Mega Code Archive
Unify Hash
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/* UnifyHash Copyright (C) 1999-2002 Jochen Hoenicke.
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU Lesser General Public License as published by
* the Free Software Foundation; either version 2, or (at your option)
* any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public License
* along with this program; see the file COPYING.LESSER. If not, write to
* the Free Software Foundation, 675 Mass Ave, Cambridge, MA 02139, USA.
*
* $Id: UnifyHash.java.in,v 1.3.2.2 2002/05/28 17:34:24 hoenicke Exp $
*/
///#ifdef JDK12
import java.lang.ref.WeakReference;
import java.lang.ref.ReferenceQueue;
///#endif
import java.util.Comparator;
import java.util.AbstractCollection;
import java.util.Iterator;
import java.util.NoSuchElementException;
import java.util.ConcurrentModificationException;
import java.lang.UnsupportedOperationException;
public class UnifyHash extends AbstractCollection {
/**
* the default capacity
*/
private static final int DEFAULT_CAPACITY = 11;
/** the default load factor of a HashMap */
private static final float DEFAULT_LOAD_FACTOR = 0.75F;
///#ifdef JDK12
private ReferenceQueue queue = new ReferenceQueue();
///#endif
static class Bucket
///#ifdef JDK12
extends WeakReference
///#endif
{
///#ifdef JDK12
public Bucket(Object o, ReferenceQueue q) {
super(o, q);
}
///#else
/// public Bucket(Object o) {
/// this.obj = o;
/// }
///
/// Object obj;
///
/// public Object get() {
/// return obj;
/// }
///#endif
int hash;
Bucket next;
}
private Bucket[] buckets;
int modCount = 0;
int size = 0;
int threshold;
float loadFactor;
public UnifyHash(int initialCapacity, float loadFactor) {
this.loadFactor = loadFactor;
buckets = new Bucket[initialCapacity];
threshold = (int) (loadFactor * initialCapacity);
}
public UnifyHash(int initialCapacity) {
this(initialCapacity, DEFAULT_LOAD_FACTOR);
}
public UnifyHash() {
this(DEFAULT_CAPACITY, DEFAULT_LOAD_FACTOR);
}
private void grow() {
Bucket[] oldBuckets = buckets;
int newCap = buckets.length * 2 + 1;
threshold = (int) (loadFactor * newCap);
buckets = new Bucket[newCap];
for (int i = 0; i < oldBuckets.length; i++) {
Bucket nextBucket;
for (Bucket b = oldBuckets[i]; b != null; b = nextBucket) {
if (i != Math.abs(b.hash % oldBuckets.length))
throw new RuntimeException(""+i+", hash: "+b.hash+", oldlength: "+oldBuckets.length);
int newSlot = Math.abs(b.hash % newCap);
nextBucket = b.next;
b.next = buckets[newSlot];
buckets[newSlot] = b;
}
}
}
///#ifdef JDK12
public final void cleanUp() {
Bucket died;
while ((died = (Bucket)queue.poll()) != null) {
int diedSlot = Math.abs(died.hash % buckets.length);
if (buckets[diedSlot] == died)
buckets[diedSlot] = died.next;
else {
Bucket b = buckets[diedSlot];
while (b.next != died)
b = b.next;
b.next = died.next;
}
size--;
}
}
///#endif
public int size() {
return size;
}
public Iterator iterator() {
///#ifdef JDK12
cleanUp();
///#endif
return new Iterator() {
private int bucket = 0;
private int known = modCount;
private Bucket nextBucket;
private Object nextVal;
{
internalNext();
}
private void internalNext() {
while (true) {
while (nextBucket == null) {
if (bucket == buckets.length)
return;
nextBucket = buckets[bucket++];
}
nextVal = nextBucket.get();
if (nextVal != null)
return;
nextBucket = nextBucket.next;
}
}
public boolean hasNext() {
return nextBucket != null;
}
public Object next() {
if (known != modCount)
throw new ConcurrentModificationException();
if (nextBucket == null)
throw new NoSuchElementException();
Object result = nextVal;
nextBucket = nextBucket.next;
internalNext();
return result;
}
public void remove() {
throw new UnsupportedOperationException();
}
};
}
public Iterator iterateHashCode(final int hash) {
///#ifdef JDK12
cleanUp();
///#endif
return new Iterator() {
private int known = modCount;
private Bucket nextBucket
= buckets[Math.abs(hash % buckets.length)];
private Object nextVal;
{
internalNext();
}
private void internalNext() {
while (nextBucket != null) {
if (nextBucket.hash == hash) {
nextVal = nextBucket.get();
if (nextVal != null)
return;
}
nextBucket = nextBucket.next;
}
}
public boolean hasNext() {
return nextBucket != null;
}
public Object next() {
if (known != modCount)
throw new ConcurrentModificationException();
if (nextBucket == null)
throw new NoSuchElementException();
Object result = nextVal;
nextBucket = nextBucket.next;
internalNext();
return result;
}
public void remove() {
throw new UnsupportedOperationException();
}
};
}
public void put(int hash, Object o) {
if (size++ > threshold)
grow();
modCount++;
int slot = Math.abs(hash % buckets.length);
///#ifdef JDK12
Bucket b = new Bucket(o, queue);
///#else
/// Bucket b = new Bucket(o);
///#endif
b.hash = hash;
b.next = buckets[slot];
buckets[slot] = b;
}
public Object unify(Object o, int hash, Comparator comparator) {
///#ifdef JDK12
cleanUp();
///#endif
int slot = Math.abs(hash % buckets.length);
for (Bucket b = buckets[slot]; b != null; b = b.next) {
Object old = b.get();
if (old != null && comparator.compare(o, old) == 0)
return old;
}
put(hash, o);
return o;
}
}
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