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NullExpr.java

package edu.ksu.cis.bandera.bir;

/* * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * *
 * Bandera, a Java(TM) analysis and transformation toolkit           *
 * Copyright (C) 1998, 1999   James Corbett (corbett@hawaii.edu)     *
 * All rights reserved.                                              *
 *                                                                   *
 * This work was done as a project in the SAnToS Laboratory,         *
 * Department of Computing and Information Sciences, Kansas State    *
 * University, USA (http://www.cis.ksu.edu/santos).                  *
 * 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 toolkit; 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 SAnToS projects, please visit the web-site *
 *                http://www.cis.ksu.edu/santos                      *
 * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * */
import ca.mcgill.sable.util.*;

/**
 * The null reference.
 * <p>
 * Note that we must know the TransSystem to create a NullExpr since
 * the type of the NullExpr is the refAny type of the TransSystem
 * (this allows the NullExpr to be assigned to any ref type in
 * the TransSystem).
 */

public class NullExpr implements Literal {

    TransSystem system;

    public NullExpr(TransSystem system) {
    this.system = system;
    }
    public void apply(Switch sw)
    {
        ((ExprSwitch) sw).caseNullExpr(this);
    }
    public boolean equals(Object o) {
    return (this.getClass() == o.getClass());
    }
    public Type getType() {
    return system.refAnyType();
    }
    public void print() {}
    public String toString() {
    return "null";
    }
}

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