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 * @LastModified: Nov 2017
36 */
37 public class LDC extends CPInstruction implements PushInstruction, ExceptionThrower {
38
39 /**
40 * Empty constructor needed for the Class.newInstance() statement in
41 * Instruction.readInstruction(). Not to be used otherwise.
42 */
43 LDC() {
44 }
45
46
47 public LDC(final int index) {
48 super(com.sun.org.apache.bcel.internal.Const.LDC_W, index);
49 setSize();
50 }
51
52
53 // Adjust to proper size
54 protected final void setSize() {
55 if (super.getIndex() <= com.sun.org.apache.bcel.internal.Const.MAX_BYTE) { // Fits in one byte?
56 super.setOpcode(com.sun.org.apache.bcel.internal.Const.LDC);
57 super.setLength(2);
58 } else {
59 super.setOpcode(com.sun.org.apache.bcel.internal.Const.LDC_W);
60 super.setLength(3);
61 }
62 }
63
64
65 /**
66 * Dump instruction as byte code to stream out.
67 * @param out Output stream
68 */
69 @Override
70 public void dump( final DataOutputStream out ) throws IOException {
71 out.writeByte(super.getOpcode());
72 if (super.getLength() == 2) { // TODO useless check?
73 out.writeByte(super.getIndex());
74 } else {
75 out.writeShort(super.getIndex());
76 }
77 }
78
79
80 /**
81 * Set the index to constant pool and adjust size.
82 */
83 @Override
84 public final void setIndex( final int index ) {
85 super.setIndex(index);
86 setSize();
87 }
88
89
90 /**
91 * Read needed data (e.g. index) from file.
92 */
93 @Override
94 protected void initFromFile( final ByteSequence bytes, final boolean wide ) throws IOException {
95 super.setLength(2);
96 super.setIndex(bytes.readUnsignedByte());
97 }
98
99
100 public Object getValue( final ConstantPoolGen cpg ) {
101 com.sun.org.apache.bcel.internal.classfile.Constant c = cpg.getConstantPool().getConstant(super.getIndex());
102 switch (c.getTag()) {
103 case com.sun.org.apache.bcel.internal.Const.CONSTANT_String:
104 final int i = ((com.sun.org.apache.bcel.internal.classfile.ConstantString) c).getStringIndex();
105 c = cpg.getConstantPool().getConstant(i);
106 return ((com.sun.org.apache.bcel.internal.classfile.ConstantUtf8) c).getBytes();
107 case com.sun.org.apache.bcel.internal.Const.CONSTANT_Float:
108 return ((com.sun.org.apache.bcel.internal.classfile.ConstantFloat) c).getBytes();
109 case com.sun.org.apache.bcel.internal.Const.CONSTANT_Integer:
110 return ((com.sun.org.apache.bcel.internal.classfile.ConstantInteger) c).getBytes();
111 case com.sun.org.apache.bcel.internal.Const.CONSTANT_Class:
112 final int nameIndex = ((com.sun.org.apache.bcel.internal.classfile.ConstantClass) c).getNameIndex();
113 c = cpg.getConstantPool().getConstant(nameIndex);
114 return new ObjectType(((com.sun.org.apache.bcel.internal.classfile.ConstantUtf8) c).getBytes());
115 default: // Never reached
116 throw new RuntimeException("Unknown or invalid constant type at " + super.getIndex());
117 }
118 }
119
120
121 @Override
122 public Type getType( final ConstantPoolGen cpg ) {
123 switch (cpg.getConstantPool().getConstant(super.getIndex()).getTag()) {
124 case com.sun.org.apache.bcel.internal.Const.CONSTANT_String:
125 return Type.STRING;
126 case com.sun.org.apache.bcel.internal.Const.CONSTANT_Float:
127 return Type.FLOAT;
128 case com.sun.org.apache.bcel.internal.Const.CONSTANT_Integer:
129 return Type.INT;
130 case com.sun.org.apache.bcel.internal.Const.CONSTANT_Class:
131 return Type.CLASS;
132 default: // Never reached
133 throw new RuntimeException("Unknown or invalid constant type at " + super.getIndex());
134 }
135 }
136
137
138 @Override
139 public Class<?>[] getExceptions() {
140 return ExceptionConst.createExceptions(ExceptionConst.EXCS.EXCS_STRING_RESOLUTION);
141 }
142
143
144 /**
145 * Call corresponding visitor method(s). The order is:
146 * Call visitor methods of implemented interfaces first, then
147 * call methods according to the class hierarchy in descending order,
148 * i.e., the most specific visitXXX() call comes last.
149 *
150 * @param v Visitor object
151 */
152 @Override
153 public void accept( final Visitor v ) {
154 v.visitStackProducer(this);
155 v.visitPushInstruction(this);
156 v.visitExceptionThrower(this);
157 v.visitTypedInstruction(this);
158 v.visitCPInstruction(this);
159 v.visitLDC(this);
160 }
161 }