/*
 *  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;

/**
 * A hashtable which maps object keys to long values.
 * 
 * Keys are compared by their object identity, i.e. two objects are equal
 * if object1 == object2.
 * 
 * @author Stephan Körnig
 * @author Wolfgang Meier (wolfgang@exist-db.org)
 */
public class Object2LongIdentityHashMap extends Object2LongHashMap {

	public Object2LongIdentityHashMap() {
		super();
	}

	public Object2LongIdentityHashMap(int iSize) {
		super(iSize);
	}

	public long get(Object key) {
		int idx = hash(key) % tabSize;
		if (idx < 0)
			idx *= -1;
		if (keys[idx] == null)
			return -1; // key does not exist
		else if (keys[idx] == key) {
			return values[idx];
		}
		int rehashVal = rehash(idx);
		for (int i = 0; i < tabSize; i++) {
			idx = (idx + rehashVal) % tabSize;
			if (keys[idx] == null) {
				return -1; // key not found
			} else if (keys[idx] == key) {
				return values[idx];
			}
		}
		return -1;
	}

	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] == 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] == key) {
				return true;
			}
		}
		return false;
	}

	public long remove(Object key) {
		int idx = hash(key) % tabSize;
		if (idx < 0)
			idx *= -1;
		if (keys[idx] == null) {
			return -1; // key does not exist
		} else if (keys[idx] == 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 -1; // key not found
			} else if (keys[idx] == key) {
				keys[idx] = REMOVED;
				--items;
				return values[idx];
			}
		}
		return -1;
	}

	protected void insert(Object key, long 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] == 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] == 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();
	}
}