1 package org.apache.bcel.classfile;
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
57 import org.apache.bcel.Constants;
58 import java.io.*;
59
60 /***
61 * This class is derived from <em>Attribute</em> and represents a constant
62 * value, i.e., a default value for initializing a class field.
63 * This class is instantiated by the <em>Attribute.readAttribute()</em> method.
64 *
65 * @version $Id: ConstantValue.java,v 1.5 2003/02/13 11:18:23 enver Exp $
66 * @author <A HREF="mailto:markus.dahm@berlin.de">M. Dahm</A>
67 * @see Attribute
68 */
69 public final class ConstantValue extends Attribute {
70 private int constantvalue_index;
71
72 /***
73 * Initialize from another object. Note that both objects use the same
74 * references (shallow copy). Use clone() for a physical copy.
75 */
76 public ConstantValue(ConstantValue c) {
77 this(c.getNameIndex(), c.getLength(), c.getConstantValueIndex(),
78 c.getConstantPool());
79 }
80
81 /***
82 * Construct object from file stream.
83 * @param name_index Name index in constant pool
84 * @param length Content length in bytes
85 * @param file Input stream
86 * @param constant_pool Array of constants
87 * @throw IOException
88 */
89 ConstantValue(int name_index, int length, DataInputStream file,
90 ConstantPool constant_pool) throws IOException
91 {
92 this(name_index, length, (int)file.readUnsignedShort(), constant_pool);
93 }
94
95 /***
96 * @param name_index Name index in constant pool
97 * @param length Content length in bytes
98 * @param constantvalue_index Index in constant pool
99 * @param constant_pool Array of constants
100 */
101 public ConstantValue(int name_index, int length,
102 int constantvalue_index,
103 ConstantPool constant_pool)
104 {
105 super(Constants.ATTR_CONSTANT_VALUE, name_index, length, constant_pool);
106 this.constantvalue_index = constantvalue_index;
107 }
108
109 /***
110 * Called by objects that are traversing the nodes of the tree implicitely
111 * defined by the contents of a Java class. I.e., the hierarchy of methods,
112 * fields, attributes, etc. spawns a tree of objects.
113 *
114 * @param v Visitor object
115 */
116 public void accept(Visitor v) {
117 v.visitConstantValue(this);
118 }
119 /***
120 * Dump constant value attribute to file stream on binary format.
121 *
122 * @param file Output file stream
123 * @throws IOException
124 */
125 public final void dump(DataOutputStream file) throws IOException
126 {
127 super.dump(file);
128 file.writeShort(constantvalue_index);
129 }
130 /***
131 * @return Index in constant pool of constant value.
132 */
133 public final int getConstantValueIndex() { return constantvalue_index; }
134
135 /***
136 * @param constantvalue_index.
137 */
138 public final void setConstantValueIndex(int constantvalue_index) {
139 this.constantvalue_index = constantvalue_index;
140 }
141
142 /***
143 * @return String representation of constant value.
144 */
145 public final String toString() {
146 Constant c = constant_pool.getConstant(constantvalue_index);
147
148 String buf;
149 int i;
150
151 // Print constant to string depending on its type
152 switch(c.getTag()) {
153 case Constants.CONSTANT_Long: buf = "" + ((ConstantLong)c).getBytes(); break;
154 case Constants.CONSTANT_Float: buf = "" + ((ConstantFloat)c).getBytes(); break;
155 case Constants.CONSTANT_Double: buf = "" + ((ConstantDouble)c).getBytes(); break;
156 case Constants.CONSTANT_Integer: buf = "" + ((ConstantInteger)c).getBytes(); break;
157 case Constants.CONSTANT_String:
158 i = ((ConstantString)c).getStringIndex();
159 c = constant_pool.getConstant(i, Constants.CONSTANT_Utf8);
160 buf = "\"" + Utility.convertString(((ConstantUtf8)c).getBytes()) + "\"";
161 break;
162
163 default:
164 throw new IllegalStateException("Type of ConstValue invalid: " + c);
165 }
166
167 return buf;
168 }
169
170 /***
171 * @return deep copy of this attribute
172 */
173 public Attribute copy(ConstantPool constant_pool) {
174 ConstantValue c = (ConstantValue)clone();
175 c.constant_pool = constant_pool;
176 return c;
177 }
178 }
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