Implemented the CBOR writer

Author: liuzicheng1987

CMakeLists.txt

@@ -2,14 +2,15 @@ cmake_minimum_required(VERSION 3.15)
 
 option(REFLECTCPP_BUILD_SHARED "Build shared library" OFF)
 option(REFLECTCPP_BSON "Enable BSON support" OFF)
+option(REFLECTCPP_CBOR "Enable CBOR support" OFF)
 option(REFLECTCPP_FLEXBUFFERS "Enable flexbuffers support" OFF)
 option(REFLECTCPP_XML "Enable XML support" OFF)
 option(REFLECTCPP_YAML "Enable YAML support" OFF)
 
 option(REFLECTCPP_BUILD_TESTS "Build tests" OFF)
 
 # enable vcpkg if require features other than JSON
-if (REFLECTCPP_BSON OR REFLECTCPP_FLEXBUFFERS OR REFLECTCPP_XML OR REFLECTCPP_YAML)
+if (REFLECTCPP_BSON OR REFLECTCPP_CBOR OR REFLECTCPP_FLEXBUFFERS OR REFLECTCPP_XML OR REFLECTCPP_YAML)
     set(CMAKE_TOOLCHAIN_FILE ${CMAKE_CURRENT_SOURCE_DIR}/vcpkg/scripts/buildsystems/vcpkg.cmake CACHE STRING "Vcpkg toolchain file")
 endif ()
 
@@ -30,6 +31,11 @@ if (REFLECTCPP_BSON)
     target_link_libraries(reflectcpp PRIVATE $<IF:$<TARGET_EXISTS:mongo::bson_static>,mongo::bson_static,mongo::bson_shared>) 
 endif ()
 
+if (REFLECTCPP_CBOR)
+    find_package(tinycbor CONFIG REQUIRED)
+    target_link_libraries(reflectcpp INTERFACE tinycbor::tinycbor)
+endif ()
+
 if (REFLECTCPP_FLEXBUFFERS)
     find_package(flatbuffers CONFIG REQUIRED)
     target_link_libraries(reflectcpp INTERFACE flatbuffers::flatbuffers)

include/rfl/cbor/Parser.hpp

@@ -0,0 +1,17 @@
+#ifndef RFL_CBOR_PARSER_HPP_
+#define RFL_CBOR_PARSER_HPP_
+
+#include "../parsing/Parser.hpp"
+#include "Reader.hpp"
+#include "Writer.hpp"
+
+namespace rfl {
+namespace cbor {
+
+template <class T>
+using Parser = parsing::Parser<Reader, Writer, T>;
+
+}
+}  // namespace rfl
+
+#endif

include/rfl/cbor/Reader.hpp

@@ -0,0 +1,228 @@
+#ifndef RFL_CBOR_READER_HPP_
+#define RFL_CBOR_READER_HPP_
+
+#include <bson/bson.h>
+
+#include <array>
+#include <concepts>
+#include <exception>
+#include <map>
+#include <memory>
+#include <sstream>
+#include <stdexcept>
+#include <string>
+#include <string_view>
+#include <type_traits>
+#include <unordered_map>
+#include <vector>
+
+#include "../Box.hpp"
+#include "../Result.hpp"
+#include "../always_false.hpp"
+
+namespace rfl {
+namespace cbor {
+
+/// Please refer to https://mongoc.org/libbson/current/api.html
+struct Reader {
+  struct CBORValue {
+    bson_value_t val_;
+  };
+
+  struct CBORInputArray {
+    CBORValue* val_;
+  };
+
+  struct CBORInputObject {
+    CBORValue* val_;
+  };
+
+  struct CBORInputVar {
+    CBORValue* val_;
+  };
+
+  using InputArrayType = CBORInputArray;
+  using InputObjectType = CBORInputObject;
+  using InputVarType = CBORInputVar;
+
+  template <class T>
+  static constexpr bool has_custom_constructor = (requires(InputVarType var) {
+    T::from_bson_obj(var);
+  });
+
+  rfl::Result<InputVarType> get_field(
+      const std::string& _name, const InputObjectType& _obj) const noexcept {
+    bson_t b;
+    bson_iter_t iter;
+    const auto doc = _obj.val_->val_.value.v_doc;
+    if (bson_init_static(&b, doc.data, doc.data_len)) {
+      if (bson_iter_init(&iter, &b)) {
+        while (bson_iter_next(&iter)) {
+          auto key = std::string(bson_iter_key(&iter));
+          if (key == _name) {
+            return to_input_var(&iter);
+          }
+        }
+      }
+    }
+    return Error("No field named '" + _name + "' was found.");
+  }
+
+  bool is_empty(const InputVarType& _var) const noexcept {
+    return _var.val_->val_.value_type == CBOR_TYPE_NULL;
+  }
+
+  template <class T>
+  rfl::Result<T> to_basic_type(const InputVarType& _var) const noexcept {
+    const auto btype = _var.val_->val_.value_type;
+    const auto value = _var.val_->val_.value;
+    if constexpr (std::is_same<std::remove_cvref_t<T>, std::string>()) {
+      switch (btype) {
+        case CBOR_TYPE_UTF8:
+          return std::string(value.v_utf8.str, value.v_utf8.len);
+
+        case CBOR_TYPE_SYMBOL:
+          return std::string(value.v_symbol.symbol, value.v_symbol.len);
+
+        default:
+          return rfl::Error(
+              "Could not cast to string. The type must be UTF8 or symbol.");
+      }
+    } else if constexpr (std::is_same<std::remove_cvref_t<T>, bool>()) {
+      if (btype != CBOR_TYPE_BOOL) {
+        return rfl::Error("Could not cast to boolean.");
+      }
+      return value.v_bool;
+    } else if constexpr (std::is_floating_point<std::remove_cvref_t<T>>() ||
+                         std::is_integral<std::remove_cvref_t<T>>()) {
+      switch (btype) {
+        case CBOR_TYPE_DOUBLE:
+          return static_cast<T>(value.v_double);
+
+        case CBOR_TYPE_INT32:
+          return static_cast<T>(value.v_int32);
+
+        case CBOR_TYPE_INT64:
+          return static_cast<T>(value.v_int64);
+
+        case CBOR_TYPE_DATE_TIME:
+          return static_cast<T>(value.v_datetime);
+
+        default:
+          return rfl::Error(
+              "Could not cast to numeric value. The type must be double, "
+              "int32, int64 or date_time.");
+      }
+    } else {
+      static_assert(rfl::always_false_v<T>, "Unsupported type.");
+    }
+  }
+
+  rfl::Result<InputArrayType> to_array(
+      const InputVarType& _var) const noexcept {
+    const auto btype = _var.val_->val_.value_type;
+    if (btype != CBOR_TYPE_ARRAY && btype != CBOR_TYPE_DOCUMENT) {
+      return Error("Could not cast to an array.");
+    }
+    return InputArrayType{_var.val_};
+  }
+
+  template <size_t size, class FunctionType>
+  std::array<std::optional<InputVarType>, size> to_fields_array(
+      const FunctionType& _fct, const InputObjectType& _obj) const noexcept {
+    std::array<std::optional<InputVarType>, size> f_arr;
+    bson_t b;
+    bson_iter_t iter;
+    const auto doc = _obj.val_->val_.value.v_doc;
+    if (bson_init_static(&b, doc.data, doc.data_len)) {
+      if (bson_iter_init(&iter, &b)) {
+        while (bson_iter_next(&iter)) {
+          const char* k = bson_iter_key(&iter);
+          const auto ix = _fct(std::string_view(k));
+          if (ix != -1) {
+            f_arr[ix] = to_input_var(&iter);
+          }
+        }
+      }
+    }
+    return f_arr;
+  }
+
+  rfl::Result<std::vector<std::pair<std::string, InputVarType>>> to_map(
+      const InputObjectType& _obj) const noexcept {
+    std::vector<std::pair<std::string, InputVarType>> map;
+    bson_t b;
+    bson_iter_t iter;
+    const auto doc = _obj.val_->val_.value.v_doc;
+    if (bson_init_static(&b, doc.data, doc.data_len)) {
+      if (bson_iter_init(&iter, &b)) {
+        while (bson_iter_next(&iter)) {
+          auto key = std::string(bson_iter_key(&iter));
+          map.emplace_back(std::make_pair(std::move(key), to_input_var(&iter)));
+        }
+      }
+    }
+    return map;
+  }
+
+  rfl::Result<InputObjectType> to_object(
+      const InputVarType& _var) const noexcept {
+    const auto btype = _var.val_->val_.value_type;
+    if (btype != CBOR_TYPE_DOCUMENT) {
+      return Error("Could not cast to a document.");
+    }
+    return InputObjectType{_var.val_};
+  }
+
+  std::vector<InputVarType> to_vec(const InputArrayType& _arr) const noexcept {
+    std::vector<InputVarType> vec;
+    bson_t b;
+    bson_iter_t iter;
+    const auto doc = _arr.val_->val_.value.v_doc;
+    if (bson_init_static(&b, doc.data, doc.data_len)) {
+      if (bson_iter_init(&iter, &b)) {
+        while (bson_iter_next(&iter)) {
+          vec.push_back(to_input_var(&iter));
+        }
+      }
+    }
+    return vec;
+  }
+
+  template <class T>
+  rfl::Result<T> use_custom_constructor(
+      const InputVarType& _var) const noexcept {
+    try {
+      return T::from_bson_obj(_var);
+    } catch (std::exception& e) {
+      return rfl::Error(e.what());
+    }
+  }
+
+ private:
+  struct CBORValues {
+    std::vector<rfl::Box<CBORValue>> vec_;
+    ~CBORValues() {
+      for (auto& v : vec_) {
+        bson_value_destroy(&(v->val_));
+      }
+    }
+  };
+
+ private:
+  InputVarType to_input_var(bson_iter_t* _iter) const noexcept {
+    values_->vec_.emplace_back(rfl::Box<CBORValue>::make());
+    auto* last_value = values_->vec_.back().get();
+    bson_value_copy(bson_iter_value(_iter), &last_value->val_);
+    return InputVarType{last_value};
+  }
+
+ private:
+  /// Contains the values inside the object.
+  rfl::Ref<CBORValues> values_;
+};
+
+}  // namespace cbor
+}  // namespace rfl
+
+#endif  // JSON_PARSER_HPP_