01: package org.mandarax.util.comparators;
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.Rule;
22:
23: /**
24: * Abstract class for clause set comparators.
25: * Implements a couple of useful count methods that can be used
26: * in subclasses.
27: * @author <A href="http://www-ist.massey.ac.nz/JBDietrich" target="_top">Jens Dietrich</A>
28: * @version 3.4 <7 March 05>
29: * @since 2.2
30: */
31: public abstract class AbstractRuleComparator extends
32: AbstractClauseSetComparator {
33:
34: /**
35: * Constructor.
36: */
37: public AbstractRuleComparator() {
38: super ();
39: }
40:
41: /**
42: * Compare two objects.
43: * @return an integer
44: * @param obj1 the first object
45: * @param obj2 the second object
46: */
47: public int compare(Object obj1, Object obj2) {
48: if (obj1 instanceof Rule && obj2 instanceof Rule)
49: return compareRules((Rule) obj1, (Rule) obj2);
50: else
51: throw new IllegalArgumentException(
52: "The rule comparator can only compare rules");
53: }
54:
55: /**
56: * Compare two rules.
57: * @return an integer
58: * @param r1 the first rule
59: * @param r2 the second rule
60: */
61: protected abstract int compareRules(Rule r1, Rule r2);
62: }
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