hphp/hack/src/utils/random_id.ml

   1 (**
   2  * Copyright (c) 2015, Facebook, Inc.
   3  * All rights reserved.
   4  *
   5  * This source code is licensed under the BSD-style license found in the
   6  * LICENSE file in the "hack" directory of this source tree. An additional grant
   7  * of patent rights can be found in the PATENTS file in the same directory.
   8  *
   9  *)
  10
  11 let () = Random.self_init ()
  12
  13 let base64_alphabet =
  14   "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/"
  15
  16 let () =
  17   assert (String.length base64_alphabet = 64)
  18
  19 let short_string () =
  20   let r = ref (Random.bits ()) in
  21   let cs = ref [] in
  22   while !r > 0 do
  23     let c = base64_alphabet.[!r mod 64] in
  24     cs := String.make 1 c :: !cs;
  25     r := !r lsr 6
  26   done;
  27   String.concat "" !cs