Code


1   /*
2    * Code.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: 1.14 $
24   */
25  
26  package org.netbeans.modules.classfile;
27  
28  import java.io.DataInputStream  ;
29  import java.io.IOException  ;
30  
31  /**
32   * The Code attribute of a method.
33   *
34   * @author  Thomas Ball
35   */
36  public final class Code {
37      private static final boolean debug = false;
38  
39      private int maxStack;
40      private int maxLocals;
41      private byte[] byteCodes;
42      private ExceptionTableEntry[] exceptionTable;
43      private int[] lineNumberTable;
44      private LocalVariableTableEntry[] localVariableTable;
45      private LocalVariableTypeTableEntry[] localVariableTypeTable;
46      private StackMapFrame[] stackMapTable;
47  
48      /** Creates a new Code object */
49      /* package-private */ Code(DataInputStream   in, ConstantPool pool) throws IOException   {
50          if (in == null)
51              throw new IllegalArgumentException  ("input stream not specified");
52          if (pool == null)
53              throw new IllegalArgumentException  ("constant pool not specified");
54          try {
55              loadCode(in, pool);
56          } catch (IndexOutOfBoundsException   e) {
57              throw new InvalidClassFileAttributeException("invalid code attribute", e);
58          }
59      }
60  
61      private void loadCode(DataInputStream   in, ConstantPool pool) 
62        throws IOException   {
63          maxStack = in.readUnsignedShort();
64          maxLocals = in.readUnsignedShort();
65          int len = in.readInt();
66          byteCodes = new byte[len];
67          in.readFully(byteCodes);
68          exceptionTable = ExceptionTableEntry.loadExceptionTable(in, pool);
69          loadCodeAttributes(in, pool);
70      }
71          
72      private void loadCodeAttributes(DataInputStream   in, ConstantPool pool) 
73        throws IOException   {
74          int count = in.readUnsignedShort();
75          for (int i = 0; i < count; i++) {
76              Object   o = pool.get(in.readUnsignedShort());
77              if (!(o instanceof CPUTF8Info))
78                  throw new InvalidClassFormatException();
79              CPUTF8Info entry = (CPUTF8Info)o;
80              int len = in.readInt();
81              String   name = entry.getName();
82              if (name.equals("LineNumberTable")) //NOI18N
83                  loadLineNumberTable(in, pool);
84              else if (name.equals("LocalVariableTable")) //NOI18N
85                  localVariableTable = 
86                      LocalVariableTableEntry.loadLocalVariableTable(in, pool);
87              else if (name.equals("LocalVariableTypeTable")) //NOI18N
88                  localVariableTypeTable = 
89                      LocalVariableTypeTableEntry.loadLocalVariableTypeTable(in, pool);
90              else if (name.equals("StackMapTable")) //NOI18N
91                  stackMapTable = StackMapFrame.loadStackMapTable(in, pool);
92              else {
93          if (debug)
94              System.out.println("skipped unknown code attribute: " + name);
95                  // ignore unknown attribute...
96                  int n;
97          while ((n = (int)in.skip(len)) > 0 && n < len)
98              len -= n;
99              }
100         }
101         if (lineNumberTable == null)
102             lineNumberTable = new int[0];
103         if (localVariableTable == null)
104             localVariableTable = new LocalVariableTableEntry[0];
105         if (localVariableTypeTable == null)
106             localVariableTypeTable = new LocalVariableTypeTableEntry[0];
107         if (stackMapTable == null)
108             stackMapTable = new StackMapFrame[0];
109     }
110     
111     private void loadLineNumberTable(DataInputStream   in, ConstantPool pool) throws IOException   {
112         int n = in.readUnsignedShort();
113         lineNumberTable = new int[n * 2];
114         for (int i = 0; i < n; i++) {
115             lineNumberTable[i * 2] = in.readUnsignedShort();     // start_pc
116             lineNumberTable[i * 2 + 1] = in.readUnsignedShort(); // line_number
117         }
118     }
119 
120     public final int getMaxStack() {
121         return maxStack;
122     }
123     
124     public final int getMaxLocals() {
125         return maxLocals;
126     }
127     
128     public final byte[] getByteCodes() {
129         return byteCodes.clone();
130     }
131     
132     public final ExceptionTableEntry[] getExceptionTable() {
133         return exceptionTable.clone();
134     }
135 
136     /**
137      * Returns an array of int pairs consisting of a start_pc and a 
138      * line_number.  For example, [0] = first pc, [1] = first line, 
139      * [2] = second pc, etc.
140      */
141     public final int[] getLineNumberTable() {
142         return lineNumberTable.clone();
143     }
144 
145     /**
146      * Returns the local variable table for this code.
147      */
148     public final LocalVariableTableEntry[] getLocalVariableTable() {
149         return localVariableTable.clone();
150     }
151 
152     /**
153      * Returns the local variable type table for this code, which 
154      * describes the generic reference type for those variables which
155      * are generic.
156      */
157     public final LocalVariableTypeTableEntry[] getLocalVariableTypeTable() {
158         return localVariableTypeTable.clone();
159     }
160     
161     /**
162      * Returns the stack map table for this code, which defines the stack frame
163      * information needed by the new classfile verifier in Java 6.
164      */
165     public final StackMapFrame[] getStackMapTable() {
166         return stackMapTable.clone();
167     }
168 
169     public String   toString() {
170     StringBuffer   sb = new StringBuffer  ("Code: bytes=");
171     sb.append(byteCodes.length);
172     sb.append(", stack=");
173     sb.append(maxStack);
174     sb.append(", locals=");
175     sb.append(maxLocals);
176     return sb.toString();
177     }
178 }
179
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