[antlr-interest] What does empty subrule mean?

[Gavin Lambert]

At 07:12 28/09/2007, Arto Viitanen wrote:
 >So, why is
 >
 >rule : | subrule | subrule ...
 >
 >allowed and what does it mean?

It means "nothing or subrule 1 or subrule2", as you'd expect.  ie. 
it's functionally equivalent to this:

rule : (subrule | subrule ...)?