; [calc.sty] Grammar "Calculator"

Language calc

Regular Grammar

  ign Ign         = ' \n\r'          ; "white" characters
  tok Tok         = '()+-*/'         ; one character tokens
  tok Int         = ('0'..'9')+      ; Integer
  tok Wrd         = "end"

Context Free Grammar

start Cmd
:exp: Exp
:end: "end"

let Exp  
:ign0: Exp1
:add : Exp  "+" Exp1
:sub : Exp  "-" Exp1

let Exp1 
:ign0: Exp2
:mlt : Exp1 "*" Exp2
:div : Exp1 "/" Exp2

let Exp2
:neg : "-" Exp2
:ign0: "(" Exp ")"
:int : Int