1 /*******************************************************************************
2 * SAT4J: a SATisfiability library for Java Copyright (C) 2004, 2012 Artois University and CNRS
3 *
4 * All rights reserved. This program and the accompanying materials
5 * are made available under the terms of the Eclipse Public License v1.0
6 * which accompanies this distribution, and is available at
7 * http://www.eclipse.org/legal/epl-v10.html
8 *
9 * Alternatively, the contents of this file may be used under the terms of
10 * either the GNU Lesser General Public License Version 2.1 or later (the
11 * "LGPL"), in which case the provisions of the LGPL are applicable instead
12 * of those above. If you wish to allow use of your version of this file only
13 * under the terms of the LGPL, and not to allow others to use your version of
14 * this file under the terms of the EPL, indicate your decision by deleting
15 * the provisions above and replace them with the notice and other provisions
16 * required by the LGPL. If you do not delete the provisions above, a recipient
17 * may use your version of this file under the terms of the EPL or the LGPL.
18 *
19 * Based on the original MiniSat specification from:
20 *
21 * An extensible SAT solver. Niklas Een and Niklas Sorensson. Proceedings of the
22 * Sixth International Conference on Theory and Applications of Satisfiability
23 * Testing, LNCS 2919, pp 502-518, 2003.
24 *
25 * See www.minisat.se for the original solver in C++.
26 *
27 * Contributors:
28 * CRIL - initial API and implementation
29 *******************************************************************************/
30 package org.sat4j.minisat.constraints.cnf;
31
32 import org.sat4j.core.LiteralsUtils;
33 import org.sat4j.minisat.core.Constr;
34 import org.sat4j.minisat.core.ILits;
35 import org.sat4j.minisat.core.UnitPropagationListener;
36 import org.sat4j.specs.IVecInt;
37
38 /**
39 *
40 * @author daniel
41 * @since 2.1
42 */
43 public class UnitClause implements Constr {
44
45 protected final int literal;
46 protected double activity;
47
48 public UnitClause(int value) {
49 this.literal = value;
50 }
51
52 public void assertConstraint(UnitPropagationListener s) {
53 s.enqueue(this.literal, this);
54 }
55
56 public void calcReason(int p, IVecInt outReason) {
57 if (p == ILits.UNDEFINED) {
58 outReason.push(LiteralsUtils.neg(this.literal));
59 }
60 }
61
62 public double getActivity() {
63 return activity;
64 }
65
66 public void incActivity(double claInc) {
67 // silent to prevent problems with xplain trick.
68 }
69
70 public void setActivity(double claInc) {
71 activity = claInc;
72 }
73
74 public boolean locked() {
75 throw new UnsupportedOperationException();
76 }
77
78 public void register() {
79 throw new UnsupportedOperationException();
80 }
81
82 public void remove(UnitPropagationListener upl) {
83 upl.unset(this.literal);
84 }
85
86 public void rescaleBy(double d) {
87 throw new UnsupportedOperationException();
88 }
89
90 public void setLearnt() {
91 throw new UnsupportedOperationException();
92 }
93
94 public boolean simplify() {
95 return false;
96 }
97
98 public boolean propagate(UnitPropagationListener s, int p) {
99 throw new UnsupportedOperationException();
100 }
101
102 public int get(int i) {
103 if (i > 0) {
104 throw new IllegalArgumentException();
105 }
106 return this.literal;
107 }
108
109 public boolean learnt() {
110 return false;
111 }
112
113 public int size() {
114 return 1;
115 }
116
117 public void forwardActivity(double claInc) {
118 // silent to prevent problems with xplain trick.
119 }
120
121 @Override
122 public String toString() {
123 return Lits.toString(this.literal);
124 }
125
126 public boolean canBePropagatedMultipleTimes() {
127 return false;
128 }
129
130 public void calcReasonOnTheFly(int p, IVecInt trail, IVecInt outReason) {
131 calcReason(p, outReason);
132 }
133 }