tomlplusplus/include/toml++/toml_formatter.h

//# This file is a part of toml++ and is subject to the the terms of the MIT license.
//# Copyright (c) 2019-2020 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_print_to_stream.h"

TOML_PUSH_WARNINGS
TOML_DISABLE_SWITCH_WARNINGS
TOML_DISABLE_PADDING_WARNINGS

TOML_NAMESPACE_START
{
	/// \brief	Format flags for modifying how TOML data is printed to streams.
	enum class format_flags : uint8_t
	{
		/// \brief None.
		none,

		/// \brief Dates and times will be emitted as quoted strings.
		quote_dates_and_times = 1,

		/// \brief Strings will be emitted as single-quoted literal strings where possible.
		allow_literal_strings = 2,

		/// \brief Strings containing newlines will be emitted as triple-quoted 'multi-line' strings where possible.
		allow_multi_line_strings = 4,
	};

	[[nodiscard]]
	TOML_ALWAYS_INLINE
	TOML_ATTR(const)
	TOML_ATTR(flatten)
	constexpr format_flags operator & (format_flags lhs, format_flags rhs) noexcept
	{
		return static_cast<format_flags>(impl::unbox_enum(lhs) & impl::unbox_enum(rhs));
	}

	[[nodiscard]]
	TOML_ALWAYS_INLINE
	TOML_ATTR(const)
	TOML_ATTR(flatten)
	constexpr format_flags operator | (format_flags lhs, format_flags rhs) noexcept
	{
		return static_cast<format_flags>( impl::unbox_enum(lhs) | impl::unbox_enum(rhs) );
	}
}
TOML_NAMESPACE_END

TOML_IMPL_NAMESPACE_START
{
	template <typename Char = char>
	class TOML_API formatter
	{
		private:
			const toml::node* source_;
			std::basic_ostream<Char>* stream_ = nullptr;
			format_flags flags_;
			int8_t indent_;
			bool naked_newline_;

		protected:
			
			[[nodiscard]] const toml::node& source() const noexcept { return *source_; }
			[[nodiscard]] std::basic_ostream<Char>& stream() const noexcept { return *stream_; }

			static constexpr size_t indent_columns = 4;
			static constexpr std::string_view indent_string = "    "sv;
			[[nodiscard]] int8_t indent() const noexcept { return indent_; }
			void indent(int8_t level) noexcept { indent_ = level; }
			void increase_indent() noexcept { indent_++; }
			void decrease_indent() noexcept { indent_--; }

			[[nodiscard]]
			bool quote_dates_and_times() const noexcept
			{
				return (flags_ & format_flags::quote_dates_and_times) != format_flags::none;
			}

			[[nodiscard]]
			bool literal_strings_allowed() const noexcept
			{
				return (flags_ & format_flags::allow_literal_strings) != format_flags::none;
			}

			[[nodiscard]]
			bool multi_line_strings_allowed() const noexcept
			{
				return (flags_ & format_flags::allow_multi_line_strings) != format_flags::none;
			}

			[[nodiscard]]
			bool naked_newline() const noexcept
			{
				return naked_newline_;
			}

			void clear_naked_newline() noexcept
			{
				naked_newline_ = false;
			}

			void attach(std::basic_ostream<Char>& stream) noexcept
			{
				indent_ = {};
				naked_newline_ = true;
				stream_ = &stream;
			}

			void detach() noexcept
			{
				stream_ = nullptr;
			}

			void print_newline(bool force = false)
			{
				if (!naked_newline_ || force)
				{
					print_to_stream('\n', *stream_);
					naked_newline_ = true;
				}
			}

			void print_indent()
			{
				for (int8_t i = 0; i < indent_; i++)
				{
					print_to_stream(indent_string, *stream_);
					naked_newline_ = false;
				}
			}

			void print_quoted_string(std::string_view str, bool allow_multi_line = true)
			{
				auto literals = literal_strings_allowed();
				if (str.empty())
				{
					print_to_stream(literals ? "''"sv : "\"\""sv, *stream_);
					clear_naked_newline();
					return;
				}

				auto multi_line = allow_multi_line && multi_line_strings_allowed();
				if (multi_line || literals)
				{
					utf8_decoder decoder;
					bool has_line_breaks = false;
					bool has_control_chars = false;
					bool has_single_quotes = false;
					for (size_t i = 0; i < str.length() && !(has_line_breaks && has_control_chars && has_single_quotes); i++)
					{
						decoder(static_cast<uint8_t>(str[i]));
						if (decoder.error())
						{
							has_line_breaks = false;
							has_control_chars = true; //force ""
							has_single_quotes = true;
							break;
						}
						else if (decoder.has_code_point())
						{
							if (is_line_break(decoder.codepoint))
								has_line_breaks = true;
							else if (is_nontab_control_character(decoder.codepoint))
								has_control_chars = true;
							else if (decoder.codepoint == U'\'')
								has_single_quotes = true;
						}
					}
					multi_line = multi_line && has_line_breaks;
					literals = literals && !has_control_chars && !(!multi_line && has_single_quotes);
				}

				if (literals)
				{
					const auto quot = multi_line ? "'''"sv : "'"sv;
					print_to_stream(quot, *stream_);
					print_to_stream(str, *stream_);
					print_to_stream(quot, *stream_);
				}
				else
				{
					const auto quot = multi_line ? R"(""")"sv : R"(")"sv;
					print_to_stream(quot, *stream_);
					print_to_stream_with_escapes(str, *stream_);
					print_to_stream(quot, *stream_);
				}
				clear_naked_newline();
			}

			template <typename T>
			void print(const value<T>& val)
			{
				if constexpr (std::is_same_v<T, std::string>)
				{
					print_quoted_string(val.get());
				}
				else
				{
					static constexpr auto is_dt =
						std::is_same_v<T, date>
						|| std::is_same_v<T, time>
						|| std::is_same_v<T, date_time>;

					if constexpr (is_dt)
					{
						if (quote_dates_and_times())
						{
							const auto quot = literal_strings_allowed() ? '\'' : '"';
							print_to_stream(quot, *stream_);
							print_to_stream(*val, *stream_);
							print_to_stream(quot, *stream_);
						}
						else
							print_to_stream(*val, *stream_);
					}
					else
						print_to_stream(*val, *stream_);

					naked_newline_ = false;
				}
			}

			void print_value(const node& val_node, node_type type)
			{
				TOML_ASSUME(type > node_type::array);
				switch (type)
				{
					case node_type::string:			print(*reinterpret_cast<const value<std::string>*>(&val_node)); break;
					case node_type::integer:		print(*reinterpret_cast<const value<int64_t>*>(&val_node)); break;
					case node_type::floating_point:	print(*reinterpret_cast<const value<double>*>(&val_node)); break;
					case node_type::boolean:		print(*reinterpret_cast<const value<bool>*>(&val_node)); break;
					case node_type::date:			print(*reinterpret_cast<const value<date>*>(&val_node)); break;
					case node_type::time:			print(*reinterpret_cast<const value<time>*>(&val_node)); break;
					case node_type::date_time:		print(*reinterpret_cast<const value<date_time>*>(&val_node)); break;
					TOML_NO_DEFAULT_CASE;
				}
			}

			formatter(const toml::node& source, format_flags flags) noexcept
				: source_{ &source },
				flags_{ flags }
			{}
	};

	#if !defined(DOXYGEN) && !TOML_HEADER_ONLY
		extern template class TOML_API formatter<char>;
	#endif

}
TOML_IMPL_NAMESPACE_END

TOML_POP_WARNINGS // TOML_DISABLE_SWITCH_WARNINGS, TOML_DISABLE_PADDING_WARNINGS