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16 package org.apache.commons.jelly.tags.core;
17
18 import org.apache.commons.jelly.JellyTagException;
19 import org.apache.commons.jelly.MissingAttributeException;
20 import org.apache.commons.jelly.TagSupport;
21 import org.apache.commons.jelly.XMLOutput;
22 import org.apache.commons.jelly.expression.Expression;
23
24 /*** A tag which conditionally evaluates its body based on some condition
25 *
26 * @author <a href="mailto:jstrachan@apache.org">James Strachan</a>
27 * @version $Revision: 155420 $
28 */
29 public class IfTag extends TagSupport {
30
31 /*** The expression to evaluate. */
32 private Expression test;
33
34 public IfTag() {
35 }
36
37
38
39 public void doTag(XMLOutput output) throws MissingAttributeException, JellyTagException {
40 if (test != null) {
41 if (test.evaluateAsBoolean(context)) {
42 invokeBody(output);
43 }
44 }
45 else {
46 throw new MissingAttributeException( "test" );
47 }
48
49 }
50
51
52
53 /*** Sets the Jelly expression to evaluate. If this returns true, the body of
54 * the tag is evaluated
55 *
56 * @param test the Jelly expression to evaluate
57 */
58 public void setTest(Expression test) {
59 this.test = test;
60 }
61 }