Package com.saxonica.ee.stream.watch

Class Trigger

java.lang.Object

com.saxonica.ee.stream.watch.AbstractWatch

com.saxonica.ee.stream.watch.PatternWatch

com.saxonica.ee.stream.watch.Trigger

All Implemented Interfaces:

Watch

public class Trigger
extends PatternWatch

A Trigger is a Watch that contains a pattern used for matching streamed nodes, and a WatchAction which is invoked when a matching node is found.

Constructor Summary

Constructors

Constructor	Description
Trigger(Pattern selection, ItemFeed action, XPathContext selectionContext)

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.
void	endSelectedParentNode(Location locationId)	Signal that the endElement event has occurred for the element whose startElement event caused the Watch to be activated.
ItemFeed	getAction()	Get the Feed representing the pipeline of operations performed by this Trigger
boolean	isMatchCurrentGroup()	Ask whether or not the pattern should use all nodes in the current group as anchor nodes (by default only the first is matched)
boolean	matchesNode(FleetingNode node, XPathContext context)	Determine whether the watch matches a given node
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	setMatchCurrentGroup(boolean matchCurrentGroup)	Set whether or not the pattern should use all nodes in the current group as anchor nodes (by default only the first is matched)
void	setSelection(Pattern selection)	Set the selection (that is, the streamable XPath expression) that defines the nodes that this Watch is looking for
Receiver	startSelectedParentNode(FleetingParentNode node, Location locationId)	Signal that an element or document node has been found that matches the selection that this Watch is looking for.

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

getAnchorNode, getSelection, matchesNodesOfKind, setAnchorNode

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

Constructor Detail

Trigger

public Trigger(Pattern selection,
               ItemFeed action,
               XPathContext selectionContext)

Method Detail

matchesNode

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

Description copied from class: PatternWatch

Determine whether the watch matches a given node

Specified by:

matchesNode in interface Watch

Overrides:

matchesNode in class PatternWatch

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

getAction

public ItemFeed getAction()

Get the Feed representing the pipeline of operations performed by this Trigger

Returns:

the Feed through which matched items are processed

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 PatternWatch

Parameters:

terminator - the callback to be used to signal early exit

Throws:

XPathException - May be raised if a dynamic error occurs

startSelectedParentNode

public Receiver startSelectedParentNode(FleetingParentNode node,
                                        Location locationId)
                                 throws XPathException

Signal that an element or document node has been found that matches the selection that this Watch is looking for. This method is called by the WatchManager while processing the startElement or startDocument event that matches the selection.

Parameters:

node - the element or document node whose start event has been matched

locationId - the location associated with the element or document node (may be the location of the instruction that created it)

Returns:

a Receiver to be notified of all events starting with the startElement/startDocument event for the matched element, and ending with the endElement event for that element; or null if this feature is not required.

Throws:

XPathException - May be raised if a dynamic error occurs

endSelectedParentNode

public void endSelectedParentNode(Location locationId)
                           throws XPathException

Signal that the endElement event has occurred for the element whose startElement event caused the Watch to be activated.

Parameters:

locationId - the location of the element

Throws:

XPathException - May be raised if a constraint implemented by this Watch is violated

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 PatternWatch

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 PatternWatch

Throws:

XPathException - May be raised if a dynamic error occurs

isMatchCurrentGroup

public boolean isMatchCurrentGroup()

Ask whether or not the pattern should use all nodes in the current group as anchor nodes (by default only the first is matched)

Returns:

true if every node in the current group is to act as an anchor node

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

Overrides:

setSelection in class PatternWatch

Parameters:

selection - the streamable XPath expression

setMatchCurrentGroup

public void setMatchCurrentGroup(boolean matchCurrentGroup)

Set whether or not the pattern should use all nodes in the current group as anchor nodes (by default only the first is matched)

Parameters:

matchCurrentGroup - true if every node in the current group is to act as an anchor node