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1   /*
2    *  Licensed to the Apache Software Foundation (ASF) under one
3    *  or more contributor license agreements.  See the NOTICE file
4    *  distributed with this work for additional information
5    *  regarding copyright ownership.  The ASF licenses this file
6    *  to you under the Apache License, Version 2.0 (the
7    *  "License"); you may not use this file except in compliance
8    *  with the License.  You may obtain a copy of the License at
9    *  
10   *    http://www.apache.org/licenses/LICENSE-2.0
11   *  
12   *  Unless required by applicable law or agreed to in writing,
13   *  software distributed under the License is distributed on an
14   *  "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
15   *  KIND, either express or implied.  See the License for the
16   *  specific language governing permissions and limitations
17   *  under the License. 
18   *  
19   */
20  
21  package org.apache.directory.server.dns.util;
22  
23  
24  import java.util.HashMap;
25  import java.util.Map;
26  
27  
28  /**
29   * A map to easily get the actual Enum instance from it's value as seen in the
30   * <a href="http://www.javaspecialists.co.za/archive/newsletter.do?issue=113">
31   * The JavaSpecialists newsletter</a>.
32   * 
33   * @param <K> 
34   * @param <E> 
35   * @author <a href="mailto:dev@directory.apache.org">Apache Directory Project</a>
36   * @version $Rev$, $Date$
37   */
38  public class ReverseEnumMap<K, E extends Enum<E> & EnumConverter<K>>
39  {
40      private Map<K, E> reverseMap = new HashMap<K, E>();
41  
42  
43      /**
44       * Creates a new instance of ReverseEnumMap.
45       *
46       * @param enumType
47       */
48      public ReverseEnumMap( Class<E> enumType )
49      {
50          for ( E e : enumType.getEnumConstants() )
51          {
52              reverseMap.put( e.convert(), e );
53          }
54      }
55  
56  
57      /**
58       * Return the enum given an ordinal value.
59       *
60       * @param value
61       * @return The enum.
62       */
63      public E get( K value )
64      {
65          E e = reverseMap.get( value );
66          if ( e == null )
67          {
68              throw new IllegalArgumentException( "Invalid enum value: " + value );
69          }
70          return e;
71      }
72  }