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
47 public UnitClause(int value) {
48 this.literal = value;
49 }
50
51 public void assertConstraint(UnitPropagationListener s) {
52 s.enqueue(this.literal, this);
53 }
54
55 public void calcReason(int p, IVecInt outReason) {
56 if (p == ILits.UNDEFINED) {
57 outReason.push(LiteralsUtils.neg(this.literal));
58 }
59 }
60
61 public double getActivity() {
62 throw new UnsupportedOperationException();
63 }
64
65 public void incActivity(double claInc) {
66 // silent to prevent problems with xplain trick.
67 }
68
69 public void setActivity(double claInc) {
70 // do nothing
71 }
72
73 public boolean locked() {
74 throw new UnsupportedOperationException();
75 }
76
77 public void register() {
78 throw new UnsupportedOperationException();
79 }
80
81 public void remove(UnitPropagationListener upl) {
82 upl.unset(this.literal);
83 }
84
85 public void rescaleBy(double d) {
86 throw new UnsupportedOperationException();
87 }
88
89 public void setLearnt() {
90 throw new UnsupportedOperationException();
91 }
92
93 public boolean simplify() {
94 return false;
95 }
96
97 public boolean propagate(UnitPropagationListener s, int p) {
98 throw new UnsupportedOperationException();
99 }
100
101 public int get(int i) {
102 if (i > 0) {
103 throw new IllegalArgumentException();
104 }
105 return this.literal;
106 }
107
108 public boolean learnt() {
109 return false;
110 }
111
112 public int size() {
113 return 1;
114 }
115
116 public void forwardActivity(double claInc) {
117 // silent to prevent problems with xplain trick.
118 }
119
120 @Override
121 public String toString() {
122 return Lits.toString(this.literal);
123 }
124
125 public boolean canBePropagatedMultipleTimes() {
126 return false;
127 }
128 }