AS中，应用递归来计算 Tree的深度

private var _treeDataDesciptor:ITreeDataDescriptor = new DefaultDataDescriptor;

private function calculateDepth(data:ICollectionView):void{
			for(var cursor:IViewCursor = data.createCursor(); !cursor.afterLast; cursor.moveNext()){
				if(_treeDataDesciptor.isBranch(cursor.current, data) 
					&&  _treeDataDesciptor.getChildren(cursor.current, data).length != 0){
					
					_currentDepth++;
					
					if(_currentDepth > _depth){
						_depth = _currentDepth;
					}
					
					var __tmp:ICollectionView = _treeDataDesciptor.getChildren(cursor.current, data);
					calculateDepth(__tmp);
					
					_currentDepth--;
				}
			}	
		}