com.sun.tools.rngom.binary.PatternInterner Maven / Gradle / Ivy
/*
* Copyright (C) 2004-2011
*
* Permission is hereby granted, free of charge, to any person obtaining a copy
* of this software and associated documentation files (the "Software"), to deal
* in the Software without restriction, including without limitation the rights
* to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
* copies of the Software, and to permit persons to whom the Software is
* furnished to do so, subject to the following conditions:
*
* The above copyright notice and this permission notice shall be included in
* all copies or substantial portions of the Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
* AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
* OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
* THE SOFTWARE.
*/
package com.sun.tools.rngom.binary;
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;
}
@SuppressWarnings("empty-statement")
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;
}
}