01: /*
02: * Copyright 2006 Sun Microsystems, Inc. All Rights Reserved.
03: * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
04: *
05: * This code is free software; you can redistribute it and/or modify it
06: * under the terms of the GNU General Public License version 2 only, as
07: * published by the Free Software Foundation. Sun designates this
08: * particular file as subject to the "Classpath" exception as provided
09: * by Sun 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 Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,
22: * CA 95054 USA or visit www.sun.com if you need additional information or
23: * have any questions.
24: */
25:
26: package com.sun.xml.internal.rngom.binary;
27:
28: final class PatternInterner {
29: private static final int INIT_SIZE = 256;
30: private static final float LOAD_FACTOR = 0.3f;
31: private Pattern[] table;
32: private int used;
33: private int usedLimit;
34:
35: PatternInterner() {
36: table = null;
37: used = 0;
38: usedLimit = 0;
39: }
40:
41: PatternInterner(PatternInterner parent) {
42: table = parent.table;
43: if (table != null)
44: table = (Pattern[]) table.clone();
45: used = parent.used;
46: usedLimit = parent.usedLimit;
47: }
48:
49: Pattern intern(Pattern p) {
50: int h;
51:
52: if (table == null) {
53: table = new Pattern[INIT_SIZE];
54: usedLimit = (int) (INIT_SIZE * LOAD_FACTOR);
55: h = firstIndex(p);
56: } else {
57: for (h = firstIndex(p); table[h] != null; h = nextIndex(h)) {
58: if (p.samePattern(table[h]))
59: return table[h];
60: }
61: }
62: if (used >= usedLimit) {
63: // rehash
64: Pattern[] oldTable = table;
65: table = new Pattern[table.length << 1];
66: for (int i = oldTable.length; i > 0;) {
67: --i;
68: if (oldTable[i] != null) {
69: int j;
70: for (j = firstIndex(oldTable[i]); table[j] != null; j = nextIndex(j))
71: ;
72: table[j] = oldTable[i];
73: }
74: }
75: for (h = firstIndex(p); table[h] != null; h = nextIndex(h))
76: ;
77: usedLimit = (int) (table.length * LOAD_FACTOR);
78: }
79: used++;
80: table[h] = p;
81: return p;
82: }
83:
84: private int firstIndex(Pattern p) {
85: return p.patternHashCode() & (table.length - 1);
86: }
87:
88: private int nextIndex(int i) {
89: return i == 0 ? table.length - 1 : i - 1;
90: }
91: }
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