// A grammar for simple arithmetic expression with operator precedences and braces
#[pub]
expr = eq
#[cache]
eq = additive "=" eq / additive
#[cache]
additive = multitive "+" additive / multitive
#[cache]
multitive = pow "*" multitive / pow
#[cache]
pow = atom "^" pow / atom
#[cache]
atom = [0-9]+ / "(" expr ")"