/*
* 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 object keys to long values.
*
* Keys are compared by their object equality, i.e. two objects are equal
* if object1.equals(object2).
*
* @author Stephan Körnig
* @author Wolfgang Meier (wolfgang@exist-db.org)
*/
public class Object2IntHashMap extends AbstractHashtable {
public static final int UNKNOWN_KEY = -1;
protected Object[] keys;
protected int[] values;
public Object2IntHashMap() {
super();
keys = new Object[tabSize];
values = new int[tabSize];
}
public Object2IntHashMap(int iSize) {
super(iSize);
keys = new Object[tabSize];
values = new int[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(Object key, int value) {
try {
insert(key, value);
} catch (HashtableOverflowException e) {
Object[] copyKeys = keys;
int[] copyValues = values;
// enlarge the table with a prime value
tabSize = (int) nextPrime(tabSize + tabSize / 2);
keys = new Object[tabSize];
values = new int[tabSize];
items = 0;
for (int k = 0; k < copyValues.length; k++) {
if (copyKeys[k] != null && copyKeys[k] != REMOVED)
put(copyKeys[k], copyValues[k]);
}
put(key, value);
}
}
public int get(Object key) {
int idx = hash(key) % tabSize;
if (idx < 0)
idx *= -1;
if (keys[idx] == null)
return UNKNOWN_KEY;
else if (keys[idx].equals(key)) {
return values[idx];
}
int rehashVal = rehash(idx);
for (int i = 0; i < tabSize; i++) {
idx = (idx + rehashVal) % tabSize;
if (keys[idx] == null) {
return UNKNOWN_KEY;
} else if (keys[idx].equals(key)) {
return values[idx];
}
}
return UNKNOWN_KEY;
}
public boolean containsKey(Object key) {
int idx = hash(key) % tabSize;
if (idx < 0)
idx *= -1;
if (keys[idx] == null)
return false; // key does not exist
else if (keys[idx].equals(key)) {
return true;
}
int rehashVal = rehash(idx);
for (int i = 0; i < tabSize; i++) {
idx = (idx + rehashVal) % tabSize;
if (keys[idx] == null) {
return false; // key not found
} else if (keys[idx].equals(key)) {
return true;
}
}
return false;
}
public int remove(Object key) {
int idx = hash(key) % tabSize;
if (idx < 0)
idx *= -1;
if (keys[idx] == null) {
return UNKNOWN_KEY;
} else if (keys[idx].equals(key)) {
keys[idx] = REMOVED;
--items;
return values[idx];
}
int rehashVal = rehash(idx);
for (int i = 0; i < tabSize; i++) {
idx = (idx + rehashVal) % tabSize;
if (keys[idx] == null) {
return UNKNOWN_KEY;
} else if (keys[idx].equals(key)) {
keys[idx] = REMOVED;
--items;
return values[idx];
}
}
return UNKNOWN_KEY;
}
public Iterator iterator() {
return new Object2LongIterator(HashtableIterator.KEYS);
}
public Iterator valueIterator() {
return new Object2LongIterator(HashtableIterator.VALUES);
}
public Iterator stableIterator() {
return new Object2LongStableIterator(HashtableIterator.KEYS);
}
protected void insert(Object key, int value) throws HashtableOverflowException {
if (key == 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 (keys[idx] == null) {
keys[idx] = key;
values[idx] = value;
++items;
return;
} else if (keys[idx] == REMOVED) {
// remember the bucket, but continue to check
// for duplicate keys
bucket = idx;
} else if (keys[idx].equals(key)) {
// duplicate value
values[idx] = value;
return;
}
int rehashVal = rehash(idx);
int rehashCnt = 1;
for (int i = 0; i < tabSize; i++) {
idx = (idx + rehashVal) % tabSize;
if (keys[idx] == REMOVED) {
bucket = idx;
} else if (keys[idx] == null) {
if (bucket > -1) {
// store key into the empty bucket first found
idx = bucket;
}
keys[idx] = key;
values[idx] = value;
++items;
return;
} else if (keys[idx].equals(key)) {
// duplicate value
values[idx] = value;
return;
}
++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;
}
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(Object o) {
return o.hashCode();
}
protected class Object2LongIterator extends HashtableIterator {
int idx = 0;
public Object2LongIterator(int type) {
super(type);
}
/* (non-Javadoc)
* @see java.util.Iterator#hasNext()
*/
public boolean hasNext() {
if (idx == tabSize)
return false;
while (keys[idx] == null || keys[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 (keys[idx] == null || keys[idx] == REMOVED) {
++idx;
if (idx == tabSize)
return null;
}
if (returnType == VALUES)
return new Long(values[idx++]);
else
return keys[idx++];
}
}
protected class Object2LongStableIterator extends HashtableIterator {
Object[] mKeys = null;
int[] mValues = null;
int idx = 0;
public Object2LongStableIterator(int type) {
super(type);
mKeys = new Object[tabSize];
System.arraycopy(keys, 0, mKeys, 0, tabSize);
mValues = new int[tabSize];
System.arraycopy(values, 0, mValues, 0, tabSize);
}
/* (non-Javadoc)
* @see java.util.Iterator#hasNext()
*/
public boolean hasNext() {
if (idx == tabSize)
return false;
while (mKeys[idx] == null || mKeys[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 (mKeys[idx] == null || mKeys[idx] == REMOVED) {
++idx;
if (idx == tabSize)
return null;
}
if (returnType == VALUES)
return new Integer(mValues[idx++]);
else
return mKeys[idx++];
}
}
}