////   This file contains the C++ code from Program 5.9 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/pgm05_09.cpp//class Container : public virtual Object, public virtual Ownership{protected:    unsigned int count;    Container ();public:    virtual unsigned int Count () const;    virtual bool IsEmpty () const;    virtual bool IsFull () const;    virtual HashValue Hash () const;    virtual void Put (ostream&) const;    virtual Iterator& NewIterator () const;    virtual void Purge () = 0;    virtual void Accept (Visitor&) const = 0;};