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#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
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);
}
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);
}
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);
}
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
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