org.eclipse.jdt.core/compiler/org/eclipse/jdt/internal/compiler/util/HashtableOfInt.java

/*******************************************************************************
 * Copyright (c) 2000, 2009 IBM Corporation and others.
 * All rights reserved. This program and the accompanying materials
 * are made available under the terms of the Eclipse Public License v1.0
 * which accompanies this distribution, and is available at
 * http://www.eclipse.org/legal/epl-v10.html
 *
 * Contributors:
 *     IBM Corporation - initial API and implementation
 *******************************************************************************/
package org.eclipse.jdt.internal.compiler.util;

 /**
  *	Hashtable for non-zero int keys.
  */

public final class HashtableOfInt {
	// to avoid using Enumerations, walk the individual tables skipping nulls
	public int[] keyTable;
	public Object[] valueTable;

	public int elementSize; // number of elements in the table
	int threshold;
public HashtableOfInt() {
	this(13);
}
public HashtableOfInt(int size) {
	this.elementSize = 0;
	this.threshold = size; // size represents the expected number of elements
	int extraRoom = (int) (size * 1.75f);
	if (this.threshold == extraRoom)
		extraRoom++;
	this.keyTable = new int[extraRoom];
	this.valueTable = new Object[extraRoom];
}
public boolean containsKey(int key) {
	int length = this.keyTable.length, index = key % length;
	int currentKey;
	while ((currentKey = this.keyTable[index]) != 0) {
		if (currentKey == key)
			return true;
		if (++index == length) {
			index = 0;
		}
	}
	return false;
}
public Object get(int key) {
	int length = this.keyTable.length, index = key % length;
	int currentKey;
	while ((currentKey = this.keyTable[index]) != 0) {
		if (currentKey == key)  return this.valueTable[index];
		if (++index == length) {
			index = 0;
		}
	}
	return null;
}
public Object put(int key, Object value) {
	int length = this.keyTable.length, index = key % length;
	int currentKey;
	while ((currentKey = this.keyTable[index]) != 0) {
		if (currentKey == key)  return this.valueTable[index] = value;
		if (++index == length) {
			index = 0;
		}
	}
	this.keyTable[index] = key;
	this.valueTable[index] = value;

	// assumes the threshold is never equal to the size of the table
	if (++this.elementSize > this.threshold)
		rehash();
	return value;
}
private void rehash() {
	HashtableOfInt newHashtable = new HashtableOfInt(this.elementSize * 2); // double the number of expected elements
	int currentKey;
	for (int i = this.keyTable.length; --i >= 0;)
		if ((currentKey = this.keyTable[i]) != 0)
			newHashtable.put(currentKey, this.valueTable[i]);

	this.keyTable = newHashtable.keyTable;
	this.valueTable = newHashtable.valueTable;
	this.threshold = newHashtable.threshold;
}
public int size() {
	return this.elementSize;
}
public String toString() {
	String s = ""; //$NON-NLS-1$
	Object object;
	for (int i = 0, length = this.valueTable.length; i < length; i++)
		if ((object = this.valueTable[i]) != null)
			s += this.keyTable[i] + " -> " + object.toString() + "\n"; //$NON-NLS-2$ //$NON-NLS-1$
	return s;
}
}