Package com.saxonica.ee.stream.watch

Class PatternWatch

java.lang.Object

com.saxonica.ee.stream.watch.AbstractWatch

com.saxonica.ee.stream.watch.PatternWatch

All Implemented Interfaces:

Watch

Direct Known Subclasses:

AccumulatorWatch, FieldWatch, MultiAccumulatorWatch, SelectorWatch, Trigger

public abstract class PatternWatch
extends AbstractWatch

A Watch represents a class that is interested in looking at nodes for the purpose of evaluating uniqueness and key constraints, or for XSLT streaming; specifically, an implementation of Watch that retains a Pattern which is evaluated to see whether a particular node matches the Watch.

Constructor Summary

Constructors

Constructor	Description
PatternWatch()

Method Summary

Modifier and Type	Method	Description
void	close()	The close() method is called immediately before the Watch is destroyed, that is, when the element whose declaration scopes the constraint implemented by this Watch goes out of scope.
FleetingParentNode	getAnchorNode()	Get the anchor node for the watch.
Pattern	getSelection()	Get the selection (that is, the restricted XPath expression) that defines the nodes that this Watch is looking for
boolean	matchesNode(FleetingNode node, XPathContext context)	Determine whether the watch matches a given node
boolean	matchesNodesOfKind(UType kind)	Ask whether the Watch is capable of matching nodes of a particular kind
void	open(Terminator terminator)	Open the watch.
void	processItem(Item item)	Signal that a node (other than an element) that matches the selection has been found.
void	setAnchorNode(FleetingParentNode anchor)	Set the anchor node for the watch.
void	setSelection(Pattern selection)	Set the selection (that is, the streamable XPath expression) that defines the nodes that this Watch is looking for

Methods inherited from class com.saxonica.ee.stream.watch.AbstractWatch

getNamespaceResolver, getPipelineConfiguration, setNamespaceResolver, setPipelineConfiguration

Methods inherited from class java.lang.Object

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

Methods inherited from interface com.saxonica.ee.stream.watch.Watch

endSelectedParentNode, startSelectedParentNode

Constructor Detail

PatternWatch

public PatternWatch()

Method Detail

matchesNode

public boolean matchesNode(FleetingNode node,
                           XPathContext context)
                    throws XPathException

Determine whether the watch matches a given node

Parameters:

node - the node to be tested

context - the XPath dynamic context

Returns:

true if the node is one of those the Watch is looking out for

Throws:

XPathException - if a dynamic error occurs

matchesNodesOfKind

public boolean matchesNodesOfKind(UType kind)

Ask whether the Watch is capable of matching nodes of a particular kind

Parameters:

kind - the node kind as a UType

Returns:

true if the watch is capabl of matching

setSelection

public void setSelection(Pattern selection)

Set the selection (that is, the streamable XPath expression) that defines the nodes that this Watch is looking for

Parameters:

selection - the streamable XPath expression

getSelection

public Pattern getSelection()

Get the selection (that is, the restricted XPath expression) that defines the nodes that this Watch is looking for

Returns:

the selection

setAnchorNode

public void setAnchorNode(FleetingParentNode anchor)

Set the anchor node for the watch. This is the node to which the watch is scoped, typically the context node for the streamable path expression that defines the root of the subtree within which nodes are being sought.

Parameters:

anchor - The anchor node within which the watch is scoped

getAnchorNode

public final FleetingParentNode getAnchorNode()

Get the anchor node for the watch. This is the node to which the watch is scoped, typically the context node for the streamable path expression that defines the root of the subtree within which nodes are being sought.

Returns:

The anchor node within which the watch is scoped

open

public void open(Terminator terminator)
          throws XPathException

Open the watch. This is done at the point where it first starts watching for nodes that match the selection.

Specified by:

open in interface Watch

Overrides:

open in class AbstractWatch

Parameters:

terminator - action to be taken on failure

Throws:

XPathException - May be raised if a dynamic error occurs

processItem

public void processItem(Item item)
                 throws XPathException

Signal that a node (other than an element) that matches the selection has been found.

Specified by:

processItem in interface Watch

Overrides:

processItem in class AbstractWatch

Parameters:

item - the node that was matched.

Throws:

XPathException - May be raised if a dynamic error occurs

close

public void close()
           throws XPathException

The close() method is called immediately before the Watch is destroyed, that is, when the element whose declaration scopes the constraint implemented by this Watch goes out of scope. The default implementation does nothing.

Specified by:

close in interface Watch

Overrides:

close in class AbstractWatch

Throws:

XPathException - May be raised if a dynamic error occurs