[antlr-interest] how to deal with optional parameters in ast

[Gavin Lambert]

At 02:56 28/03/2007, Dave Cramer wrote:
>I have a rule which is
>
>WAKEUP expr*NEWLINE-> ^(WAKEUP expr*)
>
>if the input is
>
>WAKEUP NEWLINE
>
>the ast will just be ^ WAKEUP
>
>What's the right way to deal with this ?

That seems correct to me.  What were you wanting it to do instead?

If WAKEUP is always supposed to have a parameter, then you should 
change * to + in both places.  If it's allowed to have no 
parameters, then what you have already seems like the best option 
(assuming your description is correct).