com.saxonica.ee.stream.feed

Class MotionlessFeed

java.lang.Object

com.saxonica.ee.stream.feed.ItemFeed

com.saxonica.ee.stream.feed.MotionlessFeed

All Implemented Interfaces:

Feed

public class MotionlessFeed
extends ItemFeed

A feed for an expression that typically accesses the context item but does not consume the input stream. This class only ever appears as the first thing triggered by a watch. It evaluates the non-consuming expression immediately when the start event is reported, supplying the items that result from the evaluation to the next feed in the pipeline.

Constructor Summary

Constructors

Constructor and Description
MotionlessFeed(Expression expression, Feed result, XPathContext context)

Method Summary

Modifier and Type	Method and Description
void	endSelectedParentNode(Location locationId) Signal that the endElement event has occurred for the element whose startElement event caused the Watch to be activated.
void	processItem(Item<?> item) Supply one item towards the streamed input of the expression
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.feed.ItemFeed

close, dynamicError, getContext, getExpression, getPipelineConfiguration, getReceiver, getResult, getTerminator, hasFailed, open, processItems, setExpression, setHasFailed, setPipelineConfiguration, setTerminator

Methods inherited from class java.lang.Object

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

Constructor Detail

MotionlessFeed

public MotionlessFeed(Expression expression,
                      Feed result,
                      XPathContext context)

Method Detail

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.

Specified by:

startSelectedParentNode in interface Feed

Overrides:

startSelectedParentNode in class ItemFeed

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

processItem

public void processItem(Item<?> item)
                 throws XPathException

Supply one item towards the streamed input of the expression

Specified by:

processItem in interface Feed

Specified by:

processItem in class ItemFeed

Parameters:

item - the item to be supplied

Throws:

XPathException - May be raised if a dynamic error occurs

endSelectedParentNode

public void endSelectedParentNode(Location locationId)
                           throws XPathException

Description copied from class: ItemFeed

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

Specified by:

endSelectedParentNode in interface Feed

Overrides:

endSelectedParentNode in class ItemFeed

Parameters:

locationId - the location of the element

Throws:

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