+let empty_mathml =
+ let doc =
+ Misc.domImpl#createDocument ~namespaceURI:(Some Misc.mathml_ns)
+ ~qualifiedName:(Gdome.domString "math") ~doctype:None
+ in
+ doc#get_documentElement
+
+exception History_failure
+
+type 'a memento = 'a array * int * int * int (* data, hd, tl, cur *)
+
+class type ['a] history =
+ object
+ method add : 'a -> unit
+ method next : 'a
+ method previous : 'a
+ method load: 'a memento -> unit
+ method save: 'a memento
+ end
+
+class shell_history size =
+ let size = size + 1 in
+ let decr x = let x' = x - 1 in if x' < 0 then size + x' else x' in
+ let incr x = (x + 1) mod size in
+ object (self)
+ val data = Array.create size ""
+ val mutable hd = 0 (* insertion point *)
+ val mutable tl = -1 (* oldest inserted item *)
+ val mutable cur = -1 (* current item for the history *)
+ method add s =
+ data.(hd) <- s;
+ if tl = -1 then tl <- hd;
+ hd <- incr hd;
+ if hd = tl then tl <- incr tl;
+ cur <- hd
+ method previous =
+ if cur = tl then raise History_failure;
+ cur <- decr cur;
+ data.(cur)
+ method next =
+ if cur = hd then raise History_failure;
+ cur <- incr cur;
+ if cur = hd then "" else data.(cur)
+ method load (data', hd', tl', cur') =
+ assert (Array.length data = Array.length data');
+ hd <- hd'; tl <- tl'; cur <- cur';
+ Array.blit data' 0 data 0 (Array.length data')
+ method save = (Array.copy data, hd, tl, cur)
+ end
+
+class ['a] browser_history ?memento size init =
+ object (self)
+ initializer match memento with Some m -> self#load m | _ -> ()
+ val data = Array.create size init
+ val mutable hd = 0
+ val mutable tl = 0
+ val mutable cur = 0
+ method previous =
+ if cur = tl then raise History_failure;
+ cur <- cur - 1;
+ if cur = ~-1 then cur <- size - 1;
+ data.(cur)
+ method next =
+ if cur = hd then raise History_failure;
+ cur <- cur + 1;
+ if cur = size then cur <- 0;
+ data.(cur)
+ method add (e:'a) =
+ cur <- cur + 1;
+ if cur = size then cur <- 0;
+ if cur = tl then tl <- tl + 1;
+ if tl = size then tl <- 0;
+ hd <- cur;
+ data.(cur) <- e
+ method load (data', hd', tl', cur') =
+ assert (Array.length data = Array.length data');
+ hd <- hd'; tl <- tl'; cur <- cur';
+ Array.blit data' 0 data 0 (Array.length data')
+ method save = (Array.copy data, hd, tl, cur)
+ end
+
+let dbd_instance =
+ let dbd = lazy (
+ Mysql.quick_connect
+ ~host:(Helm_registry.get "db.host")
+ ~user:(Helm_registry.get "db.user")
+ ~database:(Helm_registry.get "db.database")
+ ())
+ in
+ fun () -> Lazy.force dbd
+