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 java.util.Iterator;
31
32 import org.sat4j.core.Vec;
33 import org.sat4j.specs.IConstr;
34 import org.sat4j.specs.ISolver;
35 import org.sat4j.specs.IVec;
36
37 /**
38 * A utility class used to manage easily group of clauses to be deleted at some
39 * point in the solver.
40 *
41 * @author dlb
42 * @since 2.0
43 *
44 */
45 public class ConstrGroup implements IConstr {
46
47 private final IVec<IConstr> constrs = new Vec<IConstr>();
48 private final boolean disallowNullConstraints;
49
50 /**
51 * Create a ConstrGroup that cannot contain null constrs.
52 */
53 public ConstrGroup() {
54 this(true);
55 }
56
57 /**
58 * Create a new constrGroup.
59 *
60 * @param disallowNullConstraints
61 * should be set to false to allow adding null constraints to the
62 * group.
63 */
64 public ConstrGroup(boolean disallowNullConstraints) {
65 this.disallowNullConstraints = disallowNullConstraints;
66 }
67
68 public void add(IConstr constr) {
69 if (constr == null && disallowNullConstraints) {
70 throw new IllegalArgumentException(
71 "The constraint you entered cannot be removed from the solver.");
72 }
73 constrs.push(constr);
74 }
75
76 public void clear() {
77 constrs.clear();
78 }
79
80 public void removeFrom(ISolver solver) {
81 for (Iterator<IConstr> it = constrs.iterator(); it.hasNext();) {
82 solver.removeConstr(it.next());
83 }
84 }
85
86 public IConstr getConstr(int i) {
87 return constrs.get(i);
88 }
89
90 public int size() {
91 return constrs.size();
92 }
93
94 public boolean learnt() {
95 if (constrs.size() == 0)
96 return false;
97 return constrs.get(0).learnt();
98 }
99
100 public double getActivity() {
101 return 0;
102 }
103
104 public int get(int i) {
105 throw new UnsupportedOperationException();
106 }
107 }