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