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


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.
36  *
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
40  * DISCLAIMED. IN NO EVENT SHALL THE APACHE SOFTWARE FOUNDATION OR
41  * ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
42  * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
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,
46  * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
47  * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
48  * SUCH DAMAGE.
49  * ====================================================================
50  *
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 import java.io.*;
57 import com.sun.org.apache.bcel.internal.util.ByteSequence;
58
59 /**
60  * RET - Return from subroutine
61  *
62  * <PRE>Stack: ..., -&gt; ..., address</PRE>
63  *
64  * @version $Id: RET.java,v 1.1.1.1 2001/10/29 20:00:25 jvanzyl Exp $
65  * @author <A HREF="mailto:markus.dahm@berlin.de">M. Dahm</A>
66  */
67 public class RET extends Instruction implements IndexedInstruction, TypedInstruction {
68   private boolean wide;
69   private int index; // index to local variable containg the return address
70
71   /**
72    * Empty constructor needed for the Class.newInstance() statement in
73    * Instruction.readInstruction(). Not to be used otherwise.
74    */
75   RET() {}
76
77   public RET(int index) {
78     super(com.sun.org.apache.bcel.internal.Constants.RET, (short)2);
79     setIndex(index); // May set wide as side effect
80 }
81
82   /**
83    * Dump instruction as byte code to stream out.
84    * @param out Output stream
85    */
86   public void dump(DataOutputStream out) throws IOException {
87     if(wide)
88       out.writeByte(com.sun.org.apache.bcel.internal.Constants.WIDE);
89
90     out.writeByte(opcode);
91
92     if(wide)
93       out.writeShort(index);
94     else
95       out.writeByte(index);
96   }
97
98   private final void setWide() {
99     if(wide = index > com.sun.org.apache.bcel.internal.Constants.MAX_BYTE)
100       length = 4; // Including the wide byte
101 else
102       length = 2;
103   }
104
105   /**
106    * Read needed data (e.g. index) from file.
107    */
108   protected void initFromFile(ByteSequence bytes, boolean wide) throws IOException
109   {
110     this.wide = wide;
111
112     if(wide) {
113       index = bytes.readUnsignedShort();
114       length = 4;
115     } else {
116       index = bytes.readUnsignedByte();
117       length = 2;
118     }
119   }
120
121   /**
122    * @return index of local variable containg the return address
123    */
124   public final int getIndex() { return index; }
125
126   /**
127    * Set index of local variable containg the return address
128    */
129   public final void setIndex(int n) {
130     if(n < 0)
131       throw new ClassGenException("Negative index value: " + n);
132
133     index = n;
134     setWide();
135   }
136
137   /**
138    * @return mnemonic for instruction
139    */
140   public String JavaDoc toString(boolean verbose) {
141     return super.toString(verbose) + " " + index;
142   }
143
144   /** @return return address type
145    */
146   public Type getType(ConstantPoolGen cp) {
147       return ReturnaddressType.NO_TARGET;
148   }
149
150   /**
151    * Call corresponding visitor method(s). The order is:
152    * Call visitor methods of implemented interfaces first, then
153    * call methods according to the class hierarchy in descending order,
154    * i.e., the most specific visitXXX() call comes last.
155    *
156    * @param v Visitor object
157    */
158   public void accept(Visitor v) {
159     v.visitRET(this);
160   }
161 }
162
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