dtmdefaultbasetraversers.java

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/*
 * The Apache Software License, Version 1.1
 *
 *
 * Copyright (c) 1999 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
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 * 5. Products derived from this software may not be called "Apache",
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 * 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.xml.dtm.ref;

import org.apache.xml.dtm.*;

import javax.xml.transform.Source;

import org.apache.xml.utils.XMLStringFactory;

import org.apache.xalan.res.XSLTErrorResources;
import org.apache.xalan.res.XSLMessages;


/**
 * This class implements the traversers for DTMDefaultBase.
 *
 * PLEASE NOTE that the public interface for all traversers should be
 * in terms of DTM Node Handles... but they may use the internal node
 * identity indices within their logic, for efficiency's sake. Be very
 * careful to avoid confusing these when maintaining this code.
 * */
public abstract class DTMDefaultBaseTraversers extends DTMDefaultBase
{

  /**
   * Construct a DTMDefaultBaseTraversers object from a DOM node.
   *
   * @param mgr The DTMManager who owns this DTM.
   * @param domSource the DOM source that this DTM will wrap.
   * @param source The object that is used to specify the construction source.
   * @param dtmIdentity The DTM identity ID for this DTM.
   * @param whiteSpaceFilter The white space filter for this DTM, which may
   *                         be null.
   * @param xstringfactory The factory to use for creating XMLStrings.
   * @param doIndexing true if the caller considers it worth it to use
   *                   indexing schemes.
   */
  public DTMDefaultBaseTraversers(DTMManager mgr, Source source,
                                  int dtmIdentity,
                                  DTMWSFilter whiteSpaceFilter,
                                  XMLStringFactory xstringfactory,
                                  boolean doIndexing)
  {
    super(mgr, source, dtmIdentity, whiteSpaceFilter, xstringfactory,
          doIndexing);
  }

  /**
   * This returns a stateless "traverser", that can navigate
   * over an XPath axis, though perhaps not in document order.
   *
   * @param axis One of Axes.ANCESTORORSELF, etc.
   *
   * @return A DTMAxisTraverser, or null if the given axis isn't supported.
   */
  public DTMAxisTraverser getAxisTraverser(final int axis)
  {

    DTMAxisTraverser traverser;

    if (null == m_traversers)  // Cache of stateless traversers for this DTM
    {
      m_traversers = new DTMAxisTraverser[Axis.names.length];
      traverser = null;
    }
    else
    {
      traverser = m_traversers[axis];  // Share/reuse existing traverser

      if (traverser != null)
        return traverser;
    }

    switch (axis)  // Generate new traverser
    {
    case Axis.ANCESTOR :
      traverser = new AncestorTraverser();
      break;
    case Axis.ANCESTORORSELF :
      traverser = new AncestorOrSelfTraverser();
      break;
    case Axis.ATTRIBUTE :
      traverser = new AttributeTraverser();
      break;
    case Axis.CHILD :
      traverser = new ChildTraverser();
      break;
    case Axis.DESCENDANT :
      traverser = new DescendantTraverser();
      break;
    case Axis.DESCENDANTORSELF :
      traverser = new DescendantOrSelfTraverser();
      break;
    case Axis.FOLLOWING :
      traverser = new FollowingTraverser();
      break;
    case Axis.FOLLOWINGSIBLING :
      traverser = new FollowingSiblingTraverser();
      break;
    case Axis.NAMESPACE :
      traverser = new NamespaceTraverser();
      break;
    case Axis.NAMESPACEDECLS :
      traverser = new NamespaceDeclsTraverser();
      break;
    case Axis.PARENT :
      traverser = new ParentTraverser();
      break;
    case Axis.PRECEDING :
      traverser = new PrecedingTraverser();
      break;
    case Axis.PRECEDINGSIBLING :
      traverser = new PrecedingSiblingTraverser();
      break;
    case Axis.SELF :
      traverser = new SelfTraverser();
      break;
    case Axis.ALL :
      traverser = new AllFromRootTraverser();
      break;
    case Axis.ALLFROMNODE :
      traverser = new AllFromNodeTraverser();
      break;
    case Axis.PRECEDINGANDANCESTOR :
      traverser = new PrecedingAndAncestorTraverser();
      break;
    case Axis.DESCENDANTSFROMROOT :
      traverser = new DescendantFromRootTraverser();
      break;
    case Axis.DESCENDANTSORSELFFROMROOT :
      traverser = new DescendantOrSelfFromRootTraverser();
      break;
    case Axis.ROOT :
      traverser = new RootTraverser();
      break;
    case Axis.FILTEREDLIST :
      return null; // Don't want to throw an exception for this one.
    default :
      throw new DTMException(XSLMessages.createMessage(XSLTErrorResources.ER_UNKNOWN_AXIS_TYPE, new Object[]{Integer.toString(axis)})); //"Unknown axis traversal type: "+axis);
    }

    if (null == traverser)
      throw new DTMException(XSLMessages.createMessage(XSLTErrorResources.ER_AXIS_TRAVERSER_NOT_SUPPORTED, new Object[]{Axis.names[axis]}));
      // "Axis traverser not supported: "
      //                       + Axis.names[axis]);

    m_traversers[axis] = traverser;

    return traverser;
  }

  /**
   * Implements traversal of the Ancestor access, in reverse document order.
   */
  private class AncestorTraverser extends DTMAxisTraverser
  {

    /**
     * Traverse to the next node after the current node.
     *
     * @param context The context node if this iteration.
     * @param current The current node of the iteration.
     *
     * @return the next node in the iteration, or DTM.NULL.
     */
    public int next(int context, int current)
    {
			return getParent(current);
    }

    /**
     * Traverse to the next node after the current node that is matched
     * by the expanded type ID.
     *
     * @param context The context node of this iteration.
     * @param current The current node of the iteration.
     * @param expandedTypeID The expanded type ID that must match.
     *
     * @return the next node in the iteration, or DTM.NULL.
     */
    public int next(int context, int current, int expandedTypeID)
    {
			// Process using identities
      current = makeNodeIdentity(current);

      while (DTM.NULL != (current = m_parent.elementAt(current)))
      {
        if (m_exptype.elementAt(current) == expandedTypeID)
          return makeNodeHandle(current);
      }

      return NULL;
    }
  }

  /**
   * Implements traversal of the Ancestor access, in reverse document order.
   */
  private class AncestorOrSelfTraverser extends AncestorTraverser
  {

    /**
     * By the nature of the stateless traversal, the context node can not be
     * returned or the iteration will go into an infinate loop.  To see if
     * the self node should be processed, use this function.
     *
     * @param context The context node of this traversal.
     *
     * @return the first node in the traversal.
     */
    public int first(int context)
    {
      return context;
    }

    /**
     * By the nature of the stateless traversal, the context node can not be
     * returned or the iteration will go into an infinate loop.  To see if
     * the self node should be processed, use this function.  If the context
     * node does not match the expanded type ID, this function will return
     * false.
     *
     * @param context The context node of this traversal.
     * @param expandedTypeID The expanded type ID that must match.
     *
     * @return the first node in the traversal.
     */
    public int first(int context, int expandedTypeID)
    {
			return (getExpandedTypeID(context) == expandedTypeID)
             ? context : next(context, context, expandedTypeID);
    }
  }

  /**
   * Implements traversal of the Attribute access
   */
  private class AttributeTraverser extends DTMAxisTraverser
  {

    /**
     * Traverse to the next node after the current node.
     *
     * @param context The context node of this iteration.
     * @param current The current node of the iteration.
     *
     * @return the next node in the iteration, or DTM.NULL.
     */
    public int next(int context, int current)
    {
      return (context == current)
             ? getFirstAttribute(context) : getNextAttribute(current);
    }

    /**
     * Traverse to the next node after the current node that is matched
     * by the expanded type ID.
     *
     * @param context The context node of this iteration.
     * @param current The current node of the iteration.
     * @param expandedTypeID The expanded type ID that must match.
     *
     * @return the next node in the iteration, or DTM.NULL.
     */
    public int next(int context, int current, int expandedTypeID)
    {

      current = (context == current)
                ? getFirstAttribute(context) : getNextAttribute(current);

      do
      {
        if (getExpandedTypeID(current) == expandedTypeID)
          return current;
      }
      while (DTM.NULL != (current = getNextAttribute(current)));

      return NULL;
    }
  }

  /**
   * Implements traversal of the Ancestor access, in reverse document order.
   */
  private class ChildTraverser extends DTMAxisTraverser
  {
    
    /**
     * Get the next indexed node that matches the expanded type ID.  Before 
     * calling this function, one should first call 
     * {@link #isIndexed(int) isIndexed} to make sure that the index can 
     * contain nodes that match the given expanded type ID.
     *
     * @param axisRoot The root identity of the axis.
     * @param nextPotential The node found must match or occur after this node.
     * @param expandedTypeID The expanded type ID for the request.
     *
     * @return The node ID or NULL if not found.
     */
    protected int getNextIndexed(int axisRoot, int nextPotential,
                                 int expandedTypeID)
    {

      int nsIndex = m_expandedNameTable.getNamespaceID(expandedTypeID);
      int lnIndex = m_expandedNameTable.getLocalNameID(expandedTypeID);

      for (; ; ) 
      {
        int nextID = findElementFromIndex(nsIndex, lnIndex, nextPotential);

        if (NOTPROCESSED != nextID)
        {
          int parentID = m_parent.elementAt(nextID);
          
          // Is it a child?
          if(parentID == axisRoot)
            return nextID;
          
          // If the parent occured before the subtree root, then 
          // we know it is past the child axis.
          if(parentID < axisRoot)
              return NULL;
          
          // Otherwise, it could be a descendant below the subtree root 
          // children, or it could be after the subtree root.  So we have 
          // to climb up until the parent is less than the subtree root, in 
          // which case we return NULL, or until it is equal to the subtree 
          // root, in which case we continue to look.
          do
          {
            parentID = m_parent.elementAt(parentID);
            if(parentID < axisRoot)
              return NULL;
          }
            while(parentID > axisRoot);
          
          // System.out.println("Found node via index: "+first);
          nextPotential = nextID+1;
          continue;
        }

        nextNode();
        
        if(!(m_nextsib.elementAt(axisRoot) == NOTPROCESSED))
          break;
      }

      return DTM.NULL;
    }
        
    /**
     * By the nature of the stateless traversal, the context node can not be
     * returned or the iteration will go into an infinate loop.  So to traverse 
     * an axis, the first function must be used to get the first node.
     *
     * <p>This method needs to be overloaded only by those axis that process
     * the self node. <\p>
     *
     * @param context The context node of this traversal. This is the point
     * that the traversal starts from.
     * @return the first node in the traversal.
     */
    public int first(int context)
    {
      return getFirstChild(context);
    }
  
    /**
     * By the nature of the stateless traversal, the context node can not be
     * returned or the iteration will go into an infinate loop.  So to traverse 
     * an axis, the first function must be used to get the first node.
     *
     * <p>This method needs to be overloaded only by those axis that process
     * the self node. <\p>
     *
     * @param context The context node of this traversal. This is the point
     * of origin for the traversal -- its "root node" or starting point.
     * @param expandedTypeID The expanded type ID that must match.
     *
     * @return the first node in the traversal.