/*

 */

/*

 * 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.

 */

package com.sun.org.apache.xpath.internal.functions;

import com.sun.org.apache.xml.internal.dtm.DTM;

import com.sun.org.apache.xml.internal.dtm.DTMIterator;

import com.sun.org.apache.xpath.internal.XPathContext;

import com.sun.org.apache.xpath.internal.axes.SubContextList;

import com.sun.org.apache.xpath.internal.compiler.Compiler;

import com.sun.org.apache.xpath.internal.objects.XNumber;

import com.sun.org.apache.xpath.internal.objects.XObject;

/**

 * Execute the Position() function.

 * @xsl.usage advanced

 */

public class FuncPosition extends Function

{

    static final long serialVersionUID = -9092846348197271582L;

  private boolean m_isTopLevel;

  /**

   * Figure out if we're executing a toplevel expression.

   * If so, we can't be inside of a predicate.

   */

  public void postCompileStep(Compiler compiler)

  {

    m_isTopLevel = compiler.getLocationPathDepth() == -1;

  }

  /**

   * Get the position in the current context node list.

   *

   * @param xctxt Runtime XPath context.

   *

   * @return The current position of the itteration in the context node list,

   *         or -1 if there is no active context node list.

   */

  public int getPositionInContextNodeList(XPathContext xctxt)

  {

    // System.out.println("FuncPosition- entry");

    // If we're in a predicate, then this will return non-null.

    SubContextList iter = m_isTopLevel ? null : xctxt.getSubContextList();

    if (null != iter)

    {

      int prox = iter.getProximityPosition(xctxt);

      // System.out.println("FuncPosition- prox: "+prox);

      return prox;

    }

    DTMIterator cnl = xctxt.getContextNodeList();

    if (null != cnl)

    {

      int n = cnl.getCurrentNode();

      if(n == DTM.NULL)

      {

        if(cnl.getCurrentPos() == 0)

          return 0;

        // Then I think we're in a sort.  See sort21.xsl. So the iterator has

        // already been spent, and is not on the node we're processing.

        // It's highly possible that this is an issue for other context-list

        // functions.  Shouldn't be a problem for last(), and it shouldn't be

        // a problem for current().

        try

        {

          cnl = cnl.cloneWithReset();

        }

        catch(CloneNotSupportedException cnse)

        {

          throw new com.sun.org.apache.xml.internal.utils.WrappedRuntimeException(cnse);

        }

        int currentNode = xctxt.getContextNode();

        // System.out.println("currentNode: "+currentNode);

        while(DTM.NULL != (n = cnl.nextNode()))

        {

          if(n == currentNode)

            break;

        }

      }

      // System.out.println("n: "+n);

      // System.out.println("FuncPosition- cnl.getCurrentPos(): "+cnl.getCurrentPos());

      return cnl.getCurrentPos();

    }

    // System.out.println("FuncPosition - out of guesses: -1");

    return -1;

  }

  /**

   * 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

  {

    double pos = (double) getPositionInContextNodeList(xctxt);

    return new XNumber(pos);

  }

  /**

   * No arguments to process, so this does nothing.

   */

  {

    // no-op

  }

}