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      1 /* Copyright (C) 2003 Vladimir Roubtsov. All rights reserved.
      2  *
      3  * This program and the accompanying materials are made available under
      4  * the terms of the Common Public License v1.0 which accompanies this distribution,
      5  * and is available at http://www.eclipse.org/legal/cpl-v10.html
      6  *
      7  * $Id: ExceptionsAttribute_info.java,v 1.1.1.1 2004/05/09 16:57:47 vlad_r Exp $
      8  */
      9 package com.vladium.jcd.cls.attribute;
     10 
     11 import java.io.IOException;
     12 
     13 import com.vladium.jcd.lib.UDataInputStream;
     14 import com.vladium.jcd.lib.UDataOutputStream;
     15 
     16 // ----------------------------------------------------------------------------
     17 /**
     18  * The Exceptions attribute is a variable-length attribute used in the attributes
     19  * table of a {@link com.vladium.jcd.cls.Method_info} structure. The Exceptions
     20  * attribute indicates which checked exceptions a method may throw. There must be
     21  * exactly one Exceptions attribute in each method_info structure.<P>
     22  *
     23  * The Exceptions attribute has the following format:
     24  * <PRE>
     25  * Exceptions_attribute {
     26  *          u2 attribute_name_index;
     27  *          u4 attribute_length;
     28  *          u2 number_of_exceptions;
     29  *          u2 exception_index_table[number_of_exceptions];
     30  *  }
     31  * </PRE>
     32  * The value of the number_of_exceptions item indicates the number of entries
     33  * in the exception_index_table.<P>
     34  *
     35  * Each nonzero value in the exception_index_table array must be a valid index
     36  * into the constant_pool table. For each table item, if
     37  * exception_index_table[i] != 0 , where 0 &lt; i &lt; number_of_exceptions,
     38  * then the constant_pool entry at index exception_index_table[i] must be a
     39  * {@link com.vladium.jcd.cls.constant.CONSTANT_Class_info} structure representing
     40  * a class type that this method is declared to throw -- see {@link DeclaredExceptionTable}.
     41  *
     42  * @author (C) 2001, Vlad Roubtsov
     43  */
     44 public
     45 final class ExceptionsAttribute_info extends Attribute_info
     46 {
     47     // public: ................................................................
     48 
     49     // TODO: merge IDeclaredExceptionTable into this class
     50 
     51     public ExceptionsAttribute_info (final int attribute_name_index,
     52                                      final IDeclaredExceptionTable exceptions)
     53     {
     54         super (attribute_name_index, exceptions.length ());
     55 
     56         m_exceptions = exceptions;
     57     }
     58 
     59     public IDeclaredExceptionTable getDeclaredExceptions ()
     60     {
     61         return m_exceptions;
     62     }
     63 
     64     public long length ()
     65     {
     66         return 6 + m_exceptions.length ();
     67     }
     68 
     69     // Visitor:
     70 
     71     public void accept (final IAttributeVisitor visitor, final Object ctx)
     72     {
     73         visitor.visit (this, ctx);
     74     }
     75 
     76     public String toString ()
     77     {
     78         // TODO: return more data here
     79         return "ExceptionsAttribute_info: [attribute_name_index = " + m_name_index + ", attribute_length = " + m_attribute_length + ']';
     80     }
     81 
     82     // Cloneable:
     83 
     84     /**
     85      * Performs a deep copy.
     86      */
     87     public Object clone ()
     88     {
     89         final ExceptionsAttribute_info _clone = (ExceptionsAttribute_info) super.clone ();
     90 
     91         // do deep copy:
     92         _clone.m_exceptions = (IDeclaredExceptionTable) m_exceptions.clone ();
     93 
     94         return _clone;
     95     }
     96 
     97     // IClassFormatOutput:
     98 
     99     public void writeInClassFormat (final UDataOutputStream out) throws IOException
    100     {
    101         super.writeInClassFormat (out);
    102 
    103         m_exceptions.writeInClassFormat (out);
    104     }
    105 
    106     // protected: .............................................................
    107 
    108     // package: ...............................................................
    109 
    110 
    111 
    112     ExceptionsAttribute_info (final int attribute_name_index, final long attribute_length,
    113                               final UDataInputStream bytes)
    114         throws IOException
    115     {
    116         super (attribute_name_index, attribute_length);
    117 
    118         final int number_of_exceptions = bytes.readU2 ();
    119         m_exceptions = new DeclaredExceptionTable (number_of_exceptions);
    120 
    121         for (int i = 0; i < number_of_exceptions; i++)
    122         {
    123             final int exception_index = bytes.readU2 ();
    124 
    125             m_exceptions.add (exception_index);
    126         }
    127     }
    128 
    129     // private: ...............................................................
    130 
    131 
    132     private IDeclaredExceptionTable m_exceptions;
    133 
    134 } // end of class
    135 // ----------------------------------------------------------------------------
    136