#pragma once #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 #include <nlohmann/detail/macro_scope.hpp> 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 { v.push_back(c); } JSON_HEDLEY_NON_NULL(2) void write_characters(const CharType* s, std::size_t length) override { std::copy(s, s + length, std::back_inserter(v)); } private: std::vector<CharType>& v; }; /// 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) {} void write_character(CharType c) override { stream.put(c); } JSON_HEDLEY_NON_NULL(2) void write_characters(const CharType* s, std::size_t length) override { stream.write(s, static_cast<std::streamsize>(length)); } 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 { str.push_back(c); } JSON_HEDLEY_NON_NULL(2) void write_characters(const CharType* s, std::size_t length) override { str.append(s, length); } 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 oa; } private: output_adapter_t<CharType> oa = nullptr; }; } // namespace detail } // namespace nlohmann