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|
(* file: lexer.mll *)
(* Lexical analyzer returns one of the tokens:
the token NUM of a floating point number,
operators (PLUS, MINUS, MULTIPLY, DIVIDE, CARET, UMINUS),
or NEWLINE. It skips all blanks and tabs, unknown characters
and raises End_of_file on EOF. *)
{
open Rpncalc (* Assumes the parser file is "rpncalc.mly". *)
}
let digit = ['0'-'9']
rule token = parse
| [' ' '\t'] { token lexbuf }
| '\n' { NEWLINE }
| digit+
| "." digit+
| digit+ "." digit* as num
{ NUM (float_of_string num) }
| '+' { PLUS }
| '-' { MINUS }
| '*' { MULTIPLY }
| '/' { DIVIDE }
| '^' { CARET }
| 'n' { UMINUS }
| _ { token lexbuf }
| eof { raise End_of_file }
|
