/*
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements. See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership. The ASF licenses this file
 * to you under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
/*
 * $Id$
 */
package org.apache.xalan.templates;

import java.util.Vector;

import org.apache.xalan.transformer.TransformerImpl;
import org.apache.xpath.XPathContext;
import org.apache.xpath.functions.Function;
import org.apache.xpath.objects.ResultSequence;
import org.apache.xpath.objects.XObject;

/**
 * Implementation of xsl:merge instruction's current-merge-group() 
 * function.
 * 
 * @author Mukul Gandhi <mukulg@apache.org>
 * 
 * @xsl.usage advanced
 */
public class FuncCurrentMergeGroup extends Function
{
	
	private static final long serialVersionUID = 4774706928214182885L;

	/**
      * Evaluate the function. The function must return a valid object.
      * 
      * @param xctxt The current execution context.
      * @return a valid XObject.
      *
      * @throws javax.xml.transform.TransformerException
   */
   public XObject execute(XPathContext xctxt) throws javax.xml.transform.TransformerException
   {
       ResultSequence result = null;
       
       TransformerImpl transformer = (TransformerImpl) xctxt.getOwnerObject();                            
       ElemTemplateElement currElemTemplateElement = transformer.getCurrentElement();       
      
       ResultSequence mergeGroup = currElemTemplateElement.getMergeGroup();
       while (mergeGroup == null) {
           currElemTemplateElement = currElemTemplateElement.getParentElem();
           mergeGroup = currElemTemplateElement.getMergeGroup();
       }
       
       result = mergeGroup;
              
       return result;
   }

   @Override
   public void fixupVariables(Vector vars, int globalsSize) {
       // no op    
   }
  
}
