content: /*******************************************************************************
   * Copyright (c) 2000, 2009 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.wst.jsdt.internal.corext.refactoring.changes;
  
  import org.eclipse.core.resources.IFile;
  import org.eclipse.core.runtime.CoreException;
  import org.eclipse.core.runtime.IProgressMonitor;
  import org.eclipse.core.runtime.IStatus;
  import org.eclipse.core.runtime.Status;
  import org.eclipse.core.runtime.SubProgressMonitor;
  import org.eclipse.ltk.core.refactoring.Change;
  import org.eclipse.ltk.core.refactoring.ContentStamp;
  import org.eclipse.ltk.core.refactoring.UndoTextFileChange;
  import org.eclipse.text.edits.UndoEdit;
  import org.eclipse.wst.jsdt.core.IJavaScriptUnit;
  import org.eclipse.wst.jsdt.internal.corext.refactoring.RefactoringCoreMessages;
  import org.eclipse.wst.jsdt.internal.corext.util.Messages;
  import org.eclipse.wst.jsdt.internal.ui.JavaScriptPlugin;
  
  /* package */ class UndoCompilationUnitChange extends UndoTextFileChange {
  	
  	private IJavaScriptUnit fCUnit;
  
  	public UndoCompilationUnitChange(String name, IJavaScriptUnit unit, UndoEdit undo, ContentStamp stampToRestore, int saveMode) throws CoreException {
  		super(name, getFile(unit), undo, stampToRestore, saveMode);
  		fCUnit= unit;
  	}
  
  	private static IFile getFile(IJavaScriptUnit cunit) throws CoreException {
  		IFile file= (IFile)cunit.getResource();
  		if (file == null)
  			throw new CoreException(new Status(
  				IStatus.ERROR, 
  				JavaScriptPlugin.getPluginId(), 
  				IStatus.ERROR, 
  				Messages.format(
  					RefactoringCoreMessages.UndoCompilationUnitChange_no_resource, 
  					cunit.getElementName()), 
  				null)
  			);
  		return file;
  	}
  	
  	/**
  	 * {@inheritDoc}
  	 */
  	public Object getModifiedElement() {
  		return fCUnit;
  	}
  	
  	/**
  	 * {@inheritDoc}
  	 */
  	protected Change createUndoChange(UndoEdit edit, ContentStamp stampToRestore) throws CoreException {
  		return new UndoCompilationUnitChange(getName(), fCUnit, edit, stampToRestore, getSaveMode());
  	}
  	
  	/**
  	 * {@inheritDoc}
  	 */
  	public Change perform(IProgressMonitor pm) throws CoreException {
  		pm.beginTask("", 2); //$NON-NLS-1$
  		fCUnit.becomeWorkingCopy(new SubProgressMonitor(pm,1));
  		try {
  			return super.perform(new SubProgressMonitor(pm,1));
  		} finally {
  			fCUnit.discardWorkingCopy();
  		}
  	}
  }
  