[nnet] Admit parsing failure on non-mandatory information.

lib/nnet/nnet.ml

@@ -32,10 +32,10 @@ type t = {
   n_outputs : int;
   max_layer_size : int;
   layer_sizes : int list;
-  min_input_values : float list;
-  max_input_values : float list;
-  mean_values : float list * float;
-  range_values : float list * float;
+  min_input_values : float list option;
+  max_input_values : float list option;
+  mean_values : (float list * float) option;
+  range_values : (float list * float) option;
   weights_biases : float list list;
 }
 
@@ -154,18 +154,25 @@ let handle_nnet_weights_and_biases in_channel =
 
 (* Retrieves [filename] NNet model metadata and weights wrt NNet format
    specification (see https://github.com/sisl/NNet for details). *)
-let parse_in_channel filename in_channel =
+let parse_in_channel ?(permissive = false) filename in_channel =
   let open Result in
+  let ok_opt r =
+    match r with
+    | Ok x -> Ok (Some x)
+    | Error _ as error -> if not permissive then error else Ok None
+  in
   try
     skip_nnet_header filename in_channel >>= fun () ->
     let in_channel = Csv.of_channel in_channel in
     handle_nnet_basic_info in_channel >>= fun (n_ls, n_is, n_os, max_l_size) ->
     handle_nnet_layer_sizes n_ls in_channel >>= fun layer_sizes ->
     handle_nnet_unused_flag in_channel >>= fun () ->
-    handle_nnet_min_input_values n_is in_channel >>= fun min_input_values ->
-    handle_nnet_max_input_values n_is in_channel >>= fun max_input_values ->
-    handle_nnet_mean_values n_is in_channel >>= fun mean_values ->
-    handle_nnet_range_values n_is in_channel >>= fun range_values ->
+    ok_opt (handle_nnet_min_input_values n_is in_channel)
+    >>= fun min_input_values ->
+    ok_opt (handle_nnet_max_input_values n_is in_channel)
+    >>= fun max_input_values ->
+    ok_opt (handle_nnet_mean_values n_is in_channel) >>= fun mean_values ->
+    ok_opt (handle_nnet_range_values n_is in_channel) >>= fun range_values ->
     let weights_biases = handle_nnet_weights_and_biases in_channel in
     Csv.close_in in_channel;
     Ok
@@ -184,10 +191,10 @@ let parse_in_channel filename in_channel =
   with
   | Csv.Failure (_nrecord, _nfield, msg) -> Error msg
   | Sys_error s -> Error s
-  | Failure msg -> Error (Format.sprintf "Unexpected error: %s." msg)
+  | Failure msg -> Error (Format.sprintf "Unexpected error: %s" msg)
 
-let parse filename =
+let parse ?(permissive = false) filename =
   let in_channel = Stdlib.open_in filename in
   Fun.protect
     ~finally:(fun () -> Stdlib.close_in in_channel)
-    (fun () -> parse_in_channel filename in_channel)
+    (fun () -> parse_in_channel ~permissive filename in_channel)

lib/nnet/nnet.mli

@@ -26,15 +26,19 @@ type t = private {
   n_outputs : int;  (** Number of outputs. *)
   max_layer_size : int;  (** Maximum layer size. *)
   layer_sizes : int list;  (** Size of each layer. *)
-  min_input_values : float list;  (** Minimum values of inputs. *)
-  max_input_values : float list;  (** Maximum values of inputs. *)
-  mean_values : float list * float;
+  min_input_values : float list option;  (** Minimum values of inputs. *)
+  max_input_values : float list option;  (** Maximum values of inputs. *)
+  mean_values : (float list * float) option;
     (** Mean values of inputs and one value for all outputs. *)
-  range_values : float list * float;
+  range_values : (float list * float) option;
     (** Range values of inputs and one value for all outputs. *)
   weights_biases : float list list;  (** All weights and biases of NNet model. *)
 }
 (** NNet model metadata. *)
 
-val parse : string -> (t, string) Result.t
-(** Parse an NNet file. *)
+val parse : ?permissive:bool -> string -> (t, string) Result.t
+(** Parse an NNet file.
+
+    @param permissive
+      [false] by default. When set, parsing does not fail on non available
+      information, which are set to [None] instead. *)

lib/onnx/onnx.mli

@@ -28,7 +28,6 @@ type t = private {
 }
 (** ONNX model metadata. *)
 
+val parse : string -> (t * G.t, string) Result.t
 (** Parse an ONNX file to get metadata for CAISAR as well as its inner
     intermediate representation for the network. *)
-
-val parse : string -> (t * G.t, string) Result.t

src/language.ml

@@ -84,7 +84,7 @@ let register_svm_as_array nb_inputs nb_classes filename env =
   Wstdlib.Mstr.singleton "SVMasArray" (Pmodule.close_module th_uc)
 
 let nnet_parser env _ filename _ =
-  let model = Nnet.parse filename in
+  let model = Nnet.parse ~permissive:true filename in
   match model with
   | Error s -> Loc.errorm "%s" s
   | Ok model ->