From: Pierre Barbier de Reuille <p.barbierdereuille@...>
Date: 2006-01-08T22:48:01+09:00
Subject: Re: [QUIZ] Dice Roller (#61)

Matthew Moss a �crit :
> Wow...  You guys are just having too much fun with
> "(5d5-4)d(16/d4)+3", I think.  Heck, if y'all know Ruby so well (more
> than me, cause I'm still such a n00b), you'd be able to swap in loaded
> dice for random dice and get your min's and max's.  =)
> 
> Anyway, I just wanted to add a couple of notes.  It was made aware to
> me that the simplified BNF (in the original post) is slightly in
> error, in that it allows expressions like this:
> 
>    3dddd6
> 
> which is invalid.
> 
> A couple possible fixes:
> 
> 1. Use the expanded BNF I posted, which doesn't have this fault.
> 2. Implement your dice parser using right-associativity for 'd'
> operators (but maintain left-assoc for the other binary operators).
> 
> Feel free to do what you like.
> 
> 

Well, why do you say it's invalid ? Given the simplified BNF it must be
read as :

3d(d(d(d6)))

and it is perfectly valid as there is no other way to understand that ...

Pierre