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.core;
31
32 import java.util.Iterator;
33
34 import org.sat4j.specs.IConstr;
35 import org.sat4j.specs.ISolver;
36 import org.sat4j.specs.IVec;
37
38 /**
39 * A utility class used to manage easily group of clauses to be deleted at some
40 * point in the solver.
41 *
42 * @author dlb
43 * @since 2.0
44 *
45 */
46 public class ConstrGroup implements IConstr {
47
48 private final IVec<IConstr> constrs = new Vec<IConstr>();
49 private final boolean disallowNullConstraints;
50
51 /**
52 * Create a ConstrGroup that cannot contain null constrs.
53 */
54 public ConstrGroup() {
55 this(true);
56 }
57
58 /**
59 * Create a new constrGroup.
60 *
61 * @param disallowNullConstraints
62 * should be set to false to allow adding null constraints to the
63 * group.
64 */
65 public ConstrGroup(boolean disallowNullConstraints) {
66 this.disallowNullConstraints = disallowNullConstraints;
67 }
68
69 public void add(IConstr constr) {
70 if (constr == null && this.disallowNullConstraints) {
71 throw new IllegalArgumentException(
72 "The constraint you entered cannot be removed from the solver.");
73 }
74 this.constrs.push(constr);
75 }
76
77 public void clear() {
78 this.constrs.clear();
79 }
80
81 public void removeFrom(ISolver solver) {
82 for (Iterator<IConstr> it = this.constrs.iterator(); it.hasNext();) {
83 solver.removeConstr(it.next());
84 }
85 }
86
87 public IConstr getConstr(int i) {
88 return this.constrs.get(i);
89 }
90
91 public int size() {
92 return this.constrs.size();
93 }
94
95 public boolean learnt() {
96 if (this.constrs.size() == 0) {
97 return false;
98 }
99 return this.constrs.get(0).learnt();
100 }
101
102 public double getActivity() {
103 return 0;
104 }
105
106 public int get(int i) {
107 throw new UnsupportedOperationException();
108 }
109
110 public boolean canBePropagatedMultipleTimes() {
111 return false;
112 }
113
114 @Override
115 public String toString() {
116 return this.constrs.toString();
117 }
118 }