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    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
    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 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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