com.saxonica.ee.stream.adjunct

Class RootExpressionAdjunct

java.lang.Object

com.saxonica.ee.stream.adjunct.StreamingAdjunct

com.saxonica.ee.stream.adjunct.RootExpressionAdjunct

public class RootExpressionAdjunct
extends StreamingAdjunct

Streaming code for an expression that does not support streaming

Constructor Summary

Constructors

Constructor and Description
RootExpressionAdjunct()

Method Summary

Methods

Modifier and Type	Method and Description
PostureAndSweep	computeStreamability(boolean allowExtensions, ContextItemStaticInfo contextInfo, List<String> reasons) Get 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.
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.StreamingAdjunct

getConfiguration, getDefaultFeedMaker, getExpression, getFeedMaker, setConfiguration, setExpression

Methods inherited from class java.lang.Object

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

Constructor Detail

RootExpressionAdjunct

public RootExpressionAdjunct()

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(boolean allowExtensions,
                                   ContextItemStaticInfo contextInfo,
                                   List<String> reasons)

Get the posture and 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:

allowExtensions - if false, the definition of "guaranteed streamability" in the W3C specification is used. If true, Saxon extensions are permitted, which make some

contextInfo - Information about the context item for the expression

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

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 -

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