class REXML::XPathParser

def step(path_stack, any_type: :element, order: :forward)
  nodesets = yield
  begin
    enter(:step, path_stack, nodesets) if @debug
    nodesets = node_test(path_stack, nodesets, any_type: any_type)
    while path_stack[0] == :predicate
      path_stack.shift # :predicate
      predicate_expression = path_stack.shift.dclone
      nodesets = evaluate_predicate(predicate_expression, nodesets)
    end
    if nodesets.size == 1
      ordered_nodeset = nodesets[0]
    else
      raw_nodes = []
      nodesets.each do |nodeset|
        nodeset.each do |node|
          if node.respond_to?(:raw_node)
            raw_nodes << node.raw_node
          else
            raw_nodes << node
          end
        end
      end
      ordered_nodeset = sort(raw_nodes, order)
    end
    new_nodeset = []
    ordered_nodeset.each do |node|
      # TODO: Remove duplicated
      new_nodeset << XPathNode.new(node, position: new_nodeset.size + 1)
    end
    new_nodeset
  ensure
    leave(:step, path_stack, new_nodeset) if @debug
  end
end