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
26 package org.sat4j.minisat.core;
27
28 import java.io.Serializable;
29
30 /**
31 * Implementation of a queue.
32 *
33 * Formerly used in the solver to maintain unit literals for unit propagation.
34 * No longer used currently.
35 *
36 * @author leberre
37 */
38 public final class IntQueue implements Serializable {
39
40 private static final long serialVersionUID = 1L;
41
42 private static final int INITIAL_QUEUE_CAPACITY = 10;
43
44 /**
45 * Add an element to the queue. The queue is supposed to be large enough for
46 * that!
47 *
48 * @param x
49 * the element to add
50 */
51 public void insert(final int x) {
52 // ensure(size + 1);
53 assert size < myarray.length;
54 myarray[size++] = x;
55 }
56
57 /**
58 * returns the nexdt element in the queue. Unexpected results if the queue
59 * is empty!
60 *
61 * @return the firsst element on the queue
62 */
63 public int dequeue() {
64 assert first < size;
65 return myarray[first++];
66 }
67
68 /**
69 * Vide la queue
70 */
71 public void clear() {
72 size = 0;
73 first = 0;
74 }
75
76 /**
77 * Pour connaitre la taille de la queue.
78 *
79 * @return le nombre d'elements restant dans la queue
80 */
81 public int size() {
82 return size - first;
83 }
84
85 /**
86 * Utilisee pour accroitre dynamiquement la taille de la queue.
87 *
88 * @param nsize
89 * la taille maximale de la queue
90 */
91 public void ensure(final int nsize) {
92 if (nsize >= myarray.length) {
93 int[] narray = new int[Math.max(nsize, size * 2)];
94 System.arraycopy(myarray, 0, narray, 0, size);
95 myarray = narray;
96 }
97 }
98
99 @Override
100 public String toString() {
101 StringBuffer stb = new StringBuffer();
102 stb.append(">"); //$NON-NLS-1$
103 for (int i = first; i < size - 1; i++) {
104 stb.append(myarray[i]);
105 stb.append(" "); //$NON-NLS-1$
106 }
107 if (first != size) {
108 stb.append(myarray[size - 1]);
109 }
110 stb.append("<"); //$NON-NLS-1$
111 return stb.toString();
112 }
113
114 private int[] myarray = new int[INITIAL_QUEUE_CAPACITY];
115
116 private int size = 0;
117
118 private int first = 0;
119
120 }