org.apache.xpath.axes

Class OneStepIterator

java.lang.Object

org.apache.xpath.Expression

org.apache.xpath.patterns.NodeTest

org.apache.xpath.axes.PredicatedNodeTest

org.apache.xpath.axes.LocPathIterator

org.apache.xpath.axes.BasicTestIterator

org.apache.xpath.axes.ChildTestIterator

org.apache.xpath.axes.OneStepIterator

All Implemented Interfaces:

Serializable, Cloneable, SourceLocator, DTMIterator, PathComponent, SubContextList, ExpressionNode, XPathVisitable

public class OneStepIterator
extends ChildTestIterator

This class implements a general iterator for those LocationSteps with only one step, and perhaps a predicate.

See Also:

org.apache.xpath.axes#LocPathIterator, Serialized Form

Field Summary

Fields

Modifier and Type	Field and Description
protected int	m_axis The traversal axis from where the nodes will be filtered.
protected DTMAxisIterator	m_iterator The DTM inner traversal class, that corresponds to the super axis.

Fields inherited from class org.apache.xpath.axes.ChildTestIterator

m_traverser

Fields inherited from class org.apache.xpath.axes.LocPathIterator

m_allowDetach, m_cdtm, m_clones, m_context, m_currentContextNode, m_execContext, m_lastFetched, m_length, m_pos

Fields inherited from class org.apache.xpath.axes.PredicatedNodeTest

m_foundLast, m_lpi, m_predCount, m_proximityPositions

Fields inherited from class org.apache.xpath.patterns.NodeTest

m_name, m_whatToShow, SCORE_NODETEST, SCORE_NONE, SCORE_NSWILD, SCORE_OTHER, SCORE_QNAME, SHOW_BYFUNCTION, SUPPORTS_PRE_STRIPPING, WILD

Fields inherited from interface org.apache.xml.dtm.DTMIterator

FILTER_ACCEPT, FILTER_REJECT, FILTER_SKIP

Constructor Summary

Constructors

Constructor and Description
OneStepIterator(DTMAxisIterator iterator, int axis) Create a OneStepIterator object.

Method Summary

Modifier and Type	Method and Description
Object	clone() Get a cloned iterator.
DTMIterator	cloneWithReset() Get a cloned Iterator that is reset to the beginning of the query.
protected void	countProximityPosition(int i) Count backwards one proximity position.
boolean	deepEquals(Expression expr) Compare this object with another object and see if they are equal, include the sub heararchy.
void	detach() Detaches the iterator from the set which it iterated over, releasing any computational resources and placing the iterator in the INVALID state.
int	getAxis() Returns the axis being iterated, if it is known.
int	getLength() The number of nodes in the list.
protected int	getNextNode() Get the next node via getFirstAttribute && getNextAttribute.
protected int	getProximityPosition(int predicateIndex) Get the current sub-context position.
boolean	isReverseAxes() Tells if this is a reverse axes.
void	reset() Reset the iterator.
void	setRoot(int context, Object environment) Initialize the context values for this expression after it is cloned.

Methods inherited from class org.apache.xpath.axes.BasicTestIterator

nextNode

Methods inherited from class org.apache.xpath.axes.LocPathIterator

allowDetachToRelease, asIterator, asNode, bool, callVisitors, execute, executeCharsToContentHandler, getAnalysisBits, getContext, getCurrentContextNode, getCurrentNode, getCurrentPos, getDTM, getDTMManager, getExpandEntityReferences, getFilter, getFoundLast, getIsTopLevel, getLastPos, getPrefixResolver, getRoot, getWhatToShow, getXPathContext, incrementCurrentPos, isDocOrdered, isFresh, isMutable, isNodesetExpr, item, previousNode, returnNextNode, runTo, setCurrentContextNode, setCurrentPos, setEnvironment, setIsTopLevel, setItem, setNextPosition, setShouldCacheNodes, size

Methods inherited from class org.apache.xpath.axes.PredicatedNodeTest

acceptNode, callPredicateVisitors, canTraverseOutsideSubtree, fixupVariables, getLocPathIterator, getPredicate, getPredicateCount, getPredicateIndex, getProximityPosition, getProximityPosition, initPredicateInfo, initProximityPosition, nodeToString, resetProximityPositions, setLocPathIterator, setPredicateCount

Methods inherited from class org.apache.xpath.patterns.NodeTest

calcScore, debugWhatToShow, execute, execute, getDefaultScore, getLocalName, getNamespace, getNodeTypeTest, getStaticScore, initNodeTest, initNodeTest, setLocalName, setNamespace, setStaticScore, setWhatToShow

Methods inherited from class org.apache.xpath.Expression

asIteratorRaw, assertion, error, execute, exprAddChild, exprGetChild, exprGetNumChildren, exprGetParent, exprSetParent, getColumnNumber, getExpressionOwner, getLineNumber, getPublicId, getSystemId, isSameClass, isStableNumber, num, warn, xstr

Methods inherited from class java.lang.Object

equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Field Detail

m_axis

protected int m_axis

The traversal axis from where the nodes will be filtered.

m_iterator

protected DTMAxisIterator m_iterator

The DTM inner traversal class, that corresponds to the super axis.

Constructor Detail

OneStepIterator

public OneStepIterator(DTMAxisIterator iterator,
                       int axis)
                throws TransformerException

Create a OneStepIterator object.

Parameters:

iterator - The DTM iterator which this iterator will use.

axis - One of Axis.Child, etc., or -1 if the axis is unknown.

Throws:

TransformerException

Method Detail

setRoot

public void setRoot(int context,
                    Object environment)

Initialize the context values for this expression after it is cloned.

Specified by:

setRoot in interface DTMIterator

Overrides:

setRoot in class ChildTestIterator

Parameters:

context - The XPath runtime context for this transformation.

environment - The environment object. The environment in which this iterator operates, which should provide:

• a node (the context node... same value as "root" defined below)
• a pair of non-zero positive integers (the context position and the context size)
• a set of variable bindings
• a function library
• the set of namespace declarations in scope for the expression.

At this time the exact implementation of this environment is application dependent. Probably a proper interface will be created fairly soon.

detach

public void detach()

Detaches the iterator from the set which it iterated over, releasing any computational resources and placing the iterator in the INVALID state. Afterdetach has been invoked, calls to nextNode orpreviousNode will raise the exception INVALID_STATE_ERR.

Specified by:

detach in interface DTMIterator

Overrides:

detach in class ChildTestIterator

getNextNode

protected int getNextNode()

Get the next node via getFirstAttribute && getNextAttribute.

Overrides:

getNextNode in class ChildTestIterator

Returns:

The next node on the axis, or DTM.NULL.

clone

public Object clone()
             throws CloneNotSupportedException

Get a cloned iterator.

Specified by:

clone in interface DTMIterator

Overrides:

clone in class PredicatedNodeTest

Returns:

A new iterator that can be used without mutating this one.

Throws:

CloneNotSupportedException

cloneWithReset

public DTMIterator cloneWithReset()
                           throws CloneNotSupportedException

Get a cloned Iterator that is reset to the beginning of the query.

Specified by:

cloneWithReset in interface DTMIterator

Overrides:

cloneWithReset in class ChildTestIterator

Returns:

A cloned NodeIterator set of the start of the query.

Throws:

CloneNotSupportedException

isReverseAxes

public boolean isReverseAxes()

Tells if this is a reverse axes. Overrides AxesWalker#isReverseAxes.

Overrides:

isReverseAxes in class PredicatedNodeTest

Returns:

true for this class.

getProximityPosition

protected int getProximityPosition(int predicateIndex)

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.

Overrides:

getProximityPosition in class PredicatedNodeTest

Parameters:

predicateIndex - The predicate index of the proximity position.

Returns:

The pridicate index, or -1.

getLength

public int getLength()

The number of nodes in the list. The range of valid child node indices is 0 to length-1 inclusive.

Specified by:

getLength in interface DTMIterator

Overrides:

getLength in class LocPathIterator

Returns:

The number of nodes in the list, always greater or equal to zero.

countProximityPosition

protected void countProximityPosition(int i)

Count backwards one proximity position.

Overrides:

countProximityPosition in class PredicatedNodeTest

Parameters:

i - The predicate index.

reset

public void reset()

Reset the iterator.

Specified by:

reset in interface DTMIterator

Overrides:

reset in class LocPathIterator

getAxis

public int getAxis()

Returns the axis being iterated, if it is known.

Specified by:

getAxis in interface DTMIterator

Overrides:

getAxis in class ChildTestIterator

Returns:

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

deepEquals

public boolean deepEquals(Expression expr)

Description copied from class: Expression

Compare this object with another object and see if they are equal, include the sub heararchy.

Overrides:

deepEquals in class PredicatedNodeTest

Parameters:

expr - Another expression object.

Returns:

true if this objects class and the expr object's class are the same, and the data contained within both objects are considered equal.

See Also:

Expression.deepEquals(Expression)