com.saxonica.stream.watch
Class VoidWatch

java.lang.Object
  extended by com.saxonica.validate.AbstractWatch
      extended by com.saxonica.stream.watch.ComposingWatch
          extended by 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


Copyright (c) 2004-2011 Saxonica Limited. All rights reserved.