Function append

Source/ThirdParty/pugixml/pugixml.cpp:6813–6846

		}

		void append(const xpath_string& o, xpath_allocator* alloc)
		{
			// skip empty sources
			if (!*o._buffer) return;

			// fast append for constant empty target and constant source
			if (!*_buffer && !_uses_heap && !o._uses_heap)
			{
				_buffer = o._buffer;
			}
			else
			{
				// need to make heap copy
				size_t target_length = length();
				size_t source_length = o.length();
				size_t result_length = target_length + source_length;

				// allocate new buffer
				char_t* result = static_cast<char_t*>(alloc->reallocate(_uses_heap ? const_cast<char_t*>(_buffer) : 0, (target_length + 1) * sizeof(char_t), (result_length + 1) * sizeof(char_t)));
				assert(result);

				// append first string to the new buffer in case there was no reallocation
				if (!_uses_heap) memcpy(result, _buffer, target_length * sizeof(char_t));

				// append second string to the new buffer
				memcpy(result + target_length, o._buffer, source_length * sizeof(char_t));
				result[result_length] = 0;

				// finalize
				_buffer = result;
				_uses_heap = true;
				_length_heap = result_length;
			}
		}

		const char_t* c_str() const
		{