[antlr-interest] Syntactic predicates sanity check

[exits funnel]

Hello,

I'm pretty new to LL parsing and I just want a quick
sanity check.  Imagine that I have these rules:

a: (T2)* T3 | b T4;

b: (T2)* T5 | (T6);

Am I right to assume that withtout refactoring the
rules, I would need to use a syntactic prediate to
disambiguate the two alternatives to (a)?  Something
like this:

a: ((T2)* T3)=> (T2)* T3 | b T4;

It seems so because there can be an arbitrary number
of T2s on the input stream.  I just want to verify
that I'm not missing something because I know that
there is a performance cost associated with syntactic
predicates, so I'd like to avoid them when possible. 
Thanks!

-exits

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