public abstract class PatternStageBase
extends Stage
PatternStageBase contains the features that are common to the
traditional PatternStage engine and the Faster engine. (Eventually
the two will merge back together.) Notable, it:
remembers the graph
classifies all the triples according to the factory
execute the pipeline and pump the results into _sink_; this is asynchronous.
deliver that same _sink_ as our result. (This allows the sink to be created
as the argument to _deliver_.)