/*

 * reserved comment block

 * DO NOT REMOVE OR ALTER!

 */

/*

 * Copyright 1999-2004 The Apache Software Foundation.

 *

 * Licensed 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: DescendantIterator.java,v 1.2.4.2 2005/09/14 19:45:21 jeffsuttor Exp $

 */

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

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

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

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

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

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

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

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

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

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

import com.sun.org.apache.xpath.internal.patterns.NodeTest;

/**

 * This class implements an optimized iterator for

 * descendant, descendant-or-self, or "//foo" patterns.

 * @see com.sun.org.apache.xpath.internal.axes.LocPathIterator

 * @xsl.usage advanced

 */

public class DescendantIterator extends LocPathIterator

{

    static final long serialVersionUID = -1190338607743976938L;

  /**

   * Create a DescendantIterator object.

   *

   * @param compiler A reference to the Compiler that contains the op map.

   * @param opPos The position within the op map, which contains the

   * location path expression for this itterator.

   *

   * @throws javax.xml.transform.TransformerException

   */

  DescendantIterator(Compiler compiler, int opPos, int analysis)

          throws javax.xml.transform.TransformerException

  {

    super(compiler, opPos, analysis, false);

    int stepType = compiler.getOp(firstStepPos);

    boolean orSelf = (OpCodes.FROM_DESCENDANTS_OR_SELF == stepType);

    boolean fromRoot = false;

    if (OpCodes.FROM_SELF == stepType)

    {

      orSelf = true;

      // firstStepPos += 8;

    }

    else if(OpCodes.FROM_ROOT == stepType)

    {

      fromRoot = true;

      // Ugly code... will go away when AST work is done.

      int nextStepPos = compiler.getNextStepPos(firstStepPos);

      if(compiler.getOp(nextStepPos) == OpCodes.FROM_DESCENDANTS_OR_SELF)

        orSelf = true;

      // firstStepPos += 8;

    }

    // Find the position of the last step.

    int nextStepPos = firstStepPos;

    while(true)

    {

      nextStepPos = compiler.getNextStepPos(nextStepPos);

      if(nextStepPos > 0)

      {

        int stepOp = compiler.getOp(nextStepPos);

        if(OpCodes.ENDOP != stepOp)

          firstStepPos = nextStepPos;

        else

          break;

      }

      else

        break;

    }

    // Fix for http://nagoya.apache.org/bugzilla/show_bug.cgi?id=1336

    if((analysis & WalkerFactory.BIT_CHILD) != 0)

      orSelf = false;

    if(fromRoot)

    {

      if(orSelf)

        m_axis = Axis.DESCENDANTSORSELFFROMROOT;

      else

        m_axis = Axis.DESCENDANTSFROMROOT;

    }

    else if(orSelf)

      m_axis = Axis.DESCENDANTORSELF;

    else

      m_axis = Axis.DESCENDANT;

    int whatToShow = compiler.getWhatToShow(firstStepPos);

    if ((0 == (whatToShow

               & (DTMFilter.SHOW_ATTRIBUTE | DTMFilter.SHOW_ELEMENT

                  | DTMFilter.SHOW_PROCESSING_INSTRUCTION))) ||

                   (whatToShow == DTMFilter.SHOW_ALL))

      initNodeTest(whatToShow);

    else

    {

      initNodeTest(whatToShow, compiler.getStepNS(firstStepPos),

                              compiler.getStepLocalName(firstStepPos));

    }

    initPredicateInfo(compiler, firstStepPos);

  }

  /**

   * Create a DescendantIterator object.

   *

   */

  public DescendantIterator()

  {

    super(null);

    m_axis = Axis.DESCENDANTSORSELFFROMROOT;

    int whatToShow = DTMFilter.SHOW_ALL;

    initNodeTest(whatToShow);

  }

  /**

   *  Get a cloned Iterator that is reset to the beginning

   *  of the query.

   *

   *  @return A cloned NodeIterator set of the start of the query.

   *

   *  @throws CloneNotSupportedException

   */

  public DTMIterator cloneWithReset() throws CloneNotSupportedException

  {

    DescendantIterator clone = (DescendantIterator) super.cloneWithReset();

    clone.m_traverser = m_traverser;

    clone.resetProximityPositions();

    return clone;

  }

  /**

   *  Returns the next node in the set and advances the position of the

   * iterator in the set. After a NodeIterator is created, the first call

   * to nextNode() returns the first node in the set.

   *

   * @return  The next <code>Node</code> in the set being iterated over, or

   *   <code>null</code> if there are no more members in that set.

   *

   * @throws DOMException

   *    INVALID_STATE_ERR: Raised if this method is called after the

   *   <code>detach</code> method was invoked.

   */

  public int nextNode()

  {

        if(m_foundLast)

                return DTM.NULL;

    if(DTM.NULL == m_lastFetched)

    {

      resetProximityPositions();

    }

    int next;

    com.sun.org.apache.xpath.internal.VariableStack vars;

    int savedStart;

    if (-1 != m_stackFrame)

    {

      vars = m_execContext.getVarStack();

      // These three statements need to be combined into one operation.

      savedStart = vars.getStackFrame();

      vars.setStackFrame(m_stackFrame);

    }

    else

    {

      // Yuck.  Just to shut up the compiler!

      vars = null;

      savedStart = 0;

    }

    try

    {

      do

      {

        if(0 == m_extendedTypeID)

        {

          next = m_lastFetched = (DTM.NULL == m_lastFetched)

                       ? m_traverser.first(m_context)

                       : m_traverser.next(m_context, m_lastFetched);

        }

        else

        {

          next = m_lastFetched = (DTM.NULL == m_lastFetched)

                       ? m_traverser.first(m_context, m_extendedTypeID)

                       : m_traverser.next(m_context, m_lastFetched,

                                          m_extendedTypeID);

        }

        if (DTM.NULL != next)

        {

          if(DTMIterator.FILTER_ACCEPT == acceptNode(next))

            break;

          else

            continue;

        }

        else

          break;

      }

      while (next != DTM.NULL);

      if (DTM.NULL != next)

      {

        m_pos++;

        return next;

      }

      else

      {

        m_foundLast = true;

        return DTM.NULL;

      }

    }

    finally

    {

      if (-1 != m_stackFrame)

      {

        // These two statements need to be combined into one operation.

        vars.setStackFrame(savedStart);

      }

    }

  }

  /**

   * Initialize the context values for this expression

   * after it is cloned.

   *

   * @param context The XPath runtime context for this

   * transformation.

   */

  public void setRoot(int context, Object environment)

  {

    super.setRoot(context, environment);

    m_traverser = m_cdtm.getAxisTraverser(m_axis);

    String localName = getLocalName();

    String namespace = getNamespace();

    int what = m_whatToShow;

    // System.out.println("what: ");

    // NodeTest.debugWhatToShow(what);

    if(DTMFilter.SHOW_ALL == what

       || NodeTest.WILD.equals(localName)

       || NodeTest.WILD.equals(namespace))

    {

      m_extendedTypeID = 0;

    }

    else

    {

      int type = getNodeTypeTest(what);

      m_extendedTypeID = m_cdtm.getExpandedTypeID(namespace, localName, type);

    }

  }

  /**

   * Return the first node out of the nodeset, if this expression is

   * a nodeset expression.  This is the default implementation for

   * nodesets.

   * <p>WARNING: Do not mutate this class from this function!</p>

   * @param xctxt The XPath runtime context.

   * @return the first node out of the nodeset, or DTM.NULL.

   */

  public int asNode(XPathContext xctxt)

    throws javax.xml.transform.TransformerException

  {

    if(getPredicateCount() > 0)

      return super.asNode(xctxt);

    int current = xctxt.getCurrentNode();

    DTM dtm = xctxt.getDTM(current);

    DTMAxisTraverser traverser = dtm.getAxisTraverser(m_axis);

    String localName = getLocalName();

    String namespace = getNamespace();

    int what = m_whatToShow;

    // System.out.print(" (DescendantIterator) ");

    // System.out.println("what: ");

    // NodeTest.debugWhatToShow(what);

    if(DTMFilter.SHOW_ALL == what

       || localName == NodeTest.WILD

       || namespace == NodeTest.WILD)

    {

      return traverser.first(current);

    }

    else

    {

      int type = getNodeTypeTest(what);

      int extendedType = dtm.getExpandedTypeID(namespace, localName, type);

      return traverser.first(current, extendedType);

    }

  }

  /**

   *  Detaches the iterator from the set which it iterated over, releasing

   * any computational resources and placing the iterator in the INVALID

   * state. After<code>detach</code> has been invoked, calls to

   * <code>nextNode</code> or<code>previousNode</code> will raise the

   * exception INVALID_STATE_ERR.

   */

  public void detach()

  {

    if (m_allowDetach) {

      m_traverser = null;

      m_extendedTypeID = 0;

      // Always call the superclass detach last!

      super.detach();

    }

  }

  /**

   * Returns the axis being iterated, if it is known.

   *

   * @return Axis.CHILD, etc., or -1 if the axis is not known or is of multiple

   * types.

   */

  public int getAxis()

  {

    return m_axis;

  }

  /** The traverser to use to navigate over the descendants. */

  transient protected DTMAxisTraverser m_traverser;

  /** The axis that we are traversing. */

  protected int m_axis;

  /** The extended type ID, not set until setRoot. */

  protected int m_extendedTypeID;

  /**

   * @see Expression#deepEquals(Expression)

   */

  public boolean deepEquals(Expression expr)

  {

        if(!super.deepEquals(expr))

                return false;

        if(m_axis != ((DescendantIterator)expr).m_axis)

                return false;

        return true;

  }

}