org.apache.xpath.axes

Class DescendantIterator

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.DescendantIterator

All Implemented Interfaces:

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

public class DescendantIterator
extends LocPathIterator

This class implements an optimized iterator for descendant, descendant-or-self, or "//foo" patterns.

See Also:

LocPathIterator, Serialized Form

Field Summary

Fields

Modifier and Type	Field and Description
protected int	m_axis The axis that we are traversing.
protected int	m_extendedTypeID The extended type ID, not set until setRoot.
protected DTMAxisTraverser	m_traverser The traverser to use to navigate over the descendants.

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
DescendantIterator() Create a DescendantIterator object.

Method Summary

Modifier and Type	Method and Description
int	asNode(XPathContext xctxt) Return the first node out of the nodeset, if this expression is a nodeset expression.
DTMIterator	cloneWithReset() Get a cloned Iterator that is reset to the beginning of the query.
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	nextNode() Returns the next node in the set and advances the position of the iterator in the set.
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.LocPathIterator

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

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

acceptNode, callPredicateVisitors, canTraverseOutsideSubtree, clone, countProximityPosition, fixupVariables, getLocPathIterator, getPredicate, getPredicateCount, getPredicateIndex, getProximityPosition, getProximityPosition, getProximityPosition, initPredicateInfo, initProximityPosition, isReverseAxes, 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

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

clone

Field Detail

m_traverser

protected transient DTMAxisTraverser m_traverser

The traverser to use to navigate over the descendants.

m_axis

protected int m_axis

The axis that we are traversing.

m_extendedTypeID

protected int m_extendedTypeID

The extended type ID, not set until setRoot.

Constructor Detail

DescendantIterator

public DescendantIterator()

Create a DescendantIterator object.

Method Detail

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 LocPathIterator

Returns:

A cloned NodeIterator set of the start of the query.

Throws:

CloneNotSupportedException

nextNode

public int nextNode()

Returns the next node in the set and advances the position of the iterator in the set. After a NodeIterator is created, the first call to nextNode() returns the first node in the set.

Specified by:

nextNode in interface DTMIterator

Specified by:

nextNode in class LocPathIterator

Returns:

The next Node in the set being iterated over, or null if there are no more members in that set.

Throws:

DOMException - INVALID_STATE_ERR: Raised if this method is called after the detach method was invoked.

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 LocPathIterator

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.

asNode

public int asNode(XPathContext xctxt)
           throws TransformerException

Return the first node out of the nodeset, if this expression is a nodeset expression. This is the default implementation for nodesets.

WARNING: Do not mutate this class from this function!

Overrides:

asNode in class LocPathIterator

Parameters:

xctxt - The XPath runtime context.

Returns:

the first node out of the nodeset, or DTM.NULL.

Throws:

TransformerException

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 LocPathIterator

getAxis

public int getAxis()

Returns the axis being iterated, if it is known.

Specified by:

getAxis in interface DTMIterator

Overrides:

getAxis in class LocPathIterator

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)