preferruleswithlessvariablesinprerequisites.java

Mandarax是一个规则引擎的纯Java实现。它支持多类型的事实和基于反映的规则

package org.mandarax.util.comparators;

/*
 * Copyright (C) 1999-2004 <A href="http://www-ist.massey.ac.nz/JBDietrich" target="_top">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.Rule;

/**
 * Comparator that prefers rules with a lesser number of variables in the list of prerequisites.
 * @author <A href="http://www-ist.massey.ac.nz/JBDietrich" target="_top">Jens Dietrich</A>
 * @version 3.4 <7 March 05>
 * @since 2.2
 */
public class PreferRulesWithLessVariablesInPrerequisites extends AbstractRuleComparator {
/**
 * Constructor.
 */
public PreferRulesWithLessVariablesInPrerequisites() {
	super();
}
/**
 * Compare two rules. 
 * @return an integer
 * @param r1 the first rule
 * @param r2 the second rule
 */
protected int compareRules(Rule r1, Rule r2) {
	return countVariablesInPrerequisites(r1)-countVariablesInPrerequisites(r2);
}
/**
 * Get a descriptive name.
 * @return a string
 */
public String getName() {
	return "prefer rules with less variables in the prerequisites";	
}
}