# Note: The Term and Factor rules are right recursive. They are actually
# supposed to be left recursive, but we don't support that yet.
Start   : Expr !.;
Expr    : Term;
Term    : Factor PLUS Term
        | Factor MINUS Term
        | Factor;
Factor  : Primary TIMES Factor
        | Primary SLASH Factor
        | Primary;
Primary : ID
        | INT
        | OPEN Expr CLOSE;
PLUS    : "+" Spacing;
MINUS   : "-" Spacing;
TIMES   : "*" Spacing;
SLASH   : "/" Spacing;
OPEN    : "(" Spacing;
CLOSE   : ")" Spacing;
ID      : $([a-zA-Z_] [a-zA-Z_0-9]*) Spacing;
INT     : $([1-9] [0-9]*) Spacing;
Spacing : $((" " | "\t" | "\r" | "\n")*);