01: /*
02: * Licensed to the Apache Software Foundation (ASF) under one or more
03: * contributor license agreements. See the NOTICE file distributed with
04: * this work for additional information regarding copyright ownership.
05: * The ASF licenses this file to You under the Apache License, Version 2.0
06: * (the "License"); you may not use this file except in compliance with
07: * the License. You may obtain a copy of the License at
08: *
09: * 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: }
85: }
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