Method read_buffer

include/jsoncons/source.hpp:706–713

        }

        span<const value_type> read_buffer() 
        {
            const value_type* data = current_;
            std::size_t length = end_ - current_;
            current_ = end_;

            return span<const value_type>(data, length);
        }

        std::size_t read(value_type* p, std::size_t length)
        {