// expression grammatik som klarer paranteser. 
// standard left-factorized, fra tm's bog, s. 87

LEXING:

SKIP: 
(" "|"\t"|"\n"|"\r")

TOKENS:

NUMBER = (["0"-"9"])+ 
PLUS   = "+"
TIMES  = "*"
LP     = "("
RP     = ")"

GRAMMAR:

Exp ::= Exp2 ExpX;
ExpX ::= (PLUS Exp2 ExpX )?;

Exp2 ::= Exp3 Exp2X;
Exp2X ::= (TIMES Exp3 Exp2X)?;

Exp3 ::= (NUMBER | LP Exp RP);