/* $Id: GenDescendantClasses.java 17846 2010-01-12 19:37:12Z linus $
 *****************************************************************************
 * Copyright (c) 2009 Contributors - see below
 * All rights reserved. This program and the accompanying materials
 * are made available under the terms of the Eclipse Public License v1.0
 * which accompanies this distribution, and is available at
 * http://www.eclipse.org/legal/epl-v10.html
 *
 * Contributors:
 *    tfmorris
 *****************************************************************************
 *
 * Some portions of this file was previously release using the BSD License:
 */

// Copyright (c) 1996-2006 The Regents of the University of California. All
// Rights Reserved. Permission to use, copy, modify, and distribute this
// software and its documentation without fee, and without a written
// agreement is hereby granted, provided that the above copyright notice
// and this paragraph appear in all copies.  This software program and
// documentation are copyrighted by The Regents of the University of
// California. The software program and documentation are supplied "AS
// IS", without any accompanying services from The Regents. The Regents
// does not warrant that the operation of the program will be
// uninterrupted or error-free. The end-user understands that the program
// was developed for research purposes and is advised not to rely
// exclusively on the program for any reason.  IN NO EVENT SHALL THE
// UNIVERSITY OF CALIFORNIA BE LIABLE TO ANY PARTY FOR DIRECT, INDIRECT,
// SPECIAL, INCIDENTAL, OR CONSEQUENTIAL DAMAGES, INCLUDING LOST PROFITS,
// ARISING OUT OF THE USE OF THIS SOFTWARE AND ITS DOCUMENTATION, EVEN IF
// THE UNIVERSITY OF CALIFORNIA HAS BEEN ADVISED OF THE POSSIBILITY OF
// SUCH DAMAGE. THE UNIVERSITY OF CALIFORNIA SPECIFICALLY DISCLAIMS ANY
// WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
// MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE. THE SOFTWARE
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// UPDATES, ENHANCEMENTS, OR MODIFICATIONS.

package org.argouml.uml;

import java.util.Collection;
import java.util.Collections;
import java.util.Enumeration;
import java.util.HashSet;
import java.util.Set;

import org.argouml.model.Model;
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 not hang
 * 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) {
        Set res = new HashSet();
        if (Model.getFacade().isAGeneralizableElement(o)) {
            Object cls = o;
            accumulateDescendants(cls, res);
        }
        return Collections.enumeration(res);
    }


    /**
     * @param cls the starting class (in fact GeneralizableElement)
     * @param accum the accumulated list of descendants
     */
    private void accumulateDescendants(final Object cls, Collection accum) {
	Collection gens = Model.getFacade().getSpecializations(cls);
	if (gens == null) {
	    return;
	}
	for (Object g : gens) {
	    Object ge = Model.getFacade().getSpecific(g);
	    if (!accum.contains(ge)) {
		accum.add(ge);
		accumulateDescendants(cls, accum);
	    }
	}
    }
}