HashtableOfType.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;

import org.eclipse.jdt.core.compiler.CharOperation;
import org.eclipse.jdt.internal.compiler.lookup.ReferenceBinding;

public final class HashtableOfType {
	// to avoid using Enumerations, walk the individual tables skipping nulls
	public char[] keyTable[];

	public ReferenceBinding valueTable[];

	public int elementSize; // number of elements in the table

	int threshold;

	public HashtableOfType() {
		this(3);
	}

	public HashtableOfType(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 char[extraRoom][];
		this.valueTable= new ReferenceBinding[extraRoom];
	}

	public boolean containsKey(char[] key) {
		int length= this.keyTable.length, index= CharOperation.hashCode(key) % length;
		int keyLength= key.length;
		char[] currentKey;
		while ((currentKey= this.keyTable[index]) != null) {
			if (currentKey.length == keyLength && CharOperation.equals(currentKey, key))
				return true;
			if (++index == length) {
				index= 0;
			}
		}
		return false;
	}

	public ReferenceBinding get(char[] key) {
		int length= this.keyTable.length, index= CharOperation.hashCode(key) % length;
		int keyLength= key.length;
		char[] currentKey;
		while ((currentKey= this.keyTable[index]) != null) {
			if (currentKey.length == keyLength && CharOperation.equals(currentKey, key))
				return this.valueTable[index];
			if (++index == length) {
				index= 0;
			}
		}
		return null;
	}

	public ReferenceBinding put(char[] key, ReferenceBinding value) {
		int length= this.keyTable.length, index= CharOperation.hashCode(key) % length;
		int keyLength= key.length;
		char[] currentKey;
		while ((currentKey= this.keyTable[index]) != null) {
			if (currentKey.length == keyLength && CharOperation.equals(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() {
		HashtableOfType newHashtable= new HashtableOfType(this.elementSize < 100 ? 100 : this.elementSize * 2); // double the number of expected elements
		char[] currentKey;
		for (int i= this.keyTable.length; --i >= 0;)
			if ((currentKey= this.keyTable[i]) != null)
				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= ""; //$NON-NLS-1$
		ReferenceBinding type;
		for (int i= 0, length= this.valueTable.length; i < length; i++)
			if ((type= this.valueTable[i]) != null)
				s+= type.toString() + "\n"; //$NON-NLS-1$
		return s;
	}
}