/*******************************************************************************
 * Copyright (c) 2007, 2010 Association for Decentralized Information Management
 * in Industry THTH ry.
 * 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:
 *     VTT Technical Research Centre of Finland - initial API and implementation
 *******************************************************************************/
/*
 *
 * @author Toni Kalajainen
 */
package org.simantics.utils.datastructures.hints;

import org.simantics.utils.datastructures.hints.IHintContext.Key;

public interface IHintListener {

	/**
	 * Value has changed or new value has spawned
	 * 
	 * @param sender the stack 
	 * @param key the key 
	 * @param oldValue the old value. If this value is null, a new hint has been added
	 * @param newValue the new value. This value is never null
	 */
	void hintChanged(IHintObservable sender, Key key, Object oldValue, Object newValue);
	
	/**
	 * 
	 * @param sender the stack 
	 * @param key the key 
	 * @param oldValue the old value
	 */
	void hintRemoved(IHintObservable sender, Key key, Object oldValue);
	
}