1 /*******************************************************************************
2 * SAT4J: a SATisfiability library for Java Copyright (C) 2004-2008 Daniel Le Berre
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 *******************************************************************************/
28 package org.sat4j.tools;
29
30 import org.sat4j.core.VecInt;
31 import org.sat4j.specs.ContradictionException;
32 import org.sat4j.specs.ISolver;
33 import org.sat4j.specs.IVecInt;
34 import org.sat4j.specs.TimeoutException;
35
36 /**
37 * That class allows to iterate through all the models (implicants) of a
38 * formula.
39 *
40 * <pre>
41 * ISolver solver = new ModelIterator(SolverFactory.OneSolver());
42 * boolean unsat = true;
43 * while (solver.isSatisfiable()) {
44 * unsat = false;
45 * int[] model = solver.model();
46 * // do something with model
47 * }
48 * if (unsat) {
49 * // UNSAT case
50 * }
51 * </pre>
52 *
53 * @author leberre
54 */
55 public class ModelIterator extends SolverDecorator<ISolver> {
56
57 private static final long serialVersionUID = 1L;
58
59 private boolean trivialfalsity = false;
60
61 /**
62 * @param solver
63 */
64 public ModelIterator(ISolver solver) {
65 super(solver);
66 }
67
68 /*
69 * (non-Javadoc)
70 *
71 * @see org.sat4j.ISolver#model()
72 */
73 @Override
74 public int[] model() {
75 int[] last = super.model();
76 IVecInt clause = new VecInt(last.length);
77 for (int q : last) {
78 clause.push(-q);
79 }
80 try {
81 // System.out.println("adding " + clause);
82 addClause(clause);
83 } catch (ContradictionException e) {
84 trivialfalsity = true;
85 }
86 return last;
87 }
88
89 /*
90 * (non-Javadoc)
91 *
92 * @see org.sat4j.ISolver#isSatisfiable()
93 */
94 @Override
95 public boolean isSatisfiable() throws TimeoutException {
96 if (trivialfalsity) {
97 return false;
98 }
99 trivialfalsity = false;
100 return super.isSatisfiable(true);
101 }
102
103 /*
104 * (non-Javadoc)
105 *
106 * @see org.sat4j.ISolver#isSatisfiable(org.sat4j.datatype.VecInt)
107 */
108 @Override
109 public boolean isSatisfiable(IVecInt assumps) throws TimeoutException {
110 if (trivialfalsity) {
111 return false;
112 }
113 trivialfalsity = false;
114 return super.isSatisfiable(assumps,true);
115 }
116
117 /*
118 * (non-Javadoc)
119 *
120 * @see org.sat4j.ISolver#reset()
121 */
122 @Override
123 public void reset() {
124 trivialfalsity = false;
125 super.reset();
126 }
127 }