lexer.mll

(*
  TODO: Complete the lexical specification for the S language.
*)

{
 open Parser
 exception Eof
 exception LexicalError
 let comment_depth = ref 0
} 

let blank = [' ' '\n' '\t' '\r']+
let id = ['a'-'z' 'A'-'Z']['a'-'z' 'A'-'Z' '0'-'9' '_']*
let number = ['0'-'9']+

rule start = parse 
     | blank { start lexbuf }
     | "/*" { comment_depth :=1; comment lexbuf; start lexbuf }
     | eof   { EOF}
     | _ { raise LexicalError }

and comment = parse
     "/*" {comment_depth := !comment_depth+1; comment lexbuf}
   | "*/" {comment_depth := !comment_depth-1;
           if !comment_depth > 0 then comment lexbuf }
   | eof {raise Eof}
   | _   {comment lexbuf}