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Java > Open Source Codes > com > sun > org > apache > bcel > internal > verifier > statics > LocalVariableInfo


1 package com.sun.org.apache.bcel.internal.verifier.statics;
2
3 /* ====================================================================
4  * The Apache Software License, Version 1.1
5  *
6  * Copyright (c) 2001 The Apache Software Foundation. All rights
7  * reserved.
8  *
9  * Redistribution and use in source and binary forms, with or without
10  * modification, are permitted provided that the following conditions
11  * are met:
12  *
13  * 1. Redistributions of source code must retain the above copyright
14  * notice, this list of conditions and the following disclaimer.
15  *
16  * 2. Redistributions in binary form must reproduce the above copyright
17  * notice, this list of conditions and the following disclaimer in
18  * the documentation and/or other materials provided with the
19  * distribution.
20  *
21  * 3. The end-user documentation included with the redistribution,
22  * if any, must include the following acknowledgment:
23  * "This product includes software developed by the
24  * Apache Software Foundation (http://www.apache.org/)."
25  * Alternately, this acknowledgment may appear in the software itself,
26  * if and wherever such third-party acknowledgments normally appear.
27  *
28  * 4. The names "Apache" and "Apache Software Foundation" and
29  * "Apache BCEL" must not be used to endorse or promote products
30  * derived from this software without prior written permission. For
31  * written permission, please contact apache@apache.org.
32  *
33  * 5. Products derived from this software may not be called "Apache",
34  * "Apache BCEL", nor may "Apache" appear in their name, without
35  * prior written permission of the Apache Software Foundation.
36  *
37  * THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESSED OR IMPLIED
38  * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
39  * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
40  * DISCLAIMED. IN NO EVENT SHALL THE APACHE SOFTWARE FOUNDATION OR
41  * ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
42  * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
43  * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF
44  * USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
45  * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
46  * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
47  * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
48  * SUCH DAMAGE.
49  * ====================================================================
50  *
51  * This software consists of voluntary contributions made by many
52  * individuals on behalf of the Apache Software Foundation. For more
53  * information on the Apache Software Foundation, please see
54  * <http://www.apache.org/>.
55  */

56
57 import com.sun.org.apache.bcel.internal.Constants;
58 import com.sun.org.apache.bcel.internal.generic.Type;
59 import com.sun.org.apache.bcel.internal.verifier.exc.*;
60 import java.util.Hashtable JavaDoc;
61
62 /**
63  * A utility class holding the information about
64  * the name and the type of a local variable in
65  * a given slot (== index). This information
66  * often changes in course of byte code offsets.
67  *
68  * @version $Id: LocalVariableInfo.java,v 1.1.1.1 2001/10/29 20:00:34 jvanzyl Exp $
69  * @author <A HREF="http://www.inf.fu-berlin.de/~ehaase"/>Enver Haase</A>
70  */

71 public class LocalVariableInfo{
72
73     /** The types database. KEY: String representing the offset integer. */
74     private Hashtable JavaDoc types = new Hashtable JavaDoc();
75     /** The names database. KEY: String representing the offset integer. */
76     private Hashtable JavaDoc names = new Hashtable JavaDoc();
77
78     /**
79      * Adds a name of a local variable and a certain slot to our 'names'
80      * (Hashtable) database.
81      */

82     private void setName(int offset, String JavaDoc name){
83         names.put( ((Integer.toString(offset))), name);
84     }
85     /**
86      * Adds a type of a local variable and a certain slot to our 'types'
87      * (Hashtable) database.
88      */

89     private void setType(int offset, Type t){
90         types.put( ((Integer.toString(offset))), t);
91     }
92
93     /**
94      * Returns the type of the local variable that uses this local
95      * variable slot at the given bytecode offset.
96      * Care for legal bytecode offsets yourself, otherwise the return value
97      * might be wrong.
98      * May return 'null' if nothing is known about the type of this local
99      * variable slot at the given bytecode offset.
100      */

101     public Type getType(int offset){
102         return (Type) types.get(Integer.toString(offset));
103     }
104     /**
105      * Returns the name of the local variable that uses this local
106      * variable slot at the given bytecode offset.
107      * Care for legal bytecode offsets yourself, otherwise the return value
108      * might be wrong.
109      * May return 'null' if nothing is known about the type of this local
110      * variable slot at the given bytecode offset.
111      */

112     public String JavaDoc getName(int offset){
113         return (String JavaDoc) (names.get(Integer.toString(offset)));
114     }
115     /**
116      * Adds some information about this local variable (slot).
117      * @throws LocalVariableInfoInconsistentException if the new information conflicts
118      * with already gathered information.
119      */

120     public void add(String JavaDoc name, int startpc, int length, Type t) throws LocalVariableInfoInconsistentException{
121         for (int i=startpc; i<=startpc+length; i++){ // incl/incl-notation!
122
add(i,name,t);
123         }
124     }
125
126     /**
127      * Adds information about name and type for a given offset.
128      * @throws LocalVariableInfoInconsistentException if the new information conflicts
129      * with already gathered information.
130      */

131     private void add(int offset, String JavaDoc name, Type t) throws LocalVariableInfoInconsistentException{
132         if (getName(offset) != null){
133             if (! getName(offset).equals(name)){
134                 throw new LocalVariableInfoInconsistentException("At bytecode offset '"+offset+"' a local variable has two different names: '"+getName(offset)+"' and '"+name+"'.");
135             }
136         }
137         if (getType(offset) != null){
138             if (! getType(offset).equals(t)){
139                 throw new LocalVariableInfoInconsistentException("At bytecode offset '"+offset+"' a local variable has two different types: '"+getType(offset)+"' and '"+t+"'.");
140             }
141         }
142         setName(offset, name);
143         setType(offset, t);
144     }
145 }
146
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