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    1   package org.apache.bcel.verifier;
    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 java.util.HashMap;
    58  import java.util.Iterator;
    59  import java.util.Vector;
    60
    61  /***
    62   * This class produces instances of the Verifier class. Its purpose is to make
    63   * sure that they are singleton instances with respect to the class name they
    64   * operate on. That means, for every class (represented by a unique fully qualified
    65   * class name) there is exactly one Verifier.
    66   *
    67   * @version $Id: VerifierFactory.java,v 1.2 2002/02/07 23:22:30 enver Exp $
    68   * @author <A HREF="http://www.inf.fu-berlin.de/~ehaase"/>Enver Haase</A>
    69   * @see org.apache.bcel.verifier.Verifier
    70   */
    71  public class VerifierFactory{
    72
    73  	/***
    74  	 * The HashMap that holds the data about the already-constructed Verifier instances.
    75  	 */
    76  	private static HashMap hashMap = new HashMap();
    77
    78  	/***
    79  	 * The VerifierFactoryObserver instances that observe the VerifierFactory.
    80  	 */
    81  	private static Vector observers = new Vector();
    82
    83  	/***
    84  	 * The VerifierFactory is not instantiable.
    85  	 */
    86  	private VerifierFactory(){}
    87
    88  	/***
    89  	 * Returns the (only) verifier responsible for the class with the given name.
    90  	 * Possibly a new Verifier object is transparently created.
    91  	 * @return the (only) verifier responsible for the class with the given name.
    92  	 */
    93  	public static Verifier getVerifier(String fully_qualified_classname){
    94  		fully_qualified_classname = fully_qualified_classname;
    95
    96  		Verifier v = (Verifier) (hashMap.get(fully_qualified_classname));
    97  		if (v==null){
    98  			v = new Verifier(fully_qualified_classname);
    99  			hashMap.put(fully_qualified_classname, v);
    100 			notify(fully_qualified_classname);
    101 		}
    102
    103 		return v;
    104 	}
    105
    106 	/***
    107 	 * Notifies the observers of a newly generated Verifier.
    108 	 */
    109 	private static void notify(String fully_qualified_classname){
    110 		// notify the observers
    111 		Iterator i = observers.iterator();
    112 		while (i.hasNext()){
    113 			VerifierFactoryObserver vfo = (VerifierFactoryObserver) i.next();
    114 			vfo.update(fully_qualified_classname);
    115 		}
    116 	}
    117
    118 	/***
    119 	 * Returns all Verifier instances created so far.
    120 	 * This is useful when a Verifier recursively lets
    121 	 * the VerifierFactory create other Verifier instances
    122 	 * and if you want to verify the transitive hull of
    123 	 * referenced class files.
    124 	 */
    125 	public static Verifier[] getVerifiers(){
    126 		Verifier[] vs = new Verifier[hashMap.values().size()];
    127 		return (Verifier[]) (hashMap.values().toArray(vs));	// Because vs is big enough, vs is used to store the values into and returned!
    128 	}
    129
    130 	/***
    131 	 * Adds the VerifierFactoryObserver o to the list of observers.
    132 	 */
    133 	public static void attach(VerifierFactoryObserver o){
    134 		observers.addElement(o);
    135 	}
    136
    137 	/***
    138 	 * Removes the VerifierFactoryObserver o from the list of observers.
    139 	 */
    140 	public static void detach(VerifierFactoryObserver o){
    141 			observers.removeElement(o);
    142 	}
    143 }

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