Method eval_node_set

lib/pugixml/src/pugixml.cpp:10882–11012

		}

		xpath_node_set_raw eval_node_set(const xpath_context& c, const xpath_stack& stack, nodeset_eval_t eval)
		{
			switch (_type)
			{
			case ast_op_union:
			{
				xpath_allocator_capture cr(stack.temp);

				xpath_stack swapped_stack = {stack.temp, stack.result};

				xpath_node_set_raw ls = _left->eval_node_set(c, stack, eval);
				xpath_node_set_raw rs = _right->eval_node_set(c, swapped_stack, eval);

				// we can optimize merging two sorted sets, but this is a very rare operation, so don't bother
				ls.set_type(xpath_node_set::type_unsorted);

				ls.append(rs.begin(), rs.end(), stack.result);
				ls.remove_duplicates(stack.temp);

				return ls;
			}

			case ast_filter:
			{
				xpath_node_set_raw set = _left->eval_node_set(c, stack, _test == predicate_constant_one ? nodeset_eval_first : nodeset_eval_all);

				// either expression is a number or it contains position() call; sort by document order
				if (_test != predicate_posinv) set.sort_do();

				bool once = eval_once(set.type(), eval);

				apply_predicate(set, 0, stack, once);

				return set;
			}

			case ast_func_id:
				return xpath_node_set_raw();

			case ast_step:
			{
				switch (_axis)
				{
				case axis_ancestor:
					return step_do(c, stack, eval, axis_to_type<axis_ancestor>());

				case axis_ancestor_or_self:
					return step_do(c, stack, eval, axis_to_type<axis_ancestor_or_self>());

				case axis_attribute:
					return step_do(c, stack, eval, axis_to_type<axis_attribute>());

				case axis_child:
					return step_do(c, stack, eval, axis_to_type<axis_child>());

				case axis_descendant:
					return step_do(c, stack, eval, axis_to_type<axis_descendant>());