1 /*
2 * reserved comment block
3 * DO NOT REMOVE OR ALTER!
4 */
5 /*
6 * Licensed to the Apache Software Foundation (ASF) under one or more
7 * contributor license agreements. See the NOTICE file distributed with
8 * this work for additional information regarding copyright ownership.
9 * The ASF licenses this file to You under the Apache License, Version 2.0
10 * (the "License"); you may not use this file except in compliance with
11 * the License. You may obtain a copy of the License at
12 *
13 * http://www.apache.org/licenses/LICENSE-2.0
14 *
15 * Unless required by applicable law or agreed to in writing, software
16 * distributed under the License is distributed on an "AS IS" BASIS,
17 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
18 * See the License for the specific language governing permissions and
19 * limitations under the License.
20 */
21
22 package com.sun.org.apache.bcel.internal.generic;
23
24 import java.io.*;
25 import com.sun.org.apache.bcel.internal.util.ByteSequence;
26
27 /**
28 * LDC - Push item from constant pool.
29 *
30 * <PRE>Stack: ... -> ..., item</PRE>
31 *
32 * @author <A HREF="mailto:markus.dahm@berlin.de">M. Dahm</A>
33 */
34 public class LDC extends CPInstruction
35 implements PushInstruction, ExceptionThrower, TypedInstruction {
36 /**
37 * Empty constructor needed for the Class.newInstance() statement in
38 * Instruction.readInstruction(). Not to be used otherwise.
39 */
40 LDC() {}
41
42 public LDC(int index) {
43 super(com.sun.org.apache.bcel.internal.Constants.LDC_W, index);
44 setSize();
45 }
46
47 // Adjust to proper size
48 protected final void setSize() {
49 if(index <= com.sun.org.apache.bcel.internal.Constants.MAX_BYTE) { // Fits in one byte?
50 opcode = com.sun.org.apache.bcel.internal.Constants.LDC;
51 length = 2;
52 } else {
53 opcode = com.sun.org.apache.bcel.internal.Constants.LDC_W;
54 length = 3;
55 }
56 }
57
58 /**
59 * Dump instruction as byte code to stream out.
60 * @param out Output stream
61 */
62 public void dump(DataOutputStream out) throws IOException {
63 out.writeByte(opcode);
64
65 if(length == 2)
66 out.writeByte(index);
67 else // Applies for LDC_W
68 out.writeShort(index);
69 }
70
71 /**
72 * Set the index to constant pool and adjust size.
73 */
74 public final void setIndex(int index) {
75 super.setIndex(index);
76 setSize();
77 }
78
79 /**
80 * Read needed data (e.g. index) from file.
81 */
82 protected void initFromFile(ByteSequence bytes, boolean wide)
83 throws IOException
84 {
85 length = 2;
86 index = bytes.readUnsignedByte();
87 }
88
89 public Object getValue(ConstantPoolGen cpg) {
90 com.sun.org.apache.bcel.internal.classfile.Constant c = cpg.getConstantPool().getConstant(index);
91
92 switch(c.getTag()) {
93 case com.sun.org.apache.bcel.internal.Constants.CONSTANT_String:
94 int i = ((com.sun.org.apache.bcel.internal.classfile.ConstantString)c).getStringIndex();
95 c = cpg.getConstantPool().getConstant(i);
96 return ((com.sun.org.apache.bcel.internal.classfile.ConstantUtf8)c).getBytes();
97
98 case com.sun.org.apache.bcel.internal.Constants.CONSTANT_Float:
99 return new Float(((com.sun.org.apache.bcel.internal.classfile.ConstantFloat)c).getBytes());
100
101 case com.sun.org.apache.bcel.internal.Constants.CONSTANT_Integer:
102 return new Integer(((com.sun.org.apache.bcel.internal.classfile.ConstantInteger)c).getBytes());
103
104 default: // Never reached
105 throw new RuntimeException("Unknown or invalid constant type at " + index);
106 }
107 }
108
109 public Type getType(ConstantPoolGen cpg) {
110 switch(cpg.getConstantPool().getConstant(index).getTag()) {
111 case com.sun.org.apache.bcel.internal.Constants.CONSTANT_String: return Type.STRING;
112 case com.sun.org.apache.bcel.internal.Constants.CONSTANT_Float: return Type.FLOAT;
113 case com.sun.org.apache.bcel.internal.Constants.CONSTANT_Integer: return Type.INT;
114 default: // Never reached
115 throw new RuntimeException("Unknown or invalid constant type at " + index);
116 }
117 }
118
119 public Class[] getExceptions() {
120 return com.sun.org.apache.bcel.internal.ExceptionConstants.EXCS_STRING_RESOLUTION;
121 }
122
123 /**
124 * Call corresponding visitor method(s). The order is:
125 * Call visitor methods of implemented interfaces first, then
126 * call methods according to the class hierarchy in descending order,
127 * i.e., the most specific visitXXX() call comes last.
128 *
129 * @param v Visitor object
130 */
131 public void accept(Visitor v) {
132 v.visitStackProducer(this);
133 v.visitPushInstruction(this);
134 v.visitExceptionThrower(this);
135 v.visitTypedInstruction(this);
136 v.visitCPInstruction(this);
137 v.visitLDC(this);
138 }
139 }