/*
* eXist Open Source Native XML Database
* Copyright (C) 2001-06 Wolfgang M. Meier
* wolfgang@exist-db.org
* http://exist.sourceforge.net
*
* 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
* of the License, 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 Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
*
* $Id$
*/
package org.exist.util.hashtable;
import java.util.Iterator;
/**
* A hashtable which maps long keys to object values.
*
* @author Stephan Körnig
* @author Wolfgang Meier (wolfgang@exist-db.org)
*/
public class Long2ObjectHashMap extends AbstractHashtable {
protected long[] keys;
protected Object[] values;
public Long2ObjectHashMap() {
super();
keys = new long[tabSize];
values = new Object[tabSize];
}
public Long2ObjectHashMap(int iSize) {
super(iSize);
keys = new long[tabSize];
values = new Object[tabSize];
}
/**
* Puts a new key/value pair into the hashtable.
*
* If the key does already exist, just the value is updated.
*
* @param key
* @param value
*/
public void put(long key, Object value) {
try {
insert(key, value);
} catch (HashtableOverflowException e) {
long[] copyKeys = keys;
Object[] copyValues = values;
// enlarge the table with a prime value
tabSize = (int) nextPrime(tabSize + tabSize / 2);
keys = new long[tabSize];
values = new Object[tabSize];
items = 0;
for (int k = 0; k < copyValues.length; k++) {
if (copyValues[k] != null && copyValues[k] != REMOVED)
put(copyKeys[k], copyValues[k]);
}
put(key, value);
}
}
public Object get(long key) {
int idx = hash(key) % tabSize;
if(idx < 0)
idx *= -1;
if (values[idx] == null)
return null; // key does not exist
else if (keys[idx] == key) {
if(values[idx] == REMOVED)
return null;
return values[idx];
}
int rehashVal = rehash(idx);
for (int i = 0; i < tabSize; i++) {
idx = (idx + rehashVal) % tabSize;
if (values[idx] == null) {
return null; // key not found
} else if (keys[idx] == key) {
if(values[idx] == REMOVED)
return null;
return values[idx];
}
}
return null;
}
public Object remove(long key) {
int idx = hash(key) % tabSize;
if(idx < 0)
idx *= -1;
if (values[idx] == null) {
return null; // key does not exist
} else if (keys[idx] == key) {
if(values[idx] == REMOVED)
return null; // key has already been removed
Object o = values[idx];
values[idx] = REMOVED;
--items;
return o;
}
int rehashVal = rehash(idx);
for (int i = 0; i < tabSize; i++) {
idx = (idx + rehashVal) % tabSize;
if (values[idx] == null) {
return null; // key not found
} else if (keys[idx] == key) {
if(values[idx] == REMOVED)
return null; // key has already been removed
Object o = values[idx];
values[idx] = REMOVED;
--items;
return o;
}
}
return null;
}
public void clear() {
for (int i = 0; i < values.length; i++) {
values[i] = null;
}
items = 0;
}
public Iterator iterator() {
return new Long2ObjectIterator(Long2ObjectIterator.KEYS);
}
public Iterator valueIterator() {
return new Long2ObjectIterator(Long2ObjectIterator.VALUES);
}
protected Object insert(long key, Object value) throws HashtableOverflowException {
if (value == null)
throw new IllegalArgumentException("Illegal value: null");
int idx = hash(key) % tabSize;
if(idx < 0)
idx *= -1;
int bucket = -1;
// look for an empty bucket
if (values[idx] == null) {
keys[idx] = key;
values[idx] = value;
++items;
return null;
} else if (values[idx] == REMOVED) {
// remember the bucket, but continue to check
// for duplicate keys
bucket = idx;
} else if (keys[idx] == key) {
// duplicate value
Object dup = values[idx];
values[idx] = value;
return dup;
}
int rehashVal = rehash(idx);
int rehashCnt = 1;
for (int i = 0; i < tabSize; i++) {
idx = (idx + rehashVal) % tabSize;
if(values[idx] == REMOVED) {
if(bucket == -1)
bucket = idx;
} else if (values[idx] == null) {
if(bucket > -1) {
// store key into the empty bucket first found
idx = bucket;
}
keys[idx] = key;
values[idx] = value;
++items;
return null;
} else if(keys[idx] == key) {
// duplicate value
Object dup = values[idx];
values[idx] = value;
return dup;
}
++rehashCnt;
}
// should never happen, but just to be sure:
// if the key has not been inserted yet, do it now
if(bucket > -1) {
keys[bucket] = key;
values[bucket] = value;
++items;
return null;
}
throw new HashtableOverflowException();
}
protected int rehash(int iVal) {
int retVal = (iVal + iVal / 2) % tabSize;
if (retVal == 0)
retVal = 1;
return retVal;
}
protected final static int hash(long l) {
return (int) (l ^ (l >>> 32));
}
protected class Long2ObjectIterator extends HashtableIterator {
int idx = 0;
public Long2ObjectIterator(int type) {
super(type);
}
/* (non-Javadoc)
* @see java.util.Iterator#hasNext()
*/
public boolean hasNext() {
if (idx == tabSize)
return false;
while(values[idx] == null || values[idx] == REMOVED) {
++idx;
if(idx == tabSize)
return false;
}
return true;
}
/* (non-Javadoc)
* @see java.util.Iterator#next()
*/
public Object next() {
if(idx == tabSize)
return null;
while(values[idx] == null || values[idx] == REMOVED) {
++idx;
if(idx == tabSize)
return null;
}
if(returnType == VALUES)
return values[idx++];
else
return new Long(keys[idx++]);
}
}
}