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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.xml.sax.helpers.DefaultHandler;
    22
    23
    24  /*** A tag which executes its body but passing no output.
    25   *  <p>
    26   * Using this tag will still take the time to perform toString on each object
    27   * returned to the output (but this toString value is discarded.
    28   * A future version should go more internally so that this is avoided.
    29   *
    30   * @author <a href="mailto:paul@activemath.org">Paul Libbrecht</a>
    31   * @version $Revision: 155420 $
    32    */
    33  public class MuteTag extends TagSupport {
    34
    35      /***
    36       * Create an instance
    37       */
    38      public MuteTag() {
    39      }
    40
    41      /***
    42       * Invoke the body and produce no output.
    43       * @param output tag output, which is ignored.
    44       */
    45      public void doTag(XMLOutput output) throws JellyTagException {
    46          super.invokeBody(new MuteXMLOutput());
    47      }
    48
    49      /***
    50       * An XMLOutput which really outputs nothing, in particular, avoids calling
    51       * toString() in objects returned...
    52       */
    53      static class MuteXMLOutput extends XMLOutput {
    54          public MuteXMLOutput() {
    55              super(new DefaultHandler());
    56          }
    57
    58          /***
    59           * Do nothing, not even invoke the toString!
    60           */
    61          public void objectData(Object o) {
    62          }
    63      } // class MuteXMLOutput
    64  } // class TagSupport