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Java > Open Source Codes > org > apache > bcel > generic > RET


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 java.io.DataOutputStream JavaDoc;
20 import java.io.IOException JavaDoc;
21 import org.apache.bcel.util.ByteSequence;
22
23 /**
24  * RET - Return from subroutine
25  *
26  * <PRE>Stack: ... -&gt; ...</PRE>
27  *
28  * @version $Id: RET.java 386056 2006-03-15 11:31:56Z tcurdt $
29  * @author <A HREF="mailto:m.dahm@gmx.de">M. Dahm</A>
30  */
31 public class RET extends Instruction implements IndexedInstruction, TypedInstruction {
32
33     private boolean wide;
34     private int index; // index to local variable containg the return address
35
36
37     /**
38      * Empty constructor needed for the Class.newInstance() statement in
39      * Instruction.readInstruction(). Not to be used otherwise.
40      */
41     RET() {
42     }
43
44
45     public RET(int index) {
46         super(org.apache.bcel.Constants.RET, (short) 2);
47         setIndex(index); // May set wide as side effect
48 }
49
50
51     /**
52      * Dump instruction as byte code to stream out.
53      * @param out Output stream
54      */
55     public void dump( DataOutputStream JavaDoc out ) throws IOException JavaDoc {
56         if (wide) {
57             out.writeByte(org.apache.bcel.Constants.WIDE);
58         }
59         out.writeByte(opcode);
60         if (wide) {
61             out.writeShort(index);
62         } else {
63             out.writeByte(index);
64         }
65     }
66
67
68     private final void setWide() {
69         wide = index > org.apache.bcel.Constants.MAX_BYTE;
70         if (wide) {
71             length = 4; // Including the wide byte
72 } else {
73             length = 2;
74         }
75     }
76
77
78     /**
79      * Read needed data (e.g. index) from file.
80      */
81     protected void initFromFile( ByteSequence bytes, boolean wide ) throws IOException JavaDoc {
82         this.wide = wide;
83         if (wide) {
84             index = bytes.readUnsignedShort();
85             length = 4;
86         } else {
87             index = bytes.readUnsignedByte();
88             length = 2;
89         }
90     }
91
92
93     /**
94      * @return index of local variable containg the return address
95      */
96     public final int getIndex() {
97         return index;
98     }
99
100
101     /**
102      * Set index of local variable containg the return address
103      */
104     public final void setIndex( int n ) {
105         if (n < 0) {
106             throw new ClassGenException("Negative index value: " + n);
107         }
108         index = n;
109         setWide();
110     }
111
112
113     /**
114      * @return mnemonic for instruction
115      */
116     public String JavaDoc toString( boolean verbose ) {
117         return super.toString(verbose) + " " + index;
118     }
119
120
121     /** @return return address type
122      */
123     public Type getType( ConstantPoolGen cp ) {
124         return ReturnaddressType.NO_TARGET;
125     }
126
127
128     /**
129      * Call corresponding visitor method(s). The order is:
130      * Call visitor methods of implemented interfaces first, then
131      * call methods according to the class hierarchy in descending order,
132      * i.e., the most specific visitXXX() call comes last.
133      *
134      * @param v Visitor object
135      */
136     public void accept( Visitor v ) {
137         v.visitRET(this);
138     }
139 }
140
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