1 /*
2 * Copyright (c) 2017, Oracle and/or its affiliates. All rights reserved.
3 */
4 /*
5 * Licensed to the Apache Software Foundation (ASF) under one or more
6 * contributor license agreements. See the NOTICE file distributed with
7 * this work for additional information regarding copyright ownership.
8 * The ASF licenses this file to You under the Apache License, Version 2.0
9 * (the "License"); you may not use this file except in compliance with
10 * the License. You may obtain a copy of the License at
11 *
12 * http://www.apache.org/licenses/LICENSE-2.0
13 *
14 * Unless required by applicable law or agreed to in writing, software
15 * distributed under the License is distributed on an "AS IS" BASIS,
16 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
17 * See the License for the specific language governing permissions and
18 * limitations under the License.
19 */
20
21 package com.sun.org.apache.bcel.internal.generic;
22
23 import java.io.DataOutputStream;
24 import java.io.IOException;
25
26 import com.sun.org.apache.bcel.internal.ExceptionConst;
27 import com.sun.org.apache.bcel.internal.util.ByteSequence;
28
29 /**
30 * LDC - Push item from constant pool.
31 *
32 * <PRE>Stack: ... -> ..., item</PRE>
33 *
34 * @version $Id: LDC.java 1749603 2016-06-21 20:50:19Z ggregory $
35 */
36 public class LDC extends CPInstruction implements PushInstruction, ExceptionThrower {
37
38 /**
39 * Empty constructor needed for the Class.newInstance() statement in
40 * Instruction.readInstruction(). Not to be used otherwise.
41 */
42 LDC() {
43 }
44
45
46 public LDC(final int index) {
47 super(com.sun.org.apache.bcel.internal.Const.LDC_W, index);
48 setSize();
49 }
50
51
52 // Adjust to proper size
53 protected final void setSize() {
54 if (super.getIndex() <= com.sun.org.apache.bcel.internal.Const.MAX_BYTE) { // Fits in one byte?
55 super.setOpcode(com.sun.org.apache.bcel.internal.Const.LDC);
56 super.setLength(2);
57 } else {
58 super.setOpcode(com.sun.org.apache.bcel.internal.Const.LDC_W);
59 super.setLength(3);
60 }
61 }
62
63
64 /**
65 * Dump instruction as byte code to stream out.
66 * @param out Output stream
67 */
68 @Override
69 public void dump( final DataOutputStream out ) throws IOException {
70 out.writeByte(super.getOpcode());
71 if (super.getLength() == 2) { // TODO useless check?
72 out.writeByte(super.getIndex());
73 } else {
74 out.writeShort(super.getIndex());
75 }
76 }
77
78
79 /**
80 * Set the index to constant pool and adjust size.
81 */
82 @Override
83 public final void setIndex( final int index ) {
84 super.setIndex(index);
85 setSize();
86 }
87
88
89 /**
90 * Read needed data (e.g. index) from file.
91 */
92 @Override
93 protected void initFromFile( final ByteSequence bytes, final boolean wide ) throws IOException {
94 super.setLength(2);
95 super.setIndex(bytes.readUnsignedByte());
96 }
97
98
99 public Object getValue( final ConstantPoolGen cpg ) {
100 com.sun.org.apache.bcel.internal.classfile.Constant c = cpg.getConstantPool().getConstant(super.getIndex());
101 switch (c.getTag()) {
102 case com.sun.org.apache.bcel.internal.Const.CONSTANT_String:
103 final int i = ((com.sun.org.apache.bcel.internal.classfile.ConstantString) c).getStringIndex();
104 c = cpg.getConstantPool().getConstant(i);
105 return ((com.sun.org.apache.bcel.internal.classfile.ConstantUtf8) c).getBytes();
106 case com.sun.org.apache.bcel.internal.Const.CONSTANT_Float:
107 return new Float(((com.sun.org.apache.bcel.internal.classfile.ConstantFloat) c).getBytes());
108 case com.sun.org.apache.bcel.internal.Const.CONSTANT_Integer:
109 return Integer.valueOf(((com.sun.org.apache.bcel.internal.classfile.ConstantInteger) c).getBytes());
110 case com.sun.org.apache.bcel.internal.Const.CONSTANT_Class:
111 final int nameIndex = ((com.sun.org.apache.bcel.internal.classfile.ConstantClass) c).getNameIndex();
112 c = cpg.getConstantPool().getConstant(nameIndex);
113 return new ObjectType(((com.sun.org.apache.bcel.internal.classfile.ConstantUtf8) c).getBytes());
114 default: // Never reached
115 throw new RuntimeException("Unknown or invalid constant type at " + super.getIndex());
116 }
117 }
118
119
120 @Override
121 public Type getType( final ConstantPoolGen cpg ) {
122 switch (cpg.getConstantPool().getConstant(super.getIndex()).getTag()) {
123 case com.sun.org.apache.bcel.internal.Const.CONSTANT_String:
124 return Type.STRING;
125 case com.sun.org.apache.bcel.internal.Const.CONSTANT_Float:
126 return Type.FLOAT;
127 case com.sun.org.apache.bcel.internal.Const.CONSTANT_Integer:
128 return Type.INT;
129 case com.sun.org.apache.bcel.internal.Const.CONSTANT_Class:
130 return Type.CLASS;
131 default: // Never reached
132 throw new RuntimeException("Unknown or invalid constant type at " + super.getIndex());
133 }
134 }
135
136
137 @Override
138 public Class<?>[] getExceptions() {
139 return ExceptionConst.createExceptions(ExceptionConst.EXCS.EXCS_STRING_RESOLUTION);
140 }
141
142
143 /**
144 * Call corresponding visitor method(s). The order is:
145 * Call visitor methods of implemented interfaces first, then
146 * call methods according to the class hierarchy in descending order,
147 * i.e., the most specific visitXXX() call comes last.
148 *
149 * @param v Visitor object
150 */
151 @Override
152 public void accept( final Visitor v ) {
153 v.visitStackProducer(this);
154 v.visitPushInstruction(this);
155 v.visitExceptionThrower(this);
156 v.visitTypedInstruction(this);
157 v.visitCPInstruction(this);
158 v.visitLDC(this);
159 }
160 }