View Javadoc

    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
    22
    23  /***
    24   * A tag which conditionally evaluates its body if
    25   * none of its preceeding sibling {@link CaseTag &lt;case&gt;}
    26   * tags have been evaluated.
    27   *
    28   * This tag must be contained within the body of some
    29   * {@link SwitchTag &lt;switch&gt;} tag.
    30   *
    31   * @see SwitchTag
    32   *
    33   * @author Rodney Waldhoff
    34   * @version $Revision: 155420 $ $Date: 2005-02-27 00:06:03 +1100 (Sun, 27 Feb 2005) $
    35   */
    36  public class DefaultTag extends TagSupport {
    37
    38      public DefaultTag() {
    39      }
    40
    41      // Tag interface
    42      //-------------------------------------------------------------------------
    43
    44      public void setFallThru(boolean fallThru) {
    45          this.fallThru = fallThru;
    46      }
    47
    48      public void doTag(XMLOutput output) throws JellyTagException {
    49          SwitchTag tag = (SwitchTag)findAncestorWithClass(SwitchTag.class);
    50          if(null == tag) {
    51              throw new JellyTagException("This tag must be enclosed inside a <switch> tag" );
    52          }
    53          if(tag.hasDefaultBeenEncountered()) {
    54              throw new JellyTagException("Only one <default> tag is allowed per <switch>.");
    55          }
    56          tag.defaultEncountered();
    57          if(tag.isFallingThru() || (!tag.hasSomeCaseMatched())) {
    58              tag.caseMatched();
    59              tag.setFallingThru(fallThru);
    60              invokeBody(output);
    61          }
    62      }
    63
    64      // Attributes
    65      //-------------------------------------------------------------------------
    66      private boolean fallThru = false;
    67
    68  }