1 cananian 1.1.2.2 // AttributeExceptions.java, created Mon Jan 18 22:44:34 1999 by cananian
2 cananian 1.1.2.1 // Copyright (C) 1998 C. Scott Ananian <cananian@alumni.princeton.edu>
3 cananian 1.1.2.1 // Licensed under the terms of the GNU GPL; see COPYING for details.
4 cananian 1.1.2.1 package harpoon.IR.RawClass;
5 cananian 1.1.2.1
6 cananian 1.1.2.1 /**
7 cananian 1.1.2.1 * The <code>Exceptions</code> attribute is a variable-length
8 cananian 1.1.2.1 * attribute used in the <code>attributes</code> table of a
9 cananian 1.1.2.1 * <code>method_info</code> structure. The <code>Exceptions</code>
10 cananian 1.1.2.1 * attribute indicates which checked exceptions a method may throw. The
11 cananian 1.1.2.1 * must be exactly one <code>Exceptions</code> attribute in each
12 cananian 1.1.2.1 * <code>method_info</code> structure.
13 cananian 1.1.2.1 *
14 cananian 1.1.2.1 * @author C. Scott Ananian <cananian@alumni.princeton.edu>
15 cananian 1.3 * @version $Id: AttributeExceptions.java,v 1.3 2003/09/05 21:45:16 cananian Exp $
16 cananian 1.1.2.1 * @see "The Java Virtual Machine Specification, section 4.7.5"
17 cananian 1.1.2.1 * @see Attribute
18 cananian 1.1.2.1 * @see MethodInfo
19 cananian 1.1.2.1 */
20 cananian 1.1.2.1 public class AttributeExceptions extends Attribute {
21 cananian 1.3 /** The string naming this <code>Attribute</code> type. */
22 cananian 1.3 public static final String ATTRIBUTE_NAME = "Exceptions";
23 cananian 1.1.2.1 /** Each nonzero value in the <code>exception_index_table</code>
24 cananian 1.1.2.1 must be a valid index into the <code>constant_pool</code>
25 cananian 1.1.2.1 table. For each table item, if
26 cananian 1.1.2.1 <code>exception_index_table[i] != 0</code>, where <code>0 <= i <
27 cananian 1.1.2.1 number_of_exceptions</code>, then the <code>constant_pool</code>
28 cananian 1.1.2.1 entry at index <code>exception_index_table[i]</code> must be a
29 cananian 1.1.2.1 <code>CONSTANT_Class_info</code> structure representing a class
30 cananian 1.1.2.1 type that this method is declared to throw. */
31 cananian 1.1.2.1 public int exception_index_table[];
32 cananian 1.1.2.1
33 cananian 1.1.2.1 /** Constructor. */
34 cananian 1.1.2.1 AttributeExceptions(ClassFile parent, ClassDataInputStream in,
35 cananian 1.1.2.1 int attribute_name_index) throws java.io.IOException
36 cananian 1.1.2.1 {
37 cananian 1.1.2.1 super(parent, attribute_name_index);
38 cananian 1.1.2.1 long attribute_length = in.read_u4();
39 cananian 1.1.2.1
40 cananian 1.1.2.1 int number_of_exceptions = in.read_u2();
41 cananian 1.1.2.1 exception_index_table = new int[number_of_exceptions];
42 cananian 1.1.2.1 for(int i=0; i<number_of_exceptions; i++)
43 cananian 1.1.2.1 exception_index_table[i] = in.read_u2();
44 cananian 1.1.2.1
45 cananian 1.1.2.1 if (attribute_length != attribute_length())
46 cananian 1.1.2.1 throw new ClassDataException("Exceptions attribute with length "
47 cananian 1.1.2.1 + attribute_length);
48 cananian 1.3 assert ATTRIBUTE_NAME.equals(attribute_name());
49 cananian 1.1.2.1 }
50 cananian 1.1.2.1
51 cananian 1.1.2.1 /** Constructor. */
52 cananian 1.1.2.1 public AttributeExceptions(ClassFile parent, int attribute_name_index,
53 cananian 1.1.2.1 int exception_index_table[]) {
54 cananian 1.1.2.1 super(parent, attribute_name_index);
55 cananian 1.1.2.1 this.exception_index_table = exception_index_table;
56 cananian 1.3 assert ATTRIBUTE_NAME.equals(attribute_name());
57 cananian 1.1.2.1 }
58 cananian 1.1.2.1
59 cananian 1.1.2.1 public long attribute_length() { return 2 + 2*number_of_exceptions(); }
60 cananian 1.1.2.1
61 cananian 1.1.2.1 // convenience.
62 cananian 1.1.2.1 public int number_of_exceptions() { return exception_index_table.length; }
63 cananian 1.1.2.1 /** Returns the CONSTANT_Class_info corresponding to an entry in
64 cananian 1.1.2.1 * the exception_index_table. Returns <code>null</code> if the
65 cananian 1.1.2.1 * entry is zero.
66 cananian 1.1.2.1 */
67 cananian 1.1.2.1 public ConstantClass exception_index_table(int i) {
68 cananian 1.1.2.1 if (exception_index_table[i]==0) return null;
69 cananian 1.1.2.1 else return (ConstantClass)
70 cananian 1.1.2.1 parent.constant_pool[exception_index_table[i]];
71 cananian 1.1.2.1 }
72 cananian 1.1.2.1
73 cananian 1.1.2.1 /** Write to bytecode stream. */
74 cananian 1.1.2.1 public void write(ClassDataOutputStream out) throws java.io.IOException {
75 cananian 1.1.2.1 out.write_u2(attribute_name_index);
76 cananian 1.1.2.1 out.write_u4(attribute_length());
77 cananian 1.1.2.1 out.write_u2(number_of_exceptions());
78 cananian 1.1.2.1 for (int i=0; i<exception_index_table.length; i++)
79 cananian 1.1.2.1 out.write_u2(exception_index_table[i]);
80 cananian 1.1.2.1 }
81 cananian 1.1.2.1
82 cananian 1.1.2.1 /** Pretty-print the contents of this attribute.
83 cananian 1.1.2.1 * @param indent the indentation level to use.
84 cananian 1.1.2.1 */
85 cananian 1.1.2.1 public void print(java.io.PrintWriter pw, int indent) {
86 cananian 1.1.2.1 int in=indent;
87 cananian 1.1.2.1 indent(pw, in, "Exceptions attribute ["+number_of_exceptions()+"]:");
88 cananian 1.1.2.1 for (int i=0; i<exception_index_table.length; i++)
89 cananian 1.1.2.1 indent(pw, in+1, "#"+i+": " +
90 cananian 1.1.2.1 (exception_index_table(i)==null?"<nothing>":
91 cananian 1.1.2.1 exception_index_table(i).name()) +
92 cananian 1.1.2.1 " {"+exception_index_table[i]+"}");
93 cananian 1.1.2.1 }
94 cananian 1.2 }