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      1 /*
      2  * Licensed to the Apache Software Foundation (ASF) under one
      3  * or more contributor license agreements. See the NOTICE file
      4  * distributed with this work for additional information
      5  * regarding copyright ownership. The ASF licenses this file
      6  * to you under the Apache License, Version 2.0 (the  "License");
      7  * you may not use this file except in compliance with the License.
      8  * You may obtain a copy of the License at
      9  *
     10  *     http://www.apache.org/licenses/LICENSE-2.0
     11  *
     12  * Unless required by applicable law or agreed to in writing, software
     13  * distributed under the License is distributed on an "AS IS" BASIS,
     14  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
     15  * See the License for the specific language governing permissions and
     16  * limitations under the License.
     17  */
     18 /*
     19  * $Id: ElemFallback.java 468643 2006-10-28 06:56:03Z minchau $
     20  */
     21 package org.apache.xalan.templates;
     22 
     23 import javax.xml.transform.TransformerException;
     24 
     25 import org.apache.xalan.transformer.TransformerImpl;
     26 
     27 /**
     28  * Implement xsl:fallback.
     29  * <pre>
     30  * <!ELEMENT xsl:fallback %template;>
     31  * <!ATTLIST xsl:fallback %space-att;>
     32  * </pre>
     33  * @see <a href="http://www.w3.org/TR/xslt#fallback">fallback in XSLT Specification</a>
     34  * @xsl.usage advanced
     35  */
     36 public class ElemFallback extends ElemTemplateElement
     37 {
     38     static final long serialVersionUID = 1782962139867340703L;
     39 
     40   /**
     41    * Get an int constant identifying the type of element.
     42    * @see org.apache.xalan.templates.Constants
     43    *
     44    * @return The token ID for this element
     45    */
     46   public int getXSLToken()
     47   {
     48     return Constants.ELEMNAME_FALLBACK;
     49   }
     50 
     51   /**
     52    * Return the node name.
     53    *
     54    * @return The Element's name
     55    */
     56   public String getNodeName()
     57   {
     58     return Constants.ELEMNAME_FALLBACK_STRING;
     59   }
     60 
     61   /**
     62    * This is the normal call when xsl:fallback is instantiated.
     63    * In accordance with the XSLT 1.0 Recommendation, chapter 15,
     64    * "Normally, instantiating an xsl:fallback element does nothing."
     65    *
     66    * @param transformer non-null reference to the the current transform-time state.
     67    *
     68    * @throws TransformerException
     69    */
     70   public void execute(
     71           TransformerImpl transformer)
     72             throws TransformerException
     73   {
     74   }
     75 
     76   /**
     77    * Execute the fallback elements.  This must be explicitly called to
     78    * instantiate the content of an xsl:fallback element.
     79    * When an XSLT transformer performs fallback for an instruction
     80    * element, if the instruction element has one or more xsl:fallback
     81    * children, then the content of each of the xsl:fallback children
     82    * must be instantiated in sequence; otherwise, an error must
     83    * be signaled. The content of an xsl:fallback element is a template.
     84    *
     85    * @param transformer non-null reference to the the current transform-time state.
     86    *
     87    * @throws TransformerException
     88    */
     89   public void executeFallback(
     90           TransformerImpl transformer)
     91             throws TransformerException
     92   {
     93 
     94     int parentElemType = m_parentNode.getXSLToken();
     95     if (Constants.ELEMNAME_EXTENSIONCALL == parentElemType
     96         || Constants.ELEMNAME_UNDEFINED == parentElemType)
     97     {
     98 
     99       transformer.executeChildTemplates(this, true);
    100 
    101     }
    102     else
    103     {
    104 
    105       // Should never happen
    106       System.out.println(
    107         "Error!  parent of xsl:fallback must be an extension or unknown element!");
    108     }
    109   }
    110 }
    111