- the mathql interpreter is not helm-dependent any more

[helm.git] / helm / hbugs / common / hbugs_id_generator.ml

diff --git a/helm/hbugs/common/hbugs_id_generator.ml b/helm/hbugs/common/hbugs_id_generator.ml
index 59f67347c9f989d5b951f89c71b39cca94eb13ac..f535f473932e01fbb42669d8a8bdcb8a9f4d6926 100644 (file)
--- a/helm/hbugs/common/hbugs_id_generator.ml
+++ b/helm/hbugs/common/hbugs_id_generator.ml
@@ -1,5 +1,7 @@
 (*
- *  Copyright (C) 2003, HELM Team.
+ * Copyright (C) 2003:
+ *    Stefano Zacchiroli <zack@cs.unibo.it>
+ *    for the HELM Team http://helm.cs.unibo.it/
  *
  *  This file is part of HELM, an Hypertextual, Electronic
  *  Library of Mathematics, developed at the Computer Science
@@ -21,9 +23,43 @@
  *  MA  02111-1307, USA.
  *
  *  For details, see the HELM World-Wide-Web page,
- *  http://cs.unibo.it/helm/.
+ *  http://helm.cs.unibo.it/
  *)
 
-let new_broker_id () =  (* TODO write a real id generator! *)
-  "FOO BROKER ID!"
+let _ = Random.self_init ()
+
+let id_length = 32
+let min_ascii = 33
+let max_ascii = 126
+  (* characters forbidden inside an XML attribute value. Well, '>' and '''
+  aren't really forbidden, but are listed here ... just to be sure *)
+let forbidden_chars = (* i.e. [ '"'; '&'; '\''; '<'; '>' ] *)
+  [ 34; 38; 39; 60; 62 ]  (* assumption: is sorted! *)
+let chars_range = max_ascii - min_ascii + 1 - (List.length forbidden_chars)
+
+  (* return a random id char c such that 
+      (min_ascii <= Char.code c) &&
+      (Char.code c <= max_ascii) &&
+      (not (List.mem (Char.code c) forbidden_chars))
+  *)
+let random_id_char () =
+  let rec nth_char ascii shifts = function
+    | [] -> Char.chr (ascii + shifts)
+    | hd::tl when ascii + shifts < hd -> Char.chr (ascii + shifts)
+    | hd::tl (* when ascii + shifts >= hd *) -> nth_char ascii (shifts + 1) tl
+  in
+  nth_char (Random.int chars_range + min_ascii) 0 forbidden_chars
+
+  (* return a random id string which have length id_length *)
+let new_id () =
+  let str = String.create id_length in
+  for i = 0 to id_length - 1 do
+    String.set str i (random_id_char ())
+  done;
+  str
+
+let new_broker_id = new_id
+let new_client_id = new_id
+let new_musing_id = new_id
+let new_tutor_id = new_id