Method reallocate

Source/ThirdParty/pugixml/pugixml.cpp:6631–6674

		}

		void* reallocate(void* ptr, size_t old_size, size_t new_size)
		{
			// align size so that we're able to store pointers in subsequent blocks
			old_size = (old_size + sizeof(void*) - 1) & ~(sizeof(void*) - 1);
			new_size = (new_size + sizeof(void*) - 1) & ~(sizeof(void*) - 1);

			// we can only reallocate the last object
			assert(ptr == 0 || static_cast<char*>(ptr) + old_size == _root->data + _root_size);

			// adjust root size so that we have not allocated the object at all
			bool only_object = (_root_size == old_size);

			if (ptr) _root_size -= old_size;

			// allocate a new version (this will obviously reuse the memory if possible)
			void* result = allocate(new_size);
			assert(result);

			// we have a new block
			if (result != ptr && ptr)
			{
				// copy old data
				assert(new_size >= old_size);
				memcpy(result, ptr, old_size);

				// free the previous page if it had no other objects
				if (only_object)
				{
					assert(_root->data == result);
					assert(_root->next);

					xpath_memory_block* next = _root->next->next;

					if (next)
					{
						// deallocate the whole page, unless it was the first one
						xml_memory::deallocate(_root->next);
						_root->next = next;
					}
				}
			}

			return result;
		}

		void revert(const xpath_allocator& state)
		{