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 import java.io.Serializable;
33
34 /**
35 * Implementation of a queue.
36 *
37 * Formerly used in the solver to maintain unit literals for unit propagation.
38 * No longer used currently.
39 *
40 * @author leberre
41 */
42 public final class IntQueue implements Serializable {
43
44 private static final long serialVersionUID = 1L;
45
46 private static final int INITIAL_QUEUE_CAPACITY = 10;
47
48 /**
49 * Add an element to the queue. The queue is supposed to be large enough for
50 * that!
51 *
52 * @param x
53 * the element to add
54 */
55 public void insert(final int x) {
56 // ensure(size + 1);
57 assert this.size < this.myarray.length;
58 this.myarray[this.size++] = x;
59 }
60
61 /**
62 * returns the nexdt element in the queue. Unexpected results if the queue
63 * is empty!
64 *
65 * @return the firsst element on the queue
66 */
67 public int dequeue() {
68 assert this.first < this.size;
69 return this.myarray[this.first++];
70 }
71
72 /**
73 * Vide la queue
74 */
75 public void clear() {
76 this.size = 0;
77 this.first = 0;
78 }
79
80 /**
81 * Pour connaitre la taille de la queue.
82 *
83 * @return le nombre d'elements restant dans la queue
84 */
85 public int size() {
86 return this.size - this.first;
87 }
88
89 /**
90 * Utilisee pour accroitre dynamiquement la taille de la queue.
91 *
92 * @param nsize
93 * la taille maximale de la queue
94 */
95 public void ensure(final int nsize) {
96 if (nsize >= this.myarray.length) {
97 int[] narray = new int[Math.max(nsize, this.size * 2)];
98 System.arraycopy(this.myarray, 0, narray, 0, this.size);
99 this.myarray = narray;
100 }
101 }
102
103 @Override
104 public String toString() {
105 StringBuffer stb = new StringBuffer();
106 stb.append(">"); //$NON-NLS-1$
107 for (int i = this.first; i < this.size - 1; i++) {
108 stb.append(this.myarray[i]);
109 stb.append(" "); //$NON-NLS-1$
110 }
111 if (this.first != this.size) {
112 stb.append(this.myarray[this.size - 1]);
113 }
114 stb.append("<"); //$NON-NLS-1$
115 return stb.toString();
116 }
117
118 private int[] myarray = new int[INITIAL_QUEUE_CAPACITY];
119
120 private int size = 0;
121
122 private int first = 0;
123
124 }