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.specs;
31
32 import org.sat4j.minisat.core.Constr;
33
34 /**
35 * Interface providing the unit propagation capability.
36 *
37 * Note that this interface was in the package org.sat4j.minisat.core prior to
38 * release 2.3.4. It was moved here because of the dependency from
39 * {@link UnitClauseProvider}.
40 *
41 * @author leberre
42 */
43 public interface UnitPropagationListener {
44
45 /**
46 * satisfies a literal
47 *
48 * @param p
49 * a literal
50 * @return true if the assignment looks possible, false if a conflict
51 * occurs.
52 */
53 boolean enqueue(int p);
54
55 /**
56 * satisfies a literal
57 *
58 * @param p
59 * a literal
60 * @param from
61 * a reason explaining why p should be satisfied.
62 * @return true if the assignment looks possible, false if a conflict
63 * occurs.
64 */
65 boolean enqueue(int p, Constr from);
66
67 /**
68 * Unset a unit clause. The effect of such method is to unset all truth
69 * values on the stack until the given literal is found (that literal
70 * included).
71 *
72 * @param p
73 * @since 2.1
74 */
75 void unset(int p);
76 }