dtmdefaultbasetraversers.java

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      else
      {
				// %REVIEW% Dead code. Eliminate?
        for (int current = _firstch(makeNodeIdentity(context)); 
             DTM.NULL != current; 
             current = _nextsib(current)) 
        {
          if (m_exptype.elementAt(current) == expandedTypeID)
              return makeNodeHandle(current);
        }
        return NULL;
      }
    }

    /**
     * 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 getNextSibling(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 in Identifier space
      for (current = _nextsib(makeNodeIdentity(current)); 
           DTM.NULL != current; 
           current = _nextsib(current)) 
      {
        if (m_exptype.elementAt(current) == expandedTypeID)
            return makeNodeHandle(current);
      }
      
      return NULL;
    }
  }

  /**
   * Super class for derived classes that want a convenient way to access 
   * the indexing mechanism.
   */
  private abstract class IndexedDTMAxisTraverser extends DTMAxisTraverser
  {

    /**
     * Tell if the indexing is on and the given expanded type ID matches 
     * what is in the indexes.  Derived classes should call this before 
     * calling {@link #getNextIndexed(int, int, int) getNextIndexed} method.
     *
     * @param expandedTypeID The expanded type ID being requested.
     *
     * @return true if it is OK to call the 
     *         {@link #getNextIndexed(int, int, int) getNextIndexed} method.
     */
    protected final boolean isIndexed(int expandedTypeID)
    {
      return (m_indexing
              && ExpandedNameTable.ELEMENT
                 == m_expandedNameTable.getType(expandedTypeID)); 
    }

    /**
     * Tell if a node is outside the axis being traversed.  This method must be 
     * implemented by derived classes, and must be robust enough to handle any 
     * node that occurs after the axis root.
     *
     * @param axisRoot The root identity of the axis.
     * @param identity The node in question.
     *
     * @return true if the given node falls outside the axis being traversed.
     */
    protected abstract boolean isAfterAxis(int axisRoot, int identity);

    /**
     * Tell if the axis has been fully processed to tell if a the wait for 
     * an arriving node should terminate.  This method must be implemented 
     * be a derived class.
     *
     * @param axisRoot The root identity of the axis.
     *
     * @return true if the axis has been fully processed.
     */
    protected abstract boolean axisHasBeenProcessed(int axisRoot);

    /**
     * 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);

      while(true)
      {
        int next = findElementFromIndex(nsIndex, lnIndex, nextPotential);

        if (NOTPROCESSED != next)
        {
          if (isAfterAxis(axisRoot, next))
            return NULL;

          // System.out.println("Found node via index: "+first);
          return next;
        }
        else if(axisHasBeenProcessed(axisRoot))
          break;

        nextNode();
      }

      return DTM.NULL;
    }
  }

  /**
   * Implements traversal of the Ancestor access, in reverse document order.
   */
  private class DescendantTraverser extends IndexedDTMAxisTraverser
  {
    /**
     * Get the first potential identity that can be returned.  This should 
     * be overridded by classes that need to return the self node.
     *
     * @param identity The node identity of the root context of the traversal.
     *
     * @return The first potential node that can be in the traversal.
     */
    protected int getFirstPotential(int identity)
    {
      return identity + 1;
    }
    
    /**
     * Tell if the axis has been fully processed to tell if a the wait for 
     * an arriving node should terminate.
     *
     * @param axisRoot The root identity of the axis.
     *
     * @return true if the axis has been fully processed.
     */
    protected boolean axisHasBeenProcessed(int axisRoot)
    {
      return !(m_nextsib.elementAt(axisRoot) == NOTPROCESSED);
    }
    
    /**
     * Get the subtree root identity from the handle that was passed in by 
     * the caller.  Derived classes may override this to change the root 
     * context of the traversal.
     * 
     * @param handle handle to the root context.
     * @return identity of the root of the subtree.
     */
    protected int getSubtreeRoot(int handle)
    {
      return makeNodeIdentity(handle);
    }

    /**
     * Tell if this node identity is a descendant.  Assumes that
     * the node info for the element has already been obtained.
     *
     * %REVIEW% This is really parentFollowsRootInDocumentOrder ...
     * which fails if the parent starts after the root ends.
     * May be sufficient for this class's logic, but misleadingly named!
     *
     * @param subtreeRootIdentity The root context of the subtree in question.
     * @param identity The index number of the node in question.
     * @return true if the index is a descendant of _startNode.
     */
    protected boolean isDescendant(int subtreeRootIdentity, int identity)
    {
      return _parent(identity) >= subtreeRootIdentity;
    }

    /**
     * Tell if a node is outside the axis being traversed.  This method must be 
     * implemented by derived classes, and must be robust enough to handle any 
     * node that occurs after the axis root.
     *
     * @param axisRoot The root identity of the axis.
     * @param identity The node in question.
     *
     * @return true if the given node falls outside the axis being traversed.
     */
    protected boolean isAfterAxis(int axisRoot, int identity)
    {   
      // %REVIEW% Is there *any* cheaper way to do this?
			// Yes. In ID space, compare to axisRoot's successor
			// (next-sib or ancestor's-next-sib). Probably shallower search.
      do
      {
        if(identity == axisRoot)
          return false;
        identity = m_parent.elementAt(identity);
      }
        while(identity >= axisRoot);
        
      return true;
    }

    /**
     * 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.
     */
    public int first(int context, int expandedTypeID)
    {

      if (isIndexed(expandedTypeID))
      {
        int identity = getSubtreeRoot(context);
        int firstPotential = getFirstPotential(identity);

        return makeNodeHandle(getNextIndexed(identity, firstPotential, expandedTypeID));
      }

      return next(context, context, expandedTypeID);
    }

    /**
     * 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)
    {

      int subtreeRootIdent = getSubtreeRoot(context);

      for (current = makeNodeIdentity(current) + 1; ; current++)
      {
        int type = _type(current);  // may call nextNode()

        if (!isDescendant(subtreeRootIdent, current))
          return NULL;

        if (ATTRIBUTE_NODE == type || NAMESPACE_NODE == type)
          continue;

        return makeNodeHandle(current);  // make handle.
      }
    }

    /**
     * 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)
    {

      int subtreeRootIdent = getSubtreeRoot(context);

      current = makeNodeIdentity(current) + 1;

      if (isIndexed(expandedTypeID))
      {
        return makeNodeHandle(getNextIndexed(subtreeRootIdent, current, expandedTypeID));
      }

      for (; ; current++)
      {
        int exptype = _exptype(current);  // may call nextNode()

        if (!isDescendant(subtreeRootIdent, current))
          return NULL;

        if (exptype != expandedTypeID)
          continue;

        return makeNodeHandle(current);  // make handle.
      }
    }
  }

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

    /**
     * Get the first potential identity that can be returned, which is the 
     * axis context, in this case.
     *
     * @param identity The node identity of the root context of the traversal.
     *
     * @return The axis context.
     */
    protected int getFirstPotential(int identity)
    {
      return identity;
    }

    /**
     * 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;
    }
  }

  /**
   * Implements traversal of the entire subtree, including the root node.
   */
  private class AllFromNodeTraverser extends DescendantOrSelfTraverser
  {

    /**
     * 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)
    {

      int subtreeRootIdent = makeNodeIdentity(context);

      for (current = makeNodeIdentity(current) + 1; ; current++)
      {
        // Trickological code: _exptype() has the side-effect of
        // running nextNode until the specified node has been loaded,
        // and thus can be used to ensure that incremental construction of
        // the DTM has gotten this far. Using it just for that side-effect
        // is quite a kluge...
        _exptype(current);  // make sure it's here.

        if (!isDescendant(subtreeRootIdent, current))
          return NULL;

        return makeNodeHandle(current);  // make handle.
      }
    }
  }

  /**
   * Implements traversal of the following access, in document order.
   */
  private class FollowingTraverser extends DescendantTraverser
  {

    /**
     * Get the first of the following.
     *
     * @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)
    {
			// Compute in ID space
			context=makeNodeIdentity(context);

      int first;
      int type = _type(context);

      if ((DTM.ATTRIBUTE_NODE == type) || (DTM.NAMESPACE_NODE == type))
      {
        context = _parent(context);
        first = _firstch(context);

        if (NULL != first)
          return makeNodeHandle(first);
      }

      do
      {
        first = _nextsib(context);

        if (NULL == first)
          context = _parent(context);
      }
      while (NULL == first && NULL != context);

      return makeNodeHandle(first);
    }

    /**
     * Get the first of the following.
     *
     * @param context The context node of this traversal. This is the point
     * of origin for the traversal -- its "root node" or starting point.