src/org/apache/xpath/functions/FuncAverage.java

/*
 * 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
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 * ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
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 * 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.xpath.functions;

import org.apache.xpath.res.XPATHErrorResources;

//import org.w3c.dom.Node;
//import org.w3c.dom.traversal.NodeIterator;
import org.apache.xml.dtm.DTM;
import org.apache.xml.dtm.DTMIterator;
import org.apache.xml.xdm.XDMSequence;

import java.util.Vector;

import org.apache.xpath.XPathContext;
import org.apache.xpath.XPath;
import org.apache.xpath.objects.XObject;
import org.apache.xpath.objects.XNumber;
import org.apache.xpath.objects.XSequence;
import org.apache.xpath.objects.XString;
import org.apache.xpath.objects.XNodeSequenceSingleton;
import org.apache.xpath.objects.XObjectFactory;
import org.apache.xpath.objects.XDouble;
import org.apache.xml.dtm.XType;

/**
 * <meta name="usage" content="advanced"/>
 * Execute the Count() function.
 */
public class FuncAverage extends FunctionOneArg
{

  /**
   * Execute 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
  {
    XSequence nl = m_arg0.execute(xctxt).xseq();
	if (nl.equals(XSequence.EMPTY))
	 return XSequence.EMPTY;
	
	int count = nl.getLength();
	double sum = 0;
	XObject item;
	while ((item = nl.next()) != null)
	{
	  int type = item.getValueType();
	  if(type == XType.ANYTYPE || type == XType.ANYSIMPLETYPE)
	  {
	    type = XObject.CLASS_NUMBER;
	  }
	  if (type != XObject.CLASS_NUMBER)
       throw new javax.xml.transform.TransformerException("Argument not Numeric");
        
	  if(item instanceof XNodeSequenceSingleton)
      {
        XNodeSequenceSingleton xnss = (XNodeSequenceSingleton)item;
        sum += xnss.num();
      }
      else
       {
          sum += item.num();
       }
	}

    return new XDouble(sum/count);
  }
}