pt::grammar::peg {rules {AddOp {is {/ {t -} {t +}} mode value} Digit {is {/ {t 0} {t 1} {t 2} {t 3} {t 4} {t 5} {t 6} {t 7} {t 8} {t 9}} mode value} Expression {is {/ {n Function} {/ {x {t (} {n Expression} {t )}} {x {n Factor} {* {x {n MulOp} {n Factor}}}}}} mode value} Factor {is {x {n Term} {* {x {n AddOp} {n Term}}}} mode value} Function {is {n Sinus} mode value} MulOp {is {/ {t *} {t /}} mode value} Number {is {x {? {n Sign}} {+ {n Digit}}} mode value} Sign {is {/ {t -} {t +}} mode value} Sinus {is {x {t s} {t i} {t n} {t (} {n Expression} {t )}} mode value} Term {is {n Number} mode value}} start {n Expression}}