Overlapping functionality: IFTI, templates, is-expressions

[Russell Lewis]

BCS wrote:
>> So: can you handle arbitrary lookahead?  Or do you, like Bison, make a 
>> one-time choice of "reduce or shift" and then you're stuck with it?
> 
> Mine is a recursive decent LL parser that works by way of "assume this 
> is one of those and if not back-out and try again". So it is LL(*).

Cool!  Though that leads me to another question: when do the actions 
run?  Inline, while you're attempting paths that might fail, or only 
after you know they can't fail?