1/*
2 * Copyright (c) 2005, 2012, Oracle and/or its affiliates. All rights reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4 *
5 * This code is free software; you can redistribute it and/or modify it
6 * under the terms of the GNU General Public License version 2 only, as
7 * published by the Free Software Foundation.  Oracle designates this
8 * particular file as subject to the "Classpath" exception as provided
9 * by Oracle in the LICENSE file that accompanied this code.
10 *
11 * This code is distributed in the hope that it will be useful, but WITHOUT
12 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
13 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
14 * version 2 for more details (a copy is included in the LICENSE file that
15 * accompanied this code).
16 *
17 * You should have received a copy of the GNU General Public License version
18 * 2 along with this work; if not, write to the Free Software Foundation,
19 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
20 *
21 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
22 * or visit www.oracle.com if you need additional information or have any
23 * questions.
24 */
25/*
26 * Copyright (C) 2004-2011
27 *
28 * Permission is hereby granted, free of charge, to any person obtaining a copy
29 * of this software and associated documentation files (the "Software"), to deal
30 * in the Software without restriction, including without limitation the rights
31 * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
32 * copies of the Software, and to permit persons to whom the Software is
33 * furnished to do so, subject to the following conditions:
34 *
35 * The above copyright notice and this permission notice shall be included in
36 * all copies or substantial portions of the Software.
37 *
38 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
39 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
40 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
41 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
42 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
43 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
44 * THE SOFTWARE.
45 */
46package com.sun.xml.internal.rngom.binary;
47
48final class PatternInterner {
49    private static final int INIT_SIZE = 256;
50    private static final float LOAD_FACTOR = 0.3f;
51    private Pattern[] table;
52    private int used;
53    private int usedLimit;
54
55    PatternInterner() {
56        table = null;
57        used = 0;
58        usedLimit = 0;
59    }
60
61    PatternInterner(PatternInterner parent) {
62        table = parent.table;
63        if (table != null)
64            table = (Pattern[]) table.clone();
65        used = parent.used;
66        usedLimit = parent.usedLimit;
67    }
68
69    @SuppressWarnings("empty-statement")
70    Pattern intern(Pattern p) {
71        int h;
72
73        if (table == null) {
74            table = new Pattern[INIT_SIZE];
75            usedLimit = (int) (INIT_SIZE * LOAD_FACTOR);
76            h = firstIndex(p);
77        } else {
78            for (h = firstIndex(p); table[h] != null; h = nextIndex(h)) {
79                if (p.samePattern(table[h]))
80                    return table[h];
81            }
82        }
83        if (used >= usedLimit) {
84            // rehash
85            Pattern[] oldTable = table;
86            table = new Pattern[table.length << 1];
87            for (int i = oldTable.length; i > 0;) {
88                --i;
89                if (oldTable[i] != null) {
90                    int j;
91                    for (j = firstIndex(oldTable[i]);
92                        table[j] != null;
93                        j = nextIndex(j));
94                    table[j] = oldTable[i];
95                }
96            }
97            for (h = firstIndex(p); table[h] != null; h = nextIndex(h));
98            usedLimit = (int) (table.length * LOAD_FACTOR);
99        }
100        used++;
101        table[h] = p;
102        return p;
103    }
104
105    private int firstIndex(Pattern p) {
106        return p.patternHashCode() & (table.length - 1);
107    }
108
109    private int nextIndex(int i) {
110        return i == 0 ? table.length - 1 : i - 1;
111    }
112}
113