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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
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 }