Synthetic


1   /*
2    * Copyright  2000-2004 The Apache Software Foundation
3    *
4    *  Licensed under the Apache License, Version 2.0 (the "License"); 
5    *  you may not use this file except in compliance with the License.
6    *  You may obtain a copy of the License at
7    *
8    *      http://www.apache.org/licenses/LICENSE-2.0
9    *
10   *  Unless required by applicable law or agreed to in writing, software
11   *  distributed under the License is distributed on an "AS IS" BASIS,
12   *  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13   *  See the License for the specific language governing permissions and
14   *  limitations under the License. 
15   *
16   */
17  package org.apache.bcel.classfile;
18  
19  import java.io.DataInputStream  ;
20  import java.io.DataOutputStream  ;
21  import java.io.IOException  ;
22  import org.apache.bcel.Constants;
23  
24  /**
25   * This class is derived from <em>Attribute</em> and declares this class as
26   * `synthetic', i.e., it needs special handling.  The JVM specification
27   * states "A class member that does not appear in the source code must be
28   * marked using a Synthetic attribute."  It may appear in the ClassFile
29   * attribute table, a field_info table or a method_info table.  This class
30   * is intended to be instantiated from the
31   * <em>Attribute.readAttribute()</em> method.
32   *
33   * @version $Id: Synthetic.java 386056 2006-03-15 11:31:56Z tcurdt $
34   * @author  <A HREF="mailto:m.dahm@gmx.de">M. Dahm</A>
35   * @see     Attribute
36   */
37  public final class Synthetic extends Attribute {
38  
39      private byte[] bytes;
40  
41  
42      /**
43       * Initialize from another object. Note that both objects use the same
44       * references (shallow copy). Use copy() for a physical copy.
45       */
46      public Synthetic(Synthetic c) {
47          this(c.getNameIndex(), c.getLength(), c.getBytes(), c.getConstantPool());
48      }
49  
50  
51      /**
52       * @param name_index Index in constant pool to CONSTANT_Utf8, which
53       * should represent the string "Synthetic".
54       * @param length Content length in bytes - should be zero.
55       * @param bytes Attribute contents
56       * @param constant_pool The constant pool this attribute is associated
57       * with.
58       */
59      public Synthetic(int name_index, int length, byte[] bytes, ConstantPool constant_pool) {
60          super(Constants.ATTR_SYNTHETIC, name_index, length, constant_pool);
61          this.bytes = bytes;
62      }
63  
64  
65      /**
66       * Construct object from file stream.
67       * @param name_index Index in constant pool to CONSTANT_Utf8
68       * @param length Content length in bytes
69       * @param file Input stream
70       * @param constant_pool Array of constants
71       * @throws IOException
72       */
73      Synthetic(int name_index, int length, DataInputStream   file, ConstantPool constant_pool)
74              throws IOException   {
75          this(name_index, length, (byte[]) null, constant_pool);
76          if (length > 0) {
77              bytes = new byte[length];
78              file.readFully(bytes);
79              System.err.println("Synthetic attribute with length > 0");
80          }
81      }
82  
83  
84      /**
85       * Called by objects that are traversing the nodes of the tree implicitely
86       * defined by the contents of a Java class. I.e., the hierarchy of methods,
87       * fields, attributes, etc. spawns a tree of objects.
88       *
89       * @param v Visitor object
90       */
91      public void accept( Visitor v ) {
92          v.visitSynthetic(this);
93      }
94  
95  
96      /**
97       * Dump source file attribute to file stream in binary format.
98       *
99       * @param file Output file stream
100      * @throws IOException
101      */
102     public final void dump( DataOutputStream   file ) throws IOException   {
103         super.dump(file);
104         if (length > 0) {
105             file.write(bytes, 0, length);
106         }
107     }
108 
109 
110     /**
111      * @return data bytes.
112      */
113     public final byte[] getBytes() {
114         return bytes;
115     }
116 
117 
118     /**
119      * @param bytes
120      */
121     public final void setBytes( byte[] bytes ) {
122         this.bytes = bytes;
123     }
124 
125 
126     /**
127      * @return String representation.
128      */
129     public final String   toString() {
130         StringBuffer   buf = new StringBuffer  ("Synthetic");
131         if (length > 0) {
132             buf.append(" ").append(Utility.toHexString(bytes));
133         }
134         return buf.toString();
135     }
136 
137 
138     /**
139      * @return deep copy of this attribute
140      */
141     public Attribute copy( ConstantPool _constant_pool ) {
142         Synthetic c = (Synthetic) clone();
143         if (bytes != null) {
144             c.bytes = new byte[bytes.length];
145             System.arraycopy(bytes, 0, c.bytes, 0, bytes.length);
146         }
147         c.constant_pool = _constant_pool;
148         return c;
149     }
150 }
151
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