package org.mandarax.util.comparators;

/*
 * Copyright (C) 1999-2004 <a href="mailto:mandarax@jbdietrich.com">Jens Dietrich</a>
 *
 * This library is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Lesser General Public
 * License as published by the Free Software Foundation; either
 * version 2 of the License, or (at your option) any later version.
 *
 * This library is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 * Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public
 * License along with this library; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
 */ 

import org.mandarax.kernel.Fact;

/**
 * Abstract class for clause set comparators.
 * Implements a couple of useful count methods that can be used
 * in subclasses.
 * @author <A HREF="mailto:mandarax@jbdietrich.com">Jens Dietrich</A>
 * @version 3.3.1 <9 August 2004>
 * @since 2.2
 */
public abstract class AbstractFactComparator extends AbstractClauseSetComparator {
 
/**
 * Constructor.
 */
public AbstractFactComparator() {
	super();
}
/**
 * Compare two objects.
 * @return an integer
 * @param obj1 the first object
 * @param obj2 the second object
 */
public int compare(Object obj1, Object obj2) {
	if (obj1 instanceof Fact && obj2 instanceof Fact) return compareFacts((Fact)obj1,(Fact)obj2);
	else throw new IllegalArgumentException("The fact comparator can only compare facts");
}
/**
 * Compare two facts.
 * @return an integer
 * @param f1 the first fact
 * @param f2 the second fact
 */
protected abstract int compareFacts(Fact f1, Fact f2);
}
