/*
 * The Apache Software License, Version 1.1
 *
 *
 * Copyright (c) 1999-2003 The Apache Software Foundation.  All rights 
 * reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 *
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer. 
 *
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in
 *    the documentation and/or other materials provided with the
 *    distribution.
 *
 * 3. The end-user documentation included with the redistribution,
 *    if any, must include the following acknowledgment:  
 *       "This product includes software developed by the
 *        Apache Software Foundation (http://www.apache.org/)."
 *    Alternately, this acknowledgment may appear in the software itself,
 *    if and wherever such third-party acknowledgments normally appear.
 *
 * 4. The names "Xalan" and "Apache Software Foundation" must
 *    not be used to endorse or promote products derived from this
 *    software without prior written permission. For written 
 *    permission, please contact apache@apache.org.
 *
 * 5. Products derived from this software may not be called "Apache",
 *    nor may "Apache" appear in their name, without prior written
 *    permission of the Apache Software Foundation.
 *
 * THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESSED OR IMPLIED
 * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
 * DISCLAIMED.  IN NO EVENT SHALL THE APACHE SOFTWARE FOUNDATION OR
 * ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
 * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF
 * USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
 * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
 * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
 * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 * ====================================================================
 *
 * This software consists of voluntary contributions made by many
 * individuals on behalf of the Apache Software Foundation and was
 * originally based on software copyright (c) 1999, Lotus
 * Development Corporation., http://www.lotus.com.  For more
 * information on the Apache Software Foundation, please see
 * <http://www.apache.org/>.
 */
package org.apache.xalan.templates;

import javax.xml.transform.TransformerException;

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

/**
 * Handles the EXSLT result element within an EXSLT function element.
 */
public class ElemExsltFuncResult extends ElemVariable
{
 
  /**
   * Generate the EXSLT function return value, and assign it to the variable
   * index slot assigned for it in ElemExsltFunction compose().
   * 
   */
  public void execute(TransformerImpl transformer) throws TransformerException
  {    
    XPathContext context = transformer.getXPathContext();
    ElemExsltFunction owner = getOwnerFunction();

    if (TransformerImpl.S_DEBUG)
      transformer.getTraceManager().fireTraceEvent(this);
    
    if (owner != null)
    {
      // Verify that result has not already been set by another result
      // element. Recursion is allowed: intermediate results are cleared 
      // in the owner ElemExsltFunction execute().
      if (owner.isResultSet())
        throw new TransformerException("An EXSLT function cannot set more than one result!");
      
      int sourceNode = context.getCurrentNode();
      // Set the return value;
      XObject var = getValue(transformer, sourceNode);
      owner.setResult(var);
    }

    if (TransformerImpl.S_DEBUG)
      transformer.getTraceManager().fireTraceEndEvent(this);    
    
  }

  /**
   * Get an integer representation of the element type.
   *
   * @return An integer representation of the element, defined in the
   *     Constants class.
   * @see org.apache.xalan.templates.Constants
   */
  public int getXSLToken()
  {
    return Constants.EXSLT_ELEMNAME_FUNCRESULT;
  }
  
  /**
   * Return the node name, defined in the
   *     Constants class.
   * @see org.apache.xalan.templates.Constants
   * @return The node name
   * 
   */
   public String getNodeName()
  {
    return Constants.EXSLT_ELEMNAME_FUNCRESULT_STRING;
  }
  
  /**
   * Get the ElemExsltFunction that contains the ElemResult so we can set an ElemExsltFunction variable
   * to the local variable stack index to the return value.
   */
  public ElemExsltFunction getOwnerFunction()
  {
  	ElemTemplateElement elem = this;
  	while((elem != null) && !(elem instanceof ElemExsltFunction))
  	{
    	elem = elem.getParentElem();
  	}
  	return (ElemExsltFunction)elem;
  }
  
}