1   package org.apache.bcel.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
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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.
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35   *    prior written permission of the Apache Software Foundation.
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49   * ====================================================================
50   *
51   * This software consists of voluntary contributions made by many
52   * individuals on behalf of the Apache Software Foundation.  For more
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54   * <http://www.apache.org/>.
55   */
56  
57  import org.apache.bcel.generic.Type;
58  import org.apache.bcel.verifier.exc.*;
59  import java.util.Hashtable;
60  
61  /***
62   * A utility class holding the information about
63   * the name and the type of a local variable in
64   * a given slot (== index). This information
65   * often changes in course of byte code offsets.
66   *
67   * @version $Id: LocalVariableInfo.java,v 1.2 2002/06/13 09:32:50 enver Exp $
68   * @author <A HREF="http://www.inf.fu-berlin.de/~ehaase"/>Enver Haase</A>
69   */
70  public class LocalVariableInfo{
71  
72  	/*** The types database. KEY: String representing the offset integer. */
73  	private Hashtable types = new Hashtable();
74  	/*** The names database. KEY: String representing the offset integer. */
75  	private Hashtable names = new Hashtable();
76  
77  	/***
78  	 * Adds a name of a local variable and a certain slot to our 'names'
79  	 * (Hashtable) database.
80  	 */
81  	private void setName(int offset, String name){
82  		names.put( ((Integer.toString(offset))), name);
83  	}
84  	/***
85  	 * Adds a type of a local variable and a certain slot to our 'types'
86  	 * (Hashtable) database.
87  	 */
88  	private void setType(int offset, Type t){
89  		types.put( ((Integer.toString(offset))), t);
90  	}
91  
92  	/***
93  	 * Returns the type of the local variable that uses this local
94  	 * variable slot at the given bytecode offset.
95  	 * Care for legal bytecode offsets yourself, otherwise the return value
96  	 * might be wrong.
97  	 * May return 'null' if nothing is known about the type of this local
98  	 * variable slot at the given bytecode offset.
99  	 */
100 	public Type getType(int offset){
101 		return (Type) types.get(Integer.toString(offset));
102 	}
103 	/***
104 	 * Returns the name of the local variable that uses this local
105 	 * variable slot at the given bytecode offset.
106 	 * Care for legal bytecode offsets yourself, otherwise the return value
107 	 * might be wrong.
108 	 * May return 'null' if nothing is known about the type of this local
109 	 * variable slot at the given bytecode offset.
110 	 */
111 	public String getName(int offset){
112 		return (String) (names.get(Integer.toString(offset)));
113 	}
114 	/***
115 	 * Adds some information about this local variable (slot).
116 	 * @throws LocalVariableInfoInconsistentException if the new information conflicts
117 	 *         with already gathered information.
118 	 */
119 	public void add(String name, int startpc, int length, Type t) throws LocalVariableInfoInconsistentException{
120 		for (int i=startpc; i<=startpc+length; i++){ // incl/incl-notation!
121 			add(i,name,t);
122 		}
123 	}
124 
125 	/***
126 	 * Adds information about name and type for a given offset.
127 	 * @throws LocalVariableInfoInconsistentException if the new information conflicts
128 	 *         with already gathered information.
129 	 */
130 	private void add(int offset, String name, Type t) throws LocalVariableInfoInconsistentException{
131 		if (getName(offset) != null){
132 			if (! getName(offset).equals(name)){
133 				throw new LocalVariableInfoInconsistentException("At bytecode offset '"+offset+"' a local variable has two different names: '"+getName(offset)+"' and '"+name+"'.");
134 			}
135 		}
136 		if (getType(offset) != null){
137 			if (! getType(offset).equals(t)){
138 				throw new LocalVariableInfoInconsistentException("At bytecode offset '"+offset+"' a local variable has two different types: '"+getType(offset)+"' and '"+t+"'.");
139 			}
140 		}
141 		setName(offset, name);
142 		setType(offset, t);
143 	}
144 }
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