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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.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                  }
48                  catch (SAXException e) {
49                      throw new JellyTagException("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  }