1 /*
2  * reserved comment block
3  * DO NOT REMOVE OR ALTER!
4  */
5 package com.sun.org.apache.bcel.internal.generic;
6 
7 /* ====================================================================
8  * The Apache Software License, Version 1.1
9  *
10  * Copyright (c) 2001 The Apache Software Foundation.  All rights
11  * reserved.
12  *
13  * Redistribution and use in source and binary forms, with or without
14  * modification, are permitted provided that the following conditions
15  * are met:
16  *
17  * 1. Redistributions of source code must retain the above copyright
18  *    notice, this list of conditions and the following disclaimer.
19  *
20  * 2. Redistributions in binary form must reproduce the above copyright
21  *    notice, this list of conditions and the following disclaimer in
22  *    the documentation and/or other materials provided with the
23  *    distribution.
24  *
25  * 3. The end-user documentation included with the redistribution,
26  *    if any, must include the following acknowledgment:
27  *       "This product includes software developed by the
28  *        Apache Software Foundation (http://www.apache.org/)."
29  *    Alternately, this acknowledgment may appear in the software itself,
30  *    if and wherever such third-party acknowledgments normally appear.
31  *
32  * 4. The names "Apache" and "Apache Software Foundation" and
33  *    "Apache BCEL" must not be used to endorse or promote products
34  *    derived from this software without prior written permission. For
35  *    written permission, please contact apache@apache.org.
36  *
37  * 5. Products derived from this software may not be called "Apache",
38  *    "Apache BCEL", nor may "Apache" appear in their name, without
39  *    prior written permission of the Apache Software Foundation.
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41  * THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESSED OR IMPLIED
42  * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
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49  * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
50  * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
51  * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
52  * SUCH DAMAGE.
53  * ====================================================================
54  *
55  * This software consists of voluntary contributions made by many
56  * individuals on behalf of the Apache Software Foundation.  For more
57  * information on the Apache Software Foundation, please see
58  * <http://www.apache.org/>.
59  */
60 import java.io.*;
61 import com.sun.org.apache.bcel.internal.util.ByteSequence;
62 
63 /**
64  * LDC - Push item from constant pool.
65  *
66  * <PRE>Stack: ... -&gt; ..., item</PRE>
67  *
68  * @author  <A HREF="mailto:markus.dahm@berlin.de">M. Dahm</A>
69  */
70 public class LDC extends CPInstruction
71   implements PushInstruction, ExceptionThrower, TypedInstruction {
72   /**
73    * Empty constructor needed for the Class.newInstance() statement in
74    * Instruction.readInstruction(). Not to be used otherwise.
75    */
LDC()76   LDC() {}
77 
LDC(int index)78   public LDC(int index) {
79     super(com.sun.org.apache.bcel.internal.Constants.LDC_W, index);
80     setSize();
81   }
82 
83   // Adjust to proper size
setSize()84   protected final void setSize() {
85     if(index <= com.sun.org.apache.bcel.internal.Constants.MAX_BYTE) { // Fits in one byte?
86       opcode = com.sun.org.apache.bcel.internal.Constants.LDC;
87       length = 2;
88     } else {
89       opcode = com.sun.org.apache.bcel.internal.Constants.LDC_W;
90       length = 3;
91     }
92   }
93 
94   /**
95    * Dump instruction as byte code to stream out.
96    * @param out Output stream
97    */
dump(DataOutputStream out)98   public void dump(DataOutputStream out) throws IOException {
99     out.writeByte(opcode);
100 
101     if(length == 2)
102       out.writeByte(index);
103     else // Applies for LDC_W
104       out.writeShort(index);
105   }
106 
107   /**
108    * Set the index to constant pool and adjust size.
109    */
setIndex(int index)110   public final void setIndex(int index) {
111     super.setIndex(index);
112     setSize();
113   }
114 
115   /**
116    * Read needed data (e.g. index) from file.
117    */
initFromFile(ByteSequence bytes, boolean wide)118   protected void initFromFile(ByteSequence bytes, boolean wide)
119        throws IOException
120   {
121     length = 2;
122     index  = bytes.readUnsignedByte();
123   }
124 
getValue(ConstantPoolGen cpg)125   public Object getValue(ConstantPoolGen cpg) {
126     com.sun.org.apache.bcel.internal.classfile.Constant c = cpg.getConstantPool().getConstant(index);
127 
128     switch(c.getTag()) {
129       case com.sun.org.apache.bcel.internal.Constants.CONSTANT_String:
130         int i = ((com.sun.org.apache.bcel.internal.classfile.ConstantString)c).getStringIndex();
131         c = cpg.getConstantPool().getConstant(i);
132         return ((com.sun.org.apache.bcel.internal.classfile.ConstantUtf8)c).getBytes();
133 
134     case com.sun.org.apache.bcel.internal.Constants.CONSTANT_Float:
135         return new Float(((com.sun.org.apache.bcel.internal.classfile.ConstantFloat)c).getBytes());
136 
137     case com.sun.org.apache.bcel.internal.Constants.CONSTANT_Integer:
138         return new Integer(((com.sun.org.apache.bcel.internal.classfile.ConstantInteger)c).getBytes());
139 
140     default: // Never reached
141       throw new RuntimeException("Unknown or invalid constant type at " + index);
142       }
143   }
144 
getType(ConstantPoolGen cpg)145   public Type getType(ConstantPoolGen cpg) {
146     switch(cpg.getConstantPool().getConstant(index).getTag()) {
147     case com.sun.org.apache.bcel.internal.Constants.CONSTANT_String:  return Type.STRING;
148     case com.sun.org.apache.bcel.internal.Constants.CONSTANT_Float:   return Type.FLOAT;
149     case com.sun.org.apache.bcel.internal.Constants.CONSTANT_Integer: return Type.INT;
150     default: // Never reached
151       throw new RuntimeException("Unknown or invalid constant type at " + index);
152     }
153   }
154 
getExceptions()155   public Class[] getExceptions() {
156     return com.sun.org.apache.bcel.internal.ExceptionConstants.EXCS_STRING_RESOLUTION;
157   }
158 
159   /**
160    * Call corresponding visitor method(s). The order is:
161    * Call visitor methods of implemented interfaces first, then
162    * call methods according to the class hierarchy in descending order,
163    * i.e., the most specific visitXXX() call comes last.
164    *
165    * @param v Visitor object
166    */
accept(Visitor v)167   public void accept(Visitor v) {
168     v.visitStackProducer(this);
169     v.visitPushInstruction(this);
170     v.visitExceptionThrower(this);
171     v.visitTypedInstruction(this);
172     v.visitCPInstruction(this);
173     v.visitLDC(this);
174   }
175 }
176