Method exception_message

lesson6-Segmentation/json.hpp:10572–10599

    }

    std::string exception_message(const token_type expected, const std::string& context)
    {
        std::string error_msg = "syntax error ";

        if (!context.empty())
        {
            error_msg += "while parsing " + context + " ";
        }

        error_msg += "- ";

        if (last_token == token_type::parse_error)
        {
            error_msg += std::string(m_lexer.get_error_message()) + "; last read: '" +
                         m_lexer.get_token_string() + "'";
        }
        else
        {
            error_msg += "unexpected " + std::string(lexer_t::token_type_name(last_token));
        }

        if (expected != token_type::uninitialized)
        {
            error_msg += "; expected " + std::string(lexer_t::token_type_name(expected));
        }

        return error_msg;
    }

  private:
    /// callback function