use gadts for event, clean repo

src/event.ml

@@ -0,0 +1,59 @@
+type _ t =
+  | Keyboard : Jv.t -> [> `Keyboard ] t
+  | Mouse : Jv.t -> [> `Mouse ] t
+  | Error : Jv.t -> [> `Error ] t
+  | Basic : Jv.t -> [> `Basic ] t
+
+type _ sub =
+  | Click : [> `Mouse ] sub
+  | Move_end : [> `Basic ] sub
+  | Zoom_end : [> `Basic ] sub
+
+let of_jv_t : type kind. kind sub -> Jv.t -> kind t =
+ fun tag e ->
+  match tag with Click -> Mouse e | Move_end -> Basic e | Zoom_end -> Basic e
+
+let sub_to_string : type kind. kind sub -> string = function
+  | Click -> "click"
+  | Move_end -> "moveend"
+  | Zoom_end -> "zoomend"
+
+(** Basic events *)
+
+let get_type : type kind. kind t -> string = function
+  | Keyboard e | Mouse e | Error e | Basic e -> Jv.get e "type" |> Jv.to_string
+
+let target : type kind. kind t -> Brr.Ev.target = function
+  | Keyboard e | Mouse e | Error e | Basic e ->
+    Jv.get e "target" |> Brr.Ev.target_of_jv
+
+let source_target : type kind. kind t -> Brr.Ev.target = function
+  | Keyboard e | Mouse e | Error e | Basic e ->
+    Jv.get e "sourceTarget" |> Brr.Ev.target_of_jv
+
+let propagated_from : type kind. kind t -> Jv.t = function
+  | Keyboard e | Mouse e | Error e | Basic e -> Jv.get e "propagatedFrom"
+
+(** Keyboard & Mouse events *)
+
+let original_event : [ `Keyboard | `Mouse ] t -> Jv.t = function
+  | Keyboard e | Mouse e -> Jv.get e "originalEvent"
+
+(** Mouse events *)
+
+let container_point : [ `Mouse ] t -> Jv.t = function
+  | Mouse e -> Jv.get e "containerPoint"
+
+let layer_point : [ `Mouse ] t -> Jv.t = function
+  | Mouse e -> Jv.get e "layerPoint"
+
+let latlng : [ `Mouse ] t -> Latlng.t = function
+  | Mouse e -> Jv.get e "latlng" |> Latlng.of_jv_t
+
+(** Error events *)
+
+let code : [ `Error ] t -> int = function
+  | Error e -> Jv.get e "code" |> Jv.to_int
+
+let message : [ `Error ] t -> string = function
+  | Error e -> Jv.get e "message" |> Jv.to_string