1 /*
2 * $Header: /home/cvs/jakarta-commons/betwixt/src/java/org/apache/commons/betwixt/expression/ConstantExpression.java,v 1.3 2003/01/09 22:34:07 rdonkin Exp $
3 * $Revision: 1.3 $
4 * $Date: 2003/01/09 22:34:07 $
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 *
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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 *
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21 * notice, this list of conditions and the following disclaimer in
22 * the documentation and/or other materials provided with the
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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
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42 * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
43 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
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54 *
55 * This software consists of voluntary contributions made by many
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59 *
60 * $Id: ConstantExpression.java,v 1.3 2003/01/09 22:34:07 rdonkin Exp $
61 */
62 package org.apache.commons.betwixt.expression;
63
64 /*** <p><code>ConstantExpression</code> represents a constant expression.</p>
65 *
66 * <p> In other words, {@link #evaluate} returns a value independent of the context. </p>
67 *
68 * @author <a href="mailto:jstrachan@apache.org">James Strachan</a>
69 * @version $Revision: 1.3 $
70 */
71 public class ConstantExpression implements Expression {
72
73 /*** The value of this expression */
74 private Object value;
75
76 /*** Base constructor
77 */
78 public ConstantExpression() {
79 }
80
81 /***
82 * Convenience constructor sets <code>value</code> property.
83 * @param value the Object which is the constant value for this expression
84 */
85 public ConstantExpression(Object value) {
86 this.value = value;
87 }
88
89 /***
90 * Evaluate expression against given context.
91 *
92 * @param context evaluate expression against this context
93 * @return current value of <code>value</code> property
94 */
95 public Object evaluate(Context context) {
96 return value;
97 }
98
99 /***
100 * Do nothing
101 * @see org.apache.commons.betwixt.expression.Expression
102 */
103 public void update(Context context, String newValue) {
104 // do nothing
105 }
106
107 /***
108 * Gets the constant value of this expression
109 * @return this expression's constant value
110 */
111 public Object getValue() {
112 return value;
113 }
114
115 /***
116 * Sets the constant value of this expression
117 * @param value the constant value for this expression
118 */
119 public void setValue(Object value) {
120 this.value = value;
121 }
122
123 /***
124 * Returns something useful for logging
125 * @return something useful for logging
126 */
127 public String toString() {
128 return "ConstantExpression [value=" + value + "]";
129 }
130 }
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