01: package org.ofbiz.rules.engine;
02:
03: /**
04: * <p><b>Title:</b> Consulting Not
05: * <p><b>Description:</b> None
06: * <p>Copyright (c) 1999 Steven J. Metsker.
07: * <p>Copyright (c) 2001 The Open For Business Project - www.ofbiz.org
08: *
09: * <p>Permission is hereby granted, free of charge, to any person obtaining a
10: * copy of this software and associated documentation files (the "Software"),
11: * to deal in the Software without restriction, including without limitation
12: * the rights to use, copy, modify, merge, publish, distribute, sublicense,
13: * and/or sell copies of the Software, and to permit persons to whom the
14: * Software is furnished to do so, subject to the following conditions:
15: *
16: * <p>The above copyright notice and this permission notice shall be included
17: * in all copies or substantial portions of the Software.
18: *
19: * <p>THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS
20: * OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
21: * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.
22: * IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY
23: * CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT
24: * OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR
25: * THE USE OR OTHER DEALINGS IN THE SOFTWARE.
26: *
27: * <br>
28: * <p>A ConsultingNot is a Not that has an axiom source to consult.
29: *
30: * @author Steven J. Metsker
31: * @version 1.0
32: */
33:
34: public class ConsultingNot extends Gateway {
35: ConsultingStructure consultingStructure;
36:
37: /**
38: * Contructs a ConsultingNot from the specified consulting
39: * structure. This constructor is for use by Not.
40: */
41: protected ConsultingNot(ConsultingStructure consultingStructure) {
42:
43: super (consultingStructure.functor, consultingStructure.terms);
44: this .consultingStructure = consultingStructure;
45: }
46:
47: /**
48: * Returns <code>false</code> if there is any way to prove this
49: * structure.
50: *
51: * @return <code>false</code> if there is any way to prove
52: * this structure
53: */
54: public boolean canProveOnce() {
55: return !(consultingStructure.canUnify() && consultingStructure.resolvent
56: .canEstablish());
57: }
58:
59: /**
60: * After succeeding once, unbind any variables bound during
61: * the successful proof, and set the axioms to begin
62: * again at the beginning.
63: */
64: protected void cleanup() {
65: consultingStructure.unbind();
66: consultingStructure.axioms = null;
67: }
68:
69: /**
70: * Returns a string description of this Not.
71: *
72: * @return a string description of this Not
73: */
74: public String toString() {
75: return "not " + consultingStructure;
76: }
77: }
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