org.apache.xpath.axes

Class UnionPathIterator

Implemented Interfaces:
Cloneable, DTMIterator, java.io.Serializable, ExpressionNode, PathComponent, java.io.Serializable, SourceLocator, SubContextList, XPathVisitable

public class UnionPathIterator
extends LocPathIterator
implements Cloneable, DTMIterator, java.io.Serializable, PathComponent

This class extends NodeSetDTM, which implements DTMIterator, and fetches nodes one at a time in document order based on a XPath UnionExpr. As each node is iterated via nextNode(), the node is also stored in the NodeVector, so that previousNode() can easily be done.
See Also:
Serialized Form

Field Summary

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

m_lastFetched

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

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

UnionPathIterator()
Constructor to create an instance which you can add location paths to.
UnionPathIterator(Compiler compiler, int opPos)
Create a UnionPathIterator object, including creation of location path iterators from the opcode list, and call back into the Compiler to create predicate expressions.

Method Summary

void
addIterator(DTMIterator expr)
Add an iterator to the union list.
void
callVisitors(ExpressionOwner owner, XPathVisitor visitor)
Object
clone()
Get a cloned LocPathIterator that holds the same position as this iterator.
static LocPathIterator
createUnionIterator(Compiler compiler, int opPos)
This will return an iterator capable of handling the union of paths given.
boolean
deepEquals(Expression expr)
void
detach()
Detaches the iterator from the set which it iterated over, releasing any computational resources and placing the iterator in the INVALID state.
void
fixupVariables(java.util.Vector vars, int globalsSize)
This function is used to fixup variables from QNames to stack frame indexes at stylesheet build time.
int
getAnalysisBits()
Get the analysis bits for this walker, as defined in the WalkerFactory.
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, asNode, bool, callVisitors, cloneWithReset, detach, execute, executeCharsToContentHandler, getAnalysisBits, getAxis, getContext, getCurrentContextNode, getCurrentNode, getCurrentPos, getDTM, getDTMManager, getExpandEntityReferences, getFilter, getFoundLast, getIsTopLevel, getLastPos, getLength, getPrefixResolver, getRoot, getWhatToShow, getXPathContext, incrementCurrentPos, isDocOrdered, isFresh, isMutable, isNodesetExpr, item, nextNode, previousNode, reset, runTo, setCurrentContextNode, setCurrentPos, setEnvironment, setIsTopLevel, setItem, setRoot, setShouldCacheNodes, size

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

acceptNode, callPredicateVisitors, canTraverseOutsideSubtree, clone, deepEquals, fixupVariables, getLastPos, getLocPathIterator, getPredicate, getPredicateCount, getPredicateIndex, getProximityPosition, getProximityPosition, initProximityPosition, isReverseAxes, resetProximityPositions, setLocPathIterator, setPredicateCount

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

callVisitors, debugWhatToShow, deepEquals, execute, execute, execute, fixupVariables, getDefaultScore, getLocalName, getNamespace, getNodeTypeTest, getStaticScore, getWhatToShow, initNodeTest, initNodeTest, setLocalName, setNamespace, setStaticScore, setWhatToShow

Methods inherited from class org.apache.xpath.Expression

asIterator, asIteratorRaw, asNode, assertion, bool, canTraverseOutsideSubtree, deepEquals, error, execute, execute, execute, execute, executeCharsToContentHandler, exprAddChild, exprGetChild, exprGetNumChildren, exprGetParent, exprSetParent, fixupVariables, getColumnNumber, getExpressionOwner, getLineNumber, getPublicId, getSystemId, isNodesetExpr, isStableNumber, num, warn, xstr

Constructor Details

UnionPathIterator

public UnionPathIterator()
Constructor to create an instance which you can add location paths to.

UnionPathIterator

public UnionPathIterator(Compiler compiler,
                         int opPos)
            throws javax.xml.transform.TransformerException
Create a UnionPathIterator object, including creation of location path iterators from the opcode list, and call back into the Compiler to create predicate expressions.
Parameters:
compiler - The Compiler which is creating this expression.
opPos - The position of this iterator in the opcode list from the compiler.

Method Details

addIterator

public void addIterator(DTMIterator expr)
Add an iterator to the union list.
Parameters:
expr - non-null reference to a location path iterator.

callVisitors

public void callVisitors(ExpressionOwner owner,
                         XPathVisitor visitor)
Specified by:
callVisitors in interface XPathVisitable
Overrides:
callVisitors in interface LocPathIterator

clone

public Object clone()
            throws CloneNotSupportedException
Get a cloned LocPathIterator that holds the same position as this iterator.
Specified by:
clone in interface DTMIterator
Overrides:
clone in interface PredicatedNodeTest
Returns:
A clone of this iterator that holds the same node position.

createUnionIterator

public static LocPathIterator createUnionIterator(Compiler compiler,
                                                  int opPos)
            throws javax.xml.transform.TransformerException
This will return an iterator capable of handling the union of paths given.
Parameters:
compiler - The Compiler which is creating this expression.
opPos - The position of this iterator in the opcode list from the compiler.
Returns:
Object that is derived from LocPathIterator.

deepEquals

public boolean deepEquals(Expression expr)
Overrides:
deepEquals in interface PredicatedNodeTest

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 interface LocPathIterator

fixupVariables

public void fixupVariables(java.util.Vector vars,
                           int globalsSize)
This function is used to fixup variables from QNames to stack frame indexes at stylesheet build time.
Overrides:
fixupVariables in interface PredicatedNodeTest
Parameters:
vars - List of QNames that correspond to variables. This list should be searched backwards for the first qualified name that corresponds to the variable reference qname. The position of the QName in the vector from the start of the vector will be its position in the stack frame (but variables above the globalsTop value will need to be offset to the current stack frame).

getAnalysisBits

public int getAnalysisBits()
Get the analysis bits for this walker, as defined in the WalkerFactory.
Specified by:
getAnalysisBits in interface PathComponent
Overrides:
getAnalysisBits in interface LocPathIterator
Returns:
One of WalkerFactory#BIT_DESCENDANT, etc.

getAxis

public int getAxis()
Returns the axis being iterated, if it is known.
Specified by:
getAxis in interface DTMIterator
Overrides:
getAxis in interface LocPathIterator
Returns:
Axis.CHILD, etc., or -1 if the axis is not known or is of multiple types.

nextNode

public int nextNode()
Returns the next node in the set and advances the position of the iterator in the set. After a DTMIterator is created, the first call to nextNode() returns the first node in the set.
Specified by:
nextNode in interface DTMIterator
Overrides:
nextNode in interface LocPathIterator
Returns:
The next Node in the set being iterated over, or null if there are no more members in that set.

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 interface LocPathIterator
Parameters:
context - The XPath runtime context for this transformation.

Copyright © 2006 Apache XML Project. All Rights Reserved.