com.saxonica.stream.adjunct
Class CountAdjunct

java.lang.Object
  com.saxonica.stream.adjunct.StreamingAdjunct
      com.saxonica.stream.adjunct.CountAdjunct

public class CountAdjunct
extends StreamingAdjunct

Generate streaming code for the count() function.

Constructor Summary

CountAdjunct()

Method Summary

FeedMaker	getFeedMaker(Expression expr, int arg) Get a FeedMaker, a factory class that creates a Watch to evaluate this expression in streaming mode.
WatchMaker	getWatchMaker(Expression expression, List<String> reasonsForFailure) Get a WatchMaker, a factory class that creates a Watch to evaluate this expression in streaming mode.

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

getConfiguration, makeStreamingAdjunct, setConfiguration

Methods inherited from class java.lang.Object

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

Constructor Detail

CountAdjunct

public CountAdjunct()

Method Detail

getWatchMaker

public WatchMaker getWatchMaker(Expression expression,
                                List<String> reasonsForFailure)

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:

expression - the expression to be evaluated in streaming mode

reasonsForFailure - if non-null, this is a list supplied by the caller which will be populated by the callee with one or more messages indicating why it was not possible to allocate a WatchMaker. Normally if the list is non-empty on return, the return value from the method will be null.

Returns:

a Watchmaker to evaluate the expression, or null if it is not streamable with respect to the specificed argument.

getFeedMaker

public FeedMaker getFeedMaker(Expression expr,
                              int arg)

Description copied from class: StreamingAdjunct

Get a FeedMaker, a factory class that creates a Watch to evaluate this expression in streaming mode.

Overrides:

getFeedMaker in class StreamingAdjunct

Parameters:

expr - the expression to be evaluated in streaming mode

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.iterateSubExpressions()

Returns:

a Watchmaker to evaluate the expression, or null if it is not streamable with respect to the specificed argument.