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


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  * LDC - Push item from constant pool.
61  *
62  * <PRE>Stack: ... -&gt; ..., item</PRE>
63  *
64  * @version $Id: LDC.java,v 1.1.1.1 2001/10/29 20:00:21 jvanzyl Exp $
65  * @author <A HREF="mailto:markus.dahm@berlin.de">M. Dahm</A>
66  */
67 public class LDC extends CPInstruction
68   implements PushInstruction, ExceptionThrower, TypedInstruction {
69   /**
70    * Empty constructor needed for the Class.newInstance() statement in
71    * Instruction.readInstruction(). Not to be used otherwise.
72    */
73   LDC() {}
74
75   public LDC(int index) {
76     super(com.sun.org.apache.bcel.internal.Constants.LDC_W, index);
77     setSize();
78   }
79   
80   // Adjust to proper size
81 protected final void setSize() {
82     if(index <= com.sun.org.apache.bcel.internal.Constants.MAX_BYTE) { // Fits in one byte?
83 opcode = com.sun.org.apache.bcel.internal.Constants.LDC;
84       length = 2;
85     } else {
86       opcode = com.sun.org.apache.bcel.internal.Constants.LDC_W;
87       length = 3;
88     }
89   }
90
91   /**
92    * Dump instruction as byte code to stream out.
93    * @param out Output stream
94    */
95   public void dump(DataOutputStream out) throws IOException {
96     out.writeByte(opcode);
97
98     if(length == 2)
99       out.writeByte(index);
100     else // Applies for LDC_W
101 out.writeShort(index);
102   }
103
104   /**
105    * Set the index to constant pool and adjust size.
106    */
107   public final void setIndex(int index) {
108     super.setIndex(index);
109     setSize();
110   }
111
112   /**
113    * Read needed data (e.g. index) from file.
114    */
115   protected void initFromFile(ByteSequence bytes, boolean wide)
116        throws IOException
117   {
118     length = 2;
119     index = bytes.readUnsignedByte();
120   }
121
122   public Object JavaDoc getValue(ConstantPoolGen cpg) {
123     com.sun.org.apache.bcel.internal.classfile.Constant c = cpg.getConstantPool().getConstant(index);
124
125     switch(c.getTag()) {
126       case com.sun.org.apache.bcel.internal.Constants.CONSTANT_String:
127     int i = ((com.sun.org.apache.bcel.internal.classfile.ConstantString)c).getStringIndex();
128     c = cpg.getConstantPool().getConstant(i);
129     return ((com.sun.org.apache.bcel.internal.classfile.ConstantUtf8)c).getBytes();
130
131     case com.sun.org.apache.bcel.internal.Constants.CONSTANT_Float:
132     return new Float JavaDoc(((com.sun.org.apache.bcel.internal.classfile.ConstantFloat)c).getBytes());
133
134     case com.sun.org.apache.bcel.internal.Constants.CONSTANT_Integer:
135     return new Integer JavaDoc(((com.sun.org.apache.bcel.internal.classfile.ConstantInteger)c).getBytes());
136
137     default: // Never reached
138 throw new RuntimeException JavaDoc("Unknown or invalid constant type at " + index);
139       }
140   }
141
142   public Type getType(ConstantPoolGen cpg) {
143     switch(cpg.getConstantPool().getConstant(index).getTag()) {
144     case com.sun.org.apache.bcel.internal.Constants.CONSTANT_String: return Type.STRING;
145     case com.sun.org.apache.bcel.internal.Constants.CONSTANT_Float: return Type.FLOAT;
146     case com.sun.org.apache.bcel.internal.Constants.CONSTANT_Integer: return Type.INT;
147     default: // Never reached
148 throw new RuntimeException JavaDoc("Unknown or invalid constant type at " + index);
149     }
150   }
151
152   public Class JavaDoc[] getExceptions() {
153     return com.sun.org.apache.bcel.internal.ExceptionConstants.EXCS_STRING_RESOLUTION;
154   }
155
156   /**
157    * Call corresponding visitor method(s). The order is:
158    * Call visitor methods of implemented interfaces first, then
159    * call methods according to the class hierarchy in descending order,
160    * i.e., the most specific visitXXX() call comes last.
161    *
162    * @param v Visitor object
163    */
164   public void accept(Visitor v) {
165     v.visitStackProducer(this);
166     v.visitPushInstruction(this);
167     v.visitExceptionThrower(this);
168     v.visitTypedInstruction(this);
169     v.visitCPInstruction(this);
170     v.visitLDC(this);
171   }
172 }
173
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