debug/org.eclipse.cdt.debug.ui/src/org/eclipse/cdt/debug/internal/ui/views/ViewerState.java

/*******************************************************************************
 * Copyright (c) 2000, 2003 IBM Corporation and others.
 * All rights reserved. This program and the accompanying materials 
 * are made available under the terms of the Common Public License v1.0
 * which accompanies this distribution, and is available at
 * http://www.eclipse.org/legal/cpl-v10.html
 * 
 * Contributors:
 *     IBM Corporation - initial API and implementation
 *******************************************************************************/

package org.eclipse.cdt.debug.internal.ui.views;

import org.eclipse.jface.viewers.ISelection;
import org.eclipse.jface.viewers.TreeViewer;

/**
 * Memento of the expanded and selected items in a tree
 * viewer for.
 * 
 * @since 2.1
 */
public class ViewerState {

	private Object[] fExpandedElements = null;	
	private ISelection fSelection = null;
	
	/**
	 * Constructs a memento for the given viewer.
	 */
	public ViewerState(TreeViewer viewer) {
		saveState(viewer);
	}

	/**
	 * Saves the current state of the given viewer into
	 * this memento.
	 * 
	 * @param viewer viewer of which to save the state
	 */
	public void saveState(TreeViewer viewer) {
		fExpandedElements = viewer.getExpandedElements();
		fSelection = viewer.getSelection();
	}
	
	/**
	 * Restores the state of the given viewer to this mementos
	 * saved state.
	 * 
	 * @param viewer viewer to which state is restored
	 */
	public void restoreState(TreeViewer viewer) {
		if (fExpandedElements != null) {
			viewer.setExpandedElements(fExpandedElements);
		}
		if (fSelection != null) {
			viewer.setSelection(fSelection);
		}
	}
}