/*******************************************************************************
 * Copyright (c) 2000, 2005 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.core.internal.dtree;

/**
 * An interface for comparing two data tree objects.  Provides information
 * on how an object has changed from one tree to another.
 */
public interface IComparator {
	/**
	 * Returns an integer describing the changes between two data objects
	 * in a data tree.  The first three bits of the returned integer are
	 * used during calculation of delta trees.  The remaining bits can be
	 * assigned any meaning that is useful to the client.  If there is no
	 * change in the two data objects, this method must return 0.
	 *
	 * @see NodeComparison
	 */
	int compare(Object o1, Object o2);
}
