/*******************************************************************************
 * 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.ui.internal.contexts;

import java.util.ArrayList;
import java.util.List;

import org.eclipse.ui.contexts.ContextManagerEvent;
import org.eclipse.ui.contexts.IContextManager;
import org.eclipse.ui.contexts.IContextManagerListener;

public abstract class AbstractContextManager implements IContextManager {
	private List contextManagerListeners;

	protected AbstractContextManager() {
	}

	public void addContextManagerListener(IContextManagerListener contextManagerListener) {
		if (contextManagerListener == null)
			throw new NullPointerException();

		if (contextManagerListeners == null)
			contextManagerListeners = new ArrayList();

		if (!contextManagerListeners.contains(contextManagerListener))
			contextManagerListeners.add(contextManagerListener);
	}

	protected void fireContextManagerChanged(ContextManagerEvent contextManagerEvent) {
		if (contextManagerEvent == null)
			throw new NullPointerException();

		if (contextManagerListeners != null)
			for (int i = 0; i < contextManagerListeners.size(); i++)
				(
					(IContextManagerListener) contextManagerListeners.get(
						i)).contextManagerChanged(
					contextManagerEvent);
	}

	public void removeContextManagerListener(IContextManagerListener contextManagerListener) {
		if (contextManagerListener == null)
			throw new NullPointerException();

		if (contextManagerListeners != null)
			contextManagerListeners.remove(contextManagerListener);
	}
}