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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  package org.apache.mina.statemachine.context;
21  
22  /**
23   * {@link StateContextLookup} implementation which always returns the same
24   * {@link StateContext} instance.
25   *
26   * @author <a href="http://mina.apache.org">Apache MINA Project</a>
27   */
28  public class SingletonStateContextLookup implements StateContextLookup {
29      private final StateContext context;
30  
31      /**
32       * Creates a new instance which always returns the same 
33       * {@link DefaultStateContext} instance.
34       */
35      public SingletonStateContextLookup() {
36          context = new DefaultStateContext();
37      }
38      
39      /**
40       * Creates a new instance which uses the specified {@link StateContextFactory}
41       * to create the single instance.
42       * 
43       * @param contextFactory the {@link StateContextFactory} to use to create 
44       *        the singleton instance.
45       */
46      public SingletonStateContextLookup(StateContextFactory contextFactory) {
47          if (contextFactory == null) {
48              throw new NullPointerException("contextFactory");
49          }
50          context = contextFactory.create();
51      }
52      
53      public StateContext lookup(Object[] eventArgs) {
54          return context;
55      }
56  }