1 files changed, 39 insertions, 0 deletions
diff --git a/lib/jid.ml b/lib/jid.ml
index 19759eb..33c9a9d 100644
--- a/lib/jid.ml
+++ b/lib/jid.ml
@@ -3,3 +3,42 @@ type t = {
     domainpart : string;
     resourcepart : string option;
   }
+
+exception InvalidUTF8
+
+let of_string (jid : string) : t =
+  let open Uchar in
+  let len = String.length jid in
+  let rec to_localpart i =
+    if i <= 0 then
+      None
+    else
+      let c = String.get_utf_8_uchar jid i in
+      if not (utf_decode_is_valid c)
+      then raise InvalidUTF8
+      else
+        let k = utf_decode_length c in
+        match utf_decode_uchar c |> to_char with
+        | '@' -> Some (i + 1)
+        | _ -> to_localpart (i - k)
+  and to_resourcepart i =
+    if i >= len then
+      None
+    else
+      let c = String.get_utf_8_uchar jid i in
+      if not (utf_decode_is_valid c)
+      then raise InvalidUTF8
+      else
+        let k = utf_decode_length c in
+        match utf_decode_uchar c |> to_char with
+        | '/' -> Some i
+        | _ -> to_resourcepart (i + k)
+  in let r = to_resourcepart 0 in
+     let rv = Option.value ~default:len r in
+     let l = to_localpart (rv-1) in
+     let lv = Option.value ~default:0 l in
+     {
+       localpart = Option.map (fun i -> String.sub jid 0 (i-1)) l;
+       resourcepart = Option.map (fun i -> String.sub jid (i+1) (len-i-1)) r;
+       domainpart = String.sub jid lv (rv-lv);
+     }