--- a/src/treecms/proto/test/PreOrderTreeWalker.java	Fri Aug 27 22:25:48 2010 +0900
+++ b/src/treecms/proto/test/PreOrderTreeWalker.java	Fri Aug 27 22:51:03 2010 +0900
@@ -2,6 +2,7 @@
 
 import java.util.Iterator;
 import java.util.LinkedList;
+import java.util.List;
 
 import treecms.proto.api.NodeAPI;
 
@@ -15,26 +16,35 @@
 	}
 	
 	class IteratorState implements Iterator<NodeAPI> {
-		LinkedList<LinkedList<NodeAPI>>stack = new LinkedList<LinkedList<NodeAPI>>();
-		LinkedList<NodeAPI>children;
+		LinkedList<NodeAPI>nodeStack;
+		LinkedList<Integer>positionStack;
+		List<NodeAPI> children;
+		int position;
 		NodeAPI next;
 		
 		IteratorState(NodeAPI root) {
-			children = new LinkedList<NodeAPI>(root.getChildList());
-			stack.addLast(children);
+			children = root.getChildList();
+			nodeStack = new LinkedList<NodeAPI>();
+			positionStack = new LinkedList<Integer>();
+			nodeStack.addLast(root);
+			positionStack.addLast(0);
+			position = 0;
 		}
 
 		public boolean hasNext() {
-			while (children.isEmpty()) {
-				if (stack.isEmpty()) return false;
-				children = stack.getLast();
-				stack.removeLast();
+			while (position>=children.size()) {
+				if (nodeStack.isEmpty()) return false;
+				children = nodeStack.getLast().getChildList();
+				position = positionStack.getLast();
+				nodeStack.removeLast();
+				positionStack.removeLast();
 			}
-			next = children.get(0);
-			children.remove(0);
+			next = children.get(position++);
 			if (! next.getChildList().isEmpty()) {
-				stack.addLast(children);
-				children = new LinkedList<NodeAPI>(next.getChildList());
+				nodeStack.addLast(next);
+				positionStack.addLast(position);
+				children = next.getChildList();
+				position = 0;
 			}
 			return true;
 		}