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|
(* This example shows how to use ulex with a custom implementation
for lex buffers. *)
module Ulexing =
struct
exception Error
type t = {
buf : string;
mutable pos : int;
mutable mark_pos : int;
mutable mark_val : int;
mutable start : int;
}
let from_immutable_string s =
{ buf = s; pos = 0; mark_pos = 0; mark_val = 0; start = 0 }
let start b =
b.mark_pos <- b.pos;
b.mark_val <- (-1);
b.start <- b.pos
let mark b i =
b.mark_pos <- b.pos;
b.mark_val <- i
let backtrack b =
b.pos <- b.mark_pos;
b.mark_val
let next b =
if b.pos < String.length b.buf
then let c = Char.code b.buf.[b.pos] in b.pos <- b.pos + 1; c
else (-1)
let lexeme b =
String.sub b.buf b.start (b.pos - b.start)
end
let () =
let rec split = lexer
| ['a'-'z' 'A'-'Z']* -> print_endline (Ulexing.lexeme lexbuf); split lexbuf
| eof -> ()
| _ -> split lexbuf
in
split (Ulexing.from_immutable_string "Hello, world !")
|
