com.saxonica.ee.stream.adjunct

Class SwitchAdjunct

java.lang.Object

com.saxonica.ee.stream.adjunct.StreamingAdjunct

com.saxonica.ee.stream.adjunct.TransmissionAdjunct

com.saxonica.ee.stream.adjunct.SwitchAdjunct

All Implemented Interfaces:

FeedMaker

public class SwitchAdjunct
extends TransmissionAdjunct

Streaming code to implement a switch expression, which results from optimizing a choose where all the branches have similar test conditions. Unlike a choose, the conditions cannot be consuming: this is because the conditions must be similar, and if one is consuming then several will be consuming.

Constructor Summary

Constructors

Constructor and Description
SwitchAdjunct()

Method Summary

Modifier and Type	Method and Description
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)
Trigger	makeTransmissionFlow(WatchManager watchManager, Expression exp, Feed out, XPathContext context) Make a Trigger that implements this expression in streaming mode.
void	setExpression(Expression expression) Set the expression being processed by this StreamingAdjunct

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

computeStreamability, findConsumingArg, getConfiguration, getDefaultFeedMaker, getExpression, getFeedMaker, makeStreamingAdjunct, setConfiguration, toStreamingPattern

Methods inherited from class java.lang.Object

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

Constructor Detail

SwitchAdjunct

public SwitchAdjunct()

Method Detail

setExpression

public void setExpression(Expression expression)

Description copied from class: StreamingAdjunct

Set the expression being processed by this StreamingAdjunct

Overrides:

setExpression in class StreamingAdjunct

Parameters:

expression - the expression being processed

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

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