private LiteralsUtils() { public static int var(int p) { public static int neg(int p) {
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| LiteralsUtils | Line # 48 | 2 | 1 | 71,4% |
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| 1 | /* | |
| 2 | * SAT4J: a SATisfiability library for Java Copyright (C) 2004-2006 Daniel Le Berre | |
| 3 | * | |
| 4 | * Based on the original minisat specification from: | |
| 5 | * | |
| 6 | * An extensible SAT solver. Niklas E?n and Niklas S?rensson. Proceedings of the | |
| 7 | * Sixth International Conference on Theory and Applications of Satisfiability | |
| 8 | * Testing, LNCS 2919, pp 502-518, 2003. | |
| 9 | * | |
| 10 | * This library is free software; you can redistribute it and/or modify it under | |
| 11 | * the terms of the GNU Lesser General Public License as published by the Free | |
| 12 | * Software Foundation; either version 2.1 of the License, or (at your option) | |
| 13 | * any later version. | |
| 14 | * | |
| 15 | * This library is distributed in the hope that it will be useful, but WITHOUT | |
| 16 | * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS | |
| 17 | * FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public License for more | |
| 18 | * details. | |
| 19 | * | |
| 20 | * You should have received a copy of the GNU Lesser General Public License | |
| 21 | * along with this library; if not, write to the Free Software Foundation, Inc., | |
| 22 | * 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA | |
| 23 | * | |
| 24 | */ | |
| 25 | package org.sat4j.minisat.core; | |
| 26 | ||
| 27 | /** | |
| 28 | * Utility methods to avoid using bit manipulation inside code. One should use | |
| 29 | * Java 1.5 import static feature to use it without class qualification inside | |
| 30 | * the code. | |
| 31 | * | |
| 32 | * In the DIMACS format, the literals are represented by signed integers, 0 | |
| 33 | * denoting the end of the clause. In the solver, the literals are represented | |
| 34 | * by positive integers, in order to use them as index in arrays for instance. | |
| 35 | * | |
| 36 | * <pre> | |
| 37 | * int p : a literal (p>1) | |
| 38 | * p ˆ 1 : the negation of the literal | |
| 39 | * p >> 1 : the DIMACS number reresenting the variable. | |
| 40 | * int v : a DIMACS variable (v>0) | |
| 41 | * v << 1 : a positive literal for that variable in the solver. | |
| 42 | * v << 1 ˆ 1 : a negative literal for that variable. | |
| 43 | * </pre> | |
| 44 | * | |
| 45 | * @author leberre | |
| 46 | * | |
| 47 | */ | |
| 48 | public final class LiteralsUtils { | |
| 49 | ||
| 50 | 0 |
private LiteralsUtils() { |
| 51 | // no instance supposed to be created. | |
| 52 | } | |
| 53 | ||
| 54 | 1457102823 |
public static int var(int p) { |
| 55 | 1457102823 | assert p > 1; |
| 56 | 1457102823 | return p >> 1; |
| 57 | } | |
| 58 | ||
| 59 | 630225982 |
public static int neg(int p) { |
| 60 | 630225982 | return p ^ 1; |
| 61 | } | |
| 62 | } | |
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