Source code: org/apache/commons/jelly/tags/core/IfTag.java
1 /*
2 * Copyright 2002,2004 The Apache Software Foundation.
3 *
4 * Licensed under the Apache License, Version 2.0 (the "License");
5 * you may not use this file except in compliance with the License.
6 * You may obtain a copy of the License at
7 *
8 * http://www.apache.org/licenses/LICENSE-2.0
9 *
10 * Unless required by applicable law or agreed to in writing, software
11 * distributed under the License is distributed on an "AS IS" BASIS,
12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13 * See the License for the specific language governing permissions and
14 * limitations under the License.
15 */
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 // Tag interface
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 // Properties
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 }