Method eval_node_set

Source/ThirdParty/pugixml/pugixml.cpp:9791–9917

		}

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

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

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

				return rs;
			}

			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>());