Method step_do

Source/ThirdParty/pugixml/pugixml.cpp:9138–9182

		}

		template <class T> xpath_node_set_raw step_do(const xpath_context& c, const xpath_stack& stack, nodeset_eval_t eval, T v)
		{
			const axis_t axis = T::axis;
			const bool axis_reverse = (axis == axis_ancestor || axis == axis_ancestor_or_self || axis == axis_preceding || axis == axis_preceding_sibling);
			const xpath_node_set::type_t axis_type = axis_reverse ? xpath_node_set::type_sorted_reverse : xpath_node_set::type_sorted;

			bool once =
				(axis == axis_attribute && _test == nodetest_name) ||
				(!_right && eval_once(axis_type, eval)) ||
				(_right && !_right->_next && _right->_test == predicate_constant_one);

			xpath_node_set_raw ns;
			ns.set_type(axis_type);

			if (_left)
			{
				xpath_node_set_raw s = _left->eval_node_set(c, stack, nodeset_eval_all);

				// self axis preserves the original order
				if (axis == axis_self) ns.set_type(s.type());

				for (const xpath_node* it = s.begin(); it != s.end(); ++it)
				{
					size_t size = ns.size();

					// in general, all axes generate elements in a particular order, but there is no order guarantee if axis is applied to two nodes
					if (axis != axis_self && size != 0) ns.set_type(xpath_node_set::type_unsorted);
					
					step_fill(ns, *it, stack.result, once, v);
					if (_right) apply_predicates(ns, size, stack, eval);
				}
			}
			else
			{
				step_fill(ns, c.n, stack.result, once, v);
				if (_right) apply_predicates(ns, 0, stack, eval);
			}

			// child, attribute and self axes always generate unique set of nodes
			// for other axis, if the set stayed sorted, it stayed unique because the traversal algorithms do not visit the same node twice
			if (axis != axis_child && axis != axis_attribute && axis != axis_self && ns.type() == xpath_node_set::type_unsorted)
				ns.remove_duplicates();

			return ns;
		}
		
	public:
		xpath_ast_node(ast_type_t type, xpath_value_type rettype_, const char_t* value):