Method parse_basic_string

apps/external/toml.hpp:12155–12392

    TOML_NODISCARD
    TOML_NEVER_INLINE
    std::string_view parse_basic_string(bool multi_line) {
      return_if_error({});
      assert_not_eof();
      TOML_ASSERT_ASSUME(*cp == U'"');
      push_parse_scope("string"sv);

      // skip the '"'
      advance_and_return_if_error_or_eof({});

      // multi-line strings ignore a single line ending right at the beginning
      if (multi_line) {
        consume_line_break();
        return_if_error({});
        set_error_and_return_if_eof({});
      }

      auto& str = string_buffer;
      str.clear();
      bool escaped = false;
      bool skipping_whitespace = false;
      do {
        if (escaped) {
          escaped = false;

          // handle 'line ending slashes' in multi-line mode
          if (multi_line && is_whitespace(*cp)) {
            consume_leading_whitespace();

            if TOML_UNLIKELY (!consume_line_break())
              set_error_and_return_default(
                  "line-ending backslashes must be the last non-whitespace character on the line"sv);

            skipping_whitespace = true;
            return_if_error({});
            continue;
          }

          bool skip_escaped_codepoint = true;
          assert_not_eof();
          switch (const auto escaped_codepoint = *cp) {
            // 'regular' escape codes
            case U'b':
              str += '\b';
              break;
            case U'f':
              str += '\f';
              break;
            case U'n':
              str += '\n';
              break;
            case U'r':
              str += '\r';
              break;
            case U't':
              str += '\t';
              break;
            case U'"':
              str += '"';