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1 package com.thaiopensource.relaxng.impl;
2
3
4 final class PatternInterner {
5 private static final int INIT_SIZE = 256;
6 private static final float LOAD_FACTOR = 0.3f;
7 private Pattern[] table;
8 private int used;
9 private int usedLimit;
10
11 PatternInterner() {
12 table = null;
13 used = 0;
14 usedLimit = 0;
15 }
16
17 PatternInterner(PatternInterner parent) {
18 table = parent.table;
19 if (table != null)
20 table = (Pattern[])table.clone();
21 used = parent.used;
22 usedLimit = parent.usedLimit;
23 }
24
25 Pattern intern(Pattern p) {
26 int h;
27
28 if (table == null) {
29 table = new Pattern[INIT_SIZE];
30 usedLimit = (int)(INIT_SIZE * LOAD_FACTOR);
31 h = firstIndex(p);
32 }
33 else {
34 for (h = firstIndex(p); table[h] != null; h = nextIndex(h)) {
35 if (p.samePattern(table[h]))
36 return table[h];
37 }
38 }
39 if (used >= usedLimit) {
40 Pattern[] oldTable = table;
42 table = new Pattern[table.length << 1];
43 for (int i = oldTable.length; i > 0;) {
44 --i;
45 if (oldTable[i] != null) {
46 int j;
47 for (j = firstIndex(oldTable[i]); table[j] != null; j = nextIndex(j))
48 ;
49 table[j] = oldTable[i];
50 }
51 }
52 for (h = firstIndex(p); table[h] != null; h = nextIndex(h))
53 ;
54 usedLimit = (int)(table.length * LOAD_FACTOR);
55 }
56 used++;
57 table[h] = p;
58 return p;
59 }
60
61 private int firstIndex(Pattern p) {
62 return p.patternHashCode() & (table.length - 1);
63 }
64
65 private int nextIndex(int i) {
66 return i == 0 ? table.length - 1 : i - 1;
67 }
68 }
69 |
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