- /*
- * 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: ReverseAxesWalker.java,v 1.14 2004/02/17 04:32:08 minchau Exp $
- */
- package com.sun.org.apache.xpath.internal.axes;
-
- import com.sun.org.apache.xml.internal.dtm.DTM;
- import com.sun.org.apache.xml.internal.dtm.DTMAxisIterator;
- import com.sun.org.apache.xpath.internal.XPathContext;
-
- /**
- * Walker for a reverse axes.
- * @see <a href="http://www.w3.org/TR/xpath#predicates">XPath 2.4 Predicates</a>
- */
- public class ReverseAxesWalker extends AxesWalker
- {
-
- /**
- * Construct an AxesWalker using a LocPathIterator.
- *
- * @param locPathIterator The location path iterator that 'owns' this walker.
- */
- ReverseAxesWalker(LocPathIterator locPathIterator, int axis)
- {
- super(locPathIterator, axis);
- }
-
- /**
- * Set the root node of the TreeWalker.
- * (Not part of the DOM2 TreeWalker interface).
- *
- * @param root The context node of this step.
- */
- public void setRoot(int root)
- {
- super.setRoot(root);
- m_iterator = getDTM(root).getAxisIterator(m_axis);
- m_iterator.setStartNode(root);
- }
-
- /**
- * Detaches the walker from the set which it iterated over, releasing
- * any computational resources and placing the iterator in the INVALID
- * state.
- */
- public void detach()
- {
- m_iterator = null;
- super.detach();
- }
-
- /**
- * Get the next node in document order on the axes.
- *
- * @return the next node in document order on the axes, or null.
- */
- protected int getNextNode()
- {
- if (m_foundLast)
- return DTM.NULL;
-
- int next = m_iterator.next();
-
- if (m_isFresh)
- m_isFresh = false;
-
- if (DTM.NULL == next)
- this.m_foundLast = true;
-
- return next;
- }
-
-
- /**
- * Tells if this is a reverse axes. Overrides AxesWalker#isReverseAxes.
- *
- * @return true for this class.
- */
- public boolean isReverseAxes()
- {
- return true;
- }
-
- // /**
- // * Set the root node of the TreeWalker.
- // *
- // * @param root The context node of this step.
- // */
- // public void setRoot(int root)
- // {
- // super.setRoot(root);
- // }
-
- /**
- * Get the current sub-context position. In order to do the
- * reverse axes count, for the moment this re-searches the axes
- * up to the predicate. An optimization on this is to cache
- * the nodes searched, but, for the moment, this case is probably
- * rare enough that the added complexity isn't worth it.
- *
- * @param predicateIndex The predicate index of the proximity position.
- *
- * @return The pridicate index, or -1.
- */
- protected int getProximityPosition(int predicateIndex)
- {
- // A negative predicate index seems to occur with
- // (preceding-sibling::*|following-sibling::*)/ancestor::*[position()]/*[position()]
- // -sb
- if(predicateIndex < 0)
- return -1;
-
- int count = m_proximityPositions[predicateIndex];
-
- if (count <= 0)
- {
- AxesWalker savedWalker = wi().getLastUsedWalker();
-
- try
- {
- ReverseAxesWalker clone = (ReverseAxesWalker) this.clone();
-
- clone.setRoot(this.getRoot());
-
- clone.setPredicateCount(predicateIndex);
-
- clone.setPrevWalker(null);
- clone.setNextWalker(null);
- wi().setLastUsedWalker(clone);
-
- // Count 'em all
- count++;
- int next;
-
- while (DTM.NULL != (next = clone.nextNode()))
- {
- count++;
- }
-
- m_proximityPositions[predicateIndex] = count;
- }
- catch (CloneNotSupportedException cnse)
- {
-
- // can't happen
- }
- finally
- {
- wi().setLastUsedWalker(savedWalker);
- }
- }
-
- return count;
- }
-
- /**
- * Count backwards one proximity position.
- *
- * @param i The predicate index.
- */
- protected void countProximityPosition(int i)
- {
- if (i < m_proximityPositions.length)
- m_proximityPositions[i]--;
- }
-
- /**
- * Get the number of nodes in this node list. The function is probably ill
- * named?
- *
- *
- * @param xctxt The XPath runtime context.
- *
- * @return the number of nodes in this node list.
- */
- public int getLastPos(XPathContext xctxt)
- {
-
- int count = 0;
- AxesWalker savedWalker = wi().getLastUsedWalker();
-
- try
- {
- ReverseAxesWalker clone = (ReverseAxesWalker) this.clone();
-
- clone.setRoot(this.getRoot());
-
- clone.setPredicateCount(this.getPredicateCount() - 1);
-
- clone.setPrevWalker(null);
- clone.setNextWalker(null);
- wi().setLastUsedWalker(clone);
-
- // Count 'em all
- // count = 1;
- int next;
-
- while (DTM.NULL != (next = clone.nextNode()))
- {
- count++;
- }
- }
- catch (CloneNotSupportedException cnse)
- {
-
- // can't happen
- }
- finally
- {
- wi().setLastUsedWalker(savedWalker);
- }
-
- return count;
- }
-
- /**
- * Returns true if all the nodes in the iteration well be returned in document
- * order.
- * Warning: This can only be called after setRoot has been called!
- *
- * @return false.
- */
- public boolean isDocOrdered()
- {
- return false; // I think.
- }
-
- /** The DTM inner traversal class, that corresponds to the super axis. */
- protected DTMAxisIterator m_iterator;
- }