set.java

已经移植好的java虚拟机

/*
 *	Set.java	1.8	02/09/27 SMI
 *
 * Copyright (c) 1998 Sun Microsystems, Inc. All Rights Reserved.
 *
 * This software is the confidential and proprietary information of Sun
 * Microsystems, Inc. ("Confidential Information").  You shall not
 * disclose such Confidential Information and shall use it only in
 * accordance with the terms of the license agreement you entered into
 * with Sun.
 *
 * SUN MAKES NO REPRESENTATIONS OR WARRANTIES ABOUT THE SUITABILITY OF THE
 * SOFTWARE, EITHER EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR
 * PURPOSE, OR NON-INFRINGEMENT. SUN SHALL NOT BE LIABLE FOR ANY DAMAGES
 * SUFFERED BY LICENSEE AS A RESULT OF USING, MODIFYING OR DISTRIBUTING
 * THIS SOFTWARE OR ITS DERIVATIVES.
 * Use is subject to license terms.
 */

/*
 * Set-of-objects
 * Add, delete, query, enumerate.
 * Dead simple.
 * This set implementation is best for small, often
 * empty sets, as used by the dependenceAnalysis classes.
 * It appears that a good fraction ( 1/3 to 1/2 ) of those
 * sets are empty, and most of the rest are pretty small.
 * That is the target use of this implementation.
 * 
 */
package util;
import java.util.Enumeration;
import java.util.Vector;

public class Set {

    static private final int defaultInitial = 10;

    int	  ninitial; 	// initial allocation for this one.
    Vector setData;

    public Set( int nin ){
	ninitial = nin;
    }

    public Set(){
	ninitial = defaultInitial;
    }

    public boolean isIn( Object o ){
	return (setData==null)?false:setData.contains( o );
    }

    public void addElement( Object o ){
	// see if its already in. If not,
	// add at end.
	if ( isIn( o ) ) return;

	// now add, extending if necessary.
	if ( setData == null ){
	    setData = new Vector( ninitial );
	}
	setData.addElement( o );
    }

    public void add( Object o ){ addElement( o ); }

    public Enumeration elements(){
	return (setData==null)?EmptyEnumeration.instance:setData.elements();
    }

    public void deleteAllElements(){
	setData = null;
    }

    public int size(){ return (setData==null)?0:setData.size(); } 

}