- /*
- * 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: OneStepIterator.java,v 1.15 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.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;
-
- /**
- * This class implements a general iterator for
- * those LocationSteps with only one step, and perhaps a predicate.
- * @see com.sun.org.apache.xpath.internal.axes#LocPathIterator
- * @xsl.usage advanced
- */
- public class OneStepIterator extends ChildTestIterator
- {
- /** The traversal axis from where the nodes will be filtered. */
- protected int m_axis = -1;
-
- /** The DTM inner traversal class, that corresponds to the super axis. */
- protected DTMAxisIterator m_iterator;
-
- /**
- * Create a OneStepIterator 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
- */
- OneStepIterator(Compiler compiler, int opPos, int analysis)
- throws javax.xml.transform.TransformerException
- {
- super(compiler, opPos, analysis);
- int firstStepPos = compiler.getFirstChildPos(opPos);
-
- m_axis = WalkerFactory.getAxisFromStep(compiler, firstStepPos);
-
- }
-
-
- /**
- * Create a OneStepIterator object.
- *
- * @param iterator The DTM iterator which this iterator will use.
- * @param axis One of Axis.Child, etc., or -1 if the axis is unknown.
- *
- * @throws javax.xml.transform.TransformerException
- */
- public OneStepIterator(DTMAxisIterator iterator, int axis)
- throws javax.xml.transform.TransformerException
- {
- super(null);
-
- m_iterator = iterator;
- m_axis = axis;
- int whatToShow = DTMFilter.SHOW_ALL;
- initNodeTest(whatToShow);
- }
-
- /**
- * Initialize the context values for this expression
- * after it is cloned.
- *
- * @param execContext The XPath runtime context for this
- * transformation.
- */
- public void setRoot(int context, Object environment)
- {
- super.setRoot(context, environment);
- if(m_axis > -1)
- m_iterator = m_cdtm.getAxisIterator(m_axis);
- m_iterator.setStartNode(m_context);
- }
-
- /**
- * 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)
- {
- if(m_axis > -1)
- m_iterator = null;
-
- // Always call the superclass detach last!
- super.detach();
- }
- }
-
- /**
- * Get the next node via getFirstAttribute && getNextAttribute.
- */
- protected int getNextNode()
- {
- return m_lastFetched = m_iterator.next();
- }
-
- /**
- * Get a cloned iterator.
- *
- * @return A new iterator that can be used without mutating this one.
- *
- * @throws CloneNotSupportedException
- */
- public Object clone() throws CloneNotSupportedException
- {
- // Do not access the location path itterator during this operation!
-
- OneStepIterator clone = (OneStepIterator) super.clone();
-
- if(m_iterator != null)
- {
- clone.m_iterator = m_iterator.cloneIterator();
- }
- return clone;
- }
-
- /**
- * 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
- {
-
- OneStepIterator clone = (OneStepIterator) super.cloneWithReset();
- clone.m_iterator = m_iterator;
-
- return clone;
- }
-
-
-
- /**
- * Tells if this is a reverse axes. Overrides AxesWalker#isReverseAxes.
- *
- * @return true for this class.
- */
- public boolean isReverseAxes()
- {
- return m_iterator.isReverse();
- }
-
- /**
- * 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)
- {
- if(!isReverseAxes())
- return super.getProximityPosition(predicateIndex);
-
- // A negative predicate index seems to occur with
- // (preceding-sibling::*|following-sibling::*)/ancestor::*[position()]/*[position()]
- // -sb
- if(predicateIndex < 0)
- return -1;
-
- if (m_proximityPositions[predicateIndex] <= 0)
- {
- XPathContext xctxt = getXPathContext();
- try
- {
- OneStepIterator clone = (OneStepIterator) this.clone();
-
- int root = getRoot();
- xctxt.pushCurrentNode(root);
- clone.setRoot(root, xctxt);
-
- // clone.setPredicateCount(predicateIndex);
- clone.m_predCount = predicateIndex;
-
- // Count 'em all
- int count = 1;
- int next;
-
- while (DTM.NULL != (next = clone.nextNode()))
- {
- count++;
- }
-
- m_proximityPositions[predicateIndex] += count;
- }
- catch (CloneNotSupportedException cnse)
- {
-
- // can't happen
- }
- finally
- {
- xctxt.popCurrentNode();
- }
- }
-
- return m_proximityPositions[predicateIndex];
- }
-
- /**
- * The number of nodes in the list. The range of valid child node indices
- * is 0 to <code>length-1</code> inclusive.
- *
- * @return The number of nodes in the list, always greater or equal to zero.
- */
- public int getLength()
- {
- if(!isReverseAxes())
- return super.getLength();
-
- // Tell if this is being called from within a predicate.
- boolean isPredicateTest = (this == m_execContext.getSubContextList());
-
- // And get how many total predicates are part of this step.
- int predCount = getPredicateCount();
-
- // If we have already calculated the length, and the current predicate
- // is the first predicate, then return the length. We don't cache
- // the anything but the length of the list to the first predicate.
- if (-1 != m_length && isPredicateTest && m_predicateIndex < 1)
- return m_length;
-
- int count = 0;
-
- XPathContext xctxt = getXPathContext();
- try
- {
- OneStepIterator clone = (OneStepIterator) this.cloneWithReset();
-
- int root = getRoot();
- xctxt.pushCurrentNode(root);
- clone.setRoot(root, xctxt);
-
- clone.m_predCount = m_predicateIndex;
-
- int next;
-
- while (DTM.NULL != (next = clone.nextNode()))
- {
- count++;
- }
- }
- catch (CloneNotSupportedException cnse)
- {
- // can't happen
- }
- finally
- {
- xctxt.popCurrentNode();
- }
- if (isPredicateTest && m_predicateIndex < 1)
- m_length = count;
-
- return count;
- }
-
- /**
- * Count backwards one proximity position.
- *
- * @param i The predicate index.
- */
- protected void countProximityPosition(int i)
- {
- if(!isReverseAxes())
- super.countProximityPosition(i);
- else if (i < m_proximityPositions.length)
- m_proximityPositions[i]--;
- }
-
- /**
- * Reset the iterator.
- */
- public void reset()
- {
-
- super.reset();
- if(null != m_iterator)
- m_iterator.reset();
- }
-
- /**
- * 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;
- }
-
- /**
- * @see Expression#deepEquals(Expression)
- */
- public boolean deepEquals(Expression expr)
- {
- if(!super.deepEquals(expr))
- return false;
-
- if(m_axis != ((OneStepIterator)expr).m_axis)
- return false;
-
- return true;
- }
-
-
- }