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Jing is a validator for RELAX NG and other schema languages. This
project was taken from http://code.google.com/p/jing-trang and
mavenized for inclusion in the Wicket Stuff HTML Validator.
The code was taken from the 20091111 release.
package com.thaiopensource.relaxng.pattern;
final class PatternInterner {
private static final int INIT_SIZE = 256;
private static final float LOAD_FACTOR = 0.3f;
private Pattern[] table;
private int used;
private int usedLimit;
PatternInterner() {
table = null;
used = 0;
usedLimit = 0;
}
PatternInterner(PatternInterner parent) {
table = parent.table;
if (table != null)
table = table.clone();
used = parent.used;
usedLimit = parent.usedLimit;
}
Pattern intern(Pattern p) {
int h;
if (table == null) {
table = new Pattern[INIT_SIZE];
usedLimit = (int)(INIT_SIZE * LOAD_FACTOR);
h = firstIndex(p);
}
else {
for (h = firstIndex(p); table[h] != null; h = nextIndex(h)) {
if (p.samePattern(table[h]))
return table[h];
}
}
if (used >= usedLimit) {
// rehash
Pattern[] oldTable = table;
table = new Pattern[table.length << 1];
for (int i = oldTable.length; i > 0;) {
--i;
if (oldTable[i] != null) {
int j;
for (j = firstIndex(oldTable[i]); table[j] != null; j = nextIndex(j))
;
table[j] = oldTable[i];
}
}
for (h = firstIndex(p); table[h] != null; h = nextIndex(h))
;
usedLimit = (int)(table.length * LOAD_FACTOR);
}
used++;
table[h] = p;
return p;
}
private int firstIndex(Pattern p) {
return p.patternHashCode() & (table.length - 1);
}
private int nextIndex(int i) {
return i == 0 ? table.length - 1 : i - 1;
}
}