1 package org.apache.bcel.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 org.apache.bcel.util.ByteSequence;
58
59 /***
60 * LDC - Push item from constant pool.
61 *
62 * <PRE>Stack: ... -> ..., 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(org.apache.bcel.Constants.LDC_W, index);
77 setSize();
78 }
79
80 // Adjust to proper size
81 protected final void setSize() {
82 if(index <= org.apache.bcel.Constants.MAX_BYTE) { // Fits in one byte?
83 opcode = org.apache.bcel.Constants.LDC;
84 length = 2;
85 } else {
86 opcode = org.apache.bcel.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 getValue(ConstantPoolGen cpg) {
123 org.apache.bcel.classfile.Constant c = cpg.getConstantPool().getConstant(index);
124
125 switch(c.getTag()) {
126 case org.apache.bcel.Constants.CONSTANT_String:
127 int i = ((org.apache.bcel.classfile.ConstantString)c).getStringIndex();
128 c = cpg.getConstantPool().getConstant(i);
129 return ((org.apache.bcel.classfile.ConstantUtf8)c).getBytes();
130
131 case org.apache.bcel.Constants.CONSTANT_Float:
132 return new Float(((org.apache.bcel.classfile.ConstantFloat)c).getBytes());
133
134 case org.apache.bcel.Constants.CONSTANT_Integer:
135 return new Integer(((org.apache.bcel.classfile.ConstantInteger)c).getBytes());
136
137 default: // Never reached
138 throw new RuntimeException("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 org.apache.bcel.Constants.CONSTANT_String: return Type.STRING;
145 case org.apache.bcel.Constants.CONSTANT_Float: return Type.FLOAT;
146 case org.apache.bcel.Constants.CONSTANT_Integer: return Type.INT;
147 default: // Never reached
148 throw new RuntimeException("Unknown or invalid constant type at " + index);
149 }
150 }
151
152 public Class[] getExceptions() {
153 return org.apache.bcel.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 }
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