tomlplusplus/include/toml++/toml_print_to_stream.h

//# This file is a part of toml++ and is subject to the the terms of the MIT license.
//# Copyright (c) Mark Gillard <mark.gillard@outlook.com.au>
//# See https://github.com/marzer/tomlplusplus/blob/master/LICENSE for the full license text.
// SPDX-License-Identifier: MIT

#pragma once
#include "toml_date_time.h"
TOML_DISABLE_WARNINGS;
#include <cmath>
#if TOML_INT_CHARCONV || TOML_FLOAT_CHARCONV
	#include <charconv>
#endif
#if !TOML_INT_CHARCONV || !TOML_FLOAT_CHARCONV
	#include <sstream>
#endif
#if !TOML_INT_CHARCONV
	#include <iomanip>
#endif
TOML_ENABLE_WARNINGS;

TOML_PUSH_WARNINGS;
TOML_DISABLE_SWITCH_WARNINGS;

TOML_IMPL_NAMESPACE_START
{
	// Q: "why does print_to_stream() exist? why not just use ostream::write(), ostream::put() etc?"
	// A: - I'm supporting C++20's char8_t as well; wrapping streams allows switching string modes transparently.
	//    - I'm using <charconv> to format numerics. Faster and locale-independent.
	//    - I can avoid forcing users to drag in <sstream> and <iomanip>.

	// Q: "there's a bit of reinterpret_casting here, is any of it UB?"
	// A: - If the source string data is char and the output string is char8_t, then technically yes,
	//      but not in the other direction. I test in both modes on Clang, GCC and MSVC and have yet to
	//      see it actually causing an issue, but in the event it does present a problem it's not going to
	//      be a show-stopper since all it means is I need to do duplicate some code.
	//    - Strings in C++. Honestly.

	template <typename Char1, typename Char2>
	inline void print_to_stream(std::basic_string_view<Char1> str, std::basic_ostream<Char2>& stream)
	{
		static_assert(sizeof(Char1) == 1);
		static_assert(sizeof(Char2) == 1);
		stream.write(reinterpret_cast<const Char2*>(str.data()), static_cast<std::streamsize>(str.length()));
	}

	template <typename Char1, typename Char2>
	inline void print_to_stream(const std::basic_string<Char1>& str, std::basic_ostream<Char2>& stream)
	{
		static_assert(sizeof(Char1) == 1);
		static_assert(sizeof(Char2) == 1);
		stream.write(reinterpret_cast<const Char2*>(str.data()), static_cast<std::streamsize>(str.length()));
	}

	template <typename Char>
	inline void print_to_stream(char character, std::basic_ostream<Char>& stream)
	{
		static_assert(sizeof(Char) == 1);
		stream.put(static_cast<Char>(character));
	}

	template <typename Char>
	TOML_ATTR(nonnull)
	inline void print_to_stream(const char* str, size_t len, std::basic_ostream<Char>& stream)
	{
		static_assert(sizeof(Char) == 1);
		stream.write(reinterpret_cast<const Char*>(str), static_cast<std::streamsize>(len));
	}

	#ifdef __cpp_lib_char8_t

	template <typename Char>
	inline void print_to_stream(char8_t character, std::basic_ostream<Char>& stream)
	{
		static_assert(sizeof(Char) == 1);
		stream.put(static_cast<Char>(character));
	}

	template <typename Char>
	TOML_ATTR(nonnull)
	inline void print_to_stream(const char8_t* str, size_t len, std::basic_ostream<Char>& stream)
	{
		static_assert(sizeof(Char) == 1);
		stream.write(reinterpret_cast<const Char*>(str), static_cast<std::streamsize>(len));
	}

	#endif

	template <typename T> inline constexpr size_t charconv_buffer_length = 0;
	template <> inline constexpr size_t charconv_buffer_length<double> = 60;
	template <> inline constexpr size_t charconv_buffer_length<float> = 40;
	template <> inline constexpr size_t charconv_buffer_length<uint64_t> = 20; // strlen("18446744073709551615")
	template <> inline constexpr size_t charconv_buffer_length<int64_t> = 20;  // strlen("-9223372036854775808")
	template <> inline constexpr size_t charconv_buffer_length<int32_t> = 11;  // strlen("-2147483648")
	template <> inline constexpr size_t charconv_buffer_length<int16_t> = 6;   // strlen("-32768")
	template <> inline constexpr size_t charconv_buffer_length<int8_t> = 4;    // strlen("-128")
	template <> inline constexpr size_t charconv_buffer_length<uint32_t> = 10; // strlen("4294967295")
	template <> inline constexpr size_t charconv_buffer_length<uint16_t> = 5;  // strlen("65535")
	template <> inline constexpr size_t charconv_buffer_length<uint8_t> = 3;   // strlen("255")

	template <typename T, typename Char>
	inline void print_integer_to_stream(T val, std::basic_ostream<Char>& stream, value_flags format = {})
	{
		static_assert(
			sizeof(Char) == 1,
			"The stream's underlying character type must be 1 byte in size."
		);

		if (!val)
		{
			print_to_stream('0', stream);
			return;
		}

		int base = 10;
		if (format != value_flags::none && val >= T{})
		{
			switch (format)
			{
				case value_flags::format_as_binary: base = 2; break;
				case value_flags::format_as_octal: base = 8; break;
				case value_flags::format_as_hexadecimal: base = 16; break;
				default: break;
			}
		}

		#if TOML_INT_CHARCONV
		{
			char buf[(sizeof(T) * CHAR_BIT)];
			const auto res = std::to_chars(buf, buf + sizeof(buf), val, base);
			const auto len = static_cast<size_t>(res.ptr - buf);
			if (base == 16)
			{
				for (size_t i = 0; i < len; i++)
					if (buf[i] >= 'a')
						buf[i] -= 32;
			}
			print_to_stream(buf, len, stream);
		}
		#else
		{
			using unsigned_type = std::conditional_t<(sizeof(T) > sizeof(unsigned)), std::make_unsigned_t<T>, unsigned>;
			using cast_type = std::conditional_t<std::is_signed_v<T>, std::make_signed_t<unsigned_type>, unsigned_type>;

			if TOML_UNLIKELY(format == value_flags::format_as_binary)
			{
				bool found_one = false;
				const auto v = static_cast<unsigned_type>(val);
				unsigned_type mask = unsigned_type{ 1 } << (sizeof(unsigned_type) * CHAR_BIT - 1u);
				for (unsigned i = 0; i < sizeof(unsigned_type) * CHAR_BIT; i++)
				{
					if ((v & mask))
					{
						print_to_stream('1', stream);
						found_one = true;
					}
					else if (found_one)
						print_to_stream('0', stream);
					mask >>= 1;
				}
			}
			else
			{
				std::ostringstream ss;
				ss.imbue(std::locale::classic());
				ss << std::uppercase << std::setbase(base);
				ss << static_cast<cast_type>(val);
				const auto str = std::move(ss).str();
				print_to_stream(str, stream);
			}
		}
		#endif
	}

	#define TOML_P2S_OVERLOAD(Type)																	\
		template <typename Char>																	\
		inline void print_to_stream(Type val, std::basic_ostream<Char>& stream, value_flags format)	\
		{																							\
			static_assert(sizeof(Char) == 1);														\
			print_integer_to_stream(val, stream, format);											\
		}

	TOML_P2S_OVERLOAD(int8_t)
	TOML_P2S_OVERLOAD(int16_t)
	TOML_P2S_OVERLOAD(int32_t)
	TOML_P2S_OVERLOAD(int64_t)
	TOML_P2S_OVERLOAD(uint8_t)
	TOML_P2S_OVERLOAD(uint16_t)
	TOML_P2S_OVERLOAD(uint32_t)
	TOML_P2S_OVERLOAD(uint64_t)

	#undef TOML_P2S_OVERLOAD

	template <typename T, typename Char>
	inline void print_floating_point_to_stream(T val, std::basic_ostream<Char>& stream, bool hexfloat = false)
	{
		static_assert(
			sizeof(Char) == 1,
			"The stream's underlying character type must be 1 byte in size."
		);

		switch (impl::fpclassify(val))
		{
			case fp_class::neg_inf:
				print_to_stream("-inf"sv, stream);
				break;

			case fp_class::pos_inf:
				print_to_stream("inf"sv, stream);
				break;

			case fp_class::nan:
				print_to_stream("nan"sv, stream);
				break;

			case fp_class::ok:
			{
				static constexpr auto needs_decimal_point = [](auto&& s) noexcept
				{
					for (auto c : s)
						if (c == '.' || c == 'E' || c == 'e')
							return false;
					return true;
				};

				#if TOML_FLOAT_CHARCONV
				{
					char buf[charconv_buffer_length<T>];
					const auto res = hexfloat
						? std::to_chars(buf, buf + sizeof(buf), val, std::chars_format::hex)
						: std::to_chars(buf, buf + sizeof(buf), val);
					const auto str = std::string_view{ buf, static_cast<size_t>(res.ptr - buf) };
					print_to_stream(str, stream);
					if (!hexfloat && needs_decimal_point(str))
						print_to_stream(".0"sv, stream);
				}
				#else
				{
					std::ostringstream ss;
					ss.imbue(std::locale::classic());
					ss.precision(std::numeric_limits<T>::digits10 + 1);
					if (hexfloat)
						ss << std::hexfloat;
					ss << val;
					const auto str = std::move(ss).str();
					print_to_stream(str, stream);
					if (!hexfloat && needs_decimal_point(str))
						print_to_stream(".0"sv, stream);
				}
				#endif

				break;
			}

			TOML_NO_DEFAULT_CASE;
		}
	}

	#if !defined(DOXYGEN) && !TOML_HEADER_ONLY
		extern template TOML_API void print_floating_point_to_stream(double, std::ostream&, bool);
	#endif

	#define TOML_P2S_OVERLOAD(Type)											\
		template <typename Char>											\
		inline void print_to_stream(Type val, std::basic_ostream<Char>& stream)	\
		{																	\
			static_assert(sizeof(Char) == 1);								\
			print_floating_point_to_stream(val, stream);					\
		}

	TOML_P2S_OVERLOAD(double)

	#undef TOML_P2S_OVERLOAD

	template <typename Char>
	inline void print_to_stream(bool val, std::basic_ostream<Char>& stream)
	{
		static_assert(sizeof(Char) == 1);
		print_to_stream(val ? "true"sv : "false"sv, stream);
	}

	template <typename T, typename Char>
	inline void print_to_stream(T val, std::basic_ostream<Char>& stream, size_t zero_pad_to_digits)
	{
		static_assert(sizeof(Char) == 1);
		#if TOML_INT_CHARCONV

			char buf[charconv_buffer_length<T>];
			const auto res = std::to_chars(buf, buf + sizeof(buf), val);
			const auto len = static_cast<size_t>(res.ptr - buf);
			for (size_t i = len; i < zero_pad_to_digits; i++)
				print_to_stream('0', stream);
			print_to_stream(buf, static_cast<size_t>(res.ptr - buf), stream);

		#else

			std::ostringstream ss;
			ss.imbue(std::locale::classic());
			using cast_type = std::conditional_t<std::is_signed_v<T>, int64_t, uint64_t>;
			ss << std::setfill('0') << std::setw(static_cast<int>(zero_pad_to_digits)) << static_cast<cast_type>(val);
			const auto str = std::move(ss).str();
			print_to_stream(str, stream);

		#endif
	}

	template <typename Char>
	inline void print_to_stream(const toml::date& val, std::basic_ostream<Char>& stream)
	{
		static_assert(sizeof(Char) == 1);
		print_to_stream(val.year, stream, 4_sz);
		print_to_stream('-', stream);
		print_to_stream(val.month, stream, 2_sz);
		print_to_stream('-', stream);
		print_to_stream(val.day, stream, 2_sz);
	}

	template <typename Char>
	inline void print_to_stream(const toml::time& val, std::basic_ostream<Char>& stream)
	{
		static_assert(sizeof(Char) == 1);
		print_to_stream(val.hour, stream, 2_sz);
		print_to_stream(':', stream);
		print_to_stream(val.minute, stream, 2_sz);
		print_to_stream(':', stream);
		print_to_stream(val.second, stream, 2_sz);
		if (val.nanosecond && val.nanosecond <= 999999999u)
		{
			print_to_stream('.', stream);
			auto ns = val.nanosecond;
			size_t digits = 9_sz;
			while (ns % 10u == 0u)
			{
				ns /= 10u;
				digits--;
			}
			print_to_stream(ns, stream, digits);
		}
	}

	template <typename Char>
	inline void print_to_stream(toml::time_offset val, std::basic_ostream<Char>& stream)
	{
		static_assert(sizeof(Char) == 1);
		if (!val.minutes)
			print_to_stream('Z', stream);
		else
		{
			auto mins = static_cast<int>(val.minutes);
			if (mins < 0)
			{
				print_to_stream('-', stream);
				mins = -mins;
			}
			else
				print_to_stream('+', stream);
			const auto hours = mins / 60;
			if (hours)
			{
				print_to_stream(static_cast<unsigned int>(hours), stream, 2_sz);
				mins -= hours * 60;
			}
			else
				print_to_stream("00"sv, stream);
			print_to_stream(':', stream);
			print_to_stream(static_cast<unsigned int>(mins), stream, 2_sz);
		}
	}

	template <typename Char>
	inline void print_to_stream(const toml::date_time& val, std::basic_ostream<Char>& stream)
	{
		static_assert(sizeof(Char) == 1);
		print_to_stream(val.date, stream);
		print_to_stream('T', stream);
		print_to_stream(val.time, stream);
		if (val.offset)
			print_to_stream(*val.offset, stream);
	}

	TOML_PUSH_WARNINGS;
	TOML_DISABLE_ARITHMETIC_WARNINGS;

	template <typename T, typename Char>
	void print_to_stream_with_escapes(T && str, std::basic_ostream<Char>& stream)
	{
		static_assert(sizeof(Char) == 1);
		for (auto c : str)
		{
			if TOML_UNLIKELY(c >= '\x00' && c <= '\x1F')
				print_to_stream(low_character_escape_table[c], stream);
			else if TOML_UNLIKELY(c == '\x7F')
				print_to_stream("\\u007F"sv, stream);
			else if TOML_UNLIKELY(c == '"')
				print_to_stream("\\\""sv, stream);
			else if TOML_UNLIKELY(c == '\\')
				print_to_stream("\\\\"sv, stream);
			else
				print_to_stream(c, stream);
		}
	}

	TOML_POP_WARNINGS; // TOML_DISABLE_ARITHMETIC_WARNINGS
}
TOML_IMPL_NAMESPACE_END;

TOML_NAMESPACE_START
{
	/// \brief	Prints a source_position to a stream.
	///
	/// \detail \cpp
	/// auto tbl = toml::parse("bar = 42"sv);
	/// 
	/// std::cout << "The value for 'bar' was found on "sv
	///		<< tbl.get("bar")->source().begin()
	///		<< "\n";
	/// 
	/// \ecpp
	/// 
	/// \out
	/// The value for 'bar' was found on line 1, column 7
	/// \eout
	/// 
	/// \tparam Char The output stream's underlying character type. Must be 1 byte in size.
	/// \param 	lhs	The stream.
	/// \param 	rhs	The source_position.
	///
	/// \returns	The input stream.
	template <typename Char>
	inline std::basic_ostream<Char>& operator << (std::basic_ostream<Char>& lhs, const source_position& rhs)
	{
		static_assert(
			sizeof(Char) == 1,
			"The stream's underlying character type must be 1 byte in size."
		);
		impl::print_to_stream("line "sv, lhs);
		impl::print_to_stream(rhs.line, lhs);
		impl::print_to_stream(", column "sv, lhs);
		impl::print_to_stream(rhs.column, lhs);
		return lhs;
	}

	/// \brief	Prints a source_region to a stream.
	///
	/// \detail \cpp
	/// auto tbl = toml::parse("bar = 42", "config.toml");
	/// 
	/// std::cout << "The value for 'bar' was found on "sv
	///		<< tbl.get("bar")->source()
	///		<< "\n";
	/// 
	/// \ecpp
	/// 
	/// \out
	/// The value for 'bar' was found on line 1, column 7 of 'config.toml'
	/// \eout
	/// 
	/// \tparam Char The output stream's underlying character type. Must be 1 byte in size.
	/// \param 	lhs	The stream.
	/// \param 	rhs	The source_position.
	///
	/// \returns	The input stream.
	template <typename Char>
	inline std::basic_ostream<Char>& operator << (std::basic_ostream<Char>& lhs, const source_region& rhs)
	{
		static_assert(
			sizeof(Char) == 1,
			"The stream's underlying character type must be 1 byte in size."
		);
		lhs << rhs.begin;
		if (rhs.path)
		{
			impl::print_to_stream(" of '"sv, lhs);
			impl::print_to_stream(*rhs.path, lhs);
			impl::print_to_stream('\'', lhs);
		}
		return lhs;
	}

	#if !defined(DOXYGEN) && !TOML_HEADER_ONLY
		extern template TOML_API std::ostream& operator << (std::ostream&, const source_position&);
		extern template TOML_API std::ostream& operator << (std::ostream&, const source_region&);
	#endif
}
TOML_NAMESPACE_END;

TOML_POP_WARNINGS; // TOML_DISABLE_SWITCH_WARNINGS