Config: Use nlohmann/json

precompiled-headers.h

@@ -56,3 +56,5 @@
 #include <sys/wait.h>
 #include <termios.h>
 #include <unistd.h>
+
+#include <nlohmann/json.hpp>

src/libstore/globals.cc

@@ -9,6 +9,8 @@
 #include <dlfcn.h>
 #include <sys/utsname.h>
 
+#include <nlohmann/json.hpp>
+
 
 namespace nix {
 
@@ -160,9 +162,9 @@ template<> std::string BaseSetting<SandboxMode>::to_string() const
     else abort();
 }
 
-template<> void BaseSetting<SandboxMode>::toJSON(JSONPlaceholder & out)
+template<> nlohmann::json BaseSetting<SandboxMode>::toJSON()
 {
-    AbstractSetting::toJSON(out);
+    return AbstractSetting::toJSON();
 }
 
 template<> void BaseSetting<SandboxMode>::convertToArg(Args & args, const std::string & category)

src/libutil/config.cc

@@ -1,6 +1,7 @@
 #include "config.hh"
 #include "args.hh"
-#include "json.hh"
+
+#include <nlohmann/json.hpp>
 
 namespace nix {
 
@@ -131,15 +132,17 @@ void Config::resetOverriden()
         s.second.setting->overriden = false;
 }
 
-void Config::toJSON(JSONObject & out)
+nlohmann::json Config::toJSON()
 {
+    auto res = nlohmann::json::object();
     for (auto & s : _settings)
         if (!s.second.isAlias) {
-            JSONObject out2(out.object(s.first));
-            out2.attr("description", s.second.setting->description);
-            JSONPlaceholder out3(out2.placeholder("value"));
-            s.second.setting->toJSON(out3);
+            auto obj = nlohmann::json::object();
+            obj.emplace("description", s.second.setting->description);
+            obj.emplace("value", s.second.setting->toJSON());
+            res.emplace(s.first, obj);
         }
+    return res;
 }
 
 void Config::convertToArgs(Args & args, const std::string & category)
@@ -199,19 +202,19 @@ void AbstractSetting::setDefault(const std::string & str)
     if (!overriden) set(str);
 }
 
-void AbstractSetting::toJSON(JSONPlaceholder & out)
+nlohmann::json AbstractSetting::toJSON()
 {
-    out.write(to_string());
+    return to_string();
 }
 
 void AbstractSetting::convertToArg(Args & args, const std::string & category)
 {
 }
 
 template<typename T>
-void BaseSetting<T>::toJSON(JSONPlaceholder & out)
+nlohmann::json BaseSetting<T>::toJSON()
 {
-    out.write(value);
+    return value;
 }
 
 template<typename T>
@@ -292,11 +295,9 @@ template<> std::string BaseSetting<Strings>::to_string() const
     return concatStringsSep(" ", value);
 }
 
-template<> void BaseSetting<Strings>::toJSON(JSONPlaceholder & out)
+template<> nlohmann::json BaseSetting<Strings>::toJSON()
 {
-    JSONList list(out.list());
-    for (auto & s : value)
-        list.elem(s);
+    return value;
 }
 
 template<> void BaseSetting<StringSet>::set(const std::string & str)
@@ -309,11 +310,9 @@ template<> std::string BaseSetting<StringSet>::to_string() const
     return concatStringsSep(" ", value);
 }
 
-template<> void BaseSetting<StringSet>::toJSON(JSONPlaceholder & out)
+template<> nlohmann::json BaseSetting<StringSet>::toJSON()
 {
-    JSONList list(out.list());
-    for (auto & s : value)
-        list.elem(s);
+    return value;
 }
 
 template class BaseSetting<int>;
@@ -360,10 +359,12 @@ void GlobalConfig::resetOverriden()
         config->resetOverriden();
 }
 
-void GlobalConfig::toJSON(JSONObject & out)
+nlohmann::json GlobalConfig::toJSON()
 {
+    auto res = nlohmann::json::object();
     for (auto & config : *configRegistrations)
-        config->toJSON(out);
+        res.update(config->toJSON());
+    return res;
 }
 
 void GlobalConfig::convertToArgs(Args & args, const std::string & category)

src/libutil/config.hh

@@ -4,6 +4,8 @@
 
 #include "types.hh"
 
+#include <nlohmann/json_fwd.hpp>
+
 #pragma once
 
 namespace nix {
@@ -42,8 +44,6 @@ namespace nix {
 
 class Args;
 class AbstractSetting;
-class JSONPlaceholder;
-class JSONObject;
 
 class AbstractConfig
 {
@@ -97,7 +97,7 @@ public:
      * Outputs all settings to JSON
      * - out: JSONObject to write the configuration to
      */
-    virtual void toJSON(JSONObject & out) = 0;
+    virtual nlohmann::json toJSON() = 0;
 
     /**
      * Converts settings to `Args` to be used on the command line interface
@@ -167,7 +167,7 @@ public:
 
     void resetOverriden() override;
 
-    void toJSON(JSONObject & out) override;
+    nlohmann::json toJSON() override;
 
     void convertToArgs(Args & args, const std::string & category) override;
 };
@@ -206,7 +206,7 @@ protected:
 
     virtual std::string to_string() const = 0;
 
-    virtual void toJSON(JSONPlaceholder & out);
+    virtual nlohmann::json toJSON();
 
     virtual void convertToArg(Args & args, const std::string & category);
 
@@ -251,7 +251,7 @@ public:
 
     void convertToArg(Args & args, const std::string & category) override;
 
-    void toJSON(JSONPlaceholder & out) override;
+    nlohmann::json toJSON() override;
 };
 
 template<typename T>
@@ -319,7 +319,7 @@ struct GlobalConfig : public AbstractConfig
 
     void resetOverriden() override;
 
-    void toJSON(JSONObject & out) override;
+    nlohmann::json toJSON() override;
 
     void convertToArgs(Args & args, const std::string & category) override;
 

src/nix/show-config.cc

@@ -2,7 +2,8 @@
 #include "common-args.hh"
 #include "shared.hh"
 #include "store-api.hh"
-#include "json.hh"
+
+#include <nlohmann/json.hpp>
 
 using namespace nix;
 
@@ -19,8 +20,7 @@ struct CmdShowConfig : Command, MixJSON
     {
         if (json) {
             // FIXME: use appropriate JSON types (bool, ints, etc).
-            JSONObject jsonObj(std::cout);
-            globalConfig.toJSON(jsonObj);
+            logger->stdout("%s", globalConfig.toJSON().dump());
         } else {
             std::map<std::string, Config::SettingInfo> settings;
             globalConfig.getSettings(settings);