01: package org.mandarax.reference;
02:
03: /*
04: * Copyright (C) 1999-2004 <A href="http://www-ist.massey.ac.nz/JBDietrich" target="_top">Jens Dietrich</a>
05: *
06: * This library is free software; you can redistribute it and/or
07: * modify it under the terms of the GNU Lesser General Public
08: * License as published by the Free Software Foundation; either
09: * version 2 of the License, or (at your option) any later version.
10: *
11: * This library is distributed in the hope that it will be useful,
12: * but WITHOUT ANY WARRANTY; without even the implied warranty of
13: * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
14: * Lesser General Public License for more details.
15: *
16: * You should have received a copy of the GNU Lesser General Public
17: * License along with this library; if not, write to the Free Software
18: * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
19: */
20:
21: import org.mandarax.kernel.*;
22:
23: /**
24: * Semantic evaluation policy that evaluates complex terms only if they are in the context
25: * of a semantic predicate.
26: * @author <A href="http://www-ist.massey.ac.nz/JBDietrich" target="_top">Jens Dietrich</A>
27: * @version 3.4 <7 March 05>
28: * @since 2.0
29: */
30: public class CautiousSemanticEvaluationPolicy extends
31: DefaultSemanticEvaluationPolicy {
32:
33: /**
34: * Try to evaluate (simplify) a complex term.
35: * @param ct a complex term
36: * @param cs the clause set (context object)
37: * @param session a session
38: * @param logOn indicates whether we should log
39: * @return a term
40: */
41: public Term evaluate(ComplexTerm ct, ClauseSet cs, Session session,
42: boolean logOn) {
43:
44: if ((cs.getKey() instanceof Predicate)
45: && ((Predicate) cs.getKey()).isExecutable()) {
46: return super.evaluate(ct, cs, session, logOn);
47: } else
48: return ct;
49: }
50:
51: }
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