Function unget

Source/Utils/json.hpp:7245–7269

! @brief unget current character (read it again on next get) We implement unget by setting variable next_unget to true. The input is not changed - we just simulate ungetting by modifying chars_read_total, chars_read_current_line, and token_string. The next call to get() will behave as if the unget character is read again. */

            behave as if the unget character is read again.
            */
            void unget()
            {
                next_unget = true;

                --position.chars_read_total;

                // in case we "unget" a newline, we have to also decrement the lines_read
                if (position.chars_read_current_line == 0)
                {
                    if (position.lines_read > 0)
                    {
                        --position.lines_read;
                    }
                }
                else
                {
                    --position.chars_read_current_line;
                }

                if (JSON_HEDLEY_LIKELY(current != std::char_traits<char_type>::eof()))
                {
                    JSON_ASSERT(!token_string.empty());
                    token_string.pop_back();
                }
            }

            /// add a character to token_buffer
            void add(char_int_type c)