use common::base as common

~ = common::whitespaces*

program    =   pest::SOI ~ expr ~ pest::EOI
expr       =   prefix* ~ primary ~ postfix* ~ (infix ~ prefix* ~ primary ~ postfix* )*
  infix    =  _{ add | sub | mul | div | pow }
    add    =   "+" // Addition
    sub    =   "-" // Subtraction
    mul    =   "*" // Multiplication
    div    =   "/" // Division
    pow    =   "^" // Exponentiation
  prefix   =  _{ neg }
    neg    =   "-" // Negation
  postfix  =  _{ fac }
    fac    =   "!" // Factorial
  primary  =  _{ common::int | "(" ~ expr ~ ")" }