com.saxonica.ee.stream.adjunct

Class AxisExpressionAdjunct

java.lang.Object

com.saxonica.ee.stream.adjunct.StreamingAdjunct

com.saxonica.ee.stream.adjunct.AxisExpressionAdjunct

public class AxisExpressionAdjunct
extends StreamingAdjunct

Compile an axis expression to streaming code.

Constructor Summary

Constructors

Constructor and Description
AxisExpressionAdjunct()

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.
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, makeStreamingAdjunct, setConfiguration, setExpression

Methods inherited from class java.lang.Object

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

Constructor Detail

AxisExpressionAdjunct

public AxisExpressionAdjunct()

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

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 StreamingAdjunct

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

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