content: /*******************************************************************************
   * Copyright (c) 2000, 2007 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.ui.javaeditor.selectionactions;
  
  import org.eclipse.core.runtime.Assert;
  import org.eclipse.jface.action.Action;
  import org.eclipse.ui.PlatformUI;
  import org.eclipse.ui.texteditor.IUpdate;
  import org.eclipse.wst.jsdt.core.ISourceRange;
  import org.eclipse.wst.jsdt.internal.ui.IJavaHelpContextIds;
  import org.eclipse.wst.jsdt.internal.ui.javaeditor.JavaEditor;
  
  public class StructureSelectHistoryAction extends Action implements IUpdate {
  	private JavaEditor fEditor;
  	private SelectionHistory fHistory;
  
  	public StructureSelectHistoryAction(JavaEditor editor, SelectionHistory history) {
  		super(SelectionActionMessages.StructureSelectHistory_label);
  		setToolTipText(SelectionActionMessages.StructureSelectHistory_tooltip);
  		setDescription(SelectionActionMessages.StructureSelectHistory_description);
  		Assert.isNotNull(history);
  		Assert.isNotNull(editor);
  		fHistory= history;
  		fEditor= editor;
  		update();
  		PlatformUI.getWorkbench().getHelpSystem().setHelp(this, IJavaHelpContextIds.STRUCTURED_SELECTION_HISTORY_ACTION);
  	}
  
  	public void update() {
  		setEnabled(!fHistory.isEmpty());
  	}
  
  	public void run() {
  		ISourceRange old= fHistory.getLast();
  		if (old != null) {
  			try {
  				fHistory.ignoreSelectionChanges();
  				fEditor.selectAndReveal(old.getOffset(), old.getLength());
  			} finally {
  				fHistory.listenToSelectionChanges();
  			}
  		}
  	}
  }
  