Use Cmdliner in gen_api_main.ml (#6319)

- Drops usage of stdlib `Arg` module for argument parsing, replacing it
with Cmdliner.
- Drops some globals pertaining to the filtering of APIs.
- Drops apparent condition in `Gen_server`: `server.ml` cannot be built
without the debug flag being enabled, as the emitted OCaml code is ill
formed.
- Drops ability to specify an output file; dune's `with-stdout-to`
subsumes this behaviour, as does the piping functionality in every
shell.

The idea is hopefully that it'll be more flexible to experiment and
extend the `ocaml_backend/` targets.

Author: contificate

ocaml/idl/datamodel_main.ml

@@ -48,17 +48,15 @@ let _ =
   if num_modes_set > 1 then failwith "More than one mode on the commandline" ;
 
   let oss_filter api =
-    filter
-      (fun _ -> true)
-      (fun field -> List.mem "3.0.3" field.release.opensource)
-      (fun message -> List.mem "3.0.3" message.msg_release.opensource)
+    filter_by
+      ~field:(fun field -> List.mem "3.0.3" field.release.opensource)
+      ~message:(fun message -> List.mem "3.0.3" message.msg_release.opensource)
       api
   in
   let closed_filter api =
-    filter
-      (fun _ -> true)
-      (fun field -> List.mem "closed" field.release.internal)
-      (fun message -> List.mem "closed" message.msg_release.internal)
+    filter_by
+      ~field:(fun field -> List.mem "closed" field.release.internal)
+      ~message:(fun message -> List.mem "closed" message.msg_release.internal)
       api
   in
 
@@ -75,13 +73,12 @@ let _ =
   (* Add all implicit messages to the API directly *)
   let api = DU.add_implicit_messages ~document_order:!markdown_mode api in
   (* Only show those visible to the client *)
-  let api = filter (fun _ -> true) (Fun.const true) DU.on_client_side api in
+  let api = filter_by ~message:DU.on_client_side api in
   (* And only messages marked as not hidden from the docs, and non-internal fields *)
   let api =
-    filter
-      (fun _ -> true)
-      (fun f -> not f.internal_only)
-      (fun m -> not m.msg_hide_from_docs)
+    filter_by
+      ~field:(fun f -> not f.internal_only)
+      ~message:(fun m -> not m.msg_hide_from_docs)
       api
   in
 
@@ -94,10 +91,6 @@ let _ =
 
   if !dtd_mode then
     let api =
-      filter
-        (fun _ -> true)
-        (fun field -> field.qualifier <> DynamicRO)
-        (fun _ -> true)
-        api
+      filter_by ~field:(fun field -> field.qualifier <> DynamicRO) api
     in
     List.iter print_endline (Dtd_backend.of_objs api)

ocaml/idl/dm_api.ml

@@ -156,6 +156,10 @@ let filter (obj : obj -> bool) (field : field -> bool)
   in
   rebuild system relations
 
+let filter_by ?(obj = fun _ -> true) ?(field = fun _ -> true)
+    ?(message = fun _ -> true) =
+  filter obj field message
+
 let map (obj : obj -> obj) (field : string -> field -> field)
     (message : message -> message) ((system, relations) : api) : api =
   let system =

ocaml/idl/dm_api.mli

@@ -34,8 +34,14 @@ val get_obj_by_name : api -> objname:string -> obj
 val field_exists : api -> objname:string -> fieldname:string -> bool
 (** True if the named field exists *)
 
-val filter : (obj -> bool) -> (field -> bool) -> (message -> bool) -> api -> api
-(** Apply a predicate to every object, field and message, to generate a sub-API *)
+val filter_by :
+     ?obj:(obj -> bool)
+  -> ?field:(field -> bool)
+  -> ?message:(message -> bool)
+  -> api
+  -> api
+(** Filter an API by filtering objects, fields, and messages. The
+    default predicates retain everything. *)
 
 val map :
      (obj -> obj)

ocaml/idl/json_backend/gen_json.ml

@@ -687,13 +687,12 @@ let () =
   (* Add all implicit messages *)
   let api = add_implicit_messages api in
   (* Only include messages that are visible to a XenAPI client *)
-  let api = filter (fun _ -> true) (fun _ -> true) on_client_side api in
+  let api = filter_by ~message:on_client_side api in
   (* And only messages marked as not hidden from the docs, and non-internal fields *)
   let api =
-    filter
-      (fun _ -> true)
-      (fun f -> not f.internal_only)
-      (fun m -> not m.msg_hide_from_docs)
+    filter_by
+      ~field:(fun f -> not f.internal_only)
+      ~message:(fun m -> not m.msg_hide_from_docs)
       api
   in
   let objs = objects_of_api api in

ocaml/idl/markdown_backend.ml

@@ -528,10 +528,8 @@ let generate_errors () =
 let all api =
   (* Remove private messages that are only used internally (e.g. get_record_internal) *)
   let api =
-    Dm_api.filter
-      (fun _ -> true)
-      (fun _ -> true)
-      (fun msg ->
+    Dm_api.filter_by
+      ~message:(fun msg ->
         match msg.msg_tag with FromObject (Private _) -> false | _ -> true
       )
       api

ocaml/idl/ocaml_backend/dune

@@ -3,6 +3,7 @@
   (name gen_api_main)
   (libraries
     astring
+    cmdliner
     uuidm
     xapi-consts
     xapi-datamodel

ocaml/idl/ocaml_backend/gen_api.ml

@@ -260,7 +260,7 @@ let gen_record_type ~with_module highapi tys =
   in
   aux [] tys
 
-let gen_client highapi =
+let gen_client _config highapi =
   List.iter (List.iter print)
     (between [""]
        [
@@ -352,7 +352,7 @@ let toposort_types highapi types =
   assert (List.sort compare result = List.sort compare types) ;
   result
 
-let gen_record_deserialization highapi =
+let gen_record_deserialization _config highapi =
   let gen_of_to_string types =
     let gen_string_and_all = function
       | DT.Set (DT.Enum (_, elist) as e) ->
@@ -384,7 +384,7 @@ let gen_record_deserialization highapi =
        ]
     )
 
-let gen_client_types highapi =
+let gen_client_types _config highapi =
   let all_types = all_types_of highapi in
   let all_types = add_set_enums all_types in
   List.iter (List.iter print)
@@ -440,7 +440,7 @@ let gen_client_types highapi =
        ]
     )
 
-let gen_server highapi =
+let gen_server _config highapi =
   List.iter (List.iter print)
     (between [""]
        [
@@ -449,7 +449,7 @@ let gen_server highapi =
        ]
     )
 
-let gen_custom_actions highapi =
+let gen_custom_actions _config highapi =
   List.iter (List.iter print)
     (between [""]
        [
@@ -464,13 +464,9 @@ let gen_custom_actions highapi =
 
 open Gen_db_actions
 
-let gen_db_actions highapi =
+let gen_db_actions _config highapi =
   let highapi_in_db =
-    Dm_api.filter
-      (fun obj -> obj.DT.in_database)
-      (fun _ -> true)
-      (fun _ -> true)
-      highapi
+    Dm_api.filter_by ~obj:(fun obj -> obj.DT.in_database) highapi
   in
   let all_types_in_db = all_types_of highapi_in_db in
   let only_records =
@@ -495,4 +491,5 @@ let gen_db_actions highapi =
     @ []
     )
 
-let gen_rbac highapi = print (Gen_rbac.gen_permissions_of_static_roles highapi)
+let gen_rbac config highapi =
+  print (Gen_rbac.gen_permissions_of_static_roles config highapi)