1 cananian 1.1.2.2 // AttributeLocalVariableTable.java, created Mon Jan 18 22:44:36 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>LocalVariableTable</code> attribute is an optional
8 cananian 1.1.2.1 * variable-length attribute of a <code>Code</code> attribute. It may
9 cananian 1.1.2.1 * be used by debuggers to determine the value of a given local variable
10 cananian 1.1.2.1 * during the execution of a method. If <code>LocalVariableTable</code>
11 cananian 1.1.2.1 * attributes are present in the <code>attributes</code> table of a
12 cananian 1.1.2.1 * given <code>Code</code> attribute, then they may appear in any
13 cananian 1.1.2.1 * order. There may be no more than one <code>LocalVariableTable</code>
14 cananian 1.1.2.1 * attribute per local variable in the <code>Code</code> attribute.
15 cananian 1.1.2.1 * <p>
16 cananian 1.1.2.1 * This object represents a table mapping local variable indexes to
17 cananian 1.1.2.1 * symbolic names. This attribute is optional; typically it is
18 cananian 1.1.2.1 * not included unless debugging flags are given to the compiler.
19 cananian 1.1.2.1 *
20 cananian 1.1.2.1 * @author C. Scott Ananian <cananian@alumni.princeton.edu>
21 cananian 1.3 * @version $Id: AttributeLocalVariableTable.java,v 1.3 2003/09/05 21:45:16 cananian Exp $
22 cananian 1.1.2.1 * @see "The Java Virtual Machine Specification, section 4.7.7"
23 cananian 1.1.2.1 * @see AttributeCode
24 cananian 1.1.2.1 * @see Attribute
25 cananian 1.1.2.1 */
26 cananian 1.1.2.1 public class AttributeLocalVariableTable extends Attribute {
27 cananian 1.3 /** The string naming this <code>Attribute</code> type. */
28 cananian 1.3 public static final String ATTRIBUTE_NAME = "LocalVariableTable";
29 cananian 1.1.2.1 /** Each entry in the <code>local_variable_table</code> array
30 cananian 1.1.2.1 indicates a range of <code>code</code> offsets within which a
31 cananian 1.1.2.1 local variable has a value. It also indicates the index into
32 cananian 1.1.2.1 the local variables of the current frame at which that local
33 cananian 1.1.2.1 variable can be found. */
34 cananian 1.1.2.1 public LocalVariableTable local_variable_table[];
35 cananian 1.1.2.1
36 cananian 1.1.2.1 /** Constructor. */
37 cananian 1.1.2.1 AttributeLocalVariableTable(ClassFile parent, ClassDataInputStream in,
38 cananian 1.1.2.1 int attribute_name_index)
39 cananian 1.1.2.1 throws java.io.IOException
40 cananian 1.1.2.1 {
41 cananian 1.1.2.1 super(parent, attribute_name_index);
42 cananian 1.1.2.1 long attribute_length = in.read_u4();
43 cananian 1.1.2.1
44 cananian 1.1.2.1 int local_variable_table_length = in.read_u2();
45 cananian 1.1.2.1 local_variable_table = new LocalVariableTable[local_variable_table_length];
46 cananian 1.1.2.1 for (int i=0; i<local_variable_table_length; i++)
47 cananian 1.1.2.1 local_variable_table[i] = new LocalVariableTable(parent, in);
48 cananian 1.1.2.1
49 cananian 1.1.2.1 if (attribute_length != attribute_length())
50 cananian 1.1.2.1 throw new ClassDataException("LocalVariableTable with length "
51 cananian 1.1.2.1 + attribute_length);
52 cananian 1.3 assert ATTRIBUTE_NAME.equals(attribute_name());
53 cananian 1.1.2.1 }
54 cananian 1.1.2.1 /** Constructor. */
55 cananian 1.1.2.1 public AttributeLocalVariableTable(ClassFile parent,int attribute_name_index,
56 cananian 1.1.2.1 LocalVariableTable local_variable_table[])
57 cananian 1.1.2.1 {
58 cananian 1.1.2.1 super(parent, attribute_name_index);
59 cananian 1.1.2.1 this.local_variable_table = local_variable_table;
60 cananian 1.3 assert ATTRIBUTE_NAME.equals(attribute_name());
61 cananian 1.1.2.1 }
62 cananian 1.1.2.1
63 cananian 1.1.2.1 public long attribute_length() {
64 cananian 1.1.2.1 return 2 + 10*local_variable_table_length();
65 cananian 1.1.2.1 }
66 cananian 1.1.2.1
67 cananian 1.1.2.1 // Convenience.
68 cananian 1.1.2.1 public int local_variable_table_length()
69 cananian 1.1.2.1 { return local_variable_table.length; }
70 cananian 1.1.2.1
71 cananian 1.1.2.1 /** Write to bytecode stream. */
72 cananian 1.1.2.1 public void write(ClassDataOutputStream out) throws java.io.IOException {
73 cananian 1.1.2.1 out.write_u2(attribute_name_index);
74 cananian 1.1.2.1 out.write_u4(attribute_length());
75 cananian 1.1.2.1
76 cananian 1.1.2.1 out.write_u2(local_variable_table_length());
77 cananian 1.1.2.1 for (int i=0; i< local_variable_table.length; i++)
78 cananian 1.1.2.1 local_variable_table[i].write(out);
79 cananian 1.1.2.1 }
80 cananian 1.1.2.1
81 cananian 1.1.2.1 /** Get the (debugging) name of a local variable.
82 cananian 1.1.2.1 * @param pc the pc at which the inquiry is being made.
83 cananian 1.1.2.1 * @param index the index of the local variable to query.
84 cananian 1.1.2.1 * @return the name of the index'th local variable, or null
85 cananian 1.1.2.1 * if none can be found.
86 cananian 1.1.2.1 */
87 cananian 1.1.2.1 public String localName(int pc, int index) {
88 cananian 1.1.2.1 for (int i=0; i<local_variable_table.length; i++)
89 cananian 1.1.2.1 if ((local_variable_table[i].index == index) &&
90 cananian 1.1.2.1 (local_variable_table[i].start_pc <= pc) &&
91 cananian 1.1.2.1 (pc <= local_variable_table[i].end_pc()))
92 cananian 1.1.2.1 return local_variable_table[i].name();
93 cananian 1.1.2.1 return null;
94 cananian 1.1.2.1 }
95 cananian 1.1.2.1
96 cananian 1.1.2.1 /** Pretty-print the contents of this attribute.
97 cananian 1.1.2.1 * @param indent the indentation level to use.
98 cananian 1.1.2.1 */
99 cananian 1.1.2.1 public void print(java.io.PrintWriter pw, int indent) {
100 cananian 1.1.2.1 int in=indent;
101 cananian 1.1.2.1 indent(pw, in,
102 cananian 1.1.2.1 "LocalVariableTable attribute ["+local_variable_table.length+"]:");
103 cananian 1.1.2.1 for (int i=0; i<local_variable_table.length; i++) {
104 cananian 1.1.2.1 indent(pw, in+1, "#"+i+":");
105 cananian 1.1.2.1 local_variable_table[i].print(pw, in+2);
106 cananian 1.1.2.1 }
107 cananian 1.1.2.1 }
108 cananian 1.2 }