com.saxonica.ee.stream.adjunct

Class FilterFnStreamer

java.lang.Object

com.saxonica.ee.stream.adjunct.StreamingAdjunct

com.saxonica.ee.stream.adjunct.TransmissionAdjunct

com.saxonica.ee.stream.adjunct.FilteringAdjunct

com.saxonica.ee.stream.adjunct.FilterFnStreamer

All Implemented Interfaces:

FeedMaker

Direct Known Subclasses:

ItemsAfterStreamer, ItemsBeforeStreamer, ItemsFromStreamer, ItemsUntilStreamer

public class FilterFnStreamer
extends FilteringAdjunct

Generate streaming code for the fn:filter function. Only streamable if the operand is grounded

Constructor Summary

Constructors

Constructor and Description
FilterFnStreamer()

Method Summary

Modifier and Type	Method and Description
static boolean	checkPredicateFunction(Expression fn, java.util.List<java.lang.String> reasons)
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.
FilteringFeed.Filter	makeFilter(XPathContext context, ItemFeed out) Make a filter for the event stream

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

makeItemFeed

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

getWatchMaker, makeTransmissionFlow

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

emptyAdjunctMap, findConsumingArg, genId, 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

FilterFnStreamer

public FilterFnStreamer()

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. 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

checkPredicateFunction

public static boolean checkPredicateFunction(Expression fn,
                                             java.util.List<java.lang.String> reasons)

makeFilter

public FilteringFeed.Filter makeFilter(XPathContext context,
                                       ItemFeed out)
                                throws XPathException

Make a filter for the event stream

Specified by:

makeFilter in class FilteringAdjunct

Parameters:

context - the XPath dyamic context

out - destination for the filtered output

Returns:

a filter that can be added to the event stream

Throws:

XPathException - if a dynamic evaluation error occurs