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Java > Open Source Codes > org > apache > bcel > classfile > LocalVariableTable


1 /*
2  * Copyright 2000-2004 The Apache Software Foundation
3  *
4  * Licensed under the Apache License, Version 2.0 (the "License");
5  * you may not use this file except in compliance with the License.
6  * You may obtain a copy of the License at
7  *
8  * http://www.apache.org/licenses/LICENSE-2.0
9  *
10  * Unless required by applicable law or agreed to in writing, software
11  * distributed under the License is distributed on an "AS IS" BASIS,
12  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13  * See the License for the specific language governing permissions and
14  * limitations under the License.
15  *
16  */
17 package org.apache.bcel.classfile;
18
19 import java.io.DataInputStream JavaDoc;
20 import java.io.DataOutputStream JavaDoc;
21 import java.io.IOException JavaDoc;
22 import org.apache.bcel.Constants;
23
24 /**
25  * This class represents colection of local variables in a
26  * method. This attribute is contained in the <em>Code</em> attribute.
27  *
28  * @version $Id: LocalVariableTable.java 386056 2006-03-15 11:31:56Z tcurdt $
29  * @author <A HREF="mailto:m.dahm@gmx.de">M. Dahm</A>
30  * @see Code
31  * @see LocalVariable
32  */
33 public class LocalVariableTable extends Attribute {
34
35     private int local_variable_table_length; // Table of local
36 private LocalVariable[] local_variable_table; // variables
37
38
39     /**
40      * Initialize from another object. Note that both objects use the same
41      * references (shallow copy). Use copy() for a physical copy.
42      */
43     public LocalVariableTable(LocalVariableTable c) {
44         this(c.getNameIndex(), c.getLength(), c.getLocalVariableTable(), c.getConstantPool());
45     }
46
47
48     /**
49      * @param name_index Index in constant pool to `LocalVariableTable'
50      * @param length Content length in bytes
51      * @param local_variable_table Table of local variables
52      * @param constant_pool Array of constants
53      */
54     public LocalVariableTable(int name_index, int length, LocalVariable[] local_variable_table,
55             ConstantPool constant_pool) {
56         super(Constants.ATTR_LOCAL_VARIABLE_TABLE, name_index, length, constant_pool);
57         setLocalVariableTable(local_variable_table);
58     }
59
60
61     /**
62      * Construct object from file stream.
63      * @param name_index Index in constant pool
64      * @param length Content length in bytes
65      * @param file Input stream
66      * @param constant_pool Array of constants
67      * @throws IOException
68      */
69     LocalVariableTable(int name_index, int length, DataInputStream JavaDoc file, ConstantPool constant_pool)
70             throws IOException JavaDoc {
71         this(name_index, length, (LocalVariable[]) null, constant_pool);
72         local_variable_table_length = (file.readUnsignedShort());
73         local_variable_table = new LocalVariable[local_variable_table_length];
74         for (int i = 0; i < local_variable_table_length; i++) {
75             local_variable_table[i] = new LocalVariable(file, constant_pool);
76         }
77     }
78
79
80     /**
81      * Called by objects that are traversing the nodes of the tree implicitely
82      * defined by the contents of a Java class. I.e., the hierarchy of methods,
83      * fields, attributes, etc. spawns a tree of objects.
84      *
85      * @param v Visitor object
86      */
87     public void accept( Visitor v ) {
88         v.visitLocalVariableTable(this);
89     }
90
91
92     /**
93      * Dump local variable table attribute to file stream in binary format.
94      *
95      * @param file Output file stream
96      * @throws IOException
97      */
98     public final void dump( DataOutputStream JavaDoc file ) throws IOException JavaDoc {
99         super.dump(file);
100         file.writeShort(local_variable_table_length);
101         for (int i = 0; i < local_variable_table_length; i++) {
102             local_variable_table[i].dump(file);
103         }
104     }
105
106
107     /**
108      * @return Array of local variables of method.
109      */
110     public final LocalVariable[] getLocalVariableTable() {
111         return local_variable_table;
112     }
113
114
115     /**
116      * @return first matching variable using index
117      *
118      * @param index the variable slot
119      *
120      * @return the first LocalVariable that matches the slot or null if not found
121      *
122      * @deprecated since 5.2 because multiple variables can share the
123      * same slot, use getLocalVariable(int index, int pc) instead.
124      */
125     public final LocalVariable getLocalVariable( int index ) {
126         for (int i = 0; i < local_variable_table_length; i++) {
127             if (local_variable_table[i].getIndex() == index) {
128                 return local_variable_table[i];
129             }
130         }
131         return null;
132     }
133
134
135     /**
136      * @return matching variable using index when variable is used at supplied pc
137      *
138      * @param index the variable slot
139      * @param pc the current pc that this variable is alive
140      *
141      * @return the LocalVariable that matches or null if not found
142      */
143     public final LocalVariable getLocalVariable( int index, int pc ) {
144         for (int i = 0; i < local_variable_table_length; i++) {
145             if (local_variable_table[i].getIndex() == index) {
146                 int start_pc = local_variable_table[i].getStartPC();
147                 int end_pc = start_pc + local_variable_table[i].getLength();
148                 if ((pc >= start_pc) && (pc < end_pc)) {
149                     return local_variable_table[i];
150                 }
151             }
152         }
153         return null;
154     }
155
156
157     public final void setLocalVariableTable( LocalVariable[] local_variable_table ) {
158         this.local_variable_table = local_variable_table;
159         local_variable_table_length = (local_variable_table == null)
160                 ? 0
161                 : local_variable_table.length;
162     }
163
164
165     /**
166      * @return String representation.
167      */
168     public final String JavaDoc toString() {
169         StringBuffer JavaDoc buf = new StringBuffer JavaDoc("");
170         for (int i = 0; i < local_variable_table_length; i++) {
171             buf.append(local_variable_table[i].toString());
172             if (i < local_variable_table_length - 1) {
173                 buf.append('\n');
174             }
175         }
176         return buf.toString();
177     }
178
179
180     /**
181      * @return deep copy of this attribute
182      */
183     public Attribute copy( ConstantPool _constant_pool ) {
184         LocalVariableTable c = (LocalVariableTable) clone();
185         c.local_variable_table = new LocalVariable[local_variable_table_length];
186         for (int i = 0; i < local_variable_table_length; i++) {
187             c.local_variable_table[i] = local_variable_table[i].copy();
188         }
189         c.constant_pool = _constant_pool;
190         return c;
191     }
192
193
194     public final int getTableLength() {
195         return local_variable_table_length;
196     }
197 }
198
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