Method allocate

lib/pugixml/src/pugixml.cpp:7627–7662

		}

		void* allocate(size_t size)
		{
			// round size up to block alignment boundary
			size = (size + xpath_memory_block_alignment - 1) & ~(xpath_memory_block_alignment - 1);

			if (_root_size + size <= _root->capacity)
			{
				void* buf = &_root->data[0] + _root_size;
				_root_size += size;
				return buf;
			}
			else
			{
				// make sure we have at least 1/4th of the page free after allocation to satisfy subsequent allocation requests
				size_t block_capacity_base = sizeof(_root->data);
				size_t block_capacity_req = size + block_capacity_base / 4;
				size_t block_capacity = (block_capacity_base > block_capacity_req) ? block_capacity_base : block_capacity_req;

				size_t block_size = block_capacity + offsetof(xpath_memory_block, data);

				xpath_memory_block* block = static_cast<xpath_memory_block*>(xml_memory::allocate(block_size));
				if (!block)
				{
					if (_error) *_error = true;
					return 0;
				}

				block->next = _root;
				block->capacity = block_capacity;

				_root = block;
				_root_size = size;

				return block->data;
			}
		}

		void* reallocate(void* ptr, size_t old_size, size_t new_size)
		{