rexylib/include/rexy/detail/format/output_buffer.tpp

/**
	This file is a part of rexy's general purpose library
	Copyright (C) 2022 rexy712

	This program is free software: you can redistribute it and/or modify
	it under the terms of the GNU General Public License as published by
	the Free Software Foundation, either version 3 of the License, or
	(at your option) any later version.

	This program is distributed in the hope that it will be useful,
	but WITHOUT ANY WARRANTY; without even the implied warranty of
	MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
	GNU General Public License for more details.

	You should have received a copy of the GNU General Public License
	along with this program.  If not, see <http://www.gnu.org/licenses/>.
*/

#ifndef REXY_DETAIL_FORMAT_OUTPUT_BUFFER_TPP
#define REXY_DETAIL_FORMAT_OUTPUT_BUFFER_TPP

#include "output_buffer.hpp"

#include <cstddef> //size_t
#include <utility> //move
#include <type_traits> //is_pointer, remove_cvref, integral_constant
#include <algorithm> //min

namespace rexy::fmt::detail{

	///////////////////////format_output_buffer_base////////////////////////
	template<class Char>
	void format_output_buffer_base<Char>::clear(void){
		m_size = 0;
	}
	template<class Char>
	void format_output_buffer_base<Char>::push_back(Char c){
		if(m_size == s_bufsize){
			m_written_count += write_out();
			clear();
		}
		m_data[m_size++] = c;
	}
	template<class Char>
	constexpr std::size_t format_output_buffer_base<Char>::count(void)const{
		//include data that will be written during next call to write_out
		return m_written_count + m_size;
	}

	///////////////////////basic_format_output_buffer////////////////////////
	template<class Char, class OutIt>
	basic_format_output_buffer<Char,OutIt>::basic_format_output_buffer(OutIt out):
		m_out(out){}
	template<class Char, class OutIt>
	basic_format_output_buffer<Char,OutIt>::~basic_format_output_buffer(void){
		write_out();
	}

	template<class T>
	concept HasContainerAlias = requires{
		typename T::container_type;
	};

	template<class T, class It>
	concept HasInsertMethod = requires(T t, It i){
		{t.insert(1, i, i)}; //don't use 0 index because pointer conversion causes ambiguous call
		{t.size()};
	};

	template<class It>
	struct something : public It{
		template<class U = something, class C = decltype(U::container)>
		static std::true_type check(int);
		static std::false_type check(...);

		static constexpr bool value = decltype(check(0))::value;
	};

	template<class Char, class OutIt>
	OutIt real_write_out(const Char* start, std::size_t write_count, OutIt out){
		static constexpr bool has_container = something<OutIt>::value;//decltype(container_traits<OutIt>::check(0))::value;

		//optimize for types where direct access to the underlying container is available
		//check for a container member and a 'container_type' typedef in OutIt
		//reason for the type check is that without 'container_type' it might not be safe to access the 'container'
		if constexpr(has_container && HasContainerAlias<OutIt>){
			struct container_access : public OutIt{
				using OutIt::container;
			};
			container_access ca{out};
			auto& container = ca.container;

			if constexpr(HasInsertMethod<typename OutIt::container_type,const Char*>){
				if constexpr(std::is_pointer_v<std::remove_cvref_t<decltype(container)>>){
					container->insert(container->size(), start, start + write_count);
				}else{
					container.insert(container.size(), start, start + write_count);
				}
				return std::move(out);
			}
		}
		for(std::size_t i = 0;i < write_count;++i){
			out = start[i];
		}
		return std::move(out);
	}
	template<class Char, class OutIt>
	std::size_t basic_format_output_buffer<Char,OutIt>::write_out(void){
		m_out = real_write_out(this->m_data, this->m_size, std::move(m_out));
		return this->m_size;
	}
	template<class Char, class OutIt>
	constexpr OutIt basic_format_output_buffer<Char,OutIt>::out(void){
		return std::move(m_out);
	}

	///////////////////////basic_format_output_n_buffer////////////////////////
	template<class Char, class OutIt>
	basic_format_output_n_buffer<Char,OutIt>::basic_format_output_n_buffer(OutIt out, std::size_t max):
		m_out(out),
		m_max_write(max){}
	template<class Char, class OutIt>
	basic_format_output_n_buffer<Char,OutIt>::~basic_format_output_n_buffer(void){
		write_out();
	}

	template<class Char, class OutIt>
	std::size_t basic_format_output_n_buffer<Char,OutIt>::write_out(void){
		const auto to_write = std::min(this->size, m_max_write);

		m_out = real_write_out(this->m_data, to_write, std::move(m_out));
		m_max_write -= to_write;
		return to_write;
	}
	template<class Char, class OutIt>
	constexpr OutIt basic_format_output_n_buffer<Char,OutIt>::out(void){
		return std::move(m_out);
	}


	/////////////////////////basic_format_size_buffer//////////////////////////
	template<class Char>
	constexpr basic_format_size_buffer<Char>::~basic_format_size_buffer(void){
		write_out();
	}
	template<class Char>
	std::size_t basic_format_size_buffer<Char>::write_out(void){
		return this->m_size;
	}




}

#endif