Function get_token_string

extern/json/json.hpp:8753–8774

return the last read token (for errors only). Will never contain EOF (an arbitrary value that is not a valid char value, often -1), because 255 may legitimately occur. May contain NUL, which should be escaped.

    /// (an arbitrary value that is not a valid char value, often -1), because
    /// 255 may legitimately occur.  May contain NUL, which should be escaped.
    std::string get_token_string() const
    {
        // escape control characters
        std::string result;
        for (const auto c : token_string)
        {
            if (static_cast<unsigned char>(c) <= '\x1F')
            {
                // escape control characters
                std::array<char, 9> cs{{}};
                static_cast<void>((std::snprintf)(cs.data(), cs.size(), "<U+%.4X>", static_cast<unsigned char>(c))); // NOLINT(cppcoreguidelines-pro-type-vararg,hicpp-vararg)
                result += cs.data();
            }
            else
            {
                // add character as is
                result.push_back(static_cast<std::string::value_type>(c));
            }
        }

        return result;
    }

    /// return syntax error message
    JSON_HEDLEY_RETURNS_NON_NULL