1 /*
2 * Licensed to the Apache Software Foundation (ASF) under one or more
3 * contributor license agreements. See the NOTICE file distributed with
4 * this work for additional information regarding copyright ownership.
5 * The ASF licenses this file to You under the Apache License, Version 2.0
6 * (the "License"); you may not use this file except in compliance with
7 * the License. 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 package org.apache.commons.betwixt.expression;
18
19 /** <p><code>ConstantExpression</code> represents a constant expression.</p>
20 *
21 * <p> In other words, {@link #evaluate} returns a value independent of the context. </p>
22 *
23 * @author <a href="mailto:jstrachan@apache.org">James Strachan</a>
24 * @version $Revision: 438373 $
25 */
26 public class ConstantExpression implements Expression {
27
28 /** The value of this expression */
29 private Object value;
30
31 /** Base constructor
32 */
33 public ConstantExpression() {
34 }
35
36 /**
37 * Convenience constructor sets <code>value</code> property.
38 * @param value the Object which is the constant value for this expression
39 */
40 public ConstantExpression(Object value) {
41 this.value = value;
42 }
43
44 /**
45 * Evaluate expression against given context.
46 *
47 * @param context evaluate expression against this context
48 * @return current value of <code>value</code> property
49 */
50 public Object evaluate(Context context) {
51 return value;
52 }
53
54 /**
55 * Do nothing
56 * @see org.apache.commons.betwixt.expression.Expression
57 */
58 public void update(Context context, String newValue) {
59 // do nothing
60 }
61
62 /**
63 * Gets the constant value of this expression
64 * @return this expression's constant value
65 */
66 public Object getValue() {
67 return value;
68 }
69
70 /**
71 * Sets the constant value of this expression
72 * @param value the constant value for this expression
73 */
74 public void setValue(Object value) {
75 this.value = value;
76 }
77
78 /**
79 * Returns something useful for logging
80 * @return something useful for logging
81 */
82 public String toString() {
83 return "ConstantExpression [value=" + value + "]";
84 }
85 }