com.saxonica.ee.stream.adjunct

Class ForkAdjunct

java.lang.Object

com.saxonica.ee.stream.adjunct.StreamingAdjunct

com.saxonica.ee.stream.adjunct.ForkAdjunct

public class ForkAdjunct
extends StreamingAdjunct

Streaming code to implement an xsl:fork expression

The general strategy is to create an inversion of the expression in each prong of the fork, and to create a separate watch for each one. These watches create output which is buffered, and on completion the outputs of each watch are assembled in the right order.

The implementation is NOT multithreaded: although the prongs of the fork execute conceptually in parallel, in that they all act as listeners responding to the same sequence of events, they actually all run in the same thread.

Nested Class Summary

Nested Classes

Modifier and Type	Class and Description
static class	ForkAdjunct.FeedToEventBuffer

Constructor Summary

Constructors

Constructor and Description
ForkAdjunct()

Method Summary

Modifier and Type	Method and Description
PostureAndSweep	computeStreamability(ContextItemStaticInfoEE contextInfo, java.util.List<java.lang.String> reasons) Compute the posture and sweep of this expression as defined in the W3C streamability specifications.
WatchMaker	getWatchMaker(boolean forGrouping) Get a WatchMaker, a factory class that creates a Watch to evaluate this expression in streaming mode.

Methods inherited from class com.saxonica.ee.stream.adjunct.StreamingAdjunct

findConsumingArg, getConfiguration, getDefaultFeedMaker, getExpression, getFeedMaker, makeStreamingAdjunct, setConfiguration, setExpression, toStreamingPattern

Methods inherited from class java.lang.Object

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

Constructor Detail

ForkAdjunct

public ForkAdjunct()

Method Detail

computeStreamability

public PostureAndSweep computeStreamability(ContextItemStaticInfoEE contextInfo,
                                            java.util.List<java.lang.String> reasons)

Compute the posture and sweep of this expression as defined in the W3C streamability specifications. This must be implemented in all subclasses that don't use the general streamability rules.

Overrides:

computeStreamability in class StreamingAdjunct

Parameters:

contextInfo - Information about the context item type and posture

reasons - the caller may supply a list, in which case the implementation may add to this

Returns:

the posture and sweep of the expression

getWatchMaker

public WatchMaker getWatchMaker(boolean forGrouping)
                         throws XPathException

Description copied from class: StreamingAdjunct

Get a WatchMaker, a factory class that creates a Watch to evaluate this expression in streaming mode. This method will only be called if the getImplementationMethod() method of the expression includes the value Expression.WATCH_METHOD

Overrides:

getWatchMaker in class StreamingAdjunct

Parameters:

forGrouping - true if the selected items are being grouped

Returns:

a Watchmaker to evaluate the expression, or null if it is not streamable with respect to the specificed argument.

Throws:

XPathException - in the event of a failure