Exception_info.java revision a921fd048da6858dc24d4370e3bba15fc9cc69ca 
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: Exception_info.java,v 1.1.1.1 2004/05/09 16:57:48 vlad_r Exp $
8 */
9package com.vladium.jcd.cls.attribute;
10
11import java.io.IOException;
12
13import com.vladium.jcd.compiler.IClassFormatOutput;
14import com.vladium.jcd.lib.UDataInputStream;
15import com.vladium.jcd.lib.UDataOutputStream;
16
17// ----------------------------------------------------------------------------
18/**
19 * An Exception_info is an entry layout format for {@link ExceptionHandlerTable}. Each
20 * entry contains the following items:
21 * <PRE>
22 *    start_pc, end_pc
23 * </PRE>
24 * The values of the two items start_pc and end_pc indicate the ranges in the code
25 * array at which the exception handler is active. The value of start_pc must be
26 * a valid index into the code array of the opcode of an instruction. The value of
27 * end_pc either must be a valid index into the code array of the opcode of an
28 * instruction, or must be equal to code_length , the length of the code array.
29 * The value of start_pc must be less than the value of end_pc.<P>
30 *
31 * The start_pc is inclusive and end_pc is exclusive; that is, the exception handler
32 * must be active while the program counter is within the interval [start_pc, end_pc).
33 * <PRE>
34 *    handler_pc
35 * </PRE>
36 * The value of the handler_pc item indicates the start of the exception handler.
37 * The value of the item must be a valid index into the code array, must be the index
38 * of the opcode of an instruction, and must be less than the value of the code_length
39 * item.
40 * <PRE>
41 *    catch_type
42 * </PRE>
43 * If the value of the catch_type item is nonzero, it must be a valid index into the
44 * constant_pool table. The constant_pool entry at that index must be a
45 * {@link com.vladium.jcd.cls.constant.CONSTANT_Class_info} structure representing
46 * a class of exceptions that this exception handler is designated to catch.
47 * This class must be the class Throwable or one of its subclasses. The exception
48 * handler will be called only if the thrown exception is an instance of the given
49 * class or one of its subclasses.<P>
50 *
51 * If the value of the catch_type item is zero, this exception handler is called for
52 * all exceptions. This is used to implement finally.
53 *
54 * @author (C) 2001, Vlad Roubtsov
55 */
56public
57final class Exception_info implements Cloneable, IClassFormatOutput
58{
59    // public: ................................................................
60
61
62    public int m_start_pc, m_end_pc, m_handler_pc, m_catch_type;
63
64
65    public Exception_info (final int start_pc, final int end_pc,
66                           final int handler_pc, final int catch_type)
67    {
68        m_start_pc = start_pc;
69        m_end_pc = end_pc;
70        m_handler_pc = handler_pc;
71        m_catch_type = catch_type;
72    }
73
74
75    public String toString ()
76    {
77        return "exception_info: [start_pc/end_pc = " + m_start_pc + '/' + m_end_pc +
78               ", handler_pc = " + m_handler_pc +
79               ", catch_type = " + m_catch_type + ']';
80    }
81
82    // Cloneable:
83
84    /**
85     * Performs a deep copy.
86     */
87    public Object clone ()
88    {
89        try
90        {
91            return super.clone ();
92        }
93        catch (CloneNotSupportedException e)
94        {
95            throw new InternalError (e.toString ());
96        }
97    }
98
99    // IClassFormatOutput:
100
101    public void writeInClassFormat (final UDataOutputStream out) throws IOException
102    {
103        out.writeU2 (m_start_pc);
104        out.writeU2 (m_end_pc);
105        out.writeU2 (m_handler_pc);
106        out.writeU2 (m_catch_type);
107    }
108
109    // protected: .............................................................
110
111    // package: ...............................................................
112
113
114    Exception_info (final UDataInputStream bytes) throws IOException
115    {
116        m_start_pc = bytes.readU2 ();
117        m_end_pc = bytes.readU2 ();
118        m_handler_pc = bytes.readU2 ();
119        m_catch_type = bytes.readU2 ();
120    }
121
122    // private: ...............................................................
123
124} // end of class
125// ----------------------------------------------------------------------------
126