// $Id: GenDescendantClasses.java,v 1.8 2004/08/29 07:47:29 mvw Exp $
// Copyright (c) 1996-99 The Regents of the University of California. All
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// software and its documentation without fee, and without a written
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// does not warrant that the operation of the program will be
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package org.argouml.uml;

import java.util.Collection;
import java.util.Enumeration;
import java.util.Vector;
import org.argouml.model.ModelFacade;
import org.tigris.gef.util.ChildGenerator;
/** Utility class to generate the subclasses of a class.  It
 *  recursively moves down the class hierarchy.  But it does that in a
 *  safe way that will nothang in case of cyclic inheritance. 
 *  @stereotype singleton
 */

public class GenDescendantClasses implements ChildGenerator {
    private static final GenDescendantClasses SINGLETON = 
        new GenDescendantClasses();

    /**
     * @return Returns the sINGLETON.
     */
    public static GenDescendantClasses getSINGLETON() {
        return SINGLETON;
    }
    
    /**
     * @see org.tigris.gef.util.ChildGenerator#gen(java.lang.Object)
     */
    public Enumeration gen(Object o) {
	Vector res = new Vector();
	if (!(ModelFacade.isAGeneralizableElement(o))) return res.elements();

	Object cls = /*(MGeneralizableElement)*/ o;
	Collection gens = ModelFacade.getSpecializations(cls);
	if (gens == null) return res.elements();
	accumulateDescendants(cls, res);
	return res.elements();
    }


    /**
     * @param cls the starting class (in fact GeneralizableElement)
     * @param accum the accumulated list of descendents
     */
    public void accumulateDescendants(Object/*MGeneralizableElement*/ cls, 
            Vector accum) {
	Vector gens = new Vector(ModelFacade.getSpecializations(cls));
	if (gens == null) return;
	int size = gens.size();
	for (int i = 0; i < size; i++) {
	    Object g = /*(MGeneralization)*/ (gens.elementAt(i));
	    Object ge = ModelFacade.getChild(g);
	    if (!accum.contains(ge)) {
		accum.add(ge);
		accumulateDescendants(cls, accum);
	    }
	}
    }
} /* end class GenDescendantClasses */