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1   /*
2    * Copyright  2000-2004 The Apache Software Foundation
3    *
4    *  Licensed under the Apache License, Version 2.0 (the "License"); 
5    *  you may not use this file except in compliance with the License.
6    *  You may obtain a copy of the License at
7    *
8    *      http://www.apache.org/licenses/LICENSE-2.0
9    *
10   *  Unless required by applicable law or agreed to in writing, software
11   *  distributed under the License is distributed on an "AS IS" BASIS,
12   *  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13   *  See the License for the specific language governing permissions and
14   *  limitations under the License. 
15   *
16   */
17  package org.apache.bcel.generic;
18  
19  import org.apache.bcel.Constants;
20  
21  /*** 
22   * Returnaddress, the type JSR or JSR_W instructions push upon the stack.
23   *
24   * see vmspec2 ß3.3.3
25   * @version $Id: ReturnaddressType.java 386056 2006-03-15 11:31:56Z tcurdt $
26   * @author Enver Haase
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(Constants.T_ADDRESS, "<return address>");
39      }
40  
41  
42      /***
43       * Creates a ReturnaddressType object with a target.
44       */
45      public ReturnaddressType(InstructionHandle returnTarget) {
46          super(Constants.T_ADDRESS, "<return address targeting " + returnTarget + ">");
47          this.returnTarget = returnTarget;
48      }
49  
50  
51      /*** @return a hash code value for the object.
52       */
53      public int hashCode() {
54          if (returnTarget == null) {
55              return 0;
56          }
57          return returnTarget.hashCode();
58      }
59  
60  
61      /***
62       * Returns if the two Returnaddresses refer to the same target.
63       */
64      public boolean equals( Object rat ) {
65          if (!(rat instanceof ReturnaddressType)) {
66              return false;
67          }
68          ReturnaddressType that = (ReturnaddressType) rat;
69          if (this.returnTarget == null || that.returnTarget == null) {
70              return that.returnTarget == this.returnTarget;
71          }
72          return that.returnTarget.equals(this.returnTarget);
73      }
74  
75  
76      /***
77       * @return the target of this ReturnaddressType
78       */
79      public InstructionHandle getTarget() {
80          return returnTarget;
81      }
82  }