01: //
02: // Copyright (C) 2005 United States Government as represented by the
03: // Administrator of the National Aeronautics and Space Administration
04: // (NASA). All Rights Reserved.
05: //
06: // This software is distributed under the NASA Open Source Agreement
07: // (NOSA), version 1.3. The NOSA has been approved by the Open Source
08: // Initiative. See the file NOSA-1.3-JPF at the top of the distribution
09: // directory tree for the complete NOSA document.
10: //
11: // THE SUBJECT SOFTWARE IS PROVIDED "AS IS" WITHOUT ANY WARRANTY OF ANY
12: // KIND, EITHER EXPRESSED, IMPLIED, OR STATUTORY, INCLUDING, BUT NOT
13: // LIMITED TO, ANY WARRANTY THAT THE SUBJECT SOFTWARE WILL CONFORM TO
14: // SPECIFICATIONS, ANY IMPLIED WARRANTIES OF MERCHANTABILITY, FITNESS FOR
15: // A PARTICULAR PURPOSE, OR FREEDOM FROM INFRINGEMENT, ANY WARRANTY THAT
16: // THE SUBJECT SOFTWARE WILL BE ERROR FREE, OR ANY WARRANTY THAT
17: // DOCUMENTATION, IF PROVIDED, WILL CONFORM TO THE SUBJECT SOFTWARE.
18: //
19: package gov.nasa.jpf.search.heuristic;
20:
21: import java.util.Comparator;
22:
23: /**
24: * the default comparator for heuristic state ordering
25: *
26: * this class has to determine which state to choose if the
27: * heuristic values are equal
28: */
29: public class DefaultComparator implements Comparator {
30:
31: public int compare(Object o1, Object o2) {
32: // 2do - Hmm, that's really fifo?
33:
34: HeuristicState hs1 = (HeuristicState) o1;
35: HeuristicState hs2 = (HeuristicState) o2;
36:
37: int p1 = hs1.getPriority();
38: int p2 = hs2.getPriority();
39:
40: if (p1 == p2) {
41: int h1 = hs1.hashCode();
42: int h2 = hs2.hashCode();
43:
44: if (h1 == h2) {
45: return 0;
46: } else if (hs1.uniqueID < hs2.uniqueID) {
47: return -1;
48: } else {
49: return 1;
50: }
51: } else if (p1 < p2) {
52: return -1;
53: } else {
54: return 1;
55: }
56: }
57: }
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