1 /*
2 * SAT4J: a SATisfiability library for Java Copyright (C) 2004-2006 Daniel Le Berre
3 *
4 * Based on the original minisat specification from:
5 *
6 * An extensible SAT solver. Niklas E?n and Niklas S?rensson. Proceedings of the
7 * Sixth International Conference on Theory and Applications of Satisfiability
8 * Testing, LNCS 2919, pp 502-518, 2003.
9 *
10 * This library is free software; you can redistribute it and/or modify it under
11 * the terms of the GNU Lesser General Public License as published by the Free
12 * Software Foundation; either version 2.1 of the License, or (at your option)
13 * any later version.
14 *
15 * This library is distributed in the hope that it will be useful, but WITHOUT
16 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
17 * FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public License for more
18 * details.
19 *
20 * You should have received a copy of the GNU Lesser General Public License
21 * along with this library; if not, write to the Free Software Foundation, Inc.,
22 * 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
23 *
24 */
25
26 package org.sat4j.minisat.constraints.cnf;
27
28 import org.sat4j.minisat.core.ILits2;
29
30 /**
31 * @author leberre To change the template for this generated type comment go to
32 * Window - Preferences - Java - Code Generation - Code and Comments
33 */
34 public class Lits2 extends Lits implements ILits2 {
35
36 private static final long serialVersionUID = 1L;
37
38 private BinaryClauses[] binclauses = null;
39
40 /**
41 *
42 */
43 public Lits2() {
44 super();
45 // TODO Auto-generated constructor stub
46 }
47
48 /**
49 * To know the number of binary clauses in which the literal occurs. Please
50 * note that this method should only be used in conjunction with the
51 * BinaryClauses data structure.
52 *
53 * @param p
54 * @return the number of binary clauses in which the literal occurs.
55 */
56 public int nBinaryClauses(int p) {
57 if (binclauses == null) {
58 return 0;
59 }
60 if (binclauses[p] == null) {
61 return 0;
62 }
63 return binclauses[p].size();
64 }
65
66 public void binaryClauses(int lit1, int lit2) {
67 register(lit1, lit2);
68 register(lit2, lit1);
69 }
70
71 private void register(int p, int q) {
72 if (binclauses == null) {
73 binclauses = new BinaryClauses[2 * nVars() + 2];
74 }
75 if (binclauses[p] == null) {
76 binclauses[p] = new BinaryClauses(this, p);
77 watches[p ^ 1].insertFirstWithShifting(binclauses[p]);
78 }
79 binclauses[p].addBinaryClause(q);
80 }
81
82 }