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 represents the table of exceptions that are thrown by a
62   * method. This attribute may be used once per method.  The name of
63   * this class is <em>ExceptionTable</em> for historical reasons; The
64   * Java Virtual Machine Specification, Second Edition defines this
65   * attribute using the name <em>Exceptions</em> (which is inconsistent
66   * with the other classes).
67   *
68   * @version $Id: ExceptionTable.java,v 1.2 2002/03/11 16:16:35 mdahm Exp $
69   * @author  <A HREF="mailto:markus.dahm@berlin.de">M. Dahm</A>
70   * @see     Code
71   */
72  public final class ExceptionTable extends Attribute {
73    private int   number_of_exceptions;  // Table of indices into
74    private int[] exception_index_table; // constant pool
75  
76    /***
77     * Initialize from another object. Note that both objects use the same
78     * references (shallow copy). Use copy() for a physical copy.
79     */
80    public ExceptionTable(ExceptionTable c) {
81      this(c.getNameIndex(), c.getLength(), c.getExceptionIndexTable(),
82  	 c.getConstantPool());
83    }
84  
85    /***
86     * @param name_index Index in constant pool
87     * @param length Content length in bytes
88     * @param exception_index_table Table of indices in constant pool
89     * @param constant_pool Array of constants
90     */
91    public ExceptionTable(int        name_index, int length, 
92  			int[]      exception_index_table,
93  			ConstantPool constant_pool)
94    {
95      super(Constants.ATTR_EXCEPTIONS, name_index, length, constant_pool);
96      setExceptionIndexTable(exception_index_table);
97    }
98  
99    /***
100    * Construct object from file stream.
101    * @param name_index Index in constant pool
102    * @param length Content length in bytes
103    * @param file Input stream
104    * @param constant_pool Array of constants
105    * @throws IOException
106    */
107   ExceptionTable(int name_index, int length, DataInputStream file,
108 		 ConstantPool constant_pool) throws IOException
109   {
110     this(name_index, length, (int[])null, constant_pool);
111 
112     number_of_exceptions  = file.readUnsignedShort();
113     exception_index_table = new int[number_of_exceptions];
114 
115     for(int i=0; i < number_of_exceptions; i++)
116       exception_index_table[i] = file.readUnsignedShort();
117   }
118 
119   /***
120    * Called by objects that are traversing the nodes of the tree implicitely
121    * defined by the contents of a Java class. I.e., the hierarchy of methods,
122    * fields, attributes, etc. spawns a tree of objects.
123    *
124    * @param v Visitor object
125    */
126   public void accept(Visitor v) {
127     v.visitExceptionTable(this);
128   }
129 
130   /***
131    * Dump exceptions attribute to file stream in binary format.
132    *
133    * @param file Output file stream
134    * @throws IOException
135    */ 
136   public final void dump(DataOutputStream file) throws IOException
137   {
138     super.dump(file);
139     file.writeShort(number_of_exceptions);
140     for(int i=0; i < number_of_exceptions; i++)
141       file.writeShort(exception_index_table[i]);
142   }
143 
144   /***
145    * @return Array of indices into constant pool of thrown exceptions.
146    */  
147   public final int[] getExceptionIndexTable() {return exception_index_table;}
148   /***
149    * @return Length of exception table.
150    */  
151   public final int getNumberOfExceptions() { return number_of_exceptions; }
152 
153   /***
154    * @return class names of thrown exceptions
155    */
156   public final String[] getExceptionNames() {
157     String[] names = new String[number_of_exceptions];
158     for(int i=0; i < number_of_exceptions; i++)
159       names[i] = constant_pool.getConstantString(exception_index_table[i],
160 						 Constants.CONSTANT_Class).
161 	replace('/', '.');
162     return names;
163   }
164 
165   /***
166    * @param exception_index_table.
167    * Also redefines number_of_exceptions according to table length.
168    */
169   public final void setExceptionIndexTable(int[] exception_index_table) {
170     this.exception_index_table = exception_index_table;
171     number_of_exceptions       = (exception_index_table == null)? 0 :
172       exception_index_table.length;
173   }
174   /***
175    * @return String representation, i.e., a list of thrown exceptions.
176    */ 
177   public final String toString() {
178     StringBuffer buf = new StringBuffer("");
179     String       str;
180 
181     for(int i=0; i < number_of_exceptions; i++) {
182       str = constant_pool.getConstantString(exception_index_table[i],
183 					    Constants.CONSTANT_Class);
184       buf.append(Utility.compactClassName(str, false));
185 
186       if(i < number_of_exceptions - 1)
187 	buf.append(", ");
188     }
189 
190     return buf.toString();    
191   }
192 
193   /***
194    * @return deep copy of this attribute
195    */
196   public Attribute copy(ConstantPool constant_pool) {
197     ExceptionTable c = (ExceptionTable)clone();
198     c.exception_index_table = (int[])exception_index_table.clone();
199     c.constant_pool = constant_pool;
200     return c;
201   }
202 }
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