com.saxonica.ee.stream.adjunct

Class DocumentSorterAdjunct

java.lang.Object

com.saxonica.ee.stream.adjunct.StreamingAdjunct

com.saxonica.ee.stream.adjunct.TransmissionAdjunct

com.saxonica.ee.stream.adjunct.DocumentSorterAdjunct

All Implemented Interfaces:

FeedMaker

public class DocumentSorterAdjunct
extends TransmissionAdjunct
implements FeedMaker

Generate streaming code for a document sorting expression node. This will only be used to support streaming of a path expression of the form child::* / ancestor::*, where the only operation needed is filtering to remove duplicate ancestors (and returning of ancestors in document order). In addition, if the expression a mixture of striding and grounded nodes, then we can sort it because the streamed nodes retain their order (bug 29507)

Constructor Summary

Constructors

Constructor and Description
DocumentSorterAdjunct()

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.
FeedMaker	getFeedMaker(int arg) Get a FeedMaker, a factory class that creates a Feed to evaluate this expression in streaming mode.
WatchMaker	getWatchMaker(boolean forGrouping) Get a WatchMaker, a factory class that creates a Watch to evaluate this expression in streaming mode.
Feed	makeItemFeed(WatchManager watchManager, Feed 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

getConfiguration, getDefaultFeedMaker, getExpression, makeStreamingAdjunct, setConfiguration, setExpression

Methods inherited from class java.lang.Object

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

Constructor Detail

DocumentSorterAdjunct

public DocumentSorterAdjunct()

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

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

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

Specified by:

makeItemFeed in interface FeedMaker

Throws:

XPathException

getFeedMaker

public FeedMaker getFeedMaker(int arg)
                       throws XPathException

Description copied from class: StreamingAdjunct

Get a FeedMaker, a factory class that creates a Feed to evaluate this expression in streaming mode. In many cases the StreamingAdjunct is itself a FeedMaker, in which case it returns itself. But where an expression has several operands, it will typically create different feeds depending on which argument is the streamed input, and in such cases the individual StreamingAdjunct makes the decision which feed to use, by returning an appropriate FeedMaker.

Overrides:

getFeedMaker in class StreamingAdjunct

Parameters:

arg - identifies the argument with respect to which the expression is to be inverted: usually 0 to indicate the first argument is the value that is streamed. Argument numbering is the same as the sequence of arguments/operands returned by the method Expression.operands()

Returns:

a FeedMaker 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