NamedValue


1   /*
2    * Copyright 1999-2004 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  
17  package org.apache.taglibs.standard.lang.jstl;
18  
19  import java.util.Map  ;
20  
21  /**
22   *
23   * <p>Represents a name that can be used as the first element of a
24   * value.
25   * 
26   * @author Nathan Abramson - Art Technology Group
27   * @author Shawn Bayern
28   * @version $Change: 181177 $$DateTime: 2001/06/26 08:45:09 $$Author: pierred $
29   **/
30  
31  public class NamedValue
32    extends Expression
33  {
34    //-------------------------------------
35    // Constants
36    //-------------------------------------
37  
38    //-------------------------------------
39    // Properties
40    //-------------------------------------
41    // property name
42  
43    String   mName;
44    public String   getName ()
45    { return mName; }
46  
47    //-------------------------------------
48    /**
49     *
50     * Constructor
51     **/
52    public NamedValue (String   pName)
53    {
54      mName = pName;
55    }
56  
57    //-------------------------------------
58    // Expression methods
59    //-------------------------------------
60    /**
61     *
62     * Returns the expression in the expression language syntax
63     **/
64    public String   getExpressionString ()
65    {
66      return StringLiteral.toIdentifierToken (mName);
67    }
68  
69    //-------------------------------------
70    /**
71     *
72     * Evaluates by looking up the name in the VariableResolver
73     **/
74    public Object   evaluate (Object   pContext,
75                VariableResolver pResolver,
76                Map   functions,
77                String   defaultPrefix,
78                Logger pLogger)
79      throws ELException
80    {
81      if (pResolver == null) {
82        return null;
83      }
84      else {
85        return pResolver.resolveVariable (mName, pContext);
86      }
87    }
88  
89    //-------------------------------------
90  }
91
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