org.apache.xpath.axes

Class UnionPathIterator

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.UnionPathIterator

All Implemented Interfaces:

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

public class UnionPathIterator
extends LocPathIterator
implements Cloneable, DTMIterator, 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

Modifier and Type	Field and Description
protected LocPathIterator[]	m_exprs The location path iterators, one for each location path contained in the union expression.
protected DTMIterator[]	m_iterators The location path iterators, one for each location path contained in the union expression.

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
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

Modifier and Type	Method and Description
void	addIterator(DTMIterator expr) Add an iterator to the union list.
void	callVisitors(ExpressionOwner owner, XPathVisitor visitor) This will traverse the heararchy, calling the visitor for each member.
Object	clone() Get a cloned LocPathIterator that holds the same position as this iterator.
protected LocPathIterator	createDTMIterator(Compiler compiler, int opPos) Create a new location path 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) 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.
void	fixupVariables(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.
protected void	loadLocationPaths(Compiler compiler, int opPos, int count) Initialize the location path iterators.
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, cloneWithReset, execute, executeCharsToContentHandler, 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, countProximityPosition, 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

allowDetachToRelease, cloneWithReset, getCurrentNode, getCurrentPos, getDTM, getDTMManager, getExpandEntityReferences, getLength, getRoot, getWhatToShow, isDocOrdered, isFresh, isMutable, item, previousNode, reset, runTo, setCurrentPos, setItem, setShouldCacheNodes

Field Detail

m_exprs

protected LocPathIterator[] m_exprs

The location path iterators, one for each location path contained in the union expression.

m_iterators

protected DTMIterator[] m_iterators

The location path iterators, one for each location path contained in the union expression.

Constructor Detail

UnionPathIterator

public UnionPathIterator()

Constructor to create an instance which you can add location paths to.

UnionPathIterator

public UnionPathIterator(Compiler compiler,
                         int opPos)
                  throws 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.

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 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.

addIterator

public void addIterator(DTMIterator expr)

Add an iterator to the union list.

Parameters:

expr - non-null reference to a location path iterator.

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

createUnionIterator

public static LocPathIterator createUnionIterator(Compiler compiler,
                                                  int opPos)
                                           throws 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.

Throws:

TransformerException

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 class LocPathIterator

Returns:

One of WalkerFactory#BIT_DESCENDANT, etc.

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 class PredicatedNodeTest

Returns:

A clone of this iterator that holds the same node position.

Throws:

CloneNotSupportedException

createDTMIterator

protected LocPathIterator createDTMIterator(Compiler compiler,
                                            int opPos)
                                     throws TransformerException

Create a new location path iterator.

Parameters:

compiler - The Compiler which is creating this expression.

opPos - The position of this iterator in the

Returns:

New location path iterator.

Throws:

TransformerException

loadLocationPaths

protected void loadLocationPaths(Compiler compiler,
                                 int opPos,
                                 int count)
                          throws TransformerException

Initialize the location path iterators. Recursive.

Parameters:

compiler - The Compiler which is creating this expression.

opPos - The position of this iterator in the opcode list from the compiler.

count - The insert position of the iterator.

Throws:

TransformerException

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

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.

fixupVariables

public void fixupVariables(Vector vars,
                           int globalsSize)

This function is used to fixup variables from QNames to stack frame indexes at stylesheet build time.

Overrides:

fixupVariables in class 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).

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.

callVisitors

public void callVisitors(ExpressionOwner owner,
                         XPathVisitor visitor)

Description copied from interface: XPathVisitable

This will traverse the heararchy, calling the visitor for each member. If the called visitor method returns false, the subtree should not be called.

Specified by:

callVisitors in interface XPathVisitable

Overrides:

callVisitors in class LocPathIterator

Parameters:

owner - The owner of the visitor, where that path may be rewritten if needed.

visitor - The visitor whose appropriate method will be called.

See Also:

XPathVisitable.callVisitors(ExpressionOwner, XPathVisitor)

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)