org.eclipse.ltk.core.refactoring/src/org/eclipse/ltk/core/refactoring/CompositeChange.java - jdt/eclipse.jdt.ui - Git at Google

 /*******************************************************************************
  * Copyright (c) 2000, 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.ltk.core.refactoring;

 import java.util.ArrayList;
 import java.util.Arrays;
 import java.util.Collections;
 import java.util.Iterator;
 import java.util.List;

 import org.eclipse.core.runtime.Assert;
 import org.eclipse.core.runtime.CoreException;
 import org.eclipse.core.runtime.IProgressMonitor;
 import org.eclipse.core.runtime.ISafeRunnable;
 import org.eclipse.core.runtime.OperationCanceledException;
 import org.eclipse.core.runtime.SafeRunner;
 import org.eclipse.core.runtime.SubProgressMonitor;

 import org.eclipse.ltk.internal.core.refactoring.RefactoringCoreMessages;
 import org.eclipse.ltk.internal.core.refactoring.RefactoringCorePlugin;

 /**
  * Represents a composite change. Composite changes can be marked
  * as synthetic. A synthetic composite changes might not be rendered
  * in the refactoring preview tree to save display real-estate.
  * <p>
  * Clients may subclass this class.
  * </p>
  *
  * @see Change
  *
  * @since 3.0
  */
 public class CompositeChange extends Change {

 	private String fName;
 	private List fChanges;
 	private boolean fIsSynthetic;
 	private Change fUndoUntilException;

 	/**
 	 * Creates a new composite change with the given name.
 	 *
 	 * @param name the human readable name of the change. Will
 	 *  be used to display the change in the user interface
 	 */
 	public CompositeChange(String name) {
 		this(name, new ArrayList(2));
 	}

 	/**
 	 * Creates a new composite change with the given name and array
 	 * of children.
 	 *
 	 * @param name the human readable name of the change. Will
 	 *  be used to display the change in the user interface
 	 * @param children the initial array of children
 	 */
 	public CompositeChange(String name, Change[] children) {
 		this(name, new ArrayList(children.length));
 		addAll(children);
 	}

 	private CompositeChange(String name, List changes) {
 		Assert.isNotNull(name);
 		Assert.isNotNull(changes);
 		fName= name;
 		fChanges= changes;
 	}

 	/**
 	 * Returns whether this change is synthetic or not.
 	 *
 	 * @return <code>true</code>if this change is synthetic; otherwise
 	 *  <code>false</code>
 	 */
 	public boolean isSynthetic() {
 		return fIsSynthetic;
 	}

 	/**
 	 * Marks this change as synthetic.
 	 */
 	public void markAsSynthetic() {
 		fIsSynthetic= true;
 	}

 	/**
 	 * {@inheritDoc}
 	 */
 	public String getName() {
 		return fName;
 	}

 	/**
 	 * Adds the given change to the list of children. The change to be added
 	 * can be <code>null</code>. Adding a "null" change does nothing.
 	 *
 	 * @param change the change to add
 	 */
 	public void add(Change change) {
 		if (change != null) {
 			Assert.isTrue(change.getParent() == null);
 			fChanges.add(change);
 			change.setParent(this);
 		}
 	}

 	/**
 	 * Adds all changes in the given array to the list of children.
 	 *
 	 * @param changes the changes to add
 	 */
 	public void addAll(Change[] changes) {
 		for (int i= 0; i < changes.length; i++) {
 			add(changes[i]);
 		}
 	}

 	/**
 	 * Merges the children of the given composite change into this
 	 * change. This means the changes are removed from the given
 	 * composite change and added to this change.
 	 *
 	 * @param change the change to merge
 	 */
 	public void merge(CompositeChange change) {
 		Change[] others= change.getChildren();
 		for (int i= 0; i < others.length; i++) {
 			Change other= others[i];
 			change.remove(other);
 			add(other);
 		}
 	}

 	/**
 	 * Removes the given change from the list of children.
 	 *
 	 * @param change the change to remove
 	 *
 	 * @return <code>true</code> if the change contained the given
 	 *  child; otherwise <code>false</code> is returned
 	 */
 	public boolean remove(Change change) {
 		Assert.isNotNull(change);
 		boolean result= fChanges.remove(change);
 		if (result) {
 			change.setParent(null);
 		}
 		return result;

 	}

 	/**
 	 * Removes all changes from this composite change.
 	 *
 	 * @return the list of changes removed from this composite
 	 * change
 	 *
 	 * @since 3.1
 	 */
 	public Change[] clear() {
 		Change[] result= (Change[])fChanges.toArray(new Change[fChanges.size()]);
 		fChanges.clear();
 		return result;
 	}

 	/**
 	 * Returns the children managed by this composite change.
 	 *
 	 * @return the children of this change or an empty array if no
 	 *  children exist
 	 */
 	public Change[] getChildren() {
 		return (Change[])fChanges.toArray(new Change[fChanges.size()]);
 	}

 	/**
 	 * {@inheritDoc}
 	 * <p>
 	 * The composite change sends <code>setEnabled</code> to all its children.
 	 * </p>
 	 * <p>
 	 * Client are allowed to extend this method.
 	 * </p>
 	 */
 	public void setEnabled(boolean enabled) {
 		super.setEnabled(enabled);
 		for (Iterator iter= fChanges.iterator(); iter.hasNext(); ) {
 			((Change)iter.next()).setEnabled(enabled);
 		}
 	}

 	/**
 	 * {@inheritDoc}
 	 * <p>
 	 * The composite change sends <code>initializeValidationData</code> to all its
 	 * children.
 	 * </p>
 	 * <p>
 	 * Client are allowed to extend this method.
 	 * </p>
 	 */
 	public void initializeValidationData(IProgressMonitor pm) {
 		pm.beginTask("", fChanges.size()); //$NON-NLS-1$
 		for (Iterator iter= fChanges.iterator(); iter.hasNext();) {
 			Change change= (Change)iter.next();
 			change.initializeValidationData(new SubProgressMonitor(pm, 1));
 			pm.worked(1);
 		}
 	}

 	/**
 	 * {@inheritDoc}
 	 * <p>
 	 * The composite change sends <code>isValid</code> to all its children
 	 * until the first one returns a status with a severity of <code>FATAL
 	 * </code>. If one of the children throws an exception the remaining children
 	 * will not receive the <code>isValid</code> call.
 	 * </p>
 	 * <p>
 	 * Client are allowed to extend this method.
 	 * </p>
 	 */
 	public RefactoringStatus isValid(IProgressMonitor pm) throws CoreException {
 		RefactoringStatus result= new RefactoringStatus();
 		pm.beginTask("", fChanges.size()); //$NON-NLS-1$
 		for (Iterator iter= fChanges.iterator(); iter.hasNext() && !result.hasFatalError();) {
 			Change change= (Change)iter.next();
 			if (change.isEnabled())
 				result.merge(change.isValid(new SubProgressMonitor(pm, 1)));
 			else
 				pm.worked(1);
 			if (pm.isCanceled())
 				throw new OperationCanceledException();
 		}
 		pm.done();
 		return result;
 	}

 	/**
 	 * {@inheritDoc}
 	 * <p>
 	 * The composite change sends <code>perform</code> to all its <em>enabled</em>
 	 * children. If one of the children throws an exception the remaining children
 	 * will not receive the <code>perform</code> call. In this case the method <code>
 	 * getUndoUntilException</code> can be used to get an undo object containing the
 	 * undo objects of all executed children.
 	 * </p>
 	 * <p>
 	 * Client are allowed to extend this method.
 	 * </p>
 	 */
 	public Change perform(IProgressMonitor pm) throws CoreException {
 		fUndoUntilException= null;
 		List undos= new ArrayList(fChanges.size());
 		pm.beginTask("", fChanges.size()); //$NON-NLS-1$
 		pm.setTaskName(RefactoringCoreMessages.CompositeChange_performingChangesTask_name);
 		Change change= null;
 		boolean canceled= false;
 		try {
 			for (Iterator iter= fChanges.iterator(); iter.hasNext();) {
 				change= (Change)iter.next();
 				if (canceled && !internalProcessOnCancel(change))
 					continue;

 				if (change.isEnabled()) {
 					Change undoChange= null;
 					try {
 						undoChange= change.perform(new SubProgressMonitor(pm, 1));
 					} catch(OperationCanceledException e) {
 						canceled= true;
 						if (!internalContinueOnCancel())
 							throw e;
 						undos= null;
 					}
 					if (undos != null) {
 						if (undoChange == null) {
 							undos= null;
 						} else {
 							undos.add(undoChange);
 						}
 					}
 				}
 				// remove the change from the list of children to give
 				// the garbage collector the change to collect the change. This
 				// ensures that the memory consumption doesn't go up when
 				// producing the undo change tree.
 				iter.remove();
 				// Make sure we dispose the change since it will now longer be
 				// in the list of children when call CompositeChange#dispose()
 				final Change changeToDispose= change;
 				SafeRunner.run(new ISafeRunnable() {
 					public void run() throws Exception {
 						changeToDispose.dispose();
 					}
 					public void handleException(Throwable exception) {
 						RefactoringCorePlugin.log(exception);
 					}
 				});
 			}
 			if (canceled)
 				throw new OperationCanceledException();
 			if (undos != null) {
 				Collections.reverse(undos);
 				return createUndoChange((Change[]) undos.toArray(new Change[undos.size()]));
 			} else {
 				return null;
 			}
 		} catch (CoreException e) {
 			handleUndos(change, undos);
 			internalHandleException(change, e);
 			throw e;
 		} catch (RuntimeException e) {
 			handleUndos(change, undos);
 			internalHandleException(change, e);
 			throw e;
 		}
 	}

 	private void handleUndos(Change failedChange, List undos) {
 		if (undos == null) {
 			fUndoUntilException= null;
 			return;
 		}
 		if (failedChange instanceof CompositeChange) {
 			Change partUndoChange= ((CompositeChange)failedChange).getUndoUntilException();
 			if (partUndoChange != null) {
 				undos.add(partUndoChange);
 			}
 		}
 		if (undos.size() == 0) {
 			fUndoUntilException= new NullChange(getName());
 			return;
 		}
 		Collections.reverse(undos);
 		fUndoUntilException= createUndoChange((Change[]) undos.toArray(new Change[undos.size()]));
 	}

 	/**
 	 * Note: this is an internal method and should not be overridden outside of
 	 * the refactoring framework.
 	 * <p>
 	 * The method gets called if one of the changes managed by this
 	 * composite change generates an exception when performed.
 	 * </p>
 	 *
 	 * @param change the change that caused the exception
 	 * @param t the exception itself
 	 */
 	protected void internalHandleException(Change change, Throwable t) {
 		// do nothing
 	}

 	/**
 	 * Note: this is an internal method and should not be overridden outside of
 	 * the refactoring framework.
 	 * <p>
 	 * The method gets called if one of the changes managed by this
 	 * composite change generates an operation canceled exception when
 	 * performed.
 	 * </p>
 	 *
 	 * @return <code>true</code> if performing the change should
 	 *  continue on cancel; otherwise <code>false</code>
      *
      * @since 3.1
 	 */
 	protected boolean internalContinueOnCancel() {
 		return false;
 	}

 	/**
 	 * Note: this is an internal method and should not be overridden outside of
 	 * the refactoring framework.
 	 * <p>
 	 * The method gets called if the execution of this change got canceled,
 	 * but <code>internalContinueOnCancel</code> returned true.
 	 * </p>
 	 *
 	 * @param change the change to perform
 	 *
 	 * @return <code>true</code> if the given change should be performed although
 	 *  the execution got canceled; otherwise <code>false</code>
 	 *
 	 * @since 3.1
 	 */
 	protected boolean internalProcessOnCancel(Change change) {
 		return false;
 	}

 	/**
 	 * {@inheritDoc}
 	 * <p>
 	 * The composite change sends <code>dispose</code> to all its children. It is guaranteed
 	 * that all children receive the <code>dispose</code> call.
 	 * </p>
 	 */
 	public void dispose() {
 		for (Iterator iter= fChanges.iterator(); iter.hasNext(); ) {
 			final Change change= (Change)iter.next();
 			SafeRunner.run(new ISafeRunnable() {
 				public void run() throws Exception {
 					change.dispose();
 				}
 				public void handleException(Throwable exception) {
 					RefactoringCorePlugin.log(exception);
 				}
 			});
 		}
 	}

 	/**
 	 * Returns the undo object containing all undo changes of those children
 	 * that got successfully executed while performing this change. Returns
 	 * <code>null</code> if all changes were executed successfully.
 	 * <p>
 	 * This method is not intended to be overridden or extended.
 	 * </p>
 	 * @return the undo object containing all undo changes of those children
 	 *  that got successfully executed while performing this change
 	 */
 	public Change getUndoUntilException() {
 		return fUndoUntilException;
 	}

 	/**
 	 * Hook to create an undo change. The method should be overridden
 	 * by clients which provide their own composite change to create
 	 * a corresponding undo change.
 	 *
 	 * @param childUndos the child undo. The undo edits appear in the
 	 *  list in the reverse order of their execution. So the first
 	 *  change in the array is the undo change of the last change
 	 *  that got executed.
 	 *
 	 * @return the undo change
 	 */
 	protected Change createUndoChange(Change[] childUndos) {
 		return new CompositeChange(getName(), childUndos);
 	}

 	/**
 	 * {@inheritDoc}
 	 */
 	public Object[] getAffectedObjects() {
 		if (fChanges.size() == 0)
 			return new Object[0];
 		List result= new ArrayList();
 		for (Iterator iter= fChanges.iterator(); iter.hasNext();) {
 			Change change= (Change)iter.next();
 			Object[] affectedObjects= change.getAffectedObjects();
 			if (affectedObjects == null)
 				return null;
 			result.addAll(Arrays.asList(affectedObjects));
 		}
 		return result.toArray();
 	}

 	/**
 	 * {@inheritDoc}
 	 */
 	public Object getModifiedElement() {
 		return null;
 	}

 	/**
 	 * {@inheritDoc}
 	 *
 	 * @since 3.2
 	 */
 	public ChangeDescriptor getDescriptor() {
 		for (final Iterator iterator= fChanges.iterator(); iterator.hasNext();) {
 			final Change change= (Change) iterator.next();
 			final ChangeDescriptor descriptor= change.getDescriptor();
 			if (descriptor != null)
 				return descriptor;
 		}
 		return null;
 	}

 	public String toString() {
 		StringBuffer buff= new StringBuffer();
 		buff.append(getName());
 		buff.append("\n"); //$NON-NLS-1$
 		for (Iterator iter= fChanges.iterator(); iter.hasNext();) {
 			buff.append("<").append(iter.next().toString()).append("/>\n"); //$NON-NLS-2$ //$NON-NLS-1$
 		}
 		return buff.toString();
 	}
 }
	/*******************************************************************************
	* Copyright (c) 2000, 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.ltk.core.refactoring;

	import java.util.ArrayList;
	import java.util.Arrays;
	import java.util.Collections;
	import java.util.Iterator;
	import java.util.List;

	import org.eclipse.core.runtime.Assert;
	import org.eclipse.core.runtime.CoreException;
	import org.eclipse.core.runtime.IProgressMonitor;
	import org.eclipse.core.runtime.ISafeRunnable;
	import org.eclipse.core.runtime.OperationCanceledException;
	import org.eclipse.core.runtime.SafeRunner;
	import org.eclipse.core.runtime.SubProgressMonitor;

	import org.eclipse.ltk.internal.core.refactoring.RefactoringCoreMessages;
	import org.eclipse.ltk.internal.core.refactoring.RefactoringCorePlugin;

	/**
	* Represents a composite change. Composite changes can be marked
	* as synthetic. A synthetic composite changes might not be rendered
	* in the refactoring preview tree to save display real-estate.
	* <p>
	* Clients may subclass this class.
	* </p>
	*
	* @see Change
	*
	* @since 3.0
	*/
	public class CompositeChange extends Change {

	private String fName;
	private List fChanges;
	private boolean fIsSynthetic;
	private Change fUndoUntilException;

	/**
	* Creates a new composite change with the given name.
	*
	* @param name the human readable name of the change. Will
	* be used to display the change in the user interface
	*/
	public CompositeChange(String name) {
	this(name, new ArrayList(2));
	}

	/**
	* Creates a new composite change with the given name and array
	* of children.
	*
	* @param name the human readable name of the change. Will
	* be used to display the change in the user interface
	* @param children the initial array of children
	*/
	public CompositeChange(String name, Change[] children) {
	this(name, new ArrayList(children.length));
	addAll(children);
	}

	private CompositeChange(String name, List changes) {
	Assert.isNotNull(name);
	Assert.isNotNull(changes);
	fName= name;
	fChanges= changes;
	}

	/**
	* Returns whether this change is synthetic or not.
	*
	* @return <code>true</code>if this change is synthetic; otherwise
	* <code>false</code>
	*/
	public boolean isSynthetic() {
	return fIsSynthetic;
	}

	/**
	* Marks this change as synthetic.
	*/
	public void markAsSynthetic() {
	fIsSynthetic= true;
	}

	/**
	* {@inheritDoc}
	*/
	public String getName() {
	return fName;
	}

	/**
	* Adds the given change to the list of children. The change to be added
	* can be <code>null</code>. Adding a "null" change does nothing.
	*
	* @param change the change to add
	*/
	public void add(Change change) {
	if (change != null) {
	Assert.isTrue(change.getParent() == null);
	fChanges.add(change);
	change.setParent(this);
	}
	}

	/**
	* Adds all changes in the given array to the list of children.
	*
	* @param changes the changes to add
	*/
	public void addAll(Change[] changes) {
	for (int i= 0; i < changes.length; i++) {
	add(changes[i]);
	}
	}

	/**
	* Merges the children of the given composite change into this
	* change. This means the changes are removed from the given
	* composite change and added to this change.
	*
	* @param change the change to merge
	*/
	public void merge(CompositeChange change) {
	Change[] others= change.getChildren();
	for (int i= 0; i < others.length; i++) {
	Change other= others[i];
	change.remove(other);
	add(other);
	}
	}

	/**
	* Removes the given change from the list of children.
	*
	* @param change the change to remove
	*
	* @return <code>true</code> if the change contained the given
	* child; otherwise <code>false</code> is returned
	*/
	public boolean remove(Change change) {
	Assert.isNotNull(change);
	boolean result= fChanges.remove(change);
	if (result) {
	change.setParent(null);
	}
	return result;

	}

	/**
	* Removes all changes from this composite change.
	*
	* @return the list of changes removed from this composite
	* change
	*
	* @since 3.1
	*/
	public Change[] clear() {
	Change[] result= (Change[])fChanges.toArray(new Change[fChanges.size()]);
	fChanges.clear();
	return result;
	}

	/**
	* Returns the children managed by this composite change.
	*
	* @return the children of this change or an empty array if no
	* children exist
	*/
	public Change[] getChildren() {
	return (Change[])fChanges.toArray(new Change[fChanges.size()]);
	}

	/**
	* {@inheritDoc}
	* <p>
	* The composite change sends <code>setEnabled</code> to all its children.
	* </p>
	* <p>
	* Client are allowed to extend this method.
	* </p>
	*/
	public void setEnabled(boolean enabled) {
	super.setEnabled(enabled);
	for (Iterator iter= fChanges.iterator(); iter.hasNext(); ) {
	((Change)iter.next()).setEnabled(enabled);
	}
	}

	/**
	* {@inheritDoc}
	* <p>
	* The composite change sends <code>initializeValidationData</code> to all its
	* children.
	* </p>
	* <p>
	* Client are allowed to extend this method.
	* </p>
	*/
	public void initializeValidationData(IProgressMonitor pm) {
	pm.beginTask("", fChanges.size()); //$NON-NLS-1$
	for (Iterator iter= fChanges.iterator(); iter.hasNext();) {
	Change change= (Change)iter.next();
	change.initializeValidationData(new SubProgressMonitor(pm, 1));
	pm.worked(1);
	}
	}

	/**
	* {@inheritDoc}
	* <p>
	* The composite change sends <code>isValid</code> to all its children
	* until the first one returns a status with a severity of <code>FATAL
	* </code>. If one of the children throws an exception the remaining children
	* will not receive the <code>isValid</code> call.
	* </p>
	* <p>
	* Client are allowed to extend this method.
	* </p>
	*/
	public RefactoringStatus isValid(IProgressMonitor pm) throws CoreException {
	RefactoringStatus result= new RefactoringStatus();
	pm.beginTask("", fChanges.size()); //$NON-NLS-1$
	for (Iterator iter= fChanges.iterator(); iter.hasNext() && !result.hasFatalError();) {
	Change change= (Change)iter.next();
	if (change.isEnabled())
	result.merge(change.isValid(new SubProgressMonitor(pm, 1)));
	else
	pm.worked(1);
	if (pm.isCanceled())
	throw new OperationCanceledException();
	}
	pm.done();
	return result;
	}

	/**
	* {@inheritDoc}
	* <p>
	* The composite change sends <code>perform</code> to all its <em>enabled</em>
	* children. If one of the children throws an exception the remaining children
	* will not receive the <code>perform</code> call. In this case the method <code>
	* getUndoUntilException</code> can be used to get an undo object containing the
	* undo objects of all executed children.
	* </p>
	* <p>
	* Client are allowed to extend this method.
	* </p>
	*/
	public Change perform(IProgressMonitor pm) throws CoreException {
	fUndoUntilException= null;
	List undos= new ArrayList(fChanges.size());
	pm.beginTask("", fChanges.size()); //$NON-NLS-1$
	pm.setTaskName(RefactoringCoreMessages.CompositeChange_performingChangesTask_name);
	Change change= null;
	boolean canceled= false;
	try {
	for (Iterator iter= fChanges.iterator(); iter.hasNext();) {
	change= (Change)iter.next();
	if (canceled && !internalProcessOnCancel(change))
	continue;

	if (change.isEnabled()) {
	Change undoChange= null;
	try {
	undoChange= change.perform(new SubProgressMonitor(pm, 1));
	} catch(OperationCanceledException e) {
	canceled= true;
	if (!internalContinueOnCancel())
	throw e;
	undos= null;
	}
	if (undos != null) {
	if (undoChange == null) {
	undos= null;
	} else {
	undos.add(undoChange);
	}
	}
	}
	// remove the change from the list of children to give
	// the garbage collector the change to collect the change. This
	// ensures that the memory consumption doesn't go up when
	// producing the undo change tree.
	iter.remove();
	// Make sure we dispose the change since it will now longer be
	// in the list of children when call CompositeChange#dispose()
	final Change changeToDispose= change;
	SafeRunner.run(new ISafeRunnable() {
	public void run() throws Exception {
	changeToDispose.dispose();
	}
	public void handleException(Throwable exception) {
	RefactoringCorePlugin.log(exception);
	}
	});
	}
	if (canceled)
	throw new OperationCanceledException();
	if (undos != null) {
	Collections.reverse(undos);
	return createUndoChange((Change[]) undos.toArray(new Change[undos.size()]));
	} else {
	return null;
	}
	} catch (CoreException e) {
	handleUndos(change, undos);
	internalHandleException(change, e);
	throw e;
	} catch (RuntimeException e) {
	handleUndos(change, undos);
	internalHandleException(change, e);
	throw e;
	}
	}

	private void handleUndos(Change failedChange, List undos) {
	if (undos == null) {
	fUndoUntilException= null;
	return;
	}
	if (failedChange instanceof CompositeChange) {
	Change partUndoChange= ((CompositeChange)failedChange).getUndoUntilException();
	if (partUndoChange != null) {
	undos.add(partUndoChange);
	}
	}
	if (undos.size() == 0) {
	fUndoUntilException= new NullChange(getName());
	return;
	}
	Collections.reverse(undos);
	fUndoUntilException= createUndoChange((Change[]) undos.toArray(new Change[undos.size()]));
	}

	/**
	* Note: this is an internal method and should not be overridden outside of
	* the refactoring framework.
	* <p>
	* The method gets called if one of the changes managed by this
	* composite change generates an exception when performed.
	* </p>
	*
	* @param change the change that caused the exception
	* @param t the exception itself
	*/
	protected void internalHandleException(Change change, Throwable t) {
	// do nothing
	}

	/**
	* Note: this is an internal method and should not be overridden outside of
	* the refactoring framework.
	* <p>
	* The method gets called if one of the changes managed by this
	* composite change generates an operation canceled exception when
	* performed.
	* </p>
	*
	* @return <code>true</code> if performing the change should
	* continue on cancel; otherwise <code>false</code>
	*
	* @since 3.1
	*/
	protected boolean internalContinueOnCancel() {
	return false;
	}

	/**
	* Note: this is an internal method and should not be overridden outside of
	* the refactoring framework.
	* <p>
	* The method gets called if the execution of this change got canceled,
	* but <code>internalContinueOnCancel</code> returned true.
	* </p>
	*
	* @param change the change to perform
	*
	* @return <code>true</code> if the given change should be performed although
	* the execution got canceled; otherwise <code>false</code>
	*
	* @since 3.1
	*/
	protected boolean internalProcessOnCancel(Change change) {
	return false;
	}

	/**
	* {@inheritDoc}
	* <p>
	* The composite change sends <code>dispose</code> to all its children. It is guaranteed
	* that all children receive the <code>dispose</code> call.
	* </p>
	*/
	public void dispose() {
	for (Iterator iter= fChanges.iterator(); iter.hasNext(); ) {
	final Change change= (Change)iter.next();
	SafeRunner.run(new ISafeRunnable() {
	public void run() throws Exception {
	change.dispose();
	}
	public void handleException(Throwable exception) {
	RefactoringCorePlugin.log(exception);
	}
	});
	}
	}

	/**
	* Returns the undo object containing all undo changes of those children
	* that got successfully executed while performing this change. Returns
	* <code>null</code> if all changes were executed successfully.
	* <p>
	* This method is not intended to be overridden or extended.
	* </p>
	* @return the undo object containing all undo changes of those children
	* that got successfully executed while performing this change
	*/
	public Change getUndoUntilException() {
	return fUndoUntilException;
	}

	/**
	* Hook to create an undo change. The method should be overridden
	* by clients which provide their own composite change to create
	* a corresponding undo change.
	*
	* @param childUndos the child undo. The undo edits appear in the
	* list in the reverse order of their execution. So the first
	* change in the array is the undo change of the last change
	* that got executed.
	*
	* @return the undo change
	*/
	protected Change createUndoChange(Change[] childUndos) {
	return new CompositeChange(getName(), childUndos);
	}

	/**
	* {@inheritDoc}
	*/
	public Object[] getAffectedObjects() {
	if (fChanges.size() == 0)
	return new Object[0];
	List result= new ArrayList();
	for (Iterator iter= fChanges.iterator(); iter.hasNext();) {
	Change change= (Change)iter.next();
	Object[] affectedObjects= change.getAffectedObjects();
	if (affectedObjects == null)
	return null;
	result.addAll(Arrays.asList(affectedObjects));
	}
	return result.toArray();
	}

	/**
	* {@inheritDoc}
	*/
	public Object getModifiedElement() {
	return null;
	}

	/**
	* {@inheritDoc}
	*
	* @since 3.2
	*/
	public ChangeDescriptor getDescriptor() {
	for (final Iterator iterator= fChanges.iterator(); iterator.hasNext();) {
	final Change change= (Change) iterator.next();
	final ChangeDescriptor descriptor= change.getDescriptor();
	if (descriptor != null)
	return descriptor;
	}
	return null;
	}

	public String toString() {
	StringBuffer buff= new StringBuffer();
	buff.append(getName());
	buff.append("\n"); //$NON-NLS-1$
	for (Iterator iter= fChanges.iterator(); iter.hasNext();) {
	buff.append("<").append(iter.next().toString()).append("/>\n"); //$NON-NLS-2$ //$NON-NLS-1$
	}
	return buff.toString();
	}
	}