////   This file contains the C++ code from Program 9.7 of//   "Data Structures and Algorithms//    with Object-Oriented Design Patterns in C++"//   by Bruno R. Preiss.////   Copyright (c) 1998 by Bruno R. Preiss, P.Eng.  All rights reserved.////   http://www.pads.uwaterloo.ca/Bruno.Preiss/books/opus4/programs/pgm09_07.cpp//Tree::Iter::Iter (Tree const& _tree) :    tree (_tree),    stack (*new StackAsLinkedList ()){    stack.RescindOwnership ();    Reset ();}Tree::Iter::~Iter ()    { delete &stack; }void Tree::Iter::Reset (){    stack.Purge ();    if (!tree.IsEmpty ())	stack.Push (const_cast<Tree&> (tree));}