com.saxonica.stream.watch
Class VoidWatch

java.lang.Object
  com.saxonica.validate.AbstractWatch
      com.saxonica.stream.watch.ComposingWatch
          com.saxonica.stream.watch.VoidWatch

All Implemented Interfaces:

Watch

Direct Known Subclasses:

NonstreamingExpressionWatch

public class VoidWatch
extends ComposingWatch

This class is a Watch that always returns an empty sequence as its result.

Constructor Summary

VoidWatch(Feed result, Stack<XPathContext> contextStack)
Create the singleton VoidWatch

Method Summary

void	endSelectedParentNode(int locationId) Signal that the endElement event has occurred for the element whose startElement event caused the Watch to be activated.
void	notifySelectedLeafNode(FleetingNode node, int locationId) Signal that a node (other than an element) that matches the selection has been found.
Receiver	startSelectedParentNode(FleetingNode node, int locationId) Signal that an element has been found that matches the selection that this Watch is looking for.

Methods inherited from class com.saxonica.stream.watch.ComposingWatch

close, getContext, getContextStack, getResult, open

Methods inherited from class com.saxonica.validate.AbstractWatch

getAnchorNode, getNamespaceResolver, getPipelineConfiguration, getSelection, setAnchorNode, setNamespaceResolver, setPipelineConfiguration, setSelection

Methods inherited from class java.lang.Object

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

Constructor Detail

VoidWatch

public VoidWatch(Feed result,
                 Stack<XPathContext> contextStack)

Create the singleton VoidWatch

Method Detail

startSelectedParentNode

public Receiver startSelectedParentNode(FleetingNode node,
                                        int locationId)
                                 throws XPathException

Signal that an element has been found that matches the selection that this Watch is looking for. This method is called by the WatchManager while processing the startElement event that matches the selection. For this purpose, any attributes selected by the last step in the selection are ignored

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.

Throws:

ValidationException - May be raised if the constraint implemented by this Watch is violated @param locationId

XPathException

notifySelectedLeafNode

public void notifySelectedLeafNode(FleetingNode node,
                                   int locationId)
                            throws XPathException

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

Specified by:

notifySelectedLeafNode in interface Watch

Overrides:

notifySelectedLeafNode in class AbstractWatch

Parameters:

node - the node that was matched.

locationId -

Throws:

XPathException

endSelectedParentNode

public void endSelectedParentNode(int 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:

ValidationException - May be raised if the constraint implemented by this Watch is violated @param locationId

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