.m_value.array->cend() - 1; ++i)
+                    {
+                        o->write_characters(indent_string.c_str(), new_indent);
+                        dump(*i, true, ensure_ascii, indent_step, new_indent);
+                        o->write_characters(",\n", 2);
+                    }
+
+                    // last element
+                    assert(not val.m_value.array->empty());
+                    o->write_characters(indent_string.c_str(), new_indent);
+                    dump(val.m_value.array->back(), true, ensure_ascii, indent_step, new_indent);
 
-    /// return whether pointer points to the root document
-    bool is_root() const noexcept
-    {
-        return reference_tokens.empty();
-    }
+                    o->write_character('\n');
+                    o->write_characters(indent_string.c_str(), current_indent);
+                    o->write_character(']');
+                }
+                else
+                {
+                    o->write_character('[');
 
-    json_pointer top() const
-    {
-        if (JSON_UNLIKELY(is_root()))
-        {
-            JSON_THROW(detail::out_of_range::create(405, "JSON pointer has no parent"));
-        }
+                    // first n-1 elements
+                    for (auto i = val.m_value.array->cbegin();
+                            i != val.m_value.array->cend() - 1; ++i)
+                    {
+                        dump(*i, false, ensure_ascii, indent_step, current_indent);
+                        o->write_character(',');
+                    }
 
-        json_pointer result = *this;
-        result.reference_tokens = {reference_tokens[0]};
-        return result;
-    }
+                    // last element
+                    assert(not val.m_value.array->empty());
+                    dump(val.m_value.array->back(), false, ensure_ascii, indent_step, current_indent);
 
-    /*!
-    @brief create and return a reference to the pointed to value
+                    o->write_character(']');
+                }
 
-    @complexity Linear in the number of reference tokens.
+                return;
+            }
 
-    @throw parse_error.109 if array index is not a number
-    @throw type_error.313 if value cannot be unflattened
-    */
-    BasicJsonType& get_and_create(BasicJsonType& j) const
-    {
-        using size_type = typename BasicJsonType::size_type;
-        auto result = &j;
+            case value_t::string:
+            {
+                o->write_character('\"');
+                dump_escaped(*val.m_value.string, ensure_ascii);
+                o->write_character('\"');
+                return;
+            }
 
-        // in case no reference tokens exist, return a reference to the JSON value
-        // j which will be overwritten by a primitive value
-        for (const auto& reference_token : reference_tokens)
-        {
-            switch (result->m_type)
+            case value_t::boolean:
             {
-                case detail::value_t::null:
+                if (val.m_value.boolean)
                 {
-                    if (reference_token == "0")
-                    {
-                        // start a new array if reference token is 0
-                        result = &result->operator[](0);
-                    }
-                    else
-                    {
-                        // start a new object otherwise
-                        result = &result->operator[](reference_token);
-                    }
-                    break;
+                    o->write_characters("true", 4);
                 }
-
-                case detail::value_t::object:
+                else
                 {
-                    // create an entry in the object
-                    result = &result->operator[](reference_token);
-                    break;
+                    o->write_characters("false", 5);
                 }
+                return;
+            }
 
-                case detail::value_t::array:
-                {
-                    // create an entry in the array
-                    JSON_TRY
-                    {
-                        result = &result->operator[](static_cast<size_type>(array_index(reference_token)));
-                    }
-                    JSON_CATCH(std::invalid_argument&)
-                    {
-                        JSON_THROW(detail::parse_error::create(109, 0, "array index '" + reference_token + "' is not a number"));
-                    }
-                    break;
-                }
+            case value_t::number_integer:
+            {
+                dump_integer(val.m_value.number_integer);
+                return;
+            }
 
-                /*
-                The following code is only reached if there exists a reference
-                token _and_ the current value is primitive. In this case, we have
-                an error situation, because primitive values may only occur as
-                single value; that is, with an empty list of reference tokens.
-                */
-                default:
-                    JSON_THROW(detail::type_error::create(313, "invalid value to unflatten"));
+            case value_t::number_unsigned:
+            {
+                dump_integer(val.m_value.number_unsigned);
+                return;
             }
-        }
 
-        return *result;
-    }
+            case value_t::number_float:
+            {
+                dump_float(val.m_value.number_float);
+                return;
+            }
 
-    /*!
-    @brief return a reference to the pointed to value
+            case value_t::discarded:
+            {
+                o->write_characters("<discarded>", 11);
+                return;
+            }
 
-    @note This version does not throw if a value is not present, but tries to
-          create nested values instead. For instance, calling this function
-          with pointer `"/this/that"` on a null value is equivalent to calling
-          `operator[]("this").operator[]("that")` on that value, effectively
-          changing the null value to an object.
+            case value_t::null:
+            {
+                o->write_characters("null", 4);
+                return;
+            }
 
-    @param[in] ptr  a JSON value
+            default:            // LCOV_EXCL_LINE
+                assert(false);  // LCOV_EXCL_LINE
+        }
+    }
 
-    @return reference to the JSON value pointed to by the JSON pointer
+  private:
+    /*!
+    @brief dump escaped string
 
-    @complexity Linear in the length of the JSON pointer.
+    Escape a string by replacing certain special characters by a sequence of an
+    escape character (backslash) and another character and other control
+    characters by a sequence of "\u" followed by a four-digit hex
+    representation. The escaped string is written to output stream @a o.
 
-    @throw parse_error.106   if an array index begins with '0'
-    @throw parse_error.109   if an array index was not a number
-    @throw out_of_range.404  if the JSON pointer can not be resolved
+    @param[in] s  the string to escape
+    @param[in] ensure_ascii  whether to escape non-ASCII characters with
+                             \uXXXX sequences
+
+    @complexity Linear in the length of string @a s.
     */
-    BasicJsonType& get_unchecked(BasicJsonType* ptr) const
+    void dump_escaped(const string_t& s, const bool ensure_ascii)
     {
-        using size_type = typename BasicJsonType::size_type;
-        for (const auto& reference_token : reference_tokens)
+        std::uint32_t codepoint;
+        std::uint8_t state = UTF8_ACCEPT;
+        std::size_t bytes = 0;  // number of bytes written to string_buffer
+
+        // number of bytes written at the point of the last valid byte
+        std::size_t bytes_after_last_accept = 0;
+        std::size_t undumped_chars = 0;
+
+        for (std::size_t i = 0; i < s.size(); ++i)
         {
-            // convert null values to arrays or objects before continuing
-            if (ptr->m_type == detail::value_t::null)
+            const auto byte = static_cast<uint8_t>(s[i]);
+
+            switch (decode(state, codepoint, byte))
             {
-                // check if reference token is a number
-                const bool nums =
-                    std::all_of(reference_token.begin(), reference_token.end(),
-                                [](const char x)
+                case UTF8_ACCEPT:  // decode found a new code point
                 {
-                    return (x >= '0' and x <= '9');
-                });
+                    switch (codepoint)
+                    {
+                        case 0x08: // backspace
+                        {
+                            string_buffer[bytes++] = '\\';
+                            string_buffer[bytes++] = 'b';
+                            break;
+                        }
 
-                // change value to array for numbers or "-" or to object otherwise
-                *ptr = (nums or reference_token == "-")
-                       ? detail::value_t::array
-                       : detail::value_t::object;
-            }
+                        case 0x09: // horizontal tab
+                        {
+                            string_buffer[bytes++] = '\\';
+                            string_buffer[bytes++] = 't';
+                            break;
+                        }
 
-            switch (ptr->m_type)
-            {
-                case detail::value_t::object:
-                {
-                    // use unchecked object access
-                    ptr = &ptr->operator[](reference_token);
-                    break;
-                }
+                        case 0x0A: // newline
+                        {
+                            string_buffer[bytes++] = '\\';
+                            string_buffer[bytes++] = 'n';
+                            break;
+                        }
 
-                case detail::value_t::array:
-                {
-                    // error condition (cf. RFC 6901, Sect. 4)
-                    if (JSON_UNLIKELY(reference_token.size() > 1 and reference_token[0] == '0'))
-                    {
-                        JSON_THROW(detail::parse_error::create(106, 0,
-                                                               "array index '" + reference_token +
-                                                               "' must not begin with '0'"));
-                    }
+                        case 0x0C: // formfeed
+                        {
+                            string_buffer[bytes++] = '\\';
+                            string_buffer[bytes++] = 'f';
+                            break;
+                        }
 
-                    if (reference_token == "-")
-                    {
-                        // explicitly treat "-" as index beyond the end
-                        ptr = &ptr->operator[](ptr->m_value.array->size());
-                    }
-                    else
-                    {
-                        // convert array index to number; unchecked access
-                        JSON_TRY
+                        case 0x0D: // carriage return
                         {
-                            ptr = &ptr->operator[](
-                                static_cast<size_type>(array_index(reference_token)));
+                            string_buffer[bytes++] = '\\';
+                            string_buffer[bytes++] = 'r';
+                            break;
                         }
-                        JSON_CATCH(std::invalid_argument&)
+
+                        case 0x22: // quotation mark
+                        {
+                            string_buffer[bytes++] = '\\';
+                            string_buffer[bytes++] = '\"';
+                            break;
+                        }
+
+                        case 0x5C: // reverse solidus
+                        {
+                            string_buffer[bytes++] = '\\';
+                            string_buffer[bytes++] = '\\';
+                            break;
+                        }
+
+                        default:
                         {
-                            JSON_THROW(detail::parse_error::create(109, 0, "array index '" + reference_token + "' is not a number"));
+                            // escape control characters (0x00..0x1F) or, if
+                            // ensure_ascii parameter is used, non-ASCII characters
+                            if ((codepoint <= 0x1F) or (ensure_ascii and (codepoint >= 0x7F)))
+                            {
+                                if (codepoint <= 0xFFFF)
+                                {
+                                    (std::snprintf)(string_buffer.data() + bytes, 7, "\\u%04x",
+                                                    static_cast<std::uint16_t>(codepoint));
+                                    bytes += 6;
+                                }
+                                else
+                                {
+                                    (std::snprintf)(string_buffer.data() + bytes, 13, "\\u%04x\\u%04x",
+                                                    static_cast<std::uint16_t>(0xD7C0u + (codepoint >> 10u)),
+                                                    static_cast<std::uint16_t>(0xDC00u + (codepoint & 0x3FFu)));
+                                    bytes += 12;
+                                }
+                            }
+                            else
+                            {
+                                // copy byte to buffer (all previous bytes
+                                // been copied have in default case above)
+                                string_buffer[bytes++] = s[i];
+                            }
+                            break;
                         }
                     }
-                    break;
-                }
-
-                default:
-                    JSON_THROW(detail::out_of_range::create(404, "unresolved reference token '" + reference_token + "'"));
-            }
-        }
 
-        return *ptr;
-    }
+                    // write buffer and reset index; there must be 13 bytes
+                    // left, as this is the maximal number of bytes to be
+                    // written ("\uxxxx\uxxxx\0") for one code point
+                    if (string_buffer.size() - bytes < 13)
+                    {
+                        o->write_characters(string_buffer.data(), bytes);
+                        bytes = 0;
+                    }
 
-    /*!
-    @throw parse_error.106   if an array index begins with '0'
-    @throw parse_error.109   if an array index was not a number
-    @throw out_of_range.402  if the array index '-' is used
-    @throw out_of_range.404  if the JSON pointer can not be resolved
-    */
-    BasicJsonType& get_checked(BasicJsonType* ptr) const
-    {
-        using size_type = typename BasicJsonType::size_type;
-        for (const auto& reference_token : reference_tokens)
-        {
-            switch (ptr->m_type)
-            {
-                case detail::value_t::object:
-                {
-                    // note: at performs range check
-                    ptr = &ptr->at(reference_token);
+                    // remember the byte position of this accept
+                    bytes_after_last_accept = bytes;
+                    undumped_chars = 0;
                     break;
                 }
 
-                case detail::value_t::array:
+                case UTF8_REJECT:  // decode found invalid UTF-8 byte
                 {
-                    if (JSON_UNLIKELY(reference_token == "-"))
+                    switch (error_handler)
                     {
-                        // "-" always fails the range check
-                        JSON_THROW(detail::out_of_range::create(402,
-                                                                "array index '-' (" + std::to_string(ptr->m_value.array->size()) +
-                                                                ") is out of range"));
-                    }
+                        case error_handler_t::strict:
+                        {
+                            std::string sn(3, '\0');
+                            (std::snprintf)(&sn[0], sn.size(), "%.2X", byte);
+                            JSON_THROW(type_error::create(316, "invalid UTF-8 byte at index " + std::to_string(i) + ": 0x" + sn));
+                        }
 
-                    // error condition (cf. RFC 6901, Sect. 4)
-                    if (JSON_UNLIKELY(reference_token.size() > 1 and reference_token[0] == '0'))
-                    {
-                        JSON_THROW(detail::parse_error::create(106, 0,
-                                                               "array index '" + reference_token +
-                                                               "' must not begin with '0'"));
-                    }
+                        case error_handler_t::ignore:
+                        case error_handler_t::replace:
+                        {
+                            // in case we saw this character the first time, we
+                            // would like to read it again, because the byte
+                            // may be OK for itself, but just not OK for the
+                            // previous sequence
+                            if (undumped_chars > 0)
+                            {
+                                --i;
+                            }
 
-                    // note: at performs range check
-                    JSON_TRY
-                    {
-                        ptr = &ptr->at(static_cast<size_type>(array_index(reference_token)));
-                    }
-                    JSON_CATCH(std::invalid_argument&)
-                    {
-                        JSON_THROW(detail::parse_error::create(109, 0, "array index '" + reference_token + "' is not a number"));
-                    }
-                    break;
-                }
+                            // reset length buffer to the last accepted index;
+                            // thus removing/ignoring the invalid characters
+                            bytes = bytes_after_last_accept;
 
-                default:
-                    JSON_THROW(detail::out_of_range::create(404, "unresolved reference token '" + reference_token + "'"));
-            }
-        }
+                            if (error_handler == error_handler_t::replace)
+                            {
+                                // add a replacement character
+                                if (ensure_ascii)
+                                {
+                                    string_buffer[bytes++] = '\\';
+                                    string_buffer[bytes++] = 'u';
+                                    string_buffer[bytes++] = 'f';
+                                    string_buffer[bytes++] = 'f';
+                                    string_buffer[bytes++] = 'f';
+                                    string_buffer[bytes++] = 'd';
+                                }
+                                else
+                                {
+                                    string_buffer[bytes++] = detail::binary_writer<BasicJsonType, char>::to_char_type('\xEF');
+                                    string_buffer[bytes++] = detail::binary_writer<BasicJsonType, char>::to_char_type('\xBF');
+                                    string_buffer[bytes++] = detail::binary_writer<BasicJsonType, char>::to_char_type('\xBD');
+                                }
 
-        return *ptr;
-    }
+                                // write buffer and reset index; there must be 13 bytes
+                                // left, as this is the maximal number of bytes to be
+                                // written ("\uxxxx\uxxxx\0") for one code point
+                                if (string_buffer.size() - bytes < 13)
+                                {
+                                    o->write_characters(string_buffer.data(), bytes);
+                                    bytes = 0;
+                                }
 
-    /*!
-    @brief return a const reference to the pointed to value
+                                bytes_after_last_accept = bytes;
+                            }
 
-    @param[in] ptr  a JSON value
+                            undumped_chars = 0;
 
-    @return const reference to the JSON value pointed to by the JSON
-    pointer
+                            // continue processing the string
+                            state = UTF8_ACCEPT;
+                            break;
+                        }
 
-    @throw parse_error.106   if an array index begins with '0'
-    @throw parse_error.109   if an array index was not a number
-    @throw out_of_range.402  if the array index '-' is used
-    @throw out_of_range.404  if the JSON pointer can not be resolved
-    */
-    const BasicJsonType& get_unchecked(const BasicJsonType* ptr) const
-    {
-        using size_type = typename BasicJsonType::size_type;
-        for (const auto& reference_token : reference_tokens)
-        {
-            switch (ptr->m_type)
-            {
-                case detail::value_t::object:
-                {
-                    // use unchecked object access
-                    ptr = &ptr->operator[](reference_token);
+                        default:            // LCOV_EXCL_LINE
+                            assert(false);  // LCOV_EXCL_LINE
+                    }
                     break;
                 }
 
-                case detail::value_t::array:
+                default:  // decode found yet incomplete multi-byte code point
                 {
-                    if (JSON_UNLIKELY(reference_token == "-"))
-                    {
-                        // "-" cannot be used for const access
-                        JSON_THROW(detail::out_of_range::create(402,
-                                                                "array index '-' (" + std::to_string(ptr->m_value.array->size()) +
-                                                                ") is out of range"));
-                    }
-
-                    // error condition (cf. RFC 6901, Sect. 4)
-                    if (JSON_UNLIKELY(reference_token.size() > 1 and reference_token[0] == '0'))
-                    {
-                        JSON_THROW(detail::parse_error::create(106, 0,
-                                                               "array index '" + reference_token +
-                                                               "' must not begin with '0'"));
-                    }
-
-                    // use unchecked array access
-                    JSON_TRY
-                    {
-                        ptr = &ptr->operator[](
-                            static_cast<size_type>(array_index(reference_token)));
-                    }
-                    JSON_CATCH(std::invalid_argument&)
+                    if (not ensure_ascii)
                     {
-                        JSON_THROW(detail::parse_error::create(109, 0, "array index '" + reference_token + "' is not a number"));
+                        // code point will not be escaped - copy byte to buffer
+                        string_buffer[bytes++] = s[i];
                     }
+                    ++undumped_chars;
                     break;
                 }
-
-                default:
-                    JSON_THROW(detail::out_of_range::create(404, "unresolved reference token '" + reference_token + "'"));
             }
         }
 
-        return *ptr;
-    }
-
-    /*!
-    @throw parse_error.106   if an array index begins with '0'
-    @throw parse_error.109   if an array index was not a number
-    @throw out_of_range.402  if the array index '-' is used
-    @throw out_of_range.404  if the JSON pointer can not be resolved
-    */
-    const BasicJsonType& get_checked(const BasicJsonType* ptr) const
-    {
-        using size_type = typename BasicJsonType::size_type;
-        for (const auto& reference_token : reference_tokens)
+        // we finished processing the string
+        if (JSON_LIKELY(state == UTF8_ACCEPT))
         {
-            switch (ptr->m_type)
+            // write buffer
+            if (bytes > 0)
             {
-                case detail::value_t::object:
+                o->write_characters(string_buffer.data(), bytes);
+            }
+        }
+        else
+        {
+            // we finish reading, but do not accept: string was incomplete
+            switch (error_handler)
+            {
+                case error_handler_t::strict:
                 {
-                    // note: at performs range check
-                    ptr = &ptr->at(reference_token);
-                    break;
+                    std::string sn(3, '\0');
+                    (std::snprintf)(&sn[0], sn.size(), "%.2X", static_cast<std::uint8_t>(s.back()));
+                    JSON_THROW(type_error::create(316, "incomplete UTF-8 string; last byte: 0x" + sn));
                 }
 
-                case detail::value_t::array:
+                case error_handler_t::ignore:
                 {
-                    if (JSON_UNLIKELY(reference_token == "-"))
-                    {
-                        // "-" always fails the range check
-                        JSON_THROW(detail::out_of_range::create(402,
-                                                                "array index '-' (" + std::to_string(ptr->m_value.array->size()) +
-                                                                ") is out of range"));
-                    }
-
-                    // error condition (cf. RFC 6901, Sect. 4)
-                    if (JSON_UNLIKELY(reference_token.size() > 1 and reference_token[0] == '0'))
-                    {
-                        JSON_THROW(detail::parse_error::create(106, 0,
-                                                               "array index '" + reference_token +
-                                                               "' must not begin with '0'"));
-                    }
+                    // write all accepted bytes
+                    o->write_characters(string_buffer.data(), bytes_after_last_accept);
+                    break;
+                }
 
-                    // note: at performs range check
-                    JSON_TRY
+                case error_handler_t::replace:
+                {
+                    // write all accepted bytes
+                    o->write_characters(string_buffer.data(), bytes_after_last_accept);
+                    // add a replacement character
+                    if (ensure_ascii)
                     {
-                        ptr = &ptr->at(static_cast<size_type>(array_index(reference_token)));
+                        o->write_characters("\\ufffd", 6);
                     }
-                    JSON_CATCH(std::invalid_argument&)
+                    else
                     {
-                        JSON_THROW(detail::parse_error::create(109, 0, "array index '" + reference_token + "' is not a number"));
+                        o->write_characters("\xEF\xBF\xBD", 3);
                     }
                     break;
                 }
 
-                default:
-                    JSON_THROW(detail::out_of_range::create(404, "unresolved reference token '" + reference_token + "'"));
+                default:            // LCOV_EXCL_LINE
+                    assert(false);  // LCOV_EXCL_LINE
             }
         }
-
-        return *ptr;
     }
 
     /*!
-    @brief split the string input to reference tokens
+    @brief count digits
 
-    @note This function is only called by the json_pointer constructor.
-          All exceptions below are documented there.
+    Count the number of decimal (base 10) digits for an input unsigned integer.
 
-    @throw parse_error.107  if the pointer is not empty or begins with '/'
-    @throw parse_error.108  if character '~' is not followed by '0' or '1'
+    @param[in] x  unsigned integer number to count its digits
+    @return    number of decimal digits
     */
-    static std::vector<std::string> split(const std::string& reference_string)
+    inline unsigned int count_digits(number_unsigned_t x) noexcept
     {
-        std::vector<std::string> result;
-
-        // special case: empty reference string -> no reference tokens
-        if (reference_string.empty())
+        unsigned int n_digits = 1;
+        for (;;)
         {
-            return result;
+            if (x < 10)
+            {
+                return n_digits;
+            }
+            if (x < 100)
+            {
+                return n_digits + 1;
+            }
+            if (x < 1000)
+            {
+                return n_digits + 2;
+            }
+            if (x < 10000)
+            {
+                return n_digits + 3;
+            }
+            x = x / 10000u;
+            n_digits += 4;
         }
+    }
 
-        // check if nonempty reference string begins with slash
-        if (JSON_UNLIKELY(reference_string[0] != '/'))
-        {
-            JSON_THROW(detail::parse_error::create(107, 1,
-                                                   "JSON pointer must be empty or begin with '/' - was: '" +
-                                                   reference_string + "'"));
-        }
+    /*!
+    @brief dump an integer
 
-        // extract the reference tokens:
-        // - slash: position of the last read slash (or end of string)
-        // - start: position after the previous slash
-        for (
-            // search for the first slash after the first character
-            std::size_t slash = reference_string.find_first_of('/', 1),
-            // set the beginning of the first reference token
-            start = 1;
-            // we can stop if start == 0 (if slash == std::string::npos)
-            start != 0;
-            // set the beginning of the next reference token
-            // (will eventually be 0 if slash == std::string::npos)
-            start = (slash == std::string::npos) ? 0 : slash + 1,
-            // find next slash
-            slash = reference_string.find_first_of('/', start))
-        {
-            // use the text between the beginning of the reference token
-            // (start) and the last slash (slash).
-            auto reference_token = reference_string.substr(start, slash - start);
+    Dump a given integer to output stream @a o. Works internally with
+    @a number_buffer.
 
-            // check reference tokens are properly escaped
-            for (std::size_t pos = reference_token.find_first_of('~');
-                    pos != std::string::npos;
-                    pos = reference_token.find_first_of('~', pos + 1))
+    @param[in] x  integer number (signed or unsigned) to dump
+    @tparam NumberType either @a number_integer_t or @a number_unsigned_t
+    */
+    template<typename NumberType, detail::enable_if_t<
+                 std::is_same<NumberType, number_unsigned_t>::value or
+                 std::is_same<NumberType, number_integer_t>::value,
+                 int> = 0>
+    void dump_integer(NumberType x)
+    {
+        static constexpr std::array<std::array<char, 2>, 100> digits_to_99
+        {
             {
-                assert(reference_token[pos] == '~');
-
-                // ~ must be followed by 0 or 1
-                if (JSON_UNLIKELY(pos == reference_token.size() - 1 or
-                                  (reference_token[pos + 1] != '0' and
-                                   reference_token[pos + 1] != '1')))
-                {
-                    JSON_THROW(detail::parse_error::create(108, 0, "escape character '~' must be followed with '0' or '1'"));
-                }
+                {{'0', '0'}}, {{'0', '1'}}, {{'0', '2'}}, {{'0', '3'}}, {{'0', '4'}}, {{'0', '5'}}, {{'0', '6'}}, {{'0', '7'}}, {{'0', '8'}}, {{'0', '9'}},
+                {{'1', '0'}}, {{'1', '1'}}, {{'1', '2'}}, {{'1', '3'}}, {{'1', '4'}}, {{'1', '5'}}, {{'1', '6'}}, {{'1', '7'}}, {{'1', '8'}}, {{'1', '9'}},
+                {{'2', '0'}}, {{'2', '1'}}, {{'2', '2'}}, {{'2', '3'}}, {{'2', '4'}}, {{'2', '5'}}, {{'2', '6'}}, {{'2', '7'}}, {{'2', '8'}}, {{'2', '9'}},
+                {{'3', '0'}}, {{'3', '1'}}, {{'3', '2'}}, {{'3', '3'}}, {{'3', '4'}}, {{'3', '5'}}, {{'3', '6'}}, {{'3', '7'}}, {{'3', '8'}}, {{'3', '9'}},
+                {{'4', '0'}}, {{'4', '1'}}, {{'4', '2'}}, {{'4', '3'}}, {{'4', '4'}}, {{'4', '5'}}, {{'4', '6'}}, {{'4', '7'}}, {{'4', '8'}}, {{'4', '9'}},
+                {{'5', '0'}}, {{'5', '1'}}, {{'5', '2'}}, {{'5', '3'}}, {{'5', '4'}}, {{'5', '5'}}, {{'5', '6'}}, {{'5', '7'}}, {{'5', '8'}}, {{'5', '9'}},
+                {{'6', '0'}}, {{'6', '1'}}, {{'6', '2'}}, {{'6', '3'}}, {{'6', '4'}}, {{'6', '5'}}, {{'6', '6'}}, {{'6', '7'}}, {{'6', '8'}}, {{'6', '9'}},
+                {{'7', '0'}}, {{'7', '1'}}, {{'7', '2'}}, {{'7', '3'}}, {{'7', '4'}}, {{'7', '5'}}, {{'7', '6'}}, {{'7', '7'}}, {{'7', '8'}}, {{'7', '9'}},
+                {{'8', '0'}}, {{'8', '1'}}, {{'8', '2'}}, {{'8', '3'}}, {{'8', '4'}}, {{'8', '5'}}, {{'8', '6'}}, {{'8', '7'}}, {{'8', '8'}}, {{'8', '9'}},
+                {{'9', '0'}}, {{'9', '1'}}, {{'9', '2'}}, {{'9', '3'}}, {{'9', '4'}}, {{'9', '5'}}, {{'9', '6'}}, {{'9', '7'}}, {{'9', '8'}}, {{'9', '9'}},
             }
+        };
 
-            // finally, store the reference token
-            unescape(reference_token);
-            result.push_back(reference_token);
+        // special case for "0"
+        if (x == 0)
+        {
+            o->write_character('0');
+            return;
         }
 
-        return result;
-    }
+        // use a pointer to fill the buffer
+        auto buffer_ptr = number_buffer.begin();
 
-    /*!
-    @brief replace all occurrences of a substring by another string
+        const bool is_negative = std::is_same<NumberType, number_integer_t>::value and not(x >= 0); // see issue #755
+        number_unsigned_t abs_value;
 
-    @param[in,out] s  the string to manipulate; changed so that all
-                   occurrences of @a f are replaced with @a t
-    @param[in]     f  the substring to replace with @a t
-    @param[in]     t  the string to replace @a f
+        unsigned int n_chars;
 
-    @pre The search string @a f must not be empty. **This precondition is
-    enforced with an assertion.**
+        if (is_negative)
+        {
+            *buffer_ptr = '-';
+            abs_value = static_cast<number_unsigned_t>(std::abs(static_cast<std::intmax_t>(x)));
 
-    @since version 2.0.0
-    */
-    static void replace_substring(std::string& s, const std::string& f,
-                                  const std::string& t)
-    {
-        assert(not f.empty());
-        for (auto pos = s.find(f);                // find first occurrence of f
-                pos != std::string::npos;         // make sure f was found
-                s.replace(pos, f.size(), t),      // replace with t, and
-                pos = s.find(f, pos + t.size()))  // find next occurrence of f
-        {}
-    }
+            // account one more byte for the minus sign
+            n_chars = 1 + count_digits(abs_value);
+        }
+        else
+        {
+            abs_value = static_cast<number_unsigned_t>(x);
+            n_chars = count_digits(abs_value);
+        }
 
-    /// escape "~" to "~0" and "/" to "~1"
-    static std::string escape(std::string s)
-    {
-        replace_substring(s, "~", "~0");
-        replace_substring(s, "/", "~1");
-        return s;
-    }
+        // spare 1 byte for '\0'
+        assert(n_chars < number_buffer.size() - 1);
 
-    /// unescape "~1" to tilde and "~0" to slash (order is important!)
-    static void unescape(std::string& s)
-    {
-        replace_substring(s, "~1", "/");
-        replace_substring(s, "~0", "~");
+        // jump to the end to generate the string from backward
+        // so we later avoid reversing the result
+        buffer_ptr += n_chars;
+
+        // Fast int2ascii implementation inspired by "Fastware" talk by Andrei Alexandrescu
+        // See: https://www.youtube.com/watch?v=o4-CwDo2zpg
+        while (abs_value >= 100)
+        {
+            const auto digits_index = static_cast<unsigned>((abs_value % 100));
+            abs_value /= 100;
+            *(--buffer_ptr) = digits_to_99[digits_index][1];
+            *(--buffer_ptr) = digits_to_99[digits_index][0];
+        }
+
+        if (abs_value >= 10)
+        {
+            const auto digits_index = static_cast<unsigned>(abs_value);
+            *(--buffer_ptr) = digits_to_99[digits_index][1];
+            *(--buffer_ptr) = digits_to_99[digits_index][0];
+        }
+        else
+        {
+            *(--buffer_ptr) = static_cast<char>('0' + abs_value);
+        }
+
+        o->write_characters(number_buffer.data(), n_chars);
     }
 
     /*!
-    @param[in] reference_string  the reference string to the current value
-    @param[in] value             the value to consider
-    @param[in,out] result        the result object to insert values to
+    @brief dump a floating-point number
 
-    @note Empty objects or arrays are flattened to `null`.
+    Dump a given floating-point number to output stream @a o. Works internally
+    with @a number_buffer.
+
+    @param[in] x  floating-point number to dump
     */
-    static void flatten(const std::string& reference_string,
-                        const BasicJsonType& value,
-                        BasicJsonType& result)
+    void dump_float(number_float_t x)
     {
-        switch (value.m_type)
+        // NaN / inf
+        if (not std::isfinite(x))
         {
-            case detail::value_t::array:
-            {
-                if (value.m_value.array->empty())
-                {
-                    // flatten empty array as null
-                    result[reference_string] = nullptr;
-                }
-                else
-                {
-                    // iterate array and use index as reference string
-                    for (std::size_t i = 0; i < value.m_value.array->size(); ++i)
-                    {
-                        flatten(reference_string + "/" + std::to_string(i),
-                                value.m_value.array->operator[](i), result);
-                    }
-                }
-                break;
-            }
+            o->write_characters("null", 4);
+            return;
+        }
 
-            case detail::value_t::object:
-            {
-                if (value.m_value.object->empty())
-                {
-                    // flatten empty object as null
-                    result[reference_string] = nullptr;
-                }
-                else
-                {
-                    // iterate object and use keys as reference string
-                    for (const auto& element : *value.m_value.object)
-                    {
-                        flatten(reference_string + "/" + escape(element.first), element.second, result);
-                    }
-                }
-                break;
-            }
+        // If number_float_t is an IEEE-754 single or double precision number,
+        // use the Grisu2 algorithm to produce short numbers which are
+        // guaranteed to round-trip, using strtof and strtod, resp.
+        //
+        // NB: The test below works if <long double> == <double>.
+        static constexpr bool is_ieee_single_or_double
+            = (std::numeric_limits<number_float_t>::is_iec559 and std::numeric_limits<number_float_t>::digits == 24 and std::numeric_limits<number_float_t>::max_exponent == 128) or
+              (std::numeric_limits<number_float_t>::is_iec559 and std::numeric_limits<number_float_t>::digits == 53 and std::numeric_limits<number_float_t>::max_exponent == 1024);
 
-            default:
-            {
-                // add primitive value with its reference string
-                result[reference_string] = value;
-                break;
-            }
-        }
+        dump_float(x, std::integral_constant<bool, is_ieee_single_or_double>());
     }
 
-    /*!
-    @param[in] value  flattened JSON
+    void dump_float(number_float_t x, std::true_type /*is_ieee_single_or_double*/)
+    {
+        char* begin = number_buffer.data();
+        char* end = ::nlohmann::detail::to_chars(begin, begin + number_buffer.size(), x);
 
-    @return unflattened JSON
+        o->write_characters(begin, static_cast<size_t>(end - begin));
+    }
 
-    @throw parse_error.109 if array index is not a number
-    @throw type_error.314  if value is not an object
-    @throw type_error.315  if object values are not primitive
-    @throw type_error.313  if value cannot be unflattened
-    */
-    static BasicJsonType
-    unflatten(const BasicJsonType& value)
+    void dump_float(number_float_t x, std::false_type /*is_ieee_single_or_double*/)
     {
-        if (JSON_UNLIKELY(not value.is_object()))
+        // get number of digits for a float -> text -> float round-trip
+        static constexpr auto d = std::numeric_limits<number_float_t>::max_digits10;
+
+        // the actual conversion
+        std::ptrdiff_t len = (std::snprintf)(number_buffer.data(), number_buffer.size(), "%.*g", d, x);
+
+        // negative value indicates an error
+        assert(len > 0);
+        // check if buffer was large enough
+        assert(static_cast<std::size_t>(len) < number_buffer.size());
+
+        // erase thousands separator
+        if (thousands_sep != '\0')
         {
-            JSON_THROW(detail::type_error::create(314, "only objects can be unflattened"));
+            const auto end = std::remove(number_buffer.begin(),
+                                         number_buffer.begin() + len, thousands_sep);
+            std::fill(end, number_buffer.end(), '\0');
+            assert((end - number_buffer.begin()) <= len);
+            len = (end - number_buffer.begin());
         }
 
-        BasicJsonType result;
-
-        // iterate the JSON object values
-        for (const auto& element : *value.m_value.object)
+        // convert decimal point to '.'
+        if (decimal_point != '\0' and decimal_point != '.')
         {
-            if (JSON_UNLIKELY(not element.second.is_primitive()))
+            const auto dec_pos = std::find(number_buffer.begin(), number_buffer.end(), decimal_point);
+            if (dec_pos != number_buffer.end())
             {
-                JSON_THROW(detail::type_error::create(315, "values in object must be primitive"));
+                *dec_pos = '.';
             }
-
-            // assign value to reference pointed to by JSON pointer; Note that if
-            // the JSON pointer is "" (i.e., points to the whole value), function
-            // get_and_create returns a reference to result itself. An assignment
-            // will then create a primitive value.
-            json_pointer(element.first).get_and_create(result) = element.second;
         }
 
-        return result;
-    }
+        o->write_characters(number_buffer.data(), static_cast<std::size_t>(len));
 
-    friend bool operator==(json_pointer const& lhs,
-                           json_pointer const& rhs) noexcept
-    {
-        return (lhs.reference_tokens == rhs.reference_tokens);
-    }
+        // determine if need to append ".0"
+        const bool value_is_int_like =
+            std::none_of(number_buffer.begin(), number_buffer.begin() + len + 1,
+                         [](char c)
+        {
+            return c == '.' or c == 'e';
+        });
 
-    friend bool operator!=(json_pointer const& lhs,
-                           json_pointer const& rhs) noexcept
-    {
-        return not (lhs == rhs);
+        if (value_is_int_like)
+        {
+            o->write_characters(".0", 2);
+        }
     }
 
-    /// the reference tokens
-    std::vector<std::string> reference_tokens;
-};
-}  // namespace nlohmann
+    /*!
+    @brief check whether a string is UTF-8 encoded
 
-// #include <nlohmann/adl_serializer.hpp>
+    The function checks each byte of a string whether it is UTF-8 encoded. The
+    result of the check is stored in the @a state parameter. The function must
+    be called initially with state 0 (accept). State 1 means the string must
+    be rejected, because the current byte is not allowed. If the string is
+    completely processed, but the state is non-zero, the string ended
+    prematurely; that is, the last byte indicated more bytes should have
+    followed.
 
+    @param[in,out] state  the state of the decoding
+    @param[in,out] codep  codepoint (valid only if resulting state is UTF8_ACCEPT)
+    @param[in] byte       next byte to decode
+    @return               new state
 
-#include <utility>
+    @note The function has been edited: a std::array is used.
 
-// #include <nlohmann/detail/conversions/from_json.hpp>
+    @copyright Copyright (c) 2008-2009 Bjoern Hoehrmann <bjoern@hoehrmann.de>
+    @sa http://bjoern.hoehrmann.de/utf-8/decoder/dfa/
+    */
+    static std::uint8_t decode(std::uint8_t& state, std::uint32_t& codep, const std::uint8_t byte) noexcept
+    {
+        static const std::array<std::uint8_t, 400> utf8d =
+        {
+            {
+                0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, // 00..1F
+                0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, // 20..3F
+                0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, // 40..5F
+                0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, // 60..7F
+                1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, // 80..9F
+                7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, // A0..BF
+                8, 8, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, // C0..DF
+                0xA, 0x3, 0x3, 0x3, 0x3, 0x3, 0x3, 0x3, 0x3, 0x3, 0x3, 0x3, 0x3, 0x4, 0x3, 0x3, // E0..EF
+                0xB, 0x6, 0x6, 0x6, 0x5, 0x8, 0x8, 0x8, 0x8, 0x8, 0x8, 0x8, 0x8, 0x8, 0x8, 0x8, // F0..FF
+                0x0, 0x1, 0x2, 0x3, 0x5, 0x8, 0x7, 0x1, 0x1, 0x1, 0x4, 0x6, 0x1, 0x1, 0x1, 0x1, // s0..s0
+                1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 0, 1, 1, 1, 1, 1, 0, 1, 0, 1, 1, 1, 1, 1, 1, // s1..s2
+                1, 2, 1, 1, 1, 1, 1, 2, 1, 2, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 2, 1, 1, 1, 1, 1, 1, 1, 1, // s3..s4
+                1, 2, 1, 1, 1, 1, 1, 1, 1, 2, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 3, 1, 3, 1, 1, 1, 1, 1, 1, // s5..s6
+                1, 3, 1, 1, 1, 1, 1, 3, 1, 3, 1, 1, 1, 1, 1, 1, 1, 3, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1 // s7..s8
+            }
+        };
 
-// #include <nlohmann/detail/conversions/to_json.hpp>
+        const std::uint8_t type = utf8d[byte];
 
+        codep = (state != UTF8_ACCEPT)
+                ? (byte & 0x3fu) | (codep << 6u)
+                : (0xFFu >> type) & (byte);
 
-namespace nlohmann
-{
+        state = utf8d[256u + state * 16u + type];
+        return state;
+    }
 
-template<typename, typename>
-struct adl_serializer
-{
-    /*!
-    @brief convert a JSON value to any value type
+  private:
+    /// the output of the serializer
+    output_adapter_t<char> o = nullptr;
 
-    This function is usually called by the `get()` function of the
-    @ref basic_json class (either explicit or via conversion operators).
+    /// a (hopefully) large enough character buffer
+    std::array<char, 64> number_buffer{{}};
 
-    @param[in] j        JSON value to read from
-    @param[in,out] val  value to write to
-    */
-    template<typename BasicJsonType, typename ValueType>
-    static auto from_json(BasicJsonType&& j, ValueType& val) noexcept(
-        noexcept(::nlohmann::from_json(std::forward<BasicJsonType>(j), val)))
-    -> decltype(::nlohmann::from_json(std::forward<BasicJsonType>(j), val), void())
-    {
-        ::nlohmann::from_json(std::forward<BasicJsonType>(j), val);
-    }
+    /// the locale
+    const std::lconv* loc = nullptr;
+    /// the locale's thousand separator character
+    const char thousands_sep = '\0';
+    /// the locale's decimal point character
+    const char decimal_point = '\0';
 
-    /*!
-    @brief convert any value type to a JSON value
+    /// string buffer
+    std::array<char, 512> string_buffer{{}};
 
-    This function is usually called by the constructors of the @ref basic_json
-    class.
+    /// the indentation character
+    const char indent_char;
+    /// the indentation string
+    string_t indent_string;
 
-    @param[in,out] j  JSON value to write to
-    @param[in] val    value to read from
-    */
-    template <typename BasicJsonType, typename ValueType>
-    static auto to_json(BasicJsonType& j, ValueType&& val) noexcept(
-        noexcept(::nlohmann::to_json(j, std::forward<ValueType>(val))))
-    -> decltype(::nlohmann::to_json(j, std::forward<ValueType>(val)), void())
-    {
-        ::nlohmann::to_json(j, std::forward<ValueType>(val));
-    }
+    /// error_handler how to react on decoding errors
+    const error_handler_t error_handler;
 };
-
+}  // namespace detail
 }  // namespace nlohmann
 
+// #include <nlohmann/detail/value_t.hpp>
+
+// #include <nlohmann/json_fwd.hpp>
+
 
 /*!
 @brief namespace for Niels Lohmann
@@ -12697,6 +13084,7 @@ class basic_json
 
     @since 2.1.0
     */
+    JSON_NODISCARD
     static basic_json meta()
     {
         basic_json result;
@@ -13329,7 +13717,7 @@ class basic_json
                     object = nullptr;  // silence warning, see #821
                     if (JSON_UNLIKELY(t == value_t::null))
                     {
-                        JSON_THROW(other_error::create(500, "961c151d2e87f2686a955a9be24d316f1362bf21 3.5.0")); // LCOV_EXCL_LINE
+                        JSON_THROW(other_error::create(500, "961c151d2e87f2686a955a9be24d316f1362bf21 3.6.1")); // LCOV_EXCL_LINE
                     }
                     break;
                 }
@@ -13702,6 +14090,8 @@ class basic_json
             case value_t::discarded:
                 m_type = value_t::discarded;
                 break;
+            default:            // LCOV_EXCL_LINE
+                assert(false);  // LCOV_EXCL_LINE
         }
         assert_invariant();
     }
@@ -13789,7 +14179,7 @@ class basic_json
         bool is_an_object = std::all_of(init.begin(), init.end(),
                                         [](const detail::json_ref<basic_json>& element_ref)
         {
-            return (element_ref->is_array() and element_ref->size() == 2 and (*element_ref)[0].is_string());
+            return element_ref->is_array() and element_ref->size() == 2 and (*element_ref)[0].is_string();
         });
 
         // adjust type if type deduction is not wanted
@@ -13869,6 +14259,7 @@ class basic_json
 
     @since version 1.0.0
     */
+    JSON_NODISCARD
     static basic_json array(initializer_list_t init = {})
     {
         return basic_json(init, false, value_t::array);
@@ -13912,6 +14303,7 @@ class basic_json
 
     @since version 1.0.0
     */
+    JSON_NODISCARD
     static basic_json object(initializer_list_t init = {})
     {
         return basic_json(init, false, value_t::object);
@@ -14472,7 +14864,7 @@ class basic_json
     */
     constexpr bool is_null() const noexcept
     {
-        return (m_type == value_t::null);
+        return m_type == value_t::null;
     }
 
     /*!
@@ -14494,7 +14886,7 @@ class basic_json
     */
     constexpr bool is_boolean() const noexcept
     {
-        return (m_type == value_t::boolean);
+        return m_type == value_t::boolean;
     }
 
     /*!
@@ -14553,7 +14945,7 @@ class basic_json
     */
     constexpr bool is_number_integer() const noexcept
     {
-        return (m_type == value_t::number_integer or m_type == value_t::number_unsigned);
+        return m_type == value_t::number_integer or m_type == value_t::number_unsigned;
     }
 
     /*!
@@ -14581,7 +14973,7 @@ class basic_json
     */
     constexpr bool is_number_unsigned() const noexcept
     {
-        return (m_type == value_t::number_unsigned);
+        return m_type == value_t::number_unsigned;
     }
 
     /*!
@@ -14609,7 +15001,7 @@ class basic_json
     */
     constexpr bool is_number_float() const noexcept
     {
-        return (m_type == value_t::number_float);
+        return m_type == value_t::number_float;
     }
 
     /*!
@@ -14631,7 +15023,7 @@ class basic_json
     */
     constexpr bool is_object() const noexcept
     {
-        return (m_type == value_t::object);
+        return m_type == value_t::object;
     }
 
     /*!
@@ -14653,7 +15045,7 @@ class basic_json
     */
     constexpr bool is_array() const noexcept
     {
-        return (m_type == value_t::array);
+        return m_type == value_t::array;
     }
 
     /*!
@@ -14675,7 +15067,7 @@ class basic_json
     */
     constexpr bool is_string() const noexcept
     {
-        return (m_type == value_t::string);
+        return m_type == value_t::string;
     }
 
     /*!
@@ -14702,7 +15094,7 @@ class basic_json
     */
     constexpr bool is_discarded() const noexcept
     {
-        return (m_type == value_t::discarded);
+        return m_type == value_t::discarded;
     }
 
     /*!
@@ -15236,7 +15628,7 @@ class basic_json
 
 #ifndef _MSC_VER  // fix for issue #167 operator<< ambiguity under VS2015
                    and not std::is_same<ValueType, std::initializer_list<typename string_t::value_type>>::value
-#if defined(JSON_HAS_CPP_17) && defined(_MSC_VER) and _MSC_VER <= 1914
+#if defined(JSON_HAS_CPP_17) && (defined(__GNUC__) || (defined(_MSC_VER) and _MSC_VER <= 1914))
                    and not std::is_same<ValueType, typename std::string_view>::value
 #endif
 #endif
@@ -16274,6 +16666,8 @@ class basic_json
 
     @liveexample{The example shows how `find()` is used.,find__key_type}
 
+    @sa @ref contains(KeyT&&) const -- checks whether a key exists
+
     @since version 1.0.0
     */
     template<typename KeyT>
@@ -16334,6 +16728,36 @@ class basic_json
         return is_object() ? m_value.object->count(std::forward<KeyT>(key)) : 0;
     }
 
+    /*!
+    @brief check the existence of an element in a JSON object
+
+    Check whether an element exists in a JSON object with key equivalent to
+    @a key. If the element is not found or the JSON value is not an object,
+    false is returned.
+
+    @note This method always returns false when executed on a JSON type
+          that is not an object.
+
+    @param[in] key key value to check its existence.
+
+    @return true if an element with specified @a key exists. If no such
+    element with such key is found or the JSON value is not an object,
+    false is returned.
+
+    @complexity Logarithmic in the size of the JSON object.
+
+    @liveexample{The following code shows an example for `contains()`.,contains}
+
+    @sa @ref find(KeyT&&) -- returns an iterator to an object element
+
+    @since version 3.6.0
+    */
+    template<typename KeyT>
+    bool contains(KeyT&& key) const
+    {
+        return is_object() and m_value.object->find(std::forward<KeyT>(key)) != m_value.object->end();
+    }
+
     /// @}
 
 
@@ -17118,7 +17542,8 @@ class basic_json
 
         // add element to array (move semantics)
         m_value.array->push_back(std::move(val));
-        // invalidate object
+        // invalidate object: mark it null so we do not call the destructor
+        // cppcheck-suppress accessMoved
         val.m_type = value_t::null;
     }
 
@@ -17910,28 +18335,28 @@ class basic_json
             switch (lhs_type)
             {
                 case value_t::array:
-                    return (*lhs.m_value.array == *rhs.m_value.array);
+                    return *lhs.m_value.array == *rhs.m_value.array;
 
                 case value_t::object:
-                    return (*lhs.m_value.object == *rhs.m_value.object);
+                    return *lhs.m_value.object == *rhs.m_value.object;
 
                 case value_t::null:
                     return true;
 
                 case value_t::string:
-                    return (*lhs.m_value.string == *rhs.m_value.string);
+                    return *lhs.m_value.string == *rhs.m_value.string;
 
                 case value_t::boolean:
-                    return (lhs.m_value.boolean == rhs.m_value.boolean);
+                    return lhs.m_value.boolean == rhs.m_value.boolean;
 
                 case value_t::number_integer:
-                    return (lhs.m_value.number_integer == rhs.m_value.number_integer);
+                    return lhs.m_value.number_integer == rhs.m_value.number_integer;
 
                 case value_t::number_unsigned:
-                    return (lhs.m_value.number_unsigned == rhs.m_value.number_unsigned);
+                    return lhs.m_value.number_unsigned == rhs.m_value.number_unsigned;
 
                 case value_t::number_float:
-                    return (lhs.m_value.number_float == rhs.m_value.number_float);
+                    return lhs.m_value.number_float == rhs.m_value.number_float;
 
                 default:
                     return false;
@@ -17939,27 +18364,27 @@ class basic_json
         }
         else if (lhs_type == value_t::number_integer and rhs_type == value_t::number_float)
         {
-            return (static_cast<number_float_t>(lhs.m_value.number_integer) == rhs.m_value.number_float);
+            return static_cast<number_float_t>(lhs.m_value.number_integer) == rhs.m_value.number_float;
         }
         else if (lhs_type == value_t::number_float and rhs_type == value_t::number_integer)
         {
-            return (lhs.m_value.number_float == static_cast<number_float_t>(rhs.m_value.number_integer));
+            return lhs.m_value.number_float == static_cast<number_float_t>(rhs.m_value.number_integer);
         }
         else if (lhs_type == value_t::number_unsigned and rhs_type == value_t::number_float)
         {
-            return (static_cast<number_float_t>(lhs.m_value.number_unsigned) == rhs.m_value.number_float);
+            return static_cast<number_float_t>(lhs.m_value.number_unsigned) == rhs.m_value.number_float;
         }
         else if (lhs_type == value_t::number_float and rhs_type == value_t::number_unsigned)
         {
-            return (lhs.m_value.number_float == static_cast<number_float_t>(rhs.m_value.number_unsigned));
+            return lhs.m_value.number_float == static_cast<number_float_t>(rhs.m_value.number_unsigned);
         }
         else if (lhs_type == value_t::number_unsigned and rhs_type == value_t::number_integer)
         {
-            return (static_cast<number_integer_t>(lhs.m_value.number_unsigned) == rhs.m_value.number_integer);
+            return static_cast<number_integer_t>(lhs.m_value.number_unsigned) == rhs.m_value.number_integer;
         }
         else if (lhs_type == value_t::number_integer and rhs_type == value_t::number_unsigned)
         {
-            return (lhs.m_value.number_integer == static_cast<number_integer_t>(rhs.m_value.number_unsigned));
+            return lhs.m_value.number_integer == static_cast<number_integer_t>(rhs.m_value.number_unsigned);
         }
 
         return false;
@@ -17973,7 +18398,7 @@ class basic_json
                  std::is_scalar<ScalarType>::value, int>::type = 0>
     friend bool operator==(const_reference lhs, const ScalarType rhs) noexcept
     {
-        return (lhs == basic_json(rhs));
+        return lhs == basic_json(rhs);
     }
 
     /*!
@@ -17984,7 +18409,7 @@ class basic_json
                  std::is_scalar<ScalarType>::value, int>::type = 0>
     friend bool operator==(const ScalarType lhs, const_reference rhs) noexcept
     {
-        return (basic_json(lhs) == rhs);
+        return basic_json(lhs) == rhs;
     }
 
     /*!
@@ -18018,7 +18443,7 @@ class basic_json
                  std::is_scalar<ScalarType>::value, int>::type = 0>
     friend bool operator!=(const_reference lhs, const ScalarType rhs) noexcept
     {
-        return (lhs != basic_json(rhs));
+        return lhs != basic_json(rhs);
     }
 
     /*!
@@ -18029,7 +18454,7 @@ class basic_json
                  std::is_scalar<ScalarType>::value, int>::type = 0>
     friend bool operator!=(const ScalarType lhs, const_reference rhs) noexcept
     {
-        return (basic_json(lhs) != rhs);
+        return basic_json(lhs) != rhs;
     }
 
     /*!
@@ -18068,6 +18493,8 @@ class basic_json
             switch (lhs_type)
             {
                 case value_t::array:
+                    // note parentheses are necessary, see
+                    // https://github.com/nlohmann/json/issues/1530
                     return (*lhs.m_value.array) < (*rhs.m_value.array);
 
                 case value_t::object:
@@ -18134,7 +18561,7 @@ class basic_json
                  std::is_scalar<ScalarType>::value, int>::type = 0>
     friend bool operator<(const_reference lhs, const ScalarType rhs) noexcept
     {
-        return (lhs < basic_json(rhs));
+        return lhs < basic_json(rhs);
     }
 
     /*!
@@ -18145,7 +18572,7 @@ class basic_json
                  std::is_scalar<ScalarType>::value, int>::type = 0>
     friend bool operator<(const ScalarType lhs, const_reference rhs) noexcept
     {
-        return (basic_json(lhs) < rhs);
+        return basic_json(lhs) < rhs;
     }
 
     /*!
@@ -18180,7 +18607,7 @@ class basic_json
                  std::is_scalar<ScalarType>::value, int>::type = 0>
     friend bool operator<=(const_reference lhs, const ScalarType rhs) noexcept
     {
-        return (lhs <= basic_json(rhs));
+        return lhs <= basic_json(rhs);
     }
 
     /*!
@@ -18191,7 +18618,7 @@ class basic_json
                  std::is_scalar<ScalarType>::value, int>::type = 0>
     friend bool operator<=(const ScalarType lhs, const_reference rhs) noexcept
     {
-        return (basic_json(lhs) <= rhs);
+        return basic_json(lhs) <= rhs;
     }
 
     /*!
@@ -18226,7 +18653,7 @@ class basic_json
                  std::is_scalar<ScalarType>::value, int>::type = 0>
     friend bool operator>(const_reference lhs, const ScalarType rhs) noexcept
     {
-        return (lhs > basic_json(rhs));
+        return lhs > basic_json(rhs);
     }
 
     /*!
@@ -18237,7 +18664,7 @@ class basic_json
                  std::is_scalar<ScalarType>::value, int>::type = 0>
     friend bool operator>(const ScalarType lhs, const_reference rhs) noexcept
     {
-        return (basic_json(lhs) > rhs);
+        return basic_json(lhs) > rhs;
     }
 
     /*!
@@ -18272,7 +18699,7 @@ class basic_json
                  std::is_scalar<ScalarType>::value, int>::type = 0>
     friend bool operator>=(const_reference lhs, const ScalarType rhs) noexcept
     {
-        return (lhs >= basic_json(rhs));
+        return lhs >= basic_json(rhs);
     }
 
     /*!
@@ -18283,7 +18710,7 @@ class basic_json
                  std::is_scalar<ScalarType>::value, int>::type = 0>
     friend bool operator>=(const ScalarType lhs, const_reference rhs) noexcept
     {
-        return (basic_json(lhs) >= rhs);
+        return basic_json(lhs) >= rhs;
     }
 
     /// @}
@@ -18329,8 +18756,8 @@ class basic_json
     friend std::ostream& operator<<(std::ostream& o, const basic_json& j)
     {
         // read width member and use it as indentation parameter if nonzero
-        const bool pretty_print = (o.width() > 0);
-        const auto indentation = (pretty_print ? o.width() : 0);
+        const bool pretty_print = o.width() > 0;
+        const auto indentation = pretty_print ? o.width() : 0;
 
         // reset width to 0 for subsequent calls to this stream
         o.width(0);
@@ -18386,9 +18813,6 @@ class basic_json
     @pre The container storage is contiguous. Violating this precondition
     yields undefined behavior. **This precondition is enforced with an
     assertion.**
-    @pre Each element of the container has a size of 1 byte. Violating this
-    precondition yields undefined behavior. **This precondition is enforced
-    with a static assertion.**
 
     @warning There is no way to enforce all preconditions at compile-time. If
              the function is called with a noncompliant container and with
@@ -18402,7 +18826,9 @@ class basic_json
     @param[in] allow_exceptions  whether to throw exceptions in case of a
     parse error (optional, true by default)
 
-    @return result of the deserialization
+    @return deserialized JSON value; in case of a parse error and
+            @a allow_exceptions set to `false`, the return value will be
+            value_t::discarded.
 
     @throw parse_error.101 if a parse error occurs; example: `""unexpected end
     of input; expected string literal""`
@@ -18429,6 +18855,7 @@ class basic_json
 
     @since version 2.0.3 (contiguous containers)
     */
+    JSON_NODISCARD
     static basic_json parse(detail::input_adapter&& i,
                             const parser_callback_t cb = nullptr,
                             const bool allow_exceptions = true)
@@ -18466,9 +18893,6 @@ class basic_json
     @pre The container storage is contiguous. Violating this precondition
     yields undefined behavior. **This precondition is enforced with an
     assertion.**
-    @pre Each element of the container has a size of 1 byte. Violating this
-    precondition yields undefined behavior. **This precondition is enforced
-    with a static assertion.**
 
     @warning There is no way to enforce all preconditions at compile-time. If
              the function is called with a noncompliant container and with
@@ -18505,13 +18929,9 @@ class basic_json
                           const bool strict = true)
     {
         assert(sax);
-        switch (format)
-        {
-            case input_format_t::json:
-                return parser(std::move(i)).sax_parse(sax, strict);
-            default:
-                return detail::binary_reader<basic_json, SAX>(std::move(i)).sax_parse(format, sax, strict);
-        }
+        return format == input_format_t::json
+               ? parser(std::move(i)).sax_parse(sax, strict)
+               : detail::binary_reader<basic_json, SAX>(std::move(i)).sax_parse(format, sax, strict);
     }
 
     /*!
@@ -18544,7 +18964,9 @@ class basic_json
     @param[in] allow_exceptions  whether to throw exceptions in case of a
     parse error (optional, true by default)
 
-    @return result of the deserialization
+    @return deserialized JSON value; in case of a parse error and
+            @a allow_exceptions set to `false`, the return value will be
+            value_t::discarded.
 
     @throw parse_error.101 in case of an unexpected token
     @throw parse_error.102 if to_unicode fails or surrogate error
@@ -19175,7 +19597,9 @@ class basic_json
     @param[in] allow_exceptions  whether to throw exceptions in case of a
     parse error (optional, true by default)
 
-    @return deserialized JSON value
+    @return deserialized JSON value; in case of a parse error and
+            @a allow_exceptions set to `false`, the return value will be
+            value_t::discarded.
 
     @throw parse_error.110 if the given input ends prematurely or the end of
     file was not reached when @a strict was set to true
@@ -19200,6 +19624,7 @@ class basic_json
            @a strict parameter since 3.0.0; added @a allow_exceptions parameter
            since 3.2.0
     */
+    JSON_NODISCARD
     static basic_json from_cbor(detail::input_adapter&& i,
                                 const bool strict = true,
                                 const bool allow_exceptions = true)
@@ -19215,6 +19640,7 @@ class basic_json
     */
     template<typename A1, typename A2,
              detail::enable_if_t<std::is_constructible<detail::input_adapter, A1, A2>::value, int> = 0>
+    JSON_NODISCARD
     static basic_json from_cbor(A1 && a1, A2 && a2,
                                 const bool strict = true,
                                 const bool allow_exceptions = true)
@@ -19278,7 +19704,9 @@ class basic_json
     @param[in] allow_exceptions  whether to throw exceptions in case of a
     parse error (optional, true by default)
 
-    @return deserialized JSON value
+    @return deserialized JSON value; in case of a parse error and
+            @a allow_exceptions set to `false`, the return value will be
+            value_t::discarded.
 
     @throw parse_error.110 if the given input ends prematurely or the end of
     file was not reached when @a strict was set to true
@@ -19305,6 +19733,7 @@ class basic_json
            @a strict parameter since 3.0.0; added @a allow_exceptions parameter
            since 3.2.0
     */
+    JSON_NODISCARD
     static basic_json from_msgpack(detail::input_adapter&& i,
                                    const bool strict = true,
                                    const bool allow_exceptions = true)
@@ -19320,6 +19749,7 @@ class basic_json
     */
     template<typename A1, typename A2,
              detail::enable_if_t<std::is_constructible<detail::input_adapter, A1, A2>::value, int> = 0>
+    JSON_NODISCARD
     static basic_json from_msgpack(A1 && a1, A2 && a2,
                                    const bool strict = true,
                                    const bool allow_exceptions = true)
@@ -19365,7 +19795,9 @@ class basic_json
     @param[in] allow_exceptions  whether to throw exceptions in case of a
     parse error (optional, true by default)
 
-    @return deserialized JSON value
+    @return deserialized JSON value; in case of a parse error and
+            @a allow_exceptions set to `false`, the return value will be
+            value_t::discarded.
 
     @throw parse_error.110 if the given input ends prematurely or the end of
     file was not reached when @a strict was set to true
@@ -19389,6 +19821,7 @@ class basic_json
 
     @since version 3.1.0; added @a allow_exceptions parameter since 3.2.0
     */
+    JSON_NODISCARD
     static basic_json from_ubjson(detail::input_adapter&& i,
                                   const bool strict = true,
                                   const bool allow_exceptions = true)
@@ -19404,6 +19837,7 @@ class basic_json
     */
     template<typename A1, typename A2,
              detail::enable_if_t<std::is_constructible<detail::input_adapter, A1, A2>::value, int> = 0>
+    JSON_NODISCARD
     static basic_json from_ubjson(A1 && a1, A2 && a2,
                                   const bool strict = true,
                                   const bool allow_exceptions = true)
@@ -19454,7 +19888,9 @@ class basic_json
     @param[in] allow_exceptions  whether to throw exceptions in case of a
     parse error (optional, true by default)
 
-    @return deserialized JSON value
+    @return deserialized JSON value; in case of a parse error and
+            @a allow_exceptions set to `false`, the return value will be
+            value_t::discarded.
 
     @throw parse_error.114 if an unsupported BSON record type is encountered
 
@@ -19472,6 +19908,7 @@ class basic_json
     @sa @ref from_ubjson(detail::input_adapter&&, const bool, const bool) for the
         related UBJSON format
     */
+    JSON_NODISCARD
     static basic_json from_bson(detail::input_adapter&& i,
                                 const bool strict = true,
                                 const bool allow_exceptions = true)
@@ -19487,6 +19924,7 @@ class basic_json
     */
     template<typename A1, typename A2,
              detail::enable_if_t<std::is_constructible<detail::input_adapter, A1, A2>::value, int> = 0>
+    JSON_NODISCARD
     static basic_json from_bson(A1 && a1, A2 && a2,
                                 const bool strict = true,
                                 const bool allow_exceptions = true)
@@ -19822,63 +20260,59 @@ class basic_json
         const auto operation_add = [&result](json_pointer & ptr, basic_json val)
         {
             // adding to the root of the target document means replacing it
-            if (ptr.is_root())
+            if (ptr.empty())
             {
                 result = val;
+                return;
             }
-            else
+
+            // make sure the top element of the pointer exists
+            json_pointer top_pointer = ptr.top();
+            if (top_pointer != ptr)
             {
-                // make sure the top element of the pointer exists
-                json_pointer top_pointer = ptr.top();
-                if (top_pointer != ptr)
+                result.at(top_pointer);
+            }
+
+            // get reference to parent of JSON pointer ptr
+            const auto last_path = ptr.back();
+            ptr.pop_back();
+            basic_json& parent = result[ptr];
+
+            switch (parent.m_type)
+            {
+                case value_t::null:
+                case value_t::object:
                 {
-                    result.at(top_pointer);
+                    // use operator[] to add value
+                    parent[last_path] = val;
+                    break;
                 }
 
-                // get reference to parent of JSON pointer ptr
-                const auto last_path = ptr.pop_back();
-                basic_json& parent = result[ptr];
-
-                switch (parent.m_type)
+                case value_t::array:
                 {
-                    case value_t::null:
-                    case value_t::object:
+                    if (last_path == "-")
                     {
-                        // use operator[] to add value
-                        parent[last_path] = val;
-                        break;
+                        // special case: append to back
+                        parent.push_back(val);
                     }
-
-                    case value_t::array:
+                    else
                     {
-                        if (last_path == "-")
-                        {
-                            // special case: append to back
-                            parent.push_back(val);
-                        }
-                        else
+                        const auto idx = json_pointer::array_index(last_path);
+                        if (JSON_UNLIKELY(static_cast<size_type>(idx) > parent.size()))
                         {
-                            const auto idx = json_pointer::array_index(last_path);
-                            if (JSON_UNLIKELY(static_cast<size_type>(idx) > parent.size()))
-                            {
-                                // avoid undefined behavior
-                                JSON_THROW(out_of_range::create(401, "array index " + std::to_string(idx) + " is out of range"));
-                            }
-
-                            // default case: insert add offset
-                            parent.insert(parent.begin() + static_cast<difference_type>(idx), val);
+                            // avoid undefined behavior
+                            JSON_THROW(out_of_range::create(401, "array index " + std::to_string(idx) + " is out of range"));
                         }
-                        break;
-                    }
 
-                    // LCOV_EXCL_START
-                    default:
-                    {
-                        // if there exists a parent it cannot be primitive
-                        assert(false);
+                        // default case: insert add offset
+                        parent.insert(parent.begin() + static_cast<difference_type>(idx), val);
                     }
-                        // LCOV_EXCL_STOP
+                    break;
                 }
+
+                // if there exists a parent it cannot be primitive
+                default:            // LCOV_EXCL_LINE
+                    assert(false);  // LCOV_EXCL_LINE
             }
         };
 
@@ -19886,7 +20320,8 @@ class basic_json
         const auto operation_remove = [&result](json_pointer & ptr)
         {
             // get reference to parent of JSON pointer ptr
-            const auto last_path = ptr.pop_back();
+            const auto last_path = ptr.back();
+            ptr.pop_back();
             basic_json& parent = result.at(ptr);
 
             // remove child
@@ -20033,7 +20468,7 @@ class basic_json
                     break;
                 }
 
-                case patch_operations::invalid:
+                default:
                 {
                     // op must be "add", "remove", "replace", "move", "copy", or
                     // "test"
@@ -20078,6 +20513,7 @@ class basic_json
 
     @since version 2.0.0
     */
+    JSON_NODISCARD
     static basic_json diff(const basic_json& source, const basic_json& target,
                            const std::string& path = "")
     {
@@ -20097,106 +20533,105 @@ class basic_json
             {
                 {"op", "replace"}, {"path", path}, {"value", target}
             });
+            return result;
         }
-        else
+
+        switch (source.type())
         {
-            switch (source.type())
+            case value_t::array:
             {
-                case value_t::array:
+                // first pass: traverse common elements
+                std::size_t i = 0;
+                while (i < source.size() and i < target.size())
                 {
-                    // first pass: traverse common elements
-                    std::size_t i = 0;
-                    while (i < source.size() and i < target.size())
-                    {
-                        // recursive call to compare array values at index i
-                        auto temp_diff = diff(source[i], target[i], path + "/" + std::to_string(i));
-                        result.insert(result.end(), temp_diff.begin(), temp_diff.end());
-                        ++i;
-                    }
+                    // recursive call to compare array values at index i
+                    auto temp_diff = diff(source[i], target[i], path + "/" + std::to_string(i));
+                    result.insert(result.end(), temp_diff.begin(), temp_diff.end());
+                    ++i;
+                }
 
-                    // i now reached the end of at least one array
-                    // in a second pass, traverse the remaining elements
+                // i now reached the end of at least one array
+                // in a second pass, traverse the remaining elements
 
-                    // remove my remaining elements
-                    const auto end_index = static_cast<difference_type>(result.size());
-                    while (i < source.size())
+                // remove my remaining elements
+                const auto end_index = static_cast<difference_type>(result.size());
+                while (i < source.size())
+                {
+                    // add operations in reverse order to avoid invalid
+                    // indices
+                    result.insert(result.begin() + end_index, object(
                     {
-                        // add operations in reverse order to avoid invalid
-                        // indices
-                        result.insert(result.begin() + end_index, object(
-                        {
-                            {"op", "remove"},
-                            {"path", path + "/" + std::to_string(i)}
-                        }));
-                        ++i;
-                    }
+                        {"op", "remove"},
+                        {"path", path + "/" + std::to_string(i)}
+                    }));
+                    ++i;
+                }
 
-                    // add other remaining elements
-                    while (i < target.size())
+                // add other remaining elements
+                while (i < target.size())
+                {
+                    result.push_back(
                     {
-                        result.push_back(
-                        {
-                            {"op", "add"},
-                            {"path", path + "/" + std::to_string(i)},
-                            {"value", target[i]}
-                        });
-                        ++i;
-                    }
-
-                    break;
+                        {"op", "add"},
+                        {"path", path + "/" + std::to_string(i)},
+                        {"value", target[i]}
+                    });
+                    ++i;
                 }
 
-                case value_t::object:
+                break;
+            }
+
+            case value_t::object:
+            {
+                // first pass: traverse this object's elements
+                for (auto it = source.cbegin(); it != source.cend(); ++it)
                 {
-                    // first pass: traverse this object's elements
-                    for (auto it = source.cbegin(); it != source.cend(); ++it)
-                    {
-                        // escape the key name to be used in a JSON patch
-                        const auto key = json_pointer::escape(it.key());
+                    // escape the key name to be used in a JSON patch
+                    const auto key = json_pointer::escape(it.key());
 
-                        if (target.find(it.key()) != target.end())
-                        {
-                            // recursive call to compare object values at key it
-                            auto temp_diff = diff(it.value(), target[it.key()], path + "/" + key);
-                            result.insert(result.end(), temp_diff.begin(), temp_diff.end());
-                        }
-                        else
-                        {
-                            // found a key that is not in o -> remove it
-                            result.push_back(object(
-                            {
-                                {"op", "remove"}, {"path", path + "/" + key}
-                            }));
-                        }
+                    if (target.find(it.key()) != target.end())
+                    {
+                        // recursive call to compare object values at key it
+                        auto temp_diff = diff(it.value(), target[it.key()], path + "/" + key);
+                        result.insert(result.end(), temp_diff.begin(), temp_diff.end());
                     }
-
-                    // second pass: traverse other object's elements
-                    for (auto it = target.cbegin(); it != target.cend(); ++it)
+                    else
                     {
-                        if (source.find(it.key()) == source.end())
+                        // found a key that is not in o -> remove it
+                        result.push_back(object(
                         {
-                            // found a key that is not in this -> add it
-                            const auto key = json_pointer::escape(it.key());
-                            result.push_back(
-                            {
-                                {"op", "add"}, {"path", path + "/" + key},
-                                {"value", it.value()}
-                            });
-                        }
+                            {"op", "remove"}, {"path", path + "/" + key}
+                        }));
                     }
-
-                    break;
                 }
 
-                default:
+                // second pass: traverse other object's elements
+                for (auto it = target.cbegin(); it != target.cend(); ++it)
                 {
-                    // both primitive type: replace value
-                    result.push_back(
+                    if (source.find(it.key()) == source.end())
                     {
-                        {"op", "replace"}, {"path", path}, {"value", target}
-                    });
-                    break;
+                        // found a key that is not in this -> add it
+                        const auto key = json_pointer::escape(it.key());
+                        result.push_back(
+                        {
+                            {"op", "add"}, {"path", path + "/" + key},
+                            {"value", it.value()}
+                        });
+                    }
                 }
+
+                break;
+            }
+
+            default:
+            {
+                // both primitive type: replace value
+                result.push_back(
+                {
+                    {"op", "replace"}, {"path", path}, {"value", target}
+                });
+                break;
             }
         }
 
@@ -20397,10 +20832,11 @@ inline nlohmann::json::json_pointer operator "" _json_pointer(const char* s, std
 #undef JSON_LIKELY
 #undef JSON_UNLIKELY
 #undef JSON_DEPRECATED
+#undef JSON_NODISCARD
 #undef JSON_HAS_CPP_14
 #undef JSON_HAS_CPP_17
 #undef NLOHMANN_BASIC_JSON_TPL_DECLARATION
 #undef NLOHMANN_BASIC_JSON_TPL
 
 
-#endif
+#endif  // INCLUDE_NLOHMANN_JSON_HPP_