NameSet.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.core.builder;

import org.eclipse.jdt.core.compiler.CharOperation;

public final class NameSet {

// to avoid using Enumerations, walk the individual values skipping nulls
	public char[][] names;

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

	public int threshold;

	public NameSet(int size) {
		this.elementSize= 0;
		this.threshold= size; // size represents the expected number of elements
		int extraRoom= (int)(size * 1.5f);
		if (this.threshold == extraRoom)
			extraRoom++;
		this.names= new char[extraRoom][];
	}

	public char[] add(char[] name) {
		int length= this.names.length;
		int index= CharOperation.hashCode(name) % length;
		char[] current;
		while ((current= this.names[index]) != null) {
			if (CharOperation.equals(current, name))
				return current;
			if (++index == length)
				index= 0;
		}
		this.names[index]= name;

		// assumes the threshold is never equal to the size of the table
		if (++this.elementSize > this.threshold)
			rehash();
		return name;
	}

	private void rehash() {
		NameSet newSet= new NameSet(this.elementSize * 2); // double the number of expected elements
		char[] current;
		for (int i= this.names.length; --i >= 0;)
			if ((current= this.names[i]) != null)
				newSet.add(current);

		this.names= newSet.names;
		this.elementSize= newSet.elementSize;
		this.threshold= newSet.threshold;
	}

	public String toString() {
		String s= ""; //$NON-NLS-1$
		char[] name;
		for (int i= 0, l= this.names.length; i < l; i++)
			if ((name= this.names[i]) != null)
				s+= new String(name) + "\n"; //$NON-NLS-1$
		return s;
	}
}