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>VariableExpression</code> represents a variable expression such as
20 * <code>$foo</code> which returns the value of the given variable.</p>
21 *
22 * @author <a href="mailto:jstrachan@apache.org">James Strachan</a>
23 * @version $Revision: 438373 $
24 */
25 public class VariableExpression implements Expression {
26
27 /** The variable name */
28 private String variableName;
29
30 /** Base constructor */
31 public VariableExpression() {
32 }
33
34 /**
35 * Convenience constructor sets <code>VariableName</code> property
36 * @param variableName the name of the context variable
37 * whose value will be returned by an evaluation
38 */
39 public VariableExpression(String variableName) {
40 this.variableName = variableName;
41 }
42
43 /** Return the value of a context variable.
44 *
45 * @param context evaluate against this context
46 * @return the value of the context variable named by the <code>VariableName</code> property
47 */
48 public Object evaluate(Context context) {
49 return context.getVariable( variableName );
50 }
51
52 /**
53 * Gets the variable name
54 * @return the name of the context variable whose value will be returned by an evaluation
55 */
56 public String getVariableName() {
57 return variableName;
58 }
59
60 /**
61 * Sets the variable name
62 * @param variableName the name of the context variable
63 * whose value will be returned by an evaluation
64 */
65 public void setVariableName(String variableName) {
66 this.variableName = variableName;
67 }
68
69 /**
70 * Do nothing
71 * @see org.apache.commons.betwixt.expression.Expression
72 */
73 public void update(Context context, String newValue) {
74 // do nothing
75 }
76
77 /**
78 * Returns something useful for logging
79 * @return something useful for logging
80 */
81 public String toString() {
82 return "VariableExpression [variable name=" + variableName + "]";
83 }
84 }