1 /*******************************************************************************
2 * SAT4J: a SATisfiability library for Java Copyright (C) 2004-2008 Daniel Le Berre
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 *******************************************************************************/
28 package org.sat4j.minisat.core;
29
30 import java.io.Serializable;
31
32 /**
33 * Implementation of a queue.
34 *
35 * Formerly used in the solver to maintain unit literals for unit propagation.
36 * No longer used currently.
37 *
38 * @author leberre
39 */
40 public final class IntQueue implements Serializable {
41
42 private static final long serialVersionUID = 1L;
43
44 private static final int INITIAL_QUEUE_CAPACITY = 10;
45
46 /**
47 * Add an element to the queue. The queue is supposed to be large enough for
48 * that!
49 *
50 * @param x
51 * the element to add
52 */
53 public void insert(final int x) {
54 // ensure(size + 1);
55 assert size < myarray.length;
56 myarray[size++] = x;
57 }
58
59 /**
60 * returns the nexdt element in the queue. Unexpected results if the queue
61 * is empty!
62 *
63 * @return the firsst element on the queue
64 */
65 public int dequeue() {
66 assert first < size;
67 return myarray[first++];
68 }
69
70 /**
71 * Vide la queue
72 */
73 public void clear() {
74 size = 0;
75 first = 0;
76 }
77
78 /**
79 * Pour connaitre la taille de la queue.
80 *
81 * @return le nombre d'elements restant dans la queue
82 */
83 public int size() {
84 return size - first;
85 }
86
87 /**
88 * Utilisee pour accroitre dynamiquement la taille de la queue.
89 *
90 * @param nsize
91 * la taille maximale de la queue
92 */
93 public void ensure(final int nsize) {
94 if (nsize >= myarray.length) {
95 int[] narray = new int[Math.max(nsize, size * 2)];
96 System.arraycopy(myarray, 0, narray, 0, size);
97 myarray = narray;
98 }
99 }
100
101 @Override
102 public String toString() {
103 StringBuffer stb = new StringBuffer();
104 stb.append(">"); //$NON-NLS-1$
105 for (int i = first; i < size - 1; i++) {
106 stb.append(myarray[i]);
107 stb.append(" "); //$NON-NLS-1$
108 }
109 if (first != size) {
110 stb.append(myarray[size - 1]);
111 }
112 stb.append("<"); //$NON-NLS-1$
113 return stb.toString();
114 }
115
116 private int[] myarray = new int[INITIAL_QUEUE_CAPACITY];
117
118 private int size = 0;
119
120 private int first = 0;
121
122 }