vendor/pest_derive/examples/calc.pest

   1 WHITESPACE   =  _{ " " | "\t" | NEWLINE }
   2
   3  program      =   { SOI ~ expr ~ EOI }
   4    expr       =   { prefix* ~ primary ~ postfix* ~ (infix ~ prefix* ~ primary ~ postfix* )* }
   5      infix    =  _{ add | sub | mul | div | pow }
   6        add    =   { "+" } // Addition
   7        sub    =   { "-" } // Subtraction
   8        mul    =   { "*" } // Multiplication
   9        div    =   { "/" } // Division
  10        pow    =   { "^" } // Exponentiation
  11      prefix   =  _{ neg }
  12        neg    =   { "-" } // Negation
  13      postfix  =  _{ fac }
  14        fac    =   { "!" } // Factorial
  15      primary  =  _{ int | "(" ~ expr ~ ")" }
  16        int    =  @{ (ASCII_NONZERO_DIGIT ~ ASCII_DIGIT+ | ASCII_DIGIT) }