Returns true if the PR this transducer is running in has a chance to
be run at all in its controller. This can be false if the PR is set
to never run in a conditional controller. In such a case any controllerStarted,
and controllerFinished blocks of the JAPE grammer are still run when
the controller is starting or finishing. This method can be used in the
controllerStarted or controllerFinished blocks to prevent any unwanted
processing if the PR is disabled.
Request the current JAPE phase to be ended as soon as possible.
After the current RHS code has returned, the phase will be ended as soon
as possible if the JAPE implementation supports this feature.
The method returns false if this feature is not supported or if it is
known that ending the phase prematurely is not possible, true otherwise.
true if ending the phase prematurely is supported, false otherwise