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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  /***
    25   * A tag which conditionally evaluates its body if
    26   * my {@link #setValue value} attribute equals my ancestor
    27   * {@link SwitchTag &lt;switch&gt;} tag's
    28   * {@link SwitchTag#setOn "on"} attribute.
    29   *
    30   * This tag must be contained within the body of some
    31   * {@link SwitchTag &lt;switch&gt;} tag.
    32   *
    33   * @see SwitchTag
    34   *
    35   * @author Rodney Waldhoff
    36   * @version $Revision: 155420 $ $Date: 2005-02-27 00:06:03 +1100 (Sun, 27 Feb 2005) $
    37   */
    38  public class CaseTag extends TagSupport {
    39
    40      public CaseTag() {
    41      }
    42
    43      // Tag interface
    44      //-------------------------------------------------------------------------
    45      public void setValue(Expression value) {
    46          this.valueExpression = value;
    47      }
    48
    49      public void setFallThru(boolean fallThru) {
    50          this.fallThru = fallThru;
    51      }
    52
    53      public void doTag(XMLOutput output) throws MissingAttributeException, JellyTagException {
    54          if(null == this.valueExpression) {
    55              throw new MissingAttributeException("value");
    56          }
    57          SwitchTag tag = (SwitchTag)findAncestorWithClass(SwitchTag.class);
    58          if(null == tag) {
    59              throw new JellyTagException("This tag must be enclosed inside a <switch> tag" );
    60          }
    61          if(tag.hasDefaultBeenEncountered()) {
    62              throw new JellyTagException("<default> should be the last tag within a <switch>" );
    63          }
    64          Object value = valueExpression.evaluate(context);
    65          if(tag.isFallingThru() ||
    66             (null == tag.getValue() && null == value) ||
    67             (null != tag.getValue() && tag.getValue().equals(value))) {
    68              tag.caseMatched();
    69              tag.setFallingThru(fallThru);
    70              invokeBody(output);
    71          }
    72      }
    73
    74      // Attributes
    75      //-------------------------------------------------------------------------
    76      private Expression valueExpression = null;
    77      private boolean fallThru = false;
    78
    79  }