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1   /**
2    *
3    * Copyright 2003-2004 The Apache Software Foundation
4    *
5    *  Licensed under the Apache License, Version 2.0 (the "License");
6    *  you may not use this file except in compliance with the License.
7    *  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  
18  //
19  // This source code implements specifications defined by the Java
20  // Community Process. In order to remain compliant with the specification
21  // DO NOT add / change / or delete method signatures!
22  //
23  
24  package javax.servlet.jsp.el;
25  
26  /**
27   * <p>This class is used to customize the way an ExpressionEvaluator resolves
28   * variable references at evaluation time.  For example, instances of this class can
29   * implement their own variable lookup mechanisms, or introduce the
30   * notion of "implicit variables" which override any other variables.
31   * An instance of this class should be passed when evaluating
32   * an expression.</p>
33   *
34   * <p>An instance of this class includes the context against which resolution
35   * will happen</p>
36   *
37   * @since 2.0
38   */
39  public interface VariableResolver
40  {
41    //-------------------------------------
42    /**
43     * Resolves the specified variable.
44     * Returns null if the variable is not found.
45     * 
46     * @param pName the name of the variable to resolve
47     * @return the result of the variable resolution
48     *
49     * @throws ELException if a failure occurred while trying to resolve
50     *     the given variable
51     **/
52    public Object resolveVariable (String pName)
53      throws ELException;
54  					
55    //-------------------------------------
56  }