Function unget

Source/external/json.hpp:8675–8699

! @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)