com.saxonica.ee.stream.adjunct

Class CurrentMergeGroupStreamer

java.lang.Object

com.saxonica.ee.stream.adjunct.StreamingAdjunct

com.saxonica.ee.stream.adjunct.TransmissionAdjunct

com.saxonica.ee.stream.adjunct.CurrentMergeGroupStreamer

All Implemented Interfaces:

FeedMaker

public class CurrentMergeGroupStreamer
extends TransmissionAdjunct

Generate streaming code for a call on current-merge-group().

Constructor Summary

Constructors

Constructor and Description
CurrentMergeGroupStreamer()

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.
Feed	makeItemFeed(WatchManager watchManager, Feed out, XPathContext context)
Trigger	makeTransmissionFlow(WatchManager watchManager, Expression exp, Feed out, XPathContext context) Make a Trigger that implements this expression in streaming mode.
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

getWatchMaker

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

findConsumingArg, 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

CurrentMergeGroupStreamer

public CurrentMergeGroupStreamer()

Method Detail

computeStreamability

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

Description copied from class: StreamingAdjunct

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. The implementation should have the side-effect of computing the streamability of all subexpressions, recursively.

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; the contents are human-readable messages explaining why the expression is not streamable.

Returns:

the posture and sweep of the expression

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

makeTransmissionFlow

public Trigger makeTransmissionFlow(WatchManager watchManager,
                                    Expression exp,
                                    Feed out,
                                    XPathContext context)
                             throws XPathException

Description copied from class: TransmissionAdjunct

Make a Trigger that implements this expression in streaming mode. This method is used for an expression that is striding or crawling, and it delivers a Trigger connected to a sequence of Feeds which together have the effect of delivering a sequence of events and/or items that together represent the results of this instruction. This method MUST be implemented for every expression that has an operand whose usage is transmission (and for every such operand).

Overrides:

makeTransmissionFlow in class TransmissionAdjunct

Parameters:

watchManager - the WatchManager that fires this trigger

exp - the expression

out - the next action in the push pipeline for evaluation

context - the XPath dynamic context

Returns:

the Trigger (a Watch with a pattern)

Throws:

XPathException - if a dynamic evaluation error occurs.

makeItemFeed

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

Throws:

XPathException