com.saxonica.ee.stream.watch

Interface Watch

All Known Implementing Classes:

AbstractWatch, AccumulatorWatch, FieldWatch, KeySelectorWatch, PatternWatch, RefSelectorWatch, SelectorWatch, StreamWatch, Trigger

public interface Watch

A Watch represents a class that is interested in looking at nodes passing down a push pipeline. Originally this was for the purpose of evaluating uniqueness and key constraints while validating an instance document against a schema; now it is used for many expressions that need to be evaluated in streaming mode.

The Watch is responsible for deciding which nodes it is interested in. There is a subclass PatternWatch in which this is decided by matching an XSLT-like patternT, but not all watches make the decision in this way.

Method Summary

Modifier and Type	Method and 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.
FleetingParentNode	getAnchorNode() Get the anchor node for the watch.
NamespaceResolver	getNamespaceResolver() Get the namespace resolver in use by the Watch
PipelineConfiguration	getPipelineConfiguration() Get the pipeline configuration in use
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 a document or element node) that matches the selection has been found.
void	setAnchorNode(FleetingParentNode anchor) Set the anchor node for the watch.
void	setNamespaceResolver(NamespaceResolver resolver) Set a NamespaceResolver for use by the Watch
void	setPipelineConfiguration(PipelineConfiguration pipe) Set the pipeline configuration in use
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.

Method Detail

matchesNode

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

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

setPipelineConfiguration

void setPipelineConfiguration(PipelineConfiguration pipe)

Set the pipeline configuration in use

Parameters:

pipe - the pipeline Configuration in use

getPipelineConfiguration

PipelineConfiguration getPipelineConfiguration()

Get the pipeline configuration in use

Returns:

the pipeline configuration

setNamespaceResolver

void setNamespaceResolver(NamespaceResolver resolver)

Set a NamespaceResolver for use by the Watch

Parameters:

resolver - the namespace resolver to be used

getNamespaceResolver

NamespaceResolver getNamespaceResolver()

Get the namespace resolver in use by the Watch

Returns:

the namespace resolver

setAnchorNode

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

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

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.

Parameters:

terminator -

Throws:

XPathException - May be raised if a dynamic error occurs

startSelectedParentNode

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

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

void processItem(Item item)
          throws XPathException

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

Parameters:

item - the node that was matched.

Throws:

XPathException - May be raised if a dynamic error occurs

close

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.

Throws:

XPathException - May be raised if a dynamic error occurs