01: /*
02: * Copyright 2002,2004 The Apache Software Foundation.
03: *
04: * Licensed under the Apache License, Version 2.0 (the "License");
05: * you may not use this file except in compliance with the License.
06: * You may obtain a copy of the License at
07: *
08: * http://www.apache.org/licenses/LICENSE-2.0
09: *
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)
40: throws MissingAttributeException, JellyTagException {
41: if (test != null) {
42: if (test.evaluateAsBoolean(context)) {
43: invokeBody(output);
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: }
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