com.saxonica.ee.stream.feed

Class FeedToReceiver

java.lang.Object

com.saxonica.ee.stream.feed.ItemFeed

com.saxonica.ee.stream.feed.FeedToReceiver

All Implemented Interfaces:

Feed

public class FeedToReceiver
extends ItemFeed

Appends the output of an ItemFeed to a SequenceReceiver. This works as follows. When the startElement event for a matched node is reported, this feed simply returns a Receiver to the WatchManager. The WatchManager then notifies all events from this startElement to the matching endElement (inclusive) to that Receiver. So all the events for the matched node and its descendants are passed on unchanged. The Receiver that is actually returned to the WatchManager is the Receiver obtained from the next expression in the push pipeline, but with a simple filter attached that suppresses open() and close() events. Without this, the WatchManager would close the receiver when the endElement event occurs, which is inappropriate when the expression selects a sequence of elements.

Constructor Summary

Constructors

Constructor and Description
FeedToReceiver(Feed out, XPathContext context)

Method Summary

Modifier and Type	Method and Description
void	close() Signal the end of the sequence of items
void	endSelectedParentNode(Location locationId) Signal that the endElement event has occurred for the element whose startElement event caused the Watch to be activated.
PipelineConfiguration	getPipelineConfiguration() Get the pipeline configuration
SequenceReceiver	getReceiver() Get the destination receiver
void	open(Terminator terminator) Signal the start of a sequence of items
void	processItem(Item item) Supply an item to the feed
void	setReceiver(SequenceReceiver out) Set the destination receiver
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

dynamicError, getContext, getExpression, getResult, getTerminator, hasFailed, 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

FeedToReceiver

public FeedToReceiver(Feed out,
                      XPathContext context)

Method Detail

getPipelineConfiguration

public PipelineConfiguration getPipelineConfiguration()

Get the pipeline configuration

Specified by:

getPipelineConfiguration in interface Feed

Overrides:

getPipelineConfiguration in class ItemFeed

Returns:

the pipeline configuration

getReceiver

public SequenceReceiver getReceiver()

Get the destination receiver

Specified by:

getReceiver in interface Feed

Overrides:

getReceiver in class ItemFeed

Returns:

the receiver to which events are being written to represent the results of this instruction

setReceiver

public void setReceiver(SequenceReceiver out)

Set the destination receiver

Parameters:

out - the receiver to which events should henceforth be written

open

public void open(Terminator terminator)
          throws XPathException

Signal the start of a sequence of items

Specified by:

open in interface Feed

Overrides:

open in class ItemFeed

Parameters:

terminator -

Throws:

XPathException - to report any failure

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

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.

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

processItem

public void processItem(Item item)
                 throws XPathException

Supply an item to the feed

Specified by:

processItem in interface Feed

Specified by:

processItem in class ItemFeed

Parameters:

item - the item being fed

Throws:

XPathException - to report any failure

close

public void close()
           throws XPathException

Signal the end of the sequence of items

Specified by:

close in interface Feed

Overrides:

close in class ItemFeed

Throws:

XPathException - to report any failure