Method print_string

src/toml.hpp:16146–16238

	}

	TOML_EXTERNAL_LINKAGE
	void formatter::print_string(std::string_view str, bool allow_multi_line, bool allow_bare)
	{
		if (str.empty())
		{
			print_unformatted(literal_strings_allowed() ? "''"sv : "\"\""sv);
			return;
		}

		// pre-scan the string to determine how we should output it
		formatted_string_traits traits = {};

		if (!allow_bare)
			traits |= formatted_string_traits::non_bare;
		bool unicode_allowed = unicode_strings_allowed();

		// ascii fast path
		if (is_ascii(str.data(), str.length()))
		{
			for (auto c : str)
			{
				switch (c)
				{
					case '\n': traits |= formatted_string_traits::line_breaks; break;
					case '\t': traits |= formatted_string_traits::tabs; break;
					case '\'': traits |= formatted_string_traits::single_quotes; break;
					default:
					{
						if TOML_UNLIKELY(is_control_character(c))
							traits |= formatted_string_traits::control_chars;

						if (!is_ascii_bare_key_character(static_cast<char32_t>(c)))
							traits |= formatted_string_traits::non_bare;
						break;
					}
				}

				static constexpr auto all_ascii_traits =
					formatted_string_traits::all & ~formatted_string_traits::non_ascii;
				if (traits == all_ascii_traits)
					break;
			}
		}

		// unicode slow path
		else
		{
			traits |= formatted_string_traits::non_ascii;
			utf8_decoder decoder;

			// if the unicode is malformed just treat the string as a single-line non-literal and
			// escape all non-ascii characters (to ensure round-tripping and help with diagnostics)
			const auto bad_unicode = [&]() noexcept
			{
				traits &= ~formatted_string_traits::line_breaks;
				traits |= formatted_string_traits::control_chars | formatted_string_traits::non_bare;
				unicode_allowed = false;
			};