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.core;
29
30 import java.util.Iterator;
31
32 import org.sat4j.specs.IConstr;
33 import org.sat4j.specs.ISolver;
34 import org.sat4j.specs.IVec;
35
36 /**
37 * A utility class used to manage easily group of clauses to be deleted at some
38 * point in the solver.
39 *
40 * @author dlb
41 * @since 2.0
42 *
43 */
44 public class ConstrGroup implements IConstr {
45
46 private final IVec<IConstr> constrs = new Vec<IConstr>();
47 private final boolean disallowNullConstraints;
48
49 /**
50 * Create a ConstrGroup that cannot contain null constrs.
51 */
52 public ConstrGroup() {
53 this(true);
54 }
55
56 /**
57 * Create a new constrGroup.
58 *
59 * @param disallowNullConstraints
60 * should be set to false to allow adding null constraints to the
61 * group.
62 */
63 public ConstrGroup(boolean disallowNullConstraints) {
64 this.disallowNullConstraints = disallowNullConstraints;
65 }
66
67 public void add(IConstr constr) {
68 if (constr == null && disallowNullConstraints) {
69 throw new IllegalArgumentException(
70 "The constraint you entered cannot be removed from the solver.");
71 }
72 constrs.push(constr);
73 }
74
75 public void clear() {
76 constrs.clear();
77 }
78
79 public void removeFrom(ISolver solver) {
80 for (Iterator<IConstr> it = constrs.iterator(); it.hasNext();) {
81 solver.removeConstr(it.next());
82 }
83 }
84
85 public IConstr getConstr(int i) {
86 return constrs.get(i);
87 }
88
89 public int size() {
90 return constrs.size();
91 }
92
93 public boolean learnt() {
94 if (constrs.size() == 0)
95 return false;
96 return constrs.get(0).learnt();
97 }
98
99 public double getActivity() {
100 return 0;
101 }
102
103 public int get(int i) {
104 throw new UnsupportedOperationException();
105 }
106
107 public boolean canBePropagatedMultipleTimes() {
108 return false;
109 }
110
111 @Override
112 public String toString() {
113 return constrs.toString();
114 }
115 }