/* $Id: ModelCommand.java 17747 2010-01-10 21:16:51Z 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) 2004-2006 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
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// and this paragraph appear in all copies.  This software program and
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// California. The software program and documentation are supplied "AS
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package org.argouml.model;

/**
 * A command to record the state of an object before an undoable change.<p>
 * The model implementation should create a ModelCommand for any
 * undoable operation performed. Any mutator method should normally be
 * undoable except loading a model from file.
 * 
 * @author Bob Tarling
 */
public abstract class ModelCommand {

    /**
     * Execute this command.
     * @return any result generated by this command
     */
    public abstract Object execute();

    /**
     * Determine whether the command can be undone.
     * 
     * @return true if the command can be undone
     */
    public abstract boolean isUndoable();

    /**
     * Determine whether the command can be redone once undone.
     * 
     * @return true if the command can be redone
     */
    public abstract boolean isRedoable();

    /**
     * Undo this command.
     */
    public abstract void undo();
}