ICompositeCommand.java

/******************************************************************************
 * Copyright (c) 2006 IBM Corporation and others.
 * 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:
 *    IBM Corporation - initial API and implementation 
 ****************************************************************************/

package org.eclipse.gmf.runtime.common.core.command;

import java.util.Iterator;
import java.util.ListIterator;

import org.eclipse.core.commands.operations.ICompositeOperation;
import org.eclipse.core.commands.operations.IUndoableOperation;
import org.eclipse.core.resources.IFile;

/**
 * A self-composing undoable operation that is has a {@link CommandResult}, a
 * list of affected {@link IFile}s, and is composed of child operations.
 * <P>
 * Does not extend <code>ICompositeOperation</code> because
 * <UL>
 * <LI> {@link #remove(IUndoableOperation)} does not dispose the removed
 * operation</LI>
 * <LI> Children are explicitely composed by the client. Adding to an open
 * composite through the operation history is not supported.</LI>
 * </UL>
 * 
 * @author ldamus
 */
public interface ICompositeCommand
    extends ICommand {

    /**
     * <p>
     * Add the specified operation as a child of this operation.
     * </p>
     * 
     * @param operation
     *            the operation to be added. If the operation instance has
     *            already been added, this method will have no effect.
     */
    public abstract void add(IUndoableOperation operation);

    /**
     * <p>
     * Remove the specified operation from this operation.
     * </p>
     * <p>
     * Unlike {@link ICompositeOperation}, this does not dispose of the removed
     * operation since the composite did not create the operation.
     * </p>
     * 
     * @param operation
     *            the operation to be removed. The operation should be disposed
     *            by the receiver. This method will have no effect if the
     *            operation instance is not already a child.
     */
    public abstract void remove(IUndoableOperation operation);

    /**
     * Answers whether or not this composite operation has children.
     * 
     * @return <code>true</code> if the operation does not have children,
     *         <code>false</code> otherwise.
     */
    public abstract boolean isEmpty();

    /**
     * Queries the number of child operations that I contain.
     * 
     * @return my size
     */
    public abstract int size();

    /**
     * Obtains an iterator to traverse my child operations. Removing children
     * via this iterator correctly maintains my undo contexts.
     * 
     * @return an iterator of my children
     */
    public abstract Iterator iterator();

    /**
     * Obtains an iterator to traverse my child operations in either direction.
     * Adding and removing children via this iterator correctly maintains my
     * undo contexts.
     * <p>
     * <b>Note</b> that, unlike list iterators generally, this one does not
     * permit the addition of an operation that I already contain (the composite
     * does not permit duplicates). Moreover, only {@link IUndoableOperation}s
     * may be added, otherwise <code>ClassCastException</code>s will result.
     * </p>
     * 
     * @return an iterator of my children
     */
    public abstract ListIterator listIterator();

    /**
     * Obtains an iterator to traverse my child operations in either direction,
     * starting from the specified <code>index</code>. Adding and removing
     * children via this iterator correctly maintains my undo contexts.
     * <p>
     * <b>Note</b> that, unlike list iterators generally, this one does not
     * permit the addition of an operation that I already contain (the composite
     * does not permit duplicates). Moreover, only {@link IUndoableOperation}s
     * may be added, otherwise <code>ClassCastException</code>s will result.
     * </p>
     * 
     * @param index
     *            the index in my children at which to start iterating
     * 
     * @return an iterator of my children
     */
    public abstract ListIterator listIterator(int index);
}