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.TagSupport;
20: import org.apache.commons.jelly.XMLOutput;
21: import org.apache.commons.jelly.expression.Expression;
22: import org.xml.sax.SAXException;
23:
24: /** A tag which evaluates an expression
25: *
26: * @tag out
27: * @author <a href="mailto:jstrachan@apache.org">James Strachan</a>
28: * @version $Revision: 155420 $
29: */
30: public class ExprTag extends TagSupport {
31:
32: /** The expression to evaluate. */
33: private Expression value;
34:
35: public ExprTag() {
36: }
37:
38: // Tag interface
39: //-------------------------------------------------------------------------
40: public void doTag(XMLOutput output) throws JellyTagException {
41: if (value != null) {
42: String text = value.evaluateAsString(context);
43: if (text != null) {
44:
45: try {
46: output.write(text);
47: } catch (SAXException e) {
48: throw new JellyTagException(
49: "could not write the XMLOutput", e);
50: }
51: }
52: }
53: }
54:
55: // Properties
56: //-------------------------------------------------------------------------
57:
58: /**
59: * Sets the Jexl expression to evaluate.
60: *
61: * @required true
62: */
63: public void setValue(Expression value) {
64: this.value = value;
65: }
66: }
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