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1   /*
2    * Copyright 2001-2004 The Apache Software Foundation.
3    * 
4    * Licensed under the Apache License, Version 2.0 (the "License");
5    * you may not use this file except in compliance with the License.
6    * You may obtain a copy of the License at
7    * 
8    *      http://www.apache.org/licenses/LICENSE-2.0
9    * 
10   * Unless required by applicable law or agreed to in writing, software
11   * distributed under the License is distributed on an "AS IS" BASIS,
12   * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13   * See the License for the specific language governing permissions and
14   * limitations under the License.
15   */ 
16  package org.apache.commons.betwixt.expression;
17  
18  /*** <p><code>Expression</code> represents an arbitrary expression on a bean.</p>
19    *
20    * @author <a href="mailto:jstrachan@apache.org">James Strachan</a>
21    */
22  public interface Expression {
23  
24      /*** Evaluates the expression on the bean with the given context
25       * and returns the result 
26       *
27       * @param context evaluate against this <code>Context</code>
28       * @return the value of the expression
29       */
30      public Object evaluate(Context context);    
31      
32      
33      /* XXX 
34         Is update actually useful?
35         None of the expression implementations i can find do anything when it's called.
36         I suspect that it's been replaced by Updater
37         but i maybe i'm missing something subtle
38      */
39      /*** <p>Updates the current bean context with a new String value.
40       * This is typically used when parsing XML and updating a beans value
41       * from XML.<p>
42       *
43       * @param context update this <code>Context</code> 
44       * @param newValue the new value for this expression
45       * @deprecated 0.5 use {@link Updater} instead
46       */
47      public void update(Context context, String newValue);
48  }