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1   /*
2    * Licensed to the Apache Software Foundation (ASF) under one or more
3    * contributor license agreements.  See the NOTICE file distributed with
4    * this work for additional information regarding copyright ownership.
5    * The ASF licenses this file to You under the Apache License, Version 2.0
6    * (the "License"); you may not use this file except in compliance with
7    * the License.  You may obtain a copy of the License at
8    *
9    *     http://www.apache.org/licenses/LICENSE-2.0
10   *
11   * Unless required by applicable law or agreed to in writing, software
12   * distributed under the License is distributed on an "AS IS" BASIS,
13   * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
14   * See the License for the specific language governing permissions and
15   * limitations under the License.
16   */
17  package org.apache.commons.jxpath.servlet;
18  
19  import org.apache.commons.jxpath.Variables;
20  
21  /**
22   * Implementation of the Variables interface that provides access
23   * to a single object using a reserved name (keyword).
24   *
25   * @author Dmitri Plotnikov
26   * @version $Revision: 652925 $ $Date: 2008-05-02 18:05:41 -0400 (Fri, 02 May 2008) $
27   */
28  public class KeywordVariables implements Variables {
29      private static final long serialVersionUID = 894145608741325442L;
30  
31      private String keyword;
32      private Object object;
33  
34      /**
35       * Create a new KeywordVariables.
36       * @param keyword String
37       * @param object value
38       */
39      public KeywordVariables(String keyword, Object object) {
40          if (keyword == null) {
41              throw new IllegalArgumentException("keyword cannot be null");
42          }
43          this.keyword = keyword;
44          this.object = object;
45      }
46  
47      public boolean isDeclaredVariable(String variable) {
48          return variable.equals(keyword);
49      }
50  
51      public Object getVariable(String variable) {
52          return isDeclaredVariable(variable) ? object : null;
53      }
54  
55      public void declareVariable(String variable, Object value) {
56          throw new UnsupportedOperationException(
57              "Cannot declare new keyword variables.");
58      }
59  
60      public void undeclareVariable(String variable) {
61          throw new UnsupportedOperationException(
62              "Cannot undeclare keyword variables.");
63      }
64  }