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      1 /*
      2  * Licensed to the Apache Software Foundation (ASF) under one or more
      3  * contributor license agreements.  See the NOTICE file distributed with
      4  * this work for additional information regarding copyright ownership.
      5  * The ASF licenses this file to You under the Apache License, Version 2.0
      6  * (the "License"); you may not use this file except in compliance with
      7  * the License.  You may obtain a copy of the License at
      8  *
      9  *      http://www.apache.org/licenses/LICENSE-2.0
     10  *
     11  *  Unless required by applicable law or agreed to in writing, software
     12  *  distributed under the License is distributed on an "AS IS" BASIS,
     13  *  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
     14  *  See the License for the specific language governing permissions and
     15  *  limitations under the License.
     16  *
     17  */
     18 package org.apache.bcel.generic;
     19 
     20 import org.apache.bcel.Const;
     21 
     22 /**
     23  * Returnaddress, the type JSR or JSR_W instructions push upon the stack.
     24  *
     25  * see vmspec2 3.3.3
     26  * @version $Id$
     27  */
     28 public class ReturnaddressType extends Type {
     29 
     30     public static final ReturnaddressType NO_TARGET = new ReturnaddressType();
     31     private InstructionHandle returnTarget;
     32 
     33 
     34     /**
     35      * A Returnaddress [that doesn't know where to return to].
     36      */
     37     private ReturnaddressType() {
     38         super(Const.T_ADDRESS, "<return address>");
     39     }
     40 
     41 
     42     /**
     43      * Creates a ReturnaddressType object with a target.
     44      */
     45     public ReturnaddressType(final InstructionHandle returnTarget) {
     46         super(Const.T_ADDRESS, "<return address targeting " + returnTarget + ">");
     47         this.returnTarget = returnTarget;
     48     }
     49 
     50 
     51     /** @return a hash code value for the object.
     52      */
     53     @Override
     54     public int hashCode() {
     55         if (returnTarget == null) {
     56             return 0;
     57         }
     58         return returnTarget.hashCode();
     59     }
     60 
     61 
     62     /**
     63      * Returns if the two Returnaddresses refer to the same target.
     64      */
     65     @Override
     66     public boolean equals( final Object rat ) {
     67         if (!(rat instanceof ReturnaddressType)) {
     68             return false;
     69         }
     70         final ReturnaddressType that = (ReturnaddressType) rat;
     71         if (this.returnTarget == null || that.returnTarget == null) {
     72             return that.returnTarget == this.returnTarget;
     73         }
     74         return that.returnTarget.equals(this.returnTarget);
     75     }
     76 
     77 
     78     /**
     79      * @return the target of this ReturnaddressType
     80      */
     81     public InstructionHandle getTarget() {
     82         return returnTarget;
     83     }
     84 }
     85