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NullType.java

package ca.mcgill.sable.soot;

/* * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * *
 * Soot, a Java(TM) classfile optimization framework.                *
 * Copyright (C) 1998 Etienne Gagnon (gagnon@sable.mcgill.ca).  All  *
 * rights reserved.                                                  *
 *                                                                   *
 * This work was done as a project of the Sable Research Group,      *
 * School of Computer Science, McGill University, Canada             *
 * (http://www.sable.mcgill.ca/).  It is understood that any         *
 * modification not identified as such is not covered by the         *
 * preceding statement.                                              *
 *                                                                   *
 * This work is free software; you can redistribute it and/or        *
 * modify it under the terms of the GNU Library General Public       *
 * License as published by the Free Software Foundation; either      *
 * version 2 of the License, or (at your option) any later version.  *
 *                                                                   *
 * This work 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 *
 * Library General Public License for more details.                  *
 *                                                                   *
 * You should have received a copy of the GNU Library General Public *
 * License along with this library; if not, write to the             *
 * Free Software Foundation, Inc., 59 Temple Place - Suite 330,      *
 * Boston, MA  02111-1307, USA.                                      *
 *                                                                   *
 * Java is a trademark of Sun Microsystems, Inc.                     *
 *                                                                   *
 * To submit a bug report, send a comment, or get the latest news on *
 * this project and other Sable Research Group projects, please      *
 * visit the web site: http://www.sable.mcgill.ca/                   *
 * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * */

/*
 Reference Version
 -----------------
 This is the latest official version on which this file is based.
 The reference version is: $SootVersion: 1.beta.4 $

 Change History
 --------------
 A) Notes:

 Please use the following template.  Most recent changes should
 appear at the top of the list.

 - Modified on [date (March 1, 1900)] by [name]. [(*) if appropriate]
   [description of modification].

 Any Modification flagged with "(*)" was done as a project of the
 Sable Research Group, School of Computer Science,
 McGill University, Canada (http://www.sable.mcgill.ca/).

 You should add your copyright, using the following template, at
 the top of this file, along with other copyrights.

 *                                                                   *
 * Modifications by [name] are                                       *
 * Copyright (C) [year(s)] [your name (or company)].  All rights     *
 * reserved.                                                         *
 *                                                                   *

 B) Changes:

 - Modified on November 13, 1998 by Raja Vallee-Rai (kor@sable.mcgill.ca) (*)
   Made hashCode() deterministic.

 - Modified on November 2, 1998 by Raja Vallee-Rai (kor@sable.mcgill.ca) (*)
   Repackaged all source files and performed extensive modifications.
   First initial release of Soot.

 - Modified on October 2, 1998 by Raja Vallee-Rai (kor@sable.mcgill.ca). (*)
   Modified toString value of NullType.

 - Modified on July 5, 1998 by Etienne Gagnon (gagnon@sable.mcgill.ca). (*)
   Initial Version.
*/

import ca.mcgill.sable.util.*;

public class NullType extends Type
{
    private static NullType constant = new NullType();

    private NullType()
    {
    }
    public void apply(Switch sw)
    {
        ((TypeSwitch) sw).caseNullType(this);
    }
    public boolean equals(Object t)
    {
        return this == t;
    }
    public int hashCode()
    {
        return 0x9891DFE1;
    }
    public String toString()
    {
        return "<null>";
    }
    public static NullType v()
    {
        return constant;
    }
}

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