////   This file contains the C++ code from Program 12.23 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/pgm12_23.cpp//void PartitionAsForest::Join (Set& s, Set& t){    PartitionTree& p = dynamic_cast<PartitionTree&> (s);    PartitionTree& q = dynamic_cast<PartitionTree&> (t);    CheckArguments (p, q);    if (p.rank > q.rank)	q.parent = &p;    else    {	p.parent = &q;	if (p.rank == q.rank)	    q.rank += 1;    }    --count;}