////   This file contains the C++ code from Program 16.8 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/pgm16_08.cpp//void Graph::BreadthFirstTraversal (    Visitor& visitor, Vertex const& start) const{    Array<bool> enqueued (numberOfVertices);    for (Vertex::Number v = 0; v < numberOfVertices; ++v)	enqueued [v] = false;    Queue& queue = *new QueueAsLinkedList ();    queue.RescindOwnership ();    enqueued [start] = true;    queue.Enqueue (const_cast<Vertex&> (start));    while (!queue.IsEmpty () && !visitor.IsDone ())    {	Vertex& vertex =	    dynamic_cast<Vertex&> (queue.Dequeue ());	visitor.Visit (vertex);	Iterator& p = EmanatingEdges (vertex);	while (!p.IsDone ()) {	    Edge& edge = dynamic_cast<Edge&> (*p);	    Vertex& to = edge.Mate (vertex);	    if (!enqueued [to])	    {		enqueued [to] = true;		queue.Enqueue (to);	    }	    ++p;	}	delete &p;    }    delete &queue;}