LocalVariableTypeTableEntry


1   /*
2    * LocalVariableTypeTable.java
3    *
4    * The contents of this file are subject to the terms of the Common Development
5    * and Distribution License (the License). You may not use this file except in
6    * compliance with the License.
7    *
8    * You can obtain a copy of the License at http://www.netbeans.org/cddl.html
9    * or http://www.netbeans.org/cddl.txt.
10   *
11   * When distributing Covered Code, include this CDDL Header Notice in each file
12   * and include the License file at http://www.netbeans.org/cddl.txt.
13   * If applicable, add the following below the CDDL Header, with the fields
14   * enclosed by brackets [] replaced by your own identifying information:
15   * "Portions Copyrighted [year] [name of copyright owner]"
16   *
17   * The Original Software is NetBeans. The Initial Developer of the Original
18   * Software is Sun Microsystems, Inc. Portions Copyright 1997-2006 Sun
19   * Microsystems, Inc. All Rights Reserved.
20   *
21   * Contributor(s): Thomas Ball
22   *
23   * Version: $Revision: 1.3 $
24   */
25  
26  package org.netbeans.modules.classfile;
27  
28  import java.io.DataInputStream  ;
29  import java.io.IOException  ;
30  
31  /**
32   * An entry in the local variable type table of a method's code attribute.
33   * This table is similar to the local variable table, but differs in that
34   * it only contains the type information for those variables that are generic
35   * reference types.  Local variables that are generic reference types have
36   * entries in both tables, while other local variable types are only defined
37   * in the local variable table.
38   *
39   * @author  Thomas Ball
40   */
41  public final class LocalVariableTypeTableEntry {
42      
43      int startPC;
44      int length;
45      String   name;
46      String   signature;
47      int index;
48  
49      static LocalVariableTypeTableEntry[] loadLocalVariableTypeTable(DataInputStream   in, ConstantPool pool) 
50        throws IOException   {
51          int n = in.readUnsignedShort();
52          LocalVariableTypeTableEntry[] entries = new LocalVariableTypeTableEntry[n];
53          for (int i = 0; i < n; i++)
54              entries[i] = new LocalVariableTypeTableEntry(in, pool);
55          return entries;
56      }
57  
58      /** Creates new LocalVariableTypeTableEntry */
59      LocalVariableTypeTableEntry(DataInputStream   in, ConstantPool pool) 
60        throws IOException   {
61          loadLocalVariableEntry(in, pool);
62      }
63  
64      private void loadLocalVariableEntry(DataInputStream   in, ConstantPool pool) 
65        throws IOException   {
66          startPC = in.readUnsignedShort();
67          length = in.readUnsignedShort();
68          Object   o = pool.get(in.readUnsignedShort());
69          if (!(o instanceof CPUTF8Info))
70              throw new InvalidClassFormatException();
71          CPUTF8Info entry = (CPUTF8Info)o;
72          name = entry.getName();
73          o = pool.get(in.readUnsignedShort());
74          if (!(o instanceof CPUTF8Info))
75              throw new InvalidClassFormatException();
76          entry = (CPUTF8Info)o;
77          signature = entry.getName();
78          index = in.readUnsignedShort();
79      }
80  
81      /**
82       * Returns the first byte code offset where this variable is valid.
83       */ 
84      public final int getStartPC() {
85          return startPC;
86      }
87  
88      /**
89       * Returns the length of the range of code bytes where this variable
90       *         is valid.  
91       */
92      public final int getLength() {
93          return length;
94      }
95  
96      /**
97       * Returns the name of this variable.
98       */
99      public final String   getName() {
100         return name;
101     }
102 
103     /**
104      * Returns the generic field type signature of this variable.
105      */
106     public final String   getSignature() {
107         return signature;
108     }
109 
110     /**
111      * Returns the variable's index into the local variable array
112      *         for the current stack frame.
113      */
114     public final int getIndex() {
115         return index;
116     }
117 }
118
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