Converting Binary to Decimal

N ::= BIN N.v = BIN.v

BIN.r = 0

BIN0 ::= BIN1 B BIN1.r = BIN0.r + 1

B.r = BIN0.r

BIN0.v = BIN1.v+B.v

BIN ::= B BIN.v = B.v

B.r = BIN.r

B ::= '1' B.v = 2B.r

B ::= '0' B.v = 0