001    /*
002     *  This file is part of the Jikes RVM project (http://jikesrvm.org).
003     *
004     *  This file is licensed to You under the Eclipse Public License (EPL);
005     *  You may not use this file except in compliance with the License. You
006     *  may obtain a copy of the License at
007     *
008     *      http://www.opensource.org/licenses/eclipse-1.0.php
009     *
010     *  See the COPYRIGHT.txt file distributed with this work for information
011     *  regarding copyright ownership.
012     */
013    package org.jikesrvm.compilers.opt.ir.operand;
014    
015    import org.jikesrvm.classloader.TypeReference;
016    
017    /**
018     * This operand represents the {@code null} constant.
019     *
020     * @see Operand
021     */
022    public final class NullConstantOperand extends ConstantOperand {
023    
024      @Override
025      public Operand copy() {
026        return new NullConstantOperand();
027      }
028    
029      /**
030       * @return TypeReference.NULL_TYPE
031       */
032      @Override
033      public TypeReference getType() {
034        return TypeReference.NULL_TYPE;
035      }
036    
037      /**
038       * @return <code>true</code>
039       */
040      @Override
041      public boolean isRef() {
042        return true;
043      }
044    
045      /**
046       * @return <code>true</code>
047       */
048      @Override
049      public boolean isDefinitelyNull() {
050        return true;
051      }
052    
053      @Override
054      public boolean similar(Operand op) {
055        return op instanceof NullConstantOperand;
056      }
057    
058      /**
059       * Returns the string representation of this operand.
060       *
061       * @return a string representation of this operand.
062       */
063      @Override
064      public String toString() {
065        return "<null>";
066      }
067    }