X-Git-Url: http://matita.cs.unibo.it/gitweb/?a=blobdiff_plain;f=helm%2Focaml%2Fregistry%2Fhelm_registry.ml;h=8966bb9479b20f2b1dfe53013fb2da55b6499784;hb=dfdf5642131761008f0b0430594a83d45ab62789;hp=0c7b437238d1e57c23a9d5bcf73d83d6e4fde2b1;hpb=6556d39b592c1e56b0e7f4055242232b8bfe3c90;p=helm.git

diff --git a/helm/ocaml/registry/helm_registry.ml b/helm/ocaml/registry/helm_registry.ml
index 0c7b43723..8966bb947 100644
--- a/helm/ocaml/registry/helm_registry.ml
+++ b/helm/ocaml/registry/helm_registry.ml
@@ -29,6 +29,34 @@ let debug = false
 let debug_print s =
   if debug then prerr_endline ("Helm_registry debugging: " ^ s)
 
+  (** <helpers> *)
+
+let list_uniq l =
+  let rec aux last_element = function
+    | [] -> []
+    | hd :: tl ->
+        (match last_element with
+        | Some elt when elt = hd -> aux last_element tl
+        | _ -> hd :: aux (Some hd) tl)
+  in
+  aux None l
+
+let starts_with prefix =
+(*
+  let rex = Str.regexp (Str.quote prefix) in
+  fun s -> Str.string_match rex s 0
+*)
+  let prefix_len = String.length prefix in
+  fun s ->
+    try
+      String.sub s 0 prefix_len = prefix
+    with Invalid_argument _ -> false
+
+let hashtbl_keys tbl = Hashtbl.fold (fun k _ acc -> k :: acc) tbl []
+let hashtbl_pairs tbl = Hashtbl.fold (fun k v acc -> (k,v) :: acc) tbl []
+
+  (** </helpers> *)
+
 exception Malformed_key of string
 exception Key_not_found of string
 exception Cyclic_definition of string
@@ -36,38 +64,43 @@ exception Type_error of string * string * string (* expected type, value, msg *)
 exception Parse_error of string * int * int * string  (* file, line, col, msg *)
 exception Invalid_value of (string * string) * string (* key, value, descr *)
 
+(*
 type validator_id = int
 
-  (* root XML tag: used by save_to, ignored by load_from *)
-let root_tag = "helm_registry"
-
 let get_next_validator_id =
   let next_id = ref 0 in
   fun () ->
     incr next_id;
     !next_id
 
-let magic_size = 127
 let validators = Hashtbl.create magic_size
-let registry = Hashtbl.create magic_size
+*)
+
+  (* root XML tag: used by save_to, ignored by load_from *)
+let root_tag = "helm_registry"
+
+let magic_size = 127
 
-let backup_registry () = Hashtbl.copy registry
-let restore_registry backup =
+let backup_registry registry = Hashtbl.copy registry
+let restore_registry backup registry =
   Hashtbl.clear registry;
   Hashtbl.iter (fun key value -> Hashtbl.replace registry key value) backup
 
   (* as \\w but:
    * - no sequences of '_' longer than 1 are permitted
-   * - no uppercase letter are permitted
    *)
-let valid_step_rex_raw = "[a-z0-9]+\\(_[a-z0-9]+\\)*"
+let valid_step_rex_raw = "[a-zA-Z0-9]+\\(_[a-z0A-Z-9]+\\)*"
 let valid_key_rex_raw =
-  sprintf "%s\(\\.%s\)*" valid_step_rex_raw valid_step_rex_raw
+  sprintf "%s\\(\\.%s\\)*" valid_step_rex_raw valid_step_rex_raw
 let valid_key_rex = Str.regexp ("^" ^ valid_key_rex_raw ^ "$")
 let interpolated_key_rex = Str.regexp ("\\$(" ^ valid_key_rex_raw ^ ")")
 let dot_rex = Str.regexp "\\."
 let spaces_rex = Str.regexp "[ \t\n\r]+"
 let heading_spaces_rex = Str.regexp "^[ \t\n\r]+"
+let margin_blanks_rex =
+  Str.regexp "^\\([ \t\n\r]*\\)\\([^ \t\n\r]*\\)\\([ \t\n\r]*\\)$"
+
+let strip_blanks s = Str.global_replace margin_blanks_rex "\\2" s
 
 let split s =
   (* trailing blanks are removed per default by split *)
@@ -81,30 +114,29 @@ let (escape, unescape) =
    Netencoding.Html.decode ~in_enc ~out_enc ~entity_base:`Xml ())
 
 let key_is_valid key =
-(*   if not (Pcre.pmatch ~rex:valid_key_rex key) then *)
   if not (Str.string_match valid_key_rex key 0) then
     raise (Malformed_key key)
 
+(*
 let value_is_valid ~key ~value =
   List.iter
     (fun (validator, descr) ->
       if not (validator value) then
         raise (Invalid_value ((key, value), descr)))
     (Hashtbl.find_all validators key)
+*)
 
 let set' registry ~key ~value =
   debug_print (sprintf "Setting %s = %s" key value);
   key_is_valid key;
-  value_is_valid ~key ~value;
+(*   value_is_valid ~key ~value; *)
   Hashtbl.replace registry key value
 
-let unset = Hashtbl.remove registry
+let unset registry = Hashtbl.remove registry
 
-let env_var_of_key key =
-(*   Pcre.replace ~rex:dot_rex ~templ:"__" (String.uppercase key) *)
-  Str.global_replace dot_rex "__" (String.uppercase key)
+let env_var_of_key = Str.global_replace dot_rex "__"
 
-let get key =
+let get registry key =
   let rec aux stack key =
     key_is_valid key;
     if List.mem key stack then begin
@@ -138,19 +170,25 @@ let get key =
         aux stack key)
       value
   in
-  aux [] key
+  strip_blanks (aux [] key)
 
-let set = set' registry
+let set registry = set' registry
 
-let mk_get_set type_name (from_string: string -> 'a) (to_string: 'a -> string) =
-  let getter key =
-    let value = get key in
+let has registry key = Hashtbl.mem registry key
+
+let mk_get_set type_name
+  (from_string: string -> 'a) (to_string: 'a -> string)
+  =
+  let getter registry key =
+    let value = get registry key in
     try
       from_string value
     with exn ->
       raise (Type_error (type_name, value, Printexc.to_string exn))
   in
-  let setter ~key ~value = set ~key ~value:(to_string value) in
+  let setter registry ~key ~value =
+    set registry ~key ~value:(to_string value)
+  in
   (getter, setter)
 
 let (get_string, set_string) = (get, set)
@@ -159,135 +197,257 @@ let (get_float, set_float) = mk_get_set "float" float_of_string string_of_float
 let (get_bool, set_bool) = mk_get_set "bool" bool_of_string string_of_bool
 let (get_string_list, set_string_list) = mk_get_set "string list" split merge
 
-let get_opt getter key =
+let get_opt registry getter key =
   try
-    Some (getter key)
+    Some (getter registry key)
   with Key_not_found _ -> None
-let set_opt setter ~key ~value =
+let set_opt registry setter ~key ~value =
   match value with
-  | None -> unset key
-  | Some value -> setter ~key ~value
-let get_opt_default getter default key =
-  match get_opt getter key with
+  | None -> unset registry key
+  | Some value -> setter registry ~key ~value
+let get_opt_default registry getter default key =
+  match get_opt registry getter key with
   | None -> default
   | Some v -> v
 
+(*
 let add_validator ~key ~validator ~descr =
   let id = get_next_validator_id () in
   Hashtbl.add validators key (validator, descr);
   id
+*)
 
-open Pxp_dtd
-open Pxp_document
-open Pxp_types
-open Pxp_yacc
-
-let save_to =
-  let dtd = new dtd PxpHelmConf.pxp_config.warner `Enc_utf8 in
-  let dot_RE = Str.regexp "\\." in
-  let create_key_node key value = (* create a <key name="foo">value</key> *)
-    let element =
-      create_element_node ~valcheck:false PxpHelmConf.pxp_spec dtd "key" ["name", key]
-    in
-    let data = create_data_node PxpHelmConf.pxp_spec dtd value in
-    element#append_node data;
-    element
+type xml_tree =
+  | Cdata of string
+  | Element of string * (string * string) list * xml_tree list
+
+let dot_RE = Str.regexp "\\."
+
+let xml_tree_of_registry registry =
+  let has_child name elements =
+    List.exists
+      (function
+        | Element (_, ["name", name'], _) when name = name' -> true
+        | _ -> false)
+      elements
   in
-  let is_section name =
-    fun node ->
-      match node#node_type with
-      | T_element "section" ->
-          (try node#attribute "name" = Value name with Not_found -> false)
-      | _ -> false
+  let rec get_child name = function
+    | [] -> assert false
+    | (Element (_, ["name", name'], _) as child) :: tl when name = name' ->
+        child, tl
+    | hd :: tl ->
+        let child, rest = get_child name tl in
+        child, hd :: rest
   in
-  let add_key_node root sections key value =
-    let rec aux node = function
-      | [] ->
-          let key_node = create_key_node key value in
-          node#append_node key_node
-      | section :: tl ->
-          let next_node =
-            try
-              find ~deeply:false (is_section section) node
-            with Not_found ->
-              let section_node =
-                create_element_node ~valcheck:false PxpHelmConf.pxp_spec dtd
-                  "section" ["name", section]
-              in
-              node#append_node section_node;
-              section_node
-          in
-          aux next_node tl
-    in
-    aux root sections
+  let rec add_key path value tree =
+    match path, tree with
+    | [key], Element (name, attrs, children) ->
+        Element (name, attrs,
+          Element ("key", ["name", key],
+            [Cdata (strip_blanks value)]) :: children)
+    | dir :: path, Element (name, attrs, children) ->
+        if has_child dir children then
+          let child, rest = get_child dir children in
+          Element (name, attrs, add_key path value child :: rest)
+        else
+          Element (name, attrs,
+            ((add_key path value (Element ("section", ["name", dir], [])))
+              :: children))
+    | _ -> assert false
   in
-  fun fname ->
-    let xml_root =
-      create_element_node ~valcheck:false PxpHelmConf.pxp_spec dtd "helm_registry" []
-    in
-    Hashtbl.iter
-      (fun key value ->
-        let sections, key =
-          let hd, tl =
-            match List.rev (Str.split dot_RE key) with
-            | hd :: tl -> hd, tl
-            | _ -> assert false
-          in
-          List.rev tl, hd
-        in
-        add_key_node xml_root sections key value)
-      registry;
-      let outchan = (* let's write xml output to fname *)
-        if Unix.system "xmllint --version &> /dev/null" = Unix.WEXITED 0 then
-          (* xmllint available, use it! *)
-          Unix.open_process_out (sprintf
-            "xmllint --format --encode utf8 -o '%s' -" fname)
+  Hashtbl.fold
+    (fun k v tree -> add_key ("helm_registry" :: (Str.split dot_RE k)) v tree)
+    registry
+    (Element ("helm_registry", [], []))
+
+let rec stream_of_xml_tree = function
+  | Cdata s -> Xml.xml_cdata s
+  | Element (name, attrs, children) ->
+      Xml.xml_nempty name
+        (List.map (fun (n, v) -> (None, n, v)) attrs)
+        (stream_of_xml_trees children)
+and stream_of_xml_trees = function
+  | [] -> [< >]
+  | hd :: tl -> [< stream_of_xml_tree hd; stream_of_xml_trees tl >]
+
+let save_to registry fname =
+  let token_stream = stream_of_xml_tree (xml_tree_of_registry registry) in
+  let oc = open_out fname in
+  Xml.pp_to_outchan token_stream oc;
+  close_out oc
+
+(* PXP version *)
+(*open Pxp_dtd*)
+(*open Pxp_document*)
+(*open Pxp_types*)
+(*open Pxp_yacc*)
+
+(*let save_to =*)
+(*  let dtd = new dtd PxpHelmConf.pxp_config.warner `Enc_utf8 in*)
+(*  let create_key_node key value = |+ create a <key name="foo">value</key> +|*)
+(*    let element =*)
+(*      create_element_node ~valcheck:false PxpHelmConf.pxp_spec dtd*)
+(*        "key" ["name", key]*)
+(*    in*)
+(*    let data = create_data_node PxpHelmConf.pxp_spec dtd value in*)
+(*    element#append_node data;*)
+(*    element*)
+(*  in*)
+(*  let is_section name =*)
+(*    fun node ->*)
+(*      match node#node_type with*)
+(*      | T_element "section" ->*)
+(*          (try node#attribute "name" = Value name with Not_found -> false)*)
+(*      | _ -> false*)
+(*  in*)
+(*  let add_key_node root sections key value =*)
+(*    let rec aux node = function*)
+(*      | [] ->*)
+(*          let key_node = create_key_node key value in*)
+(*          node#append_node key_node*)
+(*      | section :: tl ->*)
+(*          let next_node =*)
+(*            try*)
+(*              find ~deeply:false (is_section section) node*)
+(*            with Not_found ->*)
+(*              let section_node =*)
+(*                create_element_node ~valcheck:false PxpHelmConf.pxp_spec dtd*)
+(*                  "section" ["name", section]*)
+(*              in*)
+(*              node#append_node section_node;*)
+(*              section_node*)
+(*          in*)
+(*          aux next_node tl*)
+(*    in*)
+(*    aux root sections*)
+(*  in*)
+(*  fun registry fname ->*)
+(*    let xml_root =*)
+(*      create_element_node ~valcheck:false PxpHelmConf.pxp_spec dtd*)
+(*      "helm_registry" []*)
+(*    in*)
+(*    Hashtbl.iter*)
+(*      (fun key value ->*)
+(*        let sections, key =*)
+(*          let hd, tl =*)
+(*            match List.rev (Str.split dot_RE key) with*)
+(*            | hd :: tl -> hd, tl*)
+(*            | _ -> assert false*)
+(*          in*)
+(*          List.rev tl, hd*)
+(*        in*)
+(*        add_key_node xml_root sections key value)*)
+(*      registry;*)
+(*      let outfile = open_out fname in*)
+(*      Unix.lockf (Unix.descr_of_out_channel outfile) Unix.F_LOCK 0; |+ blocks +|*)
+(*      if*)
+(*        Unix.system "xmllint --version &> /dev/null" = Unix.WEXITED 0*)
+(*      then begin*)
+(*        let (xmllint_in, xmllint_out) =*)
+(*          Unix.open_process "xmllint --format --encode utf8 -"*)
+(*        in*)
+(*        xml_root#write (`Out_channel xmllint_out) `Enc_utf8;*)
+(*        close_out xmllint_out;*)
+(*        try*)
+(*          while true do*)
+(*            output_string outfile (input_line xmllint_in ^ "\n")*)
+(*          done*)
+(*        with End_of_file ->*)
+(*          close_in xmllint_in;*)
+(*          ignore (Unix.close_process (xmllint_in, xmllint_out))*)
+(*      end else*)
+(*        xml_root#write (`Out_channel outfile) `Enc_utf8;*)
+(*      Unix.lockf (Unix.descr_of_out_channel outfile) Unix.F_ULOCK 0;*)
+(*      close_out outfile*)
+
+(* PXP version *)
+(*let load_from_absolute =*)
+(*  let config = PxpHelmConf.pxp_config in*)
+(*  let entry = `Entry_document [ `Extend_dtd_fully; `Parse_xml_decl ] in*)
+(*  let fold_key key_stack key =*)
+(*    match key_stack with*)
+(*    | [] -> key*)
+(*    | _ -> String.concat "." key_stack ^ "." ^ key*)
+(*  in*)
+(*  fun registry fname ->*)
+(*    debug_print ("Loading configuration from " ^ fname);*)
+(*    let document =*)
+(*      parse_wfdocument_entity config (from_file fname) PxpHelmConf.pxp_spec*)
+(*    in*)
+(*    let rec aux key_stack node =*)
+(*      node#iter_nodes (fun n ->*)
+(*        try*)
+(*          (match n#node_type with*)
+(*          | T_element "section" ->*)
+(*              let section = n#required_string_attribute "name" in*)
+(*              aux (key_stack @ [section]) n*)
+(*          | T_element "key" ->*)
+(*              let key = n#required_string_attribute "name" in*)
+(*              let value = n#data in*)
+(*              set registry ~key:(fold_key key_stack key) ~value*)
+(*          | _ -> ())*)
+(*        with exn ->*)
+(*          let (fname, line, pos) = n#position in*)
+(*          raise (Parse_error (fname, line, pos,*)
+(*            "Uncaught exception: " ^ Printexc.to_string exn)))*)
+(*    in*)
+(*    let backup = backup_registry registry in*)
+(*    Hashtbl.clear registry;*)
+(*    try*)
+(*      aux [] document#root*)
+(*    with exn ->*)
+(*      restore_registry backup registry;*)
+(*      raise exn*)
+
+(* XmlPushParser version *)
+let load_from_absolute registry fname =
+  let path = ref [] in  (* <section> elements entered so far *)
+  let in_key = ref false in (* have we entered a <key> element? *)
+  let push_path name = path := name :: !path in
+  let pop_path () = path := List.tl !path in
+  let start_element tag attrs =
+    match tag, attrs with
+    | "section", ["name", name] -> push_path name
+    | "key", ["name", name] -> in_key := true; push_path name
+    | "helm_registry", _ -> ()
+    | tag, _ ->
+        raise (Parse_error (fname, ~-1, ~-1,
+          (sprintf "unexpected element <%s> or wrong attribute set" tag)))
+  in
+  let end_element tag =
+    match tag with
+    | "section" -> pop_path ()
+    | "key" -> in_key := false; pop_path ()
+    | "helm_registry" -> ()
+    | _ -> assert false
+  in
+  let character_data text =
+    if !in_key then
+      let key = String.concat "." (List.rev !path) in
+      let value =
+        if Hashtbl.mem registry key then
+          Hashtbl.find registry key ^ text
         else
-          (* xmllint not available, write pxp ugly output directly to fname *)
-          open_out fname
+          text
       in
-      xml_root#write (`Out_channel outchan) `Enc_utf8;
-      close_out outchan
-
-let load_from_absolute =
-  let config = PxpHelmConf.pxp_config in
-  let entry = `Entry_document [ `Extend_dtd_fully; `Parse_xml_decl ] in
-  let fold_key key_stack key =
-    match key_stack with
-    | [] -> key
-    | _ -> String.concat "." key_stack ^ "." ^ key
+      set registry ~key ~value
   in
-  fun fname ->
-    debug_print ("Loading configuration from " ^ fname);
-    let document =
-      parse_wfdocument_entity config (from_file fname) PxpHelmConf.pxp_spec
-    in
-    let rec aux key_stack node =
-      node#iter_nodes (fun n ->
-        try
-          (match n#node_type with
-          | T_element "section" ->
-              let section = n#required_string_attribute "name" in
-              aux (key_stack @ [section]) n
-          | T_element "key" ->
-              let key = n#required_string_attribute "name" in
-              let value = n#data in
-              set ~key:(fold_key key_stack key) ~value
-          | _ -> ())
-        with exn ->
-          let (fname, line, pos) = n#position in
-          raise (Parse_error (fname, line, pos,
-            "Uncaught exception: " ^ Printexc.to_string exn)))
-    in
-    let backup = backup_registry () in
-    Hashtbl.clear registry;
-    try
-      aux [] document#root
-    with exn ->
-      restore_registry backup;
-      raise exn
+  let callbacks = {
+    XmlPushParser.default_callbacks with
+      XmlPushParser.start_element = Some start_element;
+      XmlPushParser.end_element = Some end_element;
+      XmlPushParser.character_data = Some character_data;
+  } in
+  let xml_parser = XmlPushParser.create_parser callbacks in
+  let backup = backup_registry registry in
+  Hashtbl.clear registry;
+  try
+    XmlPushParser.parse xml_parser (`File fname)
+  with exn ->
+    restore_registry backup registry;
+    raise exn
 
-let load_from ?path fname =
+let load_from registry ?path fname =
   if Filename.is_relative fname then begin
     let no_file_found = ref true in
     let path =
@@ -300,7 +460,7 @@ let load_from ?path fname =
         let conffile = dir ^ "/" ^ fname in
         if Sys.file_exists conffile then begin
           no_file_found := false;
-          load_from_absolute conffile
+          load_from_absolute registry conffile
         end)
        path;
     if !no_file_found then
@@ -308,9 +468,136 @@ let load_from ?path fname =
         "Helm_registry.init: no configuration file named %s in [ %s ]"
         fname (String.concat "; " path))
   end else
-    load_from_absolute fname
+    load_from_absolute registry fname
+
+let fold registry ?prefix ?(interpolate = true) f init =
+  let value_of k v = if interpolate then get registry k else strip_blanks v in
+  match prefix with
+  | None -> Hashtbl.fold (fun k v acc -> f acc k (value_of k v)) registry init
+  | Some s ->
+      let key_matches = starts_with (s ^ ".") in
+      let rec fold_filter acc = function
+        | [] -> acc
+        | (k,v) :: tl when key_matches k ->
+            fold_filter (f acc k (value_of k v)) tl
+        | _ :: tl -> fold_filter acc tl
+      in
+      fold_filter init (hashtbl_pairs registry)
 
-  (* DEBUGGING ONLY *)
+let iter registry ?prefix ?interpolate f =
+  fold registry ?prefix ?interpolate (fun _ k v -> f k v) ()
+let to_list registry ?prefix ?interpolate () =
+  fold registry ?prefix ?interpolate (fun acc k v -> (k, v) :: acc) []
 
-let dump () = Hashtbl.iter (fun k v -> printf "%s = %s\n" k v) registry
+let ls registry prefix =
+  let prefix = prefix ^ "." in
+  let prefix_len = String.length prefix in
+  let key_matches = starts_with prefix in
+  let matching_keys = (* collect matching keys' _postfixes_ *)
+    fold registry
+      (fun acc key _ ->
+        if key_matches key then
+          String.sub key prefix_len (String.length key - prefix_len) :: acc
+        else
+          acc)
+      []
+  in
+  let (sections, keys) =
+    List.fold_left
+      (fun (sections, keys) postfix ->
+        match Str.split dot_rex postfix with
+        | [key] -> (sections, key :: keys)
+        | hd_key :: _ ->  (* length > 1 => nested section found *)
+            (hd_key :: sections, keys)
+        | _ -> assert false)
+      ([], []) matching_keys
+  in
+  (list_uniq (List.sort Pervasives.compare sections), keys)
+
+(** {2 OO interface} *)
+
+class registry ?path fname =
+  object (self)
+    val _registry = Hashtbl.create magic_size
+    initializer load_from _registry ?path fname
+    method get = get _registry
+    method set = set _registry
+    method has = has _registry
+    method unset = unset _registry
+    method fold:
+      'a.
+        ?prefix:string -> ?interpolate: bool ->
+          ('a -> string -> string -> 'a) -> 'a -> 'a
+      =
+        fun ?prefix ?interpolate f init ->
+          fold _registry ?prefix ?interpolate f init
+    method iter = iter _registry
+    method to_list = to_list _registry
+    method ls = ls _registry
+    method get_string = get_string _registry
+    method get_int = get_int _registry
+    method get_float = get_float _registry
+    method get_bool = get_bool _registry
+    method get_string_list = get_string_list _registry
+    method set_string = set_string _registry
+    method set_int = set_int _registry
+    method set_float = set_float _registry
+    method set_bool = set_bool _registry
+    method set_string_list = set_string_list _registry
+    method get_opt: 'a. (string -> 'a) -> string -> 'a option =
+      fun getter key ->
+        try Some (getter key) with Key_not_found _ -> None
+    method set_opt:
+      'a. (key:string -> value:'a -> unit) -> key:string -> value:'a option ->
+        unit
+      =
+        fun setter ~key ~value ->
+          match value with
+          | None -> self#unset key
+          | Some value -> setter ~key ~value
+    method get_opt_default: 'a. (string -> 'a) -> 'a -> string -> 'a =
+      fun getter default key ->
+        match self#get_opt getter key with
+        | None -> default
+        | Some v -> v
+    method save_to = save_to _registry
+(*     method load_from = load_from _registry *)
+  end
+
+(** {2 API implementation}
+ * functional methods above are wrapped so that they work on a default
+ * (imperative) registry*)
+
+let default_registry = Hashtbl.create magic_size
+
+let get = get default_registry
+let set = set default_registry
+let has = has default_registry
+let fold ?prefix ?interpolate f init =
+  fold default_registry ?prefix ?interpolate f init
+let iter = iter default_registry
+let to_list = to_list default_registry
+let ls = ls default_registry
+let get_string = get_string default_registry
+let get_int = get_int default_registry
+let get_float = get_float default_registry
+let get_bool = get_bool default_registry
+let get_string_list = get_string_list default_registry
+let set_string = set_string default_registry
+let set_int = set_int default_registry
+let set_float = set_float default_registry
+let set_bool = set_bool default_registry
+let set_string_list = set_string_list default_registry
+let get_opt getter key = try Some (getter key) with Key_not_found _ -> None
+let set_opt setter ~key ~value =
+  match value with
+  | None -> unset default_registry key
+  | Some value -> setter ~key ~value
+let unset = unset default_registry
+let get_opt_default getter default key =
+  match get_opt getter key with
+  | None -> default
+  | Some v -> v
+let save_to = save_to default_registry
+let load_from = load_from default_registry