/// <summary> // Walks a Node in a depth-first/pre-order manner without recursion. // It returns a series of "events" that indicate one of three things: // - whether it has enters into a node // - whether it has exited from a node (i.e. it is finished with that container and its children) // - caller can control which children get entered via the enum_children method /// </summary> public static IEnumerable <WalkEvent <T> > Walk <T>(T node, EnumerateChildren <T> enum_children) { var stack = new Stack <WalkState <T> >(); // put the first item on the stack stack.Push(new WalkState <T>(node)); // As long as something is on the stack, we are not done while (stack.Count > 0) { var cur_item = stack.Pop(); if (cur_item.Entered == false) { var walkevent = WalkEvent <T> .CreateEnterEvent(cur_item.Node); yield return(walkevent); cur_item.Entered = true; stack.Push(cur_item); foreach (var child in TreeOps.efficient_reverse(enum_children(cur_item.Node))) { stack.Push(new WalkState <T>(child)); } } else { var walkevent = WalkEvent <T> .CreateExitEvent(cur_item.Node); yield return(walkevent); } } }
public static IList <TDest> CopyTree <TSrc, TDest>( TSrc src_root_node, System.Func <TSrc, IEnumerable <TSrc> > enum_src_children, System.Func <TSrc, TDest> create_dest_node, System.Action <TDest, TDest> add_dest_child) { var stack = new Stack <TDest>(); var dest_nodes = new List <TDest>(); var walkevents = TreeOps.Walk <TSrc>(src_root_node, input_node => enum_src_children(input_node)); foreach (var ev in walkevents) { if (ev.HasEnteredNode) { var new_dst_node = create_dest_node(ev.Node); if (stack.Count > 0) { // if there is node on the stack, then that node is the current node's parent var parent = stack.Peek(); add_dest_child(parent, new_dst_node); } else { // if there is nothing on the stack this is node without a parent (a root node) } stack.Push(new_dst_node); dest_nodes.Add(new_dst_node); } else if (ev.HasExitedNode) { stack.Pop(); } } return(dest_nodes); }
public static IEnumerable <T> PreOrder <T>(T root, EnumerateChildren <T> enum_children) { return(TreeOps.Walk(root, enum_children).Where(ev => ev.HasEnteredNode).Select(ev => ev.Node)); }