{
module LogoLexer

open System

open LogoParser

let lexeme = Microsoft.FSharp.Text.Lexing.LexBuffer<_>.LexemeString
}

let digit   = ['0'-'9']
let alpha   = ['a' - 'z']

let integer = digit+
let ident   = alpha+

let whitesp = ' ' | '\t'
let newline = '\n' | '\r' '\n'

rule token = parse
  | whitesp { token lexbuf }
  | newline { lexbuf.EndPos <- lexbuf.EndPos.NextLine; token lexbuf }

  | "{"     { LBRACE }
  | "}"     { RBRACE }
  | ","     { COMMA }
  | "+"     { PLUS }
  | "-"     { MINUS }
  | "*"     { MUL }
  | "/"     { DIV }
  | "("     { LPAREN }
  | ")"     { RPAREN }

  | "left"    { LTURN }
  | "right"   { RTURN }
  | "forward" { FORWARD }
  | "pen"     { PEN }
  | "color"   { COLOR }
  | "if"      { IF }
  | "repeat"  { REPEAT }
  | "split"   { SPLIT }
  | "define"  { DEFINE }

  | ident   { ID (lexeme lexbuf) }
  | integer { INT (Int32.Parse(lexeme lexbuf)) }
  | eof     { EOF }
  | _       { failwithf "Unrecognized input '%s'" (lexeme lexbuf) }