Source file deserialize.ml
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(** Module for deserializing values *)
open StdLabels
open Result
module S = Spec.Make(struct
type ('a, 'b) dir = ('a, 'b) Spec.deserialize
end)
module C = S.C
open S
type 'a sentinal = unit -> 'a Result.t
type 'a decoder = Field.t -> 'a Result.t
type (_, _) sentinal_list =
| SNil : ('a, 'a) sentinal_list
| SCons : ('a sentinal) * ('b, 'c) sentinal_list -> ('a -> 'b, 'c) sentinal_list
let error_wrong_field str field : _ Result.t =
`Wrong_field_type (str, field) |> Result.fail
let error_illegal_value str field : _ Result.t = `Illegal_value (str, field) |> Result.fail
let error_required_field_missing: _ Result.t = `Required_field_missing |> Result.fail
let read_varint ~signed ~type_name =
let open! Infix.Int64 in
function
| Field.Varint v -> begin
let v = match signed with
| true when v land 0x01L = 0L -> v / 2L
| true -> (v / 2L * -1L) - 1L
| false -> v
in
return v
end
| field -> error_wrong_field type_name field
let read_varint32 ~signed ~type_name field =
read_varint ~signed ~type_name field >>| Int64.to_int32
let rec type_of_spec: type a. a spec -> 'b * a decoder =
let int_of_int32 spec =
let (tpe, f) = type_of_spec spec in
let f field =
f field >>| Int32.to_int
in
(tpe, f)
in
let int_of_int64 spec =
let (tpe, f) = type_of_spec spec in
let f field =
f field >>| Int64.to_int
in
(tpe, f)
in
function
| Double -> (`Fixed_64_bit, function
| Field.Fixed_64_bit v -> return (Int64.float_of_bits v)
| field -> error_wrong_field "double" field)
| Float -> (`Fixed_32_bit, function
| Field.Fixed_32_bit v -> return (Int32.float_of_bits v)
| field -> error_wrong_field "float" field)
| Int32 -> (`Varint, read_varint32 ~signed:false ~type_name:"int32")
| Int32_int -> int_of_int32 Int32
| Int64 -> (`Varint, read_varint ~signed:false ~type_name:"int64")
| Int64_int -> int_of_int64 Int64
| UInt32 -> (`Varint, read_varint32 ~signed:false ~type_name:"uint32")
| UInt32_int -> int_of_int32 UInt32
| UInt64 -> (`Varint, read_varint ~signed:false ~type_name:"uint64")
| UInt64_int -> int_of_int64 UInt64
| SInt32 -> (`Varint, read_varint32 ~signed:true ~type_name:"sint32")
| SInt32_int -> int_of_int32 SInt32
| SInt64 -> (`Varint, read_varint ~signed:true ~type_name:"sint64")
| SInt64_int -> int_of_int64 SInt64
| Fixed32 -> (`Fixed_32_bit, function
| Field.Fixed_32_bit v -> return (v)
| field -> error_wrong_field "fixed32" field)
| Fixed32_int -> int_of_int32 Fixed32
| Fixed64 -> (`Fixed_64_bit, function
| Field.Fixed_64_bit v -> return v
| field -> error_wrong_field "fixed64" field)
| Fixed64_int -> int_of_int64 Fixed64
| SFixed32 -> (`Fixed_32_bit, function
| Field.Fixed_32_bit v -> return v
| field -> error_wrong_field "sfixed32" field)
| SFixed32_int -> int_of_int32 SFixed32
| SFixed64 -> (`Fixed_64_bit, function
| Field.Fixed_64_bit v -> return v
| field -> error_wrong_field "sfixed64" field)
| SFixed64_int -> int_of_int64 SFixed64
| Bool -> (`Varint, function
| Field.Varint v -> return (Int64.equal v 0L |> not)
| field -> error_wrong_field "bool" field)
| Enum of_int -> (`Varint, function
| Field.Varint v -> of_int (Int64.to_int v)
| field -> error_wrong_field "enum" field)
| String -> (`Length_delimited, function
| Field.Length_delimited {offset; length; data} -> return (String.sub ~pos:offset ~len:length data)
| field -> error_wrong_field "string" field)
| Bytes -> (`Length_delimited, function
| Field.Length_delimited {offset; length; data} -> return (String.sub ~pos:offset ~len:length data |> Bytes.of_string)
| field -> error_wrong_field "string" field)
| Message from_proto -> (`Length_delimited, function
| Field.Length_delimited {offset; length; data} -> from_proto (Reader.create ~offset ~length data)
| field -> error_wrong_field "message" field)
let default_of_field_type = function
| `Fixed_32_bit -> Field.fixed_32_bit Int32.zero
| `Fixed_64_bit -> Field.fixed_64_bit Int64.zero
| `Length_delimited -> Field.length_delimited ""
| `Varint -> Field.varint 0L
let sentinal: type a. a compound -> (int * unit decoder) list * a sentinal = function
| Basic (index, (Message deser), _) ->
let v = ref None in
let get () = match !v with
| None -> error_required_field_missing
| Some v -> return v
in
let read = function
| Field.Length_delimited {offset; length; data} ->
let reader = Reader.create ~length ~offset data in
deser reader >>| fun message -> v := Some message
| field -> error_wrong_field "message" field
in
([index, read], get)
| Basic (index, spec, Required) ->
let _, read = type_of_spec spec in
let v = ref None in
let get () = match !v with
| Some v -> return v
| None -> error_required_field_missing
in
let read field =
read field >>| fun value -> v := Some value
in
([index, read], get)
| Basic (index, spec, default) ->
let field_type, read = type_of_spec spec in
let default = match default with
| Proto2 (Some default) -> default
| Required
| Proto2 None
| Proto3 -> begin
default_of_field_type field_type
|> read
|> function
| Ok v -> v
| Error _ -> failwith "Cannot decode default field value"
end
in
let v = ref default in
let get () = return !v in
let read field =
read field >>| fun value -> v := value
in
([index, read], get)
| Basic_opt (index, spec) ->
let _, read = type_of_spec spec in
let v = ref None in
let get () = return !v in
let read field =
read field >>| fun value -> v := Some value
in
([index, read], get)
| Repeated (index, spec, _) ->
let read_field = function
| `Length_delimited -> None
| `Varint -> Some Reader.read_varint
| `Fixed_64_bit -> Some Reader.read_fixed64
| `Fixed_32_bit -> Some Reader.read_fixed32
in
let rec read_repeated reader decode read_f = match Reader.has_more reader with
| false -> return ()
| true ->
decode reader >>= fun field ->
read_f field >>= fun () ->
read_repeated reader decode read_f
in
let (field_type, read_type) = type_of_spec spec in
let v = ref [] in
let get () = return (List.rev !v) in
let rec read field = match field, read_field field_type with
| (Field.Length_delimited _ as field), None ->
read_type field >>| fun v' -> v := v' :: !v
| Field.Length_delimited { offset; length; data }, Some read_field ->
read_repeated (Reader.create ~offset ~length data) read_field read
| field, _ -> read_type field >>| fun v' -> v := v' :: !v
in
([index, read], get)
| Oneof oneofs ->
let make_reader: a Result.t ref -> a oneof -> (int * unit decoder) = fun v (Oneof_elem (index, spec, constr)) ->
let _, read = type_of_spec spec in
let read field =
read field >>| fun value -> v := Ok (constr value)
in
(index, read)
in
let v = ref (Error `Oneof_missing) in
let get () = !v in
List.map ~f:(make_reader v) oneofs, get
module Map = struct
include Map.Make (struct type t = int let compare = compare end)
let of_alist_exn l = List.fold_left ~init:empty ~f:(fun acc (k, v) ->
if mem k acc then
invalid_arg "Duplicate keys in list"
else
add k v acc
) l
end
(** Read fields - map based for nlogn lookup *)
let read_fields_map reader_list =
let map = Map.of_alist_exn reader_list in
let rec read reader =
match Reader.has_more reader with
| false -> return ()
| true -> begin
match Reader.read_field reader with
| Ok (index, field) -> begin
match Map.find_opt index map with
| Some f ->
f field >>= fun () ->
read reader
| None ->
read reader
end
| Error err -> Error err
end
in
read
(** Read fields - array based for O(1) lookup *)
let read_fields_array max_index reader_list =
let default _ = Ok () in
let readers = Array.init (max_index + 1) ~f:(fun _ -> default) in
List.iter ~f:(fun (idx, f) -> readers.(idx) <- f) reader_list;
let rec read reader =
match Reader.has_more reader with
| false -> return ()
| true -> begin
match Reader.read_field reader with
| Ok (index, field) when index <= max_index ->
readers.(index) field >>= fun () ->
read reader
| Ok _ -> return ()
| Error err -> Error err
end
in
read
let deserialize: type constr t. (constr, t) compound_list -> constr -> Reader.t -> t Result.t = fun spec constr ->
let max_index =
let rec inner: type a b. int -> (a, b) compound_list -> int = fun acc -> function
| Cons (Oneof oneofs, rest) ->
let rec max_elt: type c. int -> c oneof list -> int = fun acc -> function
| Oneof_elem (idx, _, _) :: rest -> max_elt (max idx acc) rest
| [] -> acc
in
let acc = max_elt acc oneofs in
inner acc rest
| Cons (Basic (idx, _, _), rest) ->
inner (max acc idx) rest
| Cons (Basic_opt (idx, _), rest) ->
inner (max acc idx) rest
| Cons (Repeated (idx, _, _), rest) ->
inner (max acc idx) rest
| Nil -> acc
in
inner 0 spec
in
let read_fields = match max_index < 1024 with
| true -> read_fields_array max_index
| false -> read_fields_map
in
let rec apply: type constr t. constr -> (constr, t) sentinal_list -> t Result.t = fun constr -> function
| SCons (sentinal, rest) ->
sentinal () >>= fun v -> apply (constr v) rest
| SNil -> return constr
in
let rec make_sentinals: type a b. (a, b) compound_list -> (a, b) sentinal_list * (int * unit decoder) list = function
| Cons (spec, rest) ->
let (readers, sentinal) = sentinal spec in
let (sentinals, reader_list) = make_sentinals rest in
SCons (sentinal, sentinals), List.rev_append readers reader_list
| Nil -> SNil, []
in
fun reader ->
let sentinals, reader_list = make_sentinals spec in
read_fields reader_list reader >>= fun () -> apply constr sentinals