1 /*
2 * $Header: /home/cvs/jakarta-commons/betwixt/src/java/org/apache/commons/betwixt/expression/VariableExpression.java,v 1.3 2003/01/11 09:14:01 rdonkin Exp $
3 * $Revision: 1.3 $
4 * $Date: 2003/01/11 09:14:01 $
5 *
6 * ====================================================================
7 *
8 * The Apache Software License, Version 1.1
9 *
10 * Copyright (c) 1999-2002 The Apache Software Foundation. All rights
11 * reserved.
12 *
13 * Redistribution and use in source and binary forms, with or without
14 * modification, are permitted provided that the following conditions
15 * are met:
16 *
17 * 1. Redistributions of source code must retain the above copyright
18 * notice, this list of conditions and the following disclaimer.
19 *
20 * 2. Redistributions in binary form must reproduce the above copyright
21 * notice, this list of conditions and the following disclaimer in
22 * the documentation and/or other materials provided with the
23 * distribution.
24 *
25 * 3. The end-user documentation included with the redistribution, if
26 * any, must include the following acknowlegement:
27 * "This product includes software developed by the
28 * Apache Software Foundation (http://www.apache.org/)."
29 * Alternately, this acknowlegement may appear in the software itself,
30 * if and wherever such third-party acknowlegements normally appear.
31 *
32 * 4. The names "The Jakarta Project", "Commons", and "Apache Software
33 * Foundation" must not be used to endorse or promote products derived
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35 * permission, please contact apache@apache.org.
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37 * 5. Products derived from this software may not be called "Apache"
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40 *
41 * THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESSED OR IMPLIED
42 * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
43 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
44 * DISCLAIMED. IN NO EVENT SHALL THE APACHE SOFTWARE FOUNDATION OR
45 * ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
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47 * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF
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50 * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
51 * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
52 * SUCH DAMAGE.
53 * ====================================================================
54 *
55 * This software consists of voluntary contributions made by many
56 * individuals on behalf of the Apache Software Foundation. For more
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58 * <http://www.apache.org/>.
59 *
60 * $Id: VariableExpression.java,v 1.3 2003/01/11 09:14:01 rdonkin Exp $
61 */
62 package org.apache.commons.betwixt.expression;
63
64 /*** <p><code>VariableExpression</code> represents a variable expression such as
65 * <code>$foo</code> which returns the value of the given variable.</p>
66 *
67 * @author <a href="mailto:jstrachan@apache.org">James Strachan</a>
68 * @version $Revision: 1.3 $
69 */
70 public class VariableExpression implements Expression {
71
72 /*** The variable name */
73 private String variableName;
74
75 /*** Base constructor */
76 public VariableExpression() {
77 }
78
79 /***
80 * Convenience constructor sets <code>VariableName</code> property
81 * @param variableName the name of the context variable
82 * whose value will be returned by an evaluation
83 */
84 public VariableExpression(String variableName) {
85 this.variableName = variableName;
86 }
87
88 /*** Return the value of a context variable.
89 *
90 * @param context evaluate against this context
91 * @return the value of the context variable named by the <code>VariableName</code> property
92 */
93 public Object evaluate(Context context) {
94 return context.getVariable( variableName );
95 }
96
97 /***
98 * Gets the variable name
99 * @return the name of the context variable whose value will be returned by an evaluation
100 */
101 public String getVariableName() {
102 return variableName;
103 }
104
105 /***
106 * Sets the variable name
107 * @param variableName the name of the context variable
108 * whose value will be returned by an evaluation
109 */
110 public void setVariableName(String variableName) {
111 this.variableName = variableName;
112 }
113
114 /***
115 * Do nothing
116 * @see org.apache.commons.betwixt.expression.Expression
117 */
118 public void update(Context context, String newValue) {
119 // do nothing
120 }
121
122 /***
123 * Returns something useful for logging
124 * @return something useful for logging
125 */
126 public String toString() {
127 return "VariableExpression [variable name=" + variableName + "]";
128 }
129 }
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