cautioussemanticevaluationpolicy.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.reference;

/*
 * 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.*;

/**
 * Semantic evaluation policy that evaluates complex terms only if they are in the context 
 * of a semantic predicate.
 * @author <A href="http://www-ist.massey.ac.nz/JBDietrich" target="_top">Jens Dietrich</A>
 * @version 3.4 <7 March 05>
 * @since 2.0
 */
public class CautiousSemanticEvaluationPolicy extends DefaultSemanticEvaluationPolicy{

	/**
	 * Try to evaluate (simplify) a complex term.
	 * @param ct a complex term
	 * @param cs the clause set (context object)
	 * @param session a session
	 * @param logOn indicates whether we should log
	 * @return a term
	 */
	public Term evaluate(ComplexTerm ct,ClauseSet cs, Session session,boolean logOn){
	
		if ((cs.getKey() instanceof Predicate) && ((Predicate)cs.getKey()).isExecutable()) {
			return super.evaluate(ct,cs,session,logOn);
		}
		else return ct;
	}
	
}