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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.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  }