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TymianekPLTymianekPL
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Add objects, arrays & formatter (#12)
* cppjson::JsonObject primitive, tagged union Signed-off-by: TymianekPL <tymi@tymi.org> * std::formatter specialisation for json objects Signed-off-by: TymianekPL <tymi@tymi.org> * make formatter specialisation sexy ⚡ Signed-off-by: TymianekPL <tymi@tymi.org> * sync with pr3: Changes C++23 => C++20 in .clang-format Signed-off-by: TymianekPL <tymi@tymi.org> * Add cppjson::Object Signed-off-by: TymianekPL <tymi@tymi.org> * Fix clang-format Signed-off-by: TymianekPL <tymi@tymi.org> * cppjson::Object Signed-off-by: TymianekPL <tymi@tymi.org> * mark conversions as explicitly implicit Signed-off-by: TymianekPL <tymi@tymi.org> * formatter specialisations for proxies Signed-off-by: TymianekPL <tymi@tymi.org> * Sub objects Signed-off-by: TymianekPL <tymi@tymi.org> * Fix violation of rule of 5 in JsonObject (#4) * Add declarations for JsonObject's special functions * Define copy/move constructors * Define copy/move assignment operators * Implicitly create bytes * Implicitly create bytes in exchange() * Fix includes lol (utility, cstring) * Destroy() objects * Fix ambiguous operator[] (#6) * Fix ambiguous operator[] * template typo lol * Call Destroy() in type erase Signed-off-by: TymianekPL <tymi@tymi.org> * Ensure safe cleanup of arrays Signed-off-by: TymianekPL <tymi@tymi.org> * Arrays Signed-off-by: TymianekPL <tymi@tymi.org> * add emplace * Split into multiple files & add finish arrays Signed-off-by: TymianekPL <tymi@tymi.org> --------- Signed-off-by: TymianekPL <tymi@tymi.org>
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7 files changed

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‎.clang-format‎

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@@ -2,7 +2,7 @@
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Language: Cpp
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BasedOnStyle: LLVM
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AlwaysBreakTemplateDeclarations: Yes
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BreakBeforeBraces: Attach
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BreakBeforeBraces: Allman
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ColumnLimit: 160
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SpaceAfterTemplateKeyword: true
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Standard: c++20
@@ -29,3 +29,4 @@ IncludeCategories:
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Priority: 30
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PointerAlignment: Left
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QualifierAlignment: Left
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NamespaceIndentation: All

‎Test/Test.cpp‎

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@@ -1,3 +1,30 @@
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#include <cppjson/cppjson.hpp>
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#include <print>
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int main() { cppjson::hello_world(); }
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int main()
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{
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cppjson::Object object{};
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std::println("{}", object);
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object["test1"] = "Hello World";
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object["test2"] = 123.0;
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object["sub"]["veryNested"] = 6.0;
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cppjson::Array& array = object["array"];
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array[] = 2;
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array[] = 6.0;
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array[0] = 1;
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array[] = "Stirng";
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array.EmplaceBack(nullptr);
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try
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{
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array[2] = true;
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}
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catch (const std::logic_error& error)
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{
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std::println("Error = {}", error.what());
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}
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std::println("{}", object);
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std::println("object[\"test1\"] = {}", object["test1"]);
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const std::string test = object["test1"];
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std::println("test = {}", test);
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}

‎cppjson/include/cppjson/cppjson.hpp‎

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@@ -1,5 +1,4 @@
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#pragma once
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#pragma once
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namespace cppjson {
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void hello_world();
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} // namespace cppjson
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#include "formatter.hpp"
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#include "object.hpp"

‎cppjson/include/cppjson/formatter.hpp‎

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#include <format>
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#include "object.hpp"
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template <>
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struct std::formatter<cppjson::JsonObject>
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{
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constexpr auto parse(std::format_parse_context& context) { return context.begin(); }
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auto format(const cppjson::JsonObject& object, std::format_context& context) const
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{
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switch (object._dataType)
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{
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case cppjson::JsonType::Null: return std::format_to(context.out(), "null");
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case cppjson::JsonType::Bool: return std::format_to(context.out(), "{}", object.DangerousAs<bool>());
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case cppjson::JsonType::Number: return std::format_to(context.out(), "{}", object.DangerousAs<double>());
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case cppjson::JsonType::String: return std::format_to(context.out(), "\"{}\"", object.DangerousAs<std::string>());
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case cppjson::JsonType::Object:
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{
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const auto& node = object.DangerousAs<cppjson::Object>();
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std::string built = "{ ";
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for (const auto& [key, value] : node._nodes) built += std::format("\"{}\": {}, ", key, value);
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if (!node._nodes.empty()) // remove trailing commas
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{
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built.pop_back();
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built.pop_back();
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built += " }";
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}
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else
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built += "}";
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return std::format_to(context.out(), "{}", built);
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}
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case cppjson::JsonType::Array:
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{
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const auto& array = object.DangerousAs<cppjson::Array>();
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std::string built = "[ ";
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for (const auto& element : array._objects) built += std::format("{}, ", element);
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if (!array._objects.empty()) // remove trailing commas
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{
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built.pop_back();
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built.pop_back();
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built += " ]";
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}
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else
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built += "]";
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return std::format_to(context.out(), "{}", built);
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}
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}
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throw std::logic_error("Unknown type");
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}
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};
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template <>
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struct std::formatter<cppjson::Object>
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{
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constexpr auto parse(std::format_parse_context& context) { return context.begin(); }
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auto format(const cppjson::Object& object, std::format_context& context) const
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{
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std::string built = "{ ";
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for (const auto& [key, value] : object._nodes) built += std::format("\"{}\": {}, ", key, value);
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if (!object._nodes.empty()) // remove trailing commas
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{
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built.pop_back();
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built.pop_back();
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built += " }";
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}
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else
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built += "}";
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return std::format_to(context.out(), "{}", built);
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}
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};
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template <>
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struct std::formatter<cppjson::Array>
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{
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constexpr auto parse(std::format_parse_context& context) { return context.begin(); }
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auto format(const cppjson::Array& array, std::format_context& context) const
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{
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std::string built = "[ ";
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for (const auto& element : array._objects) built += std::format("{}, ", element);
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if (!array._objects.empty()) // remove trailing commas
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{
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built.pop_back();
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built.pop_back();
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built += " ]";
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}
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else
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built += "]";
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return std::format_to(context.out(), "{}", built);
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}
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};
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template <>
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struct std::formatter<cppjson::Object::ObjectProxy>
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{
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constexpr auto parse(std::format_parse_context& context) { return context.begin(); }
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auto format(const cppjson::Object::ObjectProxy& object, std::format_context& context) const
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{
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return std::format_to(context.out(), "{}", object._object.get());
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}
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};
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template <>
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struct std::formatter<cppjson::Object::ConstObjectProxy>
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{
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constexpr auto parse(std::format_parse_context& context) { return context.begin(); }
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auto format(const cppjson::Object::ConstObjectProxy& object, std::format_context& context) const
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{
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return std::format_to(context.out(), "{}", object._object.get());
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}
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};

‎cppjson/include/cppjson/object.hpp‎

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#pragma once
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#include <algorithm>
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#include <concepts>
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#include <cstddef>
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#include <cstdint>
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#include <format>
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#include <functional>
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#include <string>
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#include <unordered_map>
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#include <vector>
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namespace cppjson
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{
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enum struct JsonType
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{
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Null,
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String,
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Object,
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Number,
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Bool,
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Array
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};
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class JsonObject
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{
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public:
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explicit JsonObject();
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JsonObject(const JsonObject& other);
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JsonObject(JsonObject&& other) noexcept;
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JsonObject& operator=(const JsonObject& other);
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JsonObject& operator=(JsonObject&& other) noexcept;
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~JsonObject();
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template <typename T>
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T& As() noexcept(false);
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template <typename T>
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const T& As() const noexcept(false);
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private:
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JsonType _dataType{};
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std::byte* _dataStorage{};
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void Destroy();
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template <typename T>
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T& DangerousAs() noexcept
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{
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return *std::launder(reinterpret_cast<T*>(this->_dataStorage));
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}
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template <typename T>
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const T& DangerousAs() const noexcept
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{
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return *std::launder(reinterpret_cast<T*>(this->_dataStorage));
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}
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57+
friend struct std::formatter<cppjson::JsonObject>;
58+
};
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class Object
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{
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public:
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explicit Object() = default;
64+
Object(const Object&) = default;
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Object(Object&&) = default;
66+
Object& operator=(const Object&) = default;
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Object& operator=(Object&&) = default;
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~Object() = default;
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class ObjectProxy
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{
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public:
73+
explicit ObjectProxy(JsonObject& object) : _object(std::ref(object)) {}
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template <typename T>
76+
requires(!std::same_as<std::remove_cvref_t<T>, JsonObject>)
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explicit(false) operator T&()
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{
79+
return this->_object.get().As<T>();
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}
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template <typename T>
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requires(!std::same_as<std::remove_cvref_t<T>, JsonObject>)
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explicit(false) operator const T&() const
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{
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return this->_object.get().As<T>();
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}
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template <typename T>
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std::conditional_t<std::integral<T> && !std::same_as<T, bool>, void, T&> operator=(T&& assignment)
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{
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if constexpr (std::integral<T> && !std::same_as<T, bool>) static_cast<double&>(*this) = static_cast<double>(assignment);
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else
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return static_cast<T&>(*this) = std::forward<T>(assignment);
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}
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template <std::size_t N>
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std::string& operator=(const char (&str)[N])
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{
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return static_cast<std::string&>(*this) = std::string{str};
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}
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ObjectProxy operator[](const std::string& key);
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template <std::size_t N>
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ObjectProxy operator[](const char (&key)[N])
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{
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return (*this)[std::string{key}];
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}
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private:
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std::reference_wrapper<JsonObject> _object;
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friend struct std::formatter<cppjson::Object::ObjectProxy>;
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};
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class ConstObjectProxy
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{
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public:
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explicit ConstObjectProxy(const JsonObject& object) : _object(std::ref(object)) {}
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template <typename T>
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explicit(false) operator const T&() const
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{
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return this->_object.get().As<T>();
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}
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ConstObjectProxy operator[](const std::string& key) const;
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private:
129+
std::reference_wrapper<const JsonObject> _object;
130+
131+
friend struct std::formatter<cppjson::Object::ConstObjectProxy>;
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};
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ObjectProxy operator[](const std::string& key) { return ObjectProxy{this->_nodes[key]}; }
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ConstObjectProxy operator[](const std::string& key) const
137+
{
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if (!this->_nodes.contains(key)) throw std::logic_error("Invalid key" + key);
139+
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return ConstObjectProxy{this->_nodes.at(key)};
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}
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private:
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std::unordered_map<std::string, JsonObject> _nodes{};
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146+
friend struct std::formatter<cppjson::JsonObject>;
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friend struct std::formatter<cppjson::Object>;
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};
149+
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class Array
151+
{
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public:
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explicit Array() = default;
154+
~Array() = default;
155+
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Object::ObjectProxy operator[]() { return Object::ObjectProxy{this->_objects.emplace_back()}; }
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Object::ObjectProxy EmplaceBack(const auto& object)
159+
{
160+
if constexpr (std::same_as<decltype(object), std::nullptr_t>) return Object::ObjectProxy{this->_objects.emplace_back()};
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else
162+
{
163+
auto& emplaced = this->_objects.emplace_back();
164+
emplaced.As<std::remove_cvref_t<decltype(object)>>() = object;
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return Object::ObjectProxy{emplaced};
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}
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}
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Object::ObjectProxy operator[](const std::size_t index)
170+
{
171+
if (index >= this->_objects.size()) throw std::logic_error("Out of bound");
172+
return Object::ObjectProxy{this->_objects.at(index)};
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}
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Object::ConstObjectProxy operator[](const std::size_t index) const
176+
{
177+
if (index >= this->_objects.size()) throw std::logic_error("Out of bound");
178+
return Object::ConstObjectProxy{this->_objects.at(index)};
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}
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private:
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std::vector<JsonObject> _objects{};
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184+
friend struct std::formatter<cppjson::JsonObject>;
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friend struct std::formatter<cppjson::Array>;
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};
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} // namespace cppjson

‎cppjson/src/cppjson.cpp‎

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1-
#include <cppjson/cppjson.hpp>
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#include <print>
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4-
void cppjson::hello_world() { std::println("Hewwo wowld"); }

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