Package com.saxonica.ee.stream.adjunct

Class VennExpressionAdjunct

java.lang.Object

com.saxonica.ee.stream.adjunct.StreamingAdjunct

com.saxonica.ee.stream.adjunct.TransmissionAdjunct

com.saxonica.ee.stream.adjunct.VennExpressionAdjunct

All Implemented Interfaces:

FeedMaker

public class VennExpressionAdjunct
extends TransmissionAdjunct

Class to handle streaming of union, intersect, and except expressions

Constructor Summary

Constructors

Constructor	Description
VennExpressionAdjunct()

Method Summary

Modifier and Type	Method	Description
PostureAndSweep	computeStreamability(ContextItemStaticInfoEE contextInfo, java.util.List<java.lang.String> reasons)	Get the "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.
ItemFeed	makeItemFeed(WatchManager watchManager, ItemFeed out, XPathContext context)
Pattern	toStreamingPattern(Configuration config)	Convert this expression to a streaming pattern (a pattern used internally to match nodes during push processing of an event stream)

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

makeTransmissionFlow

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

emptyAdjunctMap, findConsumingArg, genId, getConfiguration, getDefaultFeedMaker, getExpression, getFeedMaker, makeStreamingAdjunct, setConfiguration, setExpression

Methods inherited from class java.lang.Object

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

Constructor Detail

VennExpressionAdjunct

public VennExpressionAdjunct()

Method Detail

toStreamingPattern

public Pattern toStreamingPattern(Configuration config)

Convert this expression to a streaming pattern (a pattern used internally to match nodes during push processing of an event stream)

Overrides:

toStreamingPattern in class StreamingAdjunct

Parameters:

config - the Saxon configuration

Returns:

the equivalent pattern if conversion succeeds; otherwise null

computeStreamability

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

Get the "sweep" of this expression as defined in the W3C streamability specifications. This provides an assessment of stylesheet code against the W3C criteria for guaranteed streamability, and is implemented to allow these criteria to be tested. It is not the case that all expression that emerge as streamable from this analysis are currently capable of being streamed by Saxon

Overrides:

computeStreamability in class StreamingAdjunct

Parameters:

contextInfo - static information about the context item

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 TransmissionAdjunct

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

makeItemFeed

public ItemFeed makeItemFeed(WatchManager watchManager,
                             ItemFeed out,
                             XPathContext context)
                      throws XPathException

Throws:

XPathException