From: Matthew D Moss <matthew.moss.coder@...>
Date: 2006-01-07T17:08:31+09:00
Subject: Re: Dice Roller (#61)

I'm not sure whether this made it to the list first time I sent it, or
is just delayed. Here it is again in case folks missed it...

> I would appreciate the full BNF, please.

Okay, this is what I've done in my current version that takes care of
basic precedence and associativity.

INTEGER = /[1-9][0-9]*/

expr: fact
    | expr '+' fact
    | expr '-' fact

fact: term
    | fact '*' term
    | fact '/' term

term: unit
    | [term] 'd' dice

dice: '%'
    | unit

unit: '(' expr ')'
    | INTEGER


Actually, this is slightly different than my current version, which
after reexamining to extract this BNF, I found a minor error (in
handling of the term rules and handling of the optional arg). My own
code has a morphed version of this BNF in order to code up a recursive
descent parser, but this BNF shows one way to handle the
precedence/association rules.