/*******************************************************************************
 * Copyright (c) 2007 Matthew Hall 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:
 *     Matthew Hall - initial API and implementation (bug 208332)
 *     IBM Corporation - initial API and implementation
 *         (through ProxyObservableSet.java)
 ******************************************************************************/

package org.eclipse.core.internal.databinding.observable;

import org.eclipse.core.databinding.observable.IStaleListener;
import org.eclipse.core.databinding.observable.StaleEvent;
import org.eclipse.core.databinding.observable.list.*;

/**
 * Wraps an observable list. This object acts like an exact copy of the original
 * list, and tracks all the changes in the original. The only difference is that
 * disposing the wrapper will not dispose the original. You can use this
 * whenever you need to return an IObservableList from a method that expects the
 * caller to dispose the list, but you have an IObservableList that you don't
 * want disposed.
 * 
 * @since 1.1
 */
public class ProxyObservableList extends ObservableList {
	private IListChangeListener listChangelistener = new IListChangeListener() {
		public void handleListChange(ListChangeEvent event) {
			fireListChange(event.diff);
		}
	};

	private IStaleListener staleListener = new IStaleListener() {
		public void handleStale(StaleEvent event) {
			fireStale();
		}
	};

	private IObservableList wrappedList;

	/**
	 * Constructs a ProxyObservableList that tracks the state of the given list.
	 * 
	 * @param wrappedList
	 *            the list being wrapped
	 */
	public ProxyObservableList(IObservableList wrappedList) {
		super(wrappedList.getRealm(), wrappedList, wrappedList.getElementType());
		this.wrappedList = wrappedList;
		wrappedList.addListChangeListener(listChangelistener);
		wrappedList.addStaleListener(staleListener);
	}

	public boolean isStale() {
		getterCalled();
		return wrappedList == null ? false : wrappedList.isStale();
	}

	public void dispose() {
		if (wrappedList != null) {
			wrappedList.removeListChangeListener(listChangelistener);
			listChangelistener = null;
			wrappedList.removeStaleListener(staleListener);
			staleListener = null;
			wrappedList = null;
		}
		super.dispose();
	}
}