https://gitlab.com/nomadic-labs/data-encoding/
Tip revision: b51dcc2018d5ef05049ecd0c1e661cce0b950660 authored by Raphaƫl Proust on 21 November 2019, 00:26:07 UTC
Port commit 7f0319d2 from down-stream repository
Port commit 7f0319d2 from down-stream repository
Tip revision: b51dcc2
encoding.ml
(*****************************************************************************)
(* *)
(* Open Source License *)
(* Copyright (c) 2018 Dynamic Ledger Solutions, Inc. <contact@tezos.com> *)
(* *)
(* Permission is hereby granted, free of charge, to any person obtaining a *)
(* copy of this software and associated documentation files (the "Software"),*)
(* to deal in the Software without restriction, including without limitation *)
(* the rights to use, copy, modify, merge, publish, distribute, sublicense, *)
(* and/or sell copies of the Software, and to permit persons to whom the *)
(* Software is furnished to do so, subject to the following conditions: *)
(* *)
(* The above copyright notice and this permission notice shall be included *)
(* in all copies or substantial portions of the Software. *)
(* *)
(* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR*)
(* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, *)
(* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL *)
(* THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER*)
(* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING *)
(* FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER *)
(* DEALINGS IN THE SOFTWARE. *)
(* *)
(*****************************************************************************)
module Kind = struct
type t = [`Fixed of int | `Dynamic | `Variable]
type length = [`Fixed of int | `Variable]
type enum = [`Dynamic | `Variable]
let combine name : t -> t -> t =
fun k1 k2 ->
match (k1, k2) with
| (`Fixed n1, `Fixed n2) ->
`Fixed (n1 + n2)
| (`Dynamic, `Dynamic) | (`Fixed _, `Dynamic) | (`Dynamic, `Fixed _) ->
`Dynamic
| (`Variable, `Fixed _) | ((`Dynamic | `Fixed _), `Variable) ->
`Variable
| (`Variable, `Dynamic) ->
Printf.ksprintf
invalid_arg
"Cannot merge two %s when the left element is of variable length \
and the right one of dynamic length. You should use the reverse \
order, or wrap the second one with Data_encoding.dynamic_size."
name
| (`Variable, `Variable) ->
Printf.ksprintf
invalid_arg
"Cannot merge two %s with variable length. You should wrap one of \
them with Data_encoding.dynamic_size."
name
let merge : t -> t -> t =
fun k1 k2 ->
match (k1, k2) with
| (`Fixed n1, `Fixed n2) when n1 = n2 ->
`Fixed n1
| (`Fixed _, `Fixed _) ->
`Dynamic
| (`Dynamic, `Dynamic) | (`Fixed _, `Dynamic) | (`Dynamic, `Fixed _) ->
`Dynamic
| (`Variable, (`Dynamic | `Fixed _))
| ((`Dynamic | `Fixed _), `Variable)
| (`Variable, `Variable) ->
`Variable
let merge_list sz : t list -> t = function
| [] ->
assert false (* should be rejected by Data_encoding.union *)
| k :: ks -> (
match List.fold_left merge k ks with
| `Fixed n ->
`Fixed (n + Binary_size.tag_size sz)
| k ->
k )
end
type case_tag = Tag of int | Json_only
type 'a desc =
| Null : unit desc
| Empty : unit desc
| Ignore : unit desc
| Constant : string -> unit desc
| Bool : bool desc
| Int8 : int desc
| Uint8 : int desc
| Int16 : int desc
| Uint16 : int desc
| Int31 : int desc
| Int32 : Int32.t desc
| Int64 : Int64.t desc
| N : Z.t desc
| Z : Z.t desc
| RangedInt : {minimum : int; maximum : int} -> int desc
| RangedFloat : {minimum : float; maximum : float} -> float desc
| Float : float desc
| Bytes : Kind.length -> Bytes.t desc
| String : Kind.length -> string desc
| Padded : 'a t * int -> 'a desc
| String_enum : ('a, string * int) Hashtbl.t * 'a array -> 'a desc
| Array : int option * 'a t -> 'a array desc
| List : int option * 'a t -> 'a list desc
| Obj : 'a field -> 'a desc
| Objs : {kind : Kind.t; left : 'a t; right : 'b t} -> ('a * 'b) desc
| Tup : 'a t -> 'a desc
| Tups : {kind : Kind.t; left : 'a t; right : 'b t} -> ('a * 'b) desc
| Union : {
kind : Kind.t;
tag_size : Binary_size.tag_size;
cases : 'a case list;
}
-> 'a desc
| Mu : {
kind : Kind.enum;
name : string;
title : string option;
description : string option;
fix : 'a t -> 'a t;
}
-> 'a desc
| Conv : {
proj : 'a -> 'b;
inj : 'b -> 'a;
encoding : 'b t;
schema : Json_schema.schema option;
}
-> 'a desc
| Describe : {
id : string;
title : string option;
description : string option;
encoding : 'a t;
}
-> 'a desc
| Splitted : {
encoding : 'a t;
json_encoding : 'a Json_encoding.encoding;
is_obj : bool;
is_tup : bool;
}
-> 'a desc
| Dynamic_size : {
kind : Binary_size.unsigned_integer;
encoding : 'a t;
}
-> 'a desc
| Check_size : {limit : int; encoding : 'a t} -> 'a desc
| Delayed : (unit -> 'a t) -> 'a desc
and _ field =
| Req : {
name : string;
encoding : 'a t;
title : string option;
description : string option;
}
-> 'a field
| Opt : {
name : string;
kind : Kind.enum;
encoding : 'a t;
title : string option;
description : string option;
}
-> 'a option field
| Dft : {
name : string;
encoding : 'a t;
default : 'a;
title : string option;
description : string option;
}
-> 'a field
and 'a case =
| Case : {
title : string;
description : string option;
encoding : 'a t;
proj : 't -> 'a option;
inj : 'a -> 't;
tag : case_tag;
}
-> 't case
and 'a t = {
encoding : 'a desc;
mutable json_encoding : 'a Json_encoding.encoding option;
}
type 'a encoding = 'a t
let rec classify : type a. a t -> Kind.t = fun e -> classify_desc e.encoding
and classify_desc : type a. a desc -> Kind.t =
fun e ->
match e with
(* Fixed *)
| Null ->
`Fixed 0
| Empty ->
`Fixed 0
| Constant _ ->
`Fixed 0
| Bool ->
`Fixed Binary_size.bool
| Int8 ->
`Fixed Binary_size.int8
| Uint8 ->
`Fixed Binary_size.uint8
| Int16 ->
`Fixed Binary_size.int16
| Uint16 ->
`Fixed Binary_size.uint16
| Int31 ->
`Fixed Binary_size.int31
| Int32 ->
`Fixed Binary_size.int32
| Int64 ->
`Fixed Binary_size.int64
| N ->
`Dynamic
| Z ->
`Dynamic
| RangedInt {minimum; maximum} ->
`Fixed Binary_size.(integer_to_size @@ range_to_size ~minimum ~maximum)
| Float ->
`Fixed Binary_size.float
| RangedFloat _ ->
`Fixed Binary_size.float
(* Tagged *)
| Bytes kind ->
(kind :> Kind.t)
| String kind ->
(kind :> Kind.t)
| Padded ({encoding; _}, n) -> (
match classify_desc encoding with
| `Fixed m ->
`Fixed (n + m)
| _ ->
assert false (* by construction (see [Fixed.padded]) *) )
| String_enum (_, cases) ->
`Fixed Binary_size.(integer_to_size @@ enum_size cases)
| Obj (Opt {kind; _}) ->
(kind :> Kind.t)
| Objs {kind; _} ->
kind
| Tups {kind; _} ->
kind
| Union {kind; _} ->
(kind :> Kind.t)
| Mu {kind; _} ->
(kind :> Kind.t)
(* Variable *)
| Ignore ->
`Fixed 0
| Array _ ->
`Variable
| List _ ->
`Variable
(* Recursive *)
| Obj (Req {encoding; _}) ->
classify encoding
| Obj (Dft {encoding; _}) ->
classify encoding
| Tup encoding ->
classify encoding
| Conv {encoding; _} ->
classify encoding
| Describe {encoding; _} ->
classify encoding
| Splitted {encoding; _} ->
classify encoding
| Dynamic_size _ ->
`Dynamic
| Check_size {encoding; _} ->
classify encoding
| Delayed f ->
classify (f ())
let make ?json_encoding encoding = {encoding; json_encoding}
module Fixed = struct
let string n =
if n <= 0 then
invalid_arg
"Cannot create a string encoding of negative or null fixed length." ;
make @@ String (`Fixed n)
let bytes n =
if n <= 0 then
invalid_arg
"Cannot create a byte encoding of negative or null fixed length." ;
make @@ Bytes (`Fixed n)
let add_padding e n =
if n <= 0 then
invalid_arg "Cannot create a padding of negative or null fixed length." ;
match classify e with
| `Fixed _ ->
make @@ Padded (e, n)
| _ ->
invalid_arg "Cannot pad non-fixed size encoding"
end
let rec is_zeroable : type t. t encoding -> bool =
fun e ->
(* Whether an encoding can ever produce zero-byte of encoding. It is dnagerous
to place zero-size elements in a collection (list/array) because
they are indistinguishable from the abscence of elements. *)
match e.encoding with
(* trivially true *)
| Null ->
true (* always true *)
| Empty ->
true (* always true *)
| Ignore ->
true (* always true *)
| Constant _ ->
true (* always true *)
(* trivially false *)
| Bool ->
false
| Int8 ->
false
| Uint8 ->
false
| Int16 ->
false
| Uint16 ->
false
| Int31 ->
false
| Int32 ->
false
| Int64 ->
false
| N ->
false
| Z ->
false
| RangedInt _ ->
false
| RangedFloat _ ->
false
| Float ->
false
| Bytes _ ->
false
| String _ ->
false
| Padded _ ->
false
| String_enum _ ->
false
(* true in some cases, but in practice always protected by Dynamic *)
| Array _ ->
true (* 0-element array *)
| List _ ->
true (* 0-element list *)
(* represented as whatever is inside: truth mostly propagates *)
| Obj (Req {encoding = e; _}) ->
is_zeroable e (* represented as-is *)
| Obj (Opt {kind = `Variable; _}) ->
true (* optional field ommited *)
| Obj (Dft {encoding = e; _}) ->
is_zeroable e (* represented as-is *)
| Obj _ ->
false
| Objs {left; right; _} ->
is_zeroable left && is_zeroable right
| Tup e ->
is_zeroable e
| Tups {left; right; _} ->
is_zeroable left && is_zeroable right
| Union _ ->
false (* includes a tag *)
(* other recursive cases: truth propagates *)
| Mu {kind = `Dynamic; _} ->
false (* size prefix *)
| Mu {kind = `Variable; fix; _} ->
is_zeroable (fix e)
| Conv {encoding; _} ->
is_zeroable encoding
| Describe {encoding; _} ->
is_zeroable encoding
| Splitted {encoding; _} ->
is_zeroable encoding
| Check_size {encoding; _} ->
is_zeroable encoding
(* Unscrutable: true by default *)
| Delayed f ->
is_zeroable (f ())
(* Protected against zeroable *)
| Dynamic_size _ ->
false
(* always some data for size *)
module Variable = struct
let string = make @@ String `Variable
let bytes = make @@ Bytes `Variable
let check_not_variable name e =
match classify e with
| `Variable ->
Printf.ksprintf
invalid_arg
"Cannot insert variable length element in %s. You should wrap the \
contents using Data_encoding.dynamic_size."
name
| `Dynamic | `Fixed _ ->
()
let check_not_zeroable name e =
if is_zeroable e then
Printf.ksprintf
invalid_arg
"Cannot insert potentially zero-sized element in %s."
name
else ()
let array ?max_length e =
check_not_variable "an array" e ;
check_not_zeroable "an array" e ;
let encoding = make @@ Array (max_length, e) in
match (classify e, max_length) with
| (`Fixed n, Some max_length) ->
let limit = n * max_length in
make @@ Check_size {limit; encoding}
| (_, _) ->
encoding
let list ?max_length e =
check_not_variable "a list" e ;
check_not_zeroable "a list" e ;
let encoding = make @@ List (max_length, e) in
match (classify e, max_length) with
| (`Fixed n, Some max_length) ->
let limit = n * max_length in
make @@ Check_size {limit; encoding}
| (_, _) ->
encoding
end
let dynamic_size ?(kind = `Uint30) e =
make @@ Dynamic_size {kind; encoding = e}
let check_size limit encoding = make @@ Check_size {limit; encoding}
let delayed f = make @@ Delayed f
let null = make @@ Null
let empty = make @@ Empty
let unit = make @@ Ignore
let constant s = make @@ Constant s
let bool = make @@ Bool
let int8 = make @@ Int8
let uint8 = make @@ Uint8
let int16 = make @@ Int16
let uint16 = make @@ Uint16
let int31 = make @@ Int31
let int32 = make @@ Int32
let ranged_int minimum maximum =
let minimum = min minimum maximum and maximum = max minimum maximum in
if minimum < -(1 lsl 30) || (1 lsl 30) - 1 < maximum then
invalid_arg "Data_encoding.ranged_int" ;
make @@ RangedInt {minimum; maximum}
let ranged_float minimum maximum =
let minimum = min minimum maximum and maximum = max minimum maximum in
make @@ RangedFloat {minimum; maximum}
let int64 = make @@ Int64
let n = make @@ N
let z = make @@ Z
let float = make @@ Float
let string = dynamic_size Variable.string
let bytes = dynamic_size Variable.bytes
let array ?max_length e = dynamic_size (Variable.array ?max_length e)
let list ?max_length e = dynamic_size (Variable.list ?max_length e)
let string_enum = function
| [] ->
invalid_arg "data_encoding.string_enum: cannot have zero cases"
| [_case] ->
invalid_arg
"data_encoding.string_enum: cannot have a single case, use constant \
instead"
| _ :: _ as cases ->
let arr = Array.of_list (List.map snd cases) in
let tbl = Hashtbl.create (Array.length arr) in
List.iteri (fun ind (str, a) -> Hashtbl.add tbl a (str, ind)) cases ;
make @@ String_enum (tbl, arr)
let conv proj inj ?schema encoding = make @@ Conv {proj; inj; encoding; schema}
let def id ?title ?description encoding =
make @@ Describe {id; title; description; encoding}
let req ?title ?description n t =
Req {name = n; encoding = t; title; description}
let opt ?title ?description n encoding =
let kind =
match classify encoding with
| `Variable ->
`Variable
| `Fixed _ | `Dynamic ->
`Dynamic
in
Opt {name = n; kind; encoding; title; description}
let varopt ?title ?description n encoding =
Opt {name = n; kind = `Variable; encoding; title; description}
let dft ?title ?description n t d =
Dft {name = n; encoding = t; default = d; title; description}
let raw_splitted ~json ~binary =
make
@@ Splitted
{
encoding = binary;
json_encoding = json;
is_obj = false;
is_tup = false;
}
let rec is_obj : type a. a t -> bool =
fun e ->
match e.encoding with
| Obj _ ->
true
| Objs _ (* by construction *) ->
true
| Conv {encoding = e; _} ->
is_obj e
| Dynamic_size {encoding = e; _} ->
is_obj e
| Union {cases; _} ->
List.for_all (fun (Case {encoding = e; _}) -> is_obj e) cases
| Empty ->
true
| Ignore ->
true
| Mu {fix; _} ->
is_obj (fix e)
| Splitted {is_obj; _} ->
is_obj
| Delayed f ->
is_obj (f ())
| Describe {encoding; _} ->
is_obj encoding
| _ ->
false
let rec is_tup : type a. a t -> bool =
fun e ->
match e.encoding with
| Tup _ ->
true
| Tups _ (* by construction *) ->
true
| Conv {encoding = e; _} ->
is_tup e
| Dynamic_size {encoding = e; _} ->
is_tup e
| Union {cases; _} ->
List.for_all (function Case {encoding = e; _} -> is_tup e) cases
| Mu {fix; _} ->
is_tup (fix e)
| Splitted {is_tup; _} ->
is_tup
| Delayed f ->
is_tup (f ())
| Describe {encoding; _} ->
is_tup encoding
| _ ->
false
let raw_merge_objs left right =
let kind = Kind.combine "objects" (classify left) (classify right) in
make @@ Objs {kind; left; right}
let obj1 f1 = make @@ Obj f1
let obj2 f2 f1 = raw_merge_objs (obj1 f2) (obj1 f1)
let obj3 f3 f2 f1 = raw_merge_objs (obj1 f3) (obj2 f2 f1)
let obj4 f4 f3 f2 f1 = raw_merge_objs (obj2 f4 f3) (obj2 f2 f1)
let obj5 f5 f4 f3 f2 f1 = raw_merge_objs (obj1 f5) (obj4 f4 f3 f2 f1)
let obj6 f6 f5 f4 f3 f2 f1 = raw_merge_objs (obj2 f6 f5) (obj4 f4 f3 f2 f1)
let obj7 f7 f6 f5 f4 f3 f2 f1 =
raw_merge_objs (obj3 f7 f6 f5) (obj4 f4 f3 f2 f1)
let obj8 f8 f7 f6 f5 f4 f3 f2 f1 =
raw_merge_objs (obj4 f8 f7 f6 f5) (obj4 f4 f3 f2 f1)
let obj9 f9 f8 f7 f6 f5 f4 f3 f2 f1 =
raw_merge_objs (obj1 f9) (obj8 f8 f7 f6 f5 f4 f3 f2 f1)
let obj10 f10 f9 f8 f7 f6 f5 f4 f3 f2 f1 =
raw_merge_objs (obj2 f10 f9) (obj8 f8 f7 f6 f5 f4 f3 f2 f1)
let merge_objs o1 o2 =
if is_obj o1 && is_obj o2 then raw_merge_objs o1 o2
else invalid_arg "Json_encoding.merge_objs"
let raw_merge_tups left right =
let kind = Kind.combine "tuples" (classify left) (classify right) in
make @@ Tups {kind; left; right}
let tup1 e1 = make @@ Tup e1
let tup2 e2 e1 = raw_merge_tups (tup1 e2) (tup1 e1)
let tup3 e3 e2 e1 = raw_merge_tups (tup1 e3) (tup2 e2 e1)
let tup4 e4 e3 e2 e1 = raw_merge_tups (tup2 e4 e3) (tup2 e2 e1)
let tup5 e5 e4 e3 e2 e1 = raw_merge_tups (tup1 e5) (tup4 e4 e3 e2 e1)
let tup6 e6 e5 e4 e3 e2 e1 = raw_merge_tups (tup2 e6 e5) (tup4 e4 e3 e2 e1)
let tup7 e7 e6 e5 e4 e3 e2 e1 =
raw_merge_tups (tup3 e7 e6 e5) (tup4 e4 e3 e2 e1)
let tup8 e8 e7 e6 e5 e4 e3 e2 e1 =
raw_merge_tups (tup4 e8 e7 e6 e5) (tup4 e4 e3 e2 e1)
let tup9 e9 e8 e7 e6 e5 e4 e3 e2 e1 =
raw_merge_tups (tup1 e9) (tup8 e8 e7 e6 e5 e4 e3 e2 e1)
let tup10 e10 e9 e8 e7 e6 e5 e4 e3 e2 e1 =
raw_merge_tups (tup2 e10 e9) (tup8 e8 e7 e6 e5 e4 e3 e2 e1)
let merge_tups t1 t2 =
if is_tup t1 && is_tup t2 then raw_merge_tups t1 t2
else invalid_arg "Tezos_serial.Encoding.merge_tups"
let conv3 ty =
conv (fun (c, b, a) -> (c, (b, a))) (fun (c, (b, a)) -> (c, b, a)) ty
let obj3 f3 f2 f1 = conv3 (obj3 f3 f2 f1)
let tup3 f3 f2 f1 = conv3 (tup3 f3 f2 f1)
let conv4 ty =
conv
(fun (d, c, b, a) -> ((d, c), (b, a)))
(fun ((d, c), (b, a)) -> (d, c, b, a))
ty
let obj4 f4 f3 f2 f1 = conv4 (obj4 f4 f3 f2 f1)
let tup4 f4 f3 f2 f1 = conv4 (tup4 f4 f3 f2 f1)
let conv5 ty =
conv
(fun (e, d, c, b, a) -> (e, ((d, c), (b, a))))
(fun (e, ((d, c), (b, a))) -> (e, d, c, b, a))
ty
let obj5 f5 f4 f3 f2 f1 = conv5 (obj5 f5 f4 f3 f2 f1)
let tup5 f5 f4 f3 f2 f1 = conv5 (tup5 f5 f4 f3 f2 f1)
let conv6 ty =
conv
(fun (f, e, d, c, b, a) -> ((f, e), ((d, c), (b, a))))
(fun ((f, e), ((d, c), (b, a))) -> (f, e, d, c, b, a))
ty
let obj6 f6 f5 f4 f3 f2 f1 = conv6 (obj6 f6 f5 f4 f3 f2 f1)
let tup6 f6 f5 f4 f3 f2 f1 = conv6 (tup6 f6 f5 f4 f3 f2 f1)
let conv7 ty =
conv
(fun (g, f, e, d, c, b, a) -> ((g, (f, e)), ((d, c), (b, a))))
(fun ((g, (f, e)), ((d, c), (b, a))) -> (g, f, e, d, c, b, a))
ty
let obj7 f7 f6 f5 f4 f3 f2 f1 = conv7 (obj7 f7 f6 f5 f4 f3 f2 f1)
let tup7 f7 f6 f5 f4 f3 f2 f1 = conv7 (tup7 f7 f6 f5 f4 f3 f2 f1)
let conv8 ty =
conv
(fun (h, g, f, e, d, c, b, a) -> (((h, g), (f, e)), ((d, c), (b, a))))
(fun (((h, g), (f, e)), ((d, c), (b, a))) -> (h, g, f, e, d, c, b, a))
ty
let obj8 f8 f7 f6 f5 f4 f3 f2 f1 = conv8 (obj8 f8 f7 f6 f5 f4 f3 f2 f1)
let tup8 f8 f7 f6 f5 f4 f3 f2 f1 = conv8 (tup8 f8 f7 f6 f5 f4 f3 f2 f1)
let conv9 ty =
conv
(fun (i, h, g, f, e, d, c, b, a) ->
(i, (((h, g), (f, e)), ((d, c), (b, a)))))
(fun (i, (((h, g), (f, e)), ((d, c), (b, a)))) ->
(i, h, g, f, e, d, c, b, a))
ty
let obj9 f9 f8 f7 f6 f5 f4 f3 f2 f1 = conv9 (obj9 f9 f8 f7 f6 f5 f4 f3 f2 f1)
let tup9 f9 f8 f7 f6 f5 f4 f3 f2 f1 = conv9 (tup9 f9 f8 f7 f6 f5 f4 f3 f2 f1)
let conv10 ty =
conv
(fun (j, i, h, g, f, e, d, c, b, a) ->
((j, i), (((h, g), (f, e)), ((d, c), (b, a)))))
(fun ((j, i), (((h, g), (f, e)), ((d, c), (b, a)))) ->
(j, i, h, g, f, e, d, c, b, a))
ty
let obj10 f10 f9 f8 f7 f6 f5 f4 f3 f2 f1 =
conv10 (obj10 f10 f9 f8 f7 f6 f5 f4 f3 f2 f1)
let tup10 f10 f9 f8 f7 f6 f5 f4 f3 f2 f1 =
conv10 (tup10 f10 f9 f8 f7 f6 f5 f4 f3 f2 f1)
let check_cases tag_size cases =
if cases = [] then invalid_arg "Data_encoding.union: empty list of cases." ;
let max_tag = match tag_size with `Uint8 -> 256 | `Uint16 -> 256 * 256 in
ignore
@@ List.fold_left
(fun others (Case {tag; _}) ->
match tag with
| Json_only ->
others
| Tag tag ->
if List.mem tag others then
Format.kasprintf
invalid_arg
"The tag %d appears twice in an union."
tag ;
if tag < 0 || max_tag <= tag then
Format.kasprintf invalid_arg "The tag %d is invalid." tag ;
tag :: others)
[]
cases
let union ?(tag_size = `Uint8) cases =
check_cases tag_size cases ;
let kinds = List.map (fun (Case {encoding; _}) -> classify encoding) cases in
let kind = Kind.merge_list tag_size kinds in
make @@ Union {kind; tag_size; cases}
let case ~title ?description tag encoding proj inj =
Case {title; description; encoding; proj; inj; tag}
let rec is_nullable : type t. t encoding -> bool =
fun e ->
match e.encoding with
| Null ->
true
| Empty ->
false
| Ignore ->
true
| Constant _ ->
false
| Bool ->
false
| Int8 ->
false
| Uint8 ->
false
| Int16 ->
false
| Uint16 ->
false
| Int31 ->
false
| Int32 ->
false
| Int64 ->
false
| N ->
false
| Z ->
false
| RangedInt _ ->
false
| RangedFloat _ ->
false
| Float ->
false
| Bytes _ ->
false
| String _ ->
false
| Padded (e, _) ->
is_nullable e
| String_enum _ ->
false
| Array _ ->
false
| List _ ->
false
| Obj _ ->
false
| Objs _ ->
false
| Tup _ ->
false
| Tups _ ->
false
| Union {cases; _} ->
List.exists (fun (Case {encoding = e; _}) -> is_nullable e) cases
| Mu {fix; _} ->
is_nullable (fix e)
| Conv {encoding = e; _} ->
is_nullable e
| Describe {encoding = e; _} ->
is_nullable e
| Splitted {json_encoding; _} ->
Json_encoding.is_nullable json_encoding
| Dynamic_size {encoding = e; _} ->
is_nullable e
| Check_size {encoding = e; _} ->
is_nullable e
| Delayed _ ->
true
let option ty =
if is_nullable ty then
invalid_arg "Data_encoding.option: cannot nest nullable encodings" ;
(* TODO add a special construct `Option` in the GADT *)
union
~tag_size:`Uint8
[
case (Tag 1) ty ~title:"Some" (fun x -> x) (fun x -> Some x);
case
(Tag 0)
null
~title:"None"
(function None -> Some () | Some _ -> None)
(fun () -> None);
]
let mu name ?title ?description fix =
let kind =
try
let precursor =
make @@ Mu {kind = `Dynamic; name; title; description; fix}
in
match classify @@ fix precursor with
| `Fixed _ | `Dynamic ->
`Dynamic
| `Variable ->
raise Exit
with Exit | _ (* TODO variability error *) ->
let precursor =
make @@ Mu {kind = `Variable; name; title; description; fix}
in
ignore (classify @@ fix precursor) ;
`Variable
in
make @@ Mu {kind; name; title; description; fix}
let result ok_enc error_enc =
union
~tag_size:`Uint8
[
case
(Tag 1)
ok_enc
~title:"Ok"
(function Ok x -> Some x | Error _ -> None)
(fun x -> Ok x);
case
(Tag 0)
error_enc
~title:"Result"
(function Ok _ -> None | Error x -> Some x)
(fun x -> Error x);
]