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Java > Open Source Codes > com > sun > org > apache > bcel > internal > generic > JsrInstruction


1 package com.sun.org.apache.bcel.internal.generic;
2
3 /* ====================================================================
4  * The Apache Software License, Version 1.1
5  *
6  * Copyright (c) 2001 The Apache Software Foundation. All rights
7  * reserved.
8  *
9  * Redistribution and use in source and binary forms, with or without
10  * modification, are permitted provided that the following conditions
11  * are met:
12  *
13  * 1. Redistributions of source code must retain the above copyright
14  * notice, this list of conditions and the following disclaimer.
15  *
16  * 2. Redistributions in binary form must reproduce the above copyright
17  * notice, this list of conditions and the following disclaimer in
18  * the documentation and/or other materials provided with the
19  * distribution.
20  *
21  * 3. The end-user documentation included with the redistribution,
22  * if any, must include the following acknowledgment:
23  * "This product includes software developed by the
24  * Apache Software Foundation (http://www.apache.org/)."
25  * Alternately, this acknowledgment may appear in the software itself,
26  * if and wherever such third-party acknowledgments normally appear.
27  *
28  * 4. The names "Apache" and "Apache Software Foundation" and
29  * "Apache BCEL" must not be used to endorse or promote products
30  * derived from this software without prior written permission. For
31  * written permission, please contact apache@apache.org.
32  *
33  * 5. Products derived from this software may not be called "Apache",
34  * "Apache BCEL", nor may "Apache" appear in their name, without
35  * prior written permission of the Apache Software Foundation.
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37  * THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESSED OR IMPLIED
38  * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
39  * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
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43  * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF
44  * USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
45  * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
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51  * This software consists of voluntary contributions made by many
52  * individuals on behalf of the Apache Software Foundation. For more
53  * information on the Apache Software Foundation, please see
54  * <http://www.apache.org/>.
55  */
56
57 /**
58  * Super class for JSR - Jump to subroutine
59  *
60  * @version $Id: JsrInstruction.java,v 1.1.1.1 2001/10/29 20:00:20 jvanzyl Exp $
61  * @author <A HREF="mailto:markus.dahm@berlin.de">M. Dahm</A>
62  */
63 public abstract class JsrInstruction extends BranchInstruction
64   implements UnconditionalBranch, TypedInstruction, StackProducer
65 {
66   JsrInstruction(short opcode, InstructionHandle target) {
67     super(opcode, target);
68   }
69
70   /**
71    * Empty constructor needed for the Class.newInstance() statement in
72    * Instruction.readInstruction(). Not to be used otherwise.
73    */
74   JsrInstruction(){}
75
76   /** @return return address type
77    */
78   public Type getType(ConstantPoolGen cp) {
79     return new ReturnaddressType(physicalSuccessor());
80   }
81
82
83  /**
84   * Returns an InstructionHandle to the physical successor
85   * of this JsrInstruction. <B>For this method to work,
86   * this JsrInstruction object must not be shared between
87   * multiple InstructionHandle objects!</B>
88   * Formally, there must not be InstructionHandle objects
89   * i, j where i != j and i.getInstruction() == this ==
90   * j.getInstruction().
91   * @return an InstructionHandle to the "next" instruction that
92   * will be executed when RETurned from a subroutine.
93   */
94   public InstructionHandle physicalSuccessor(){
95     InstructionHandle ih = this.target;
96         
97     // Rewind!
98 while(ih.getPrev() != null)
99       ih = ih.getPrev();
100     
101     // Find the handle for "this" JsrInstruction object.
102 while(ih.getInstruction() != this)
103       ih = ih.getNext();
104     
105     InstructionHandle toThis = ih;
106     
107     while(ih != null){
108         ih = ih.getNext();
109         if ((ih != null) && (ih.getInstruction() == this))
110         throw new RuntimeException JavaDoc("physicalSuccessor() called on a shared JsrInstruction.");
111     }
112     
113     // Return the physical successor
114 return toThis.getNext();
115   }
116 }
117
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