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type 'a t = Json.t -> 'a
let make f = f
exception DecoderError
let decode f json = f json
let unit = function
| `Null -> ()
| _ -> raise DecoderError
let bool = function
| `Bool b -> b
| _ -> raise DecoderError
let int = function
| `Int i -> i
| _ -> raise DecoderError
let float = function
| `Float f -> f
| _ -> raise DecoderError
let char = function
| `String s when String.length s = 1 -> s.[0]
| _ -> raise DecoderError
let string = function
| `String s -> s
| _ -> raise DecoderError
let list f = function
| `List l -> List.map f l
| _ -> raise DecoderError
let array f = function
| `List l -> Array.map f (Array.of_list l)
| _ -> raise DecoderError
let obj_list f = function
| `Assoc l -> List.map (fun (k, v) -> k, f v) l
| _ -> raise DecoderError
let obj_array f = function
| `Assoc l -> Array.map (fun (k, v) -> k, f v) (Array.of_list l)
| _ -> raise DecoderError
let optional f j =
match f j with
| exception DecoderError -> None
| v -> Some v
let map f c j = f (c j)
let field s f = function
| `Assoc v -> f (List.assoc s v)
| _ -> raise DecoderError
let fieldOptional s f = function
| `Assoc v ->
begin match List.assoc s v with
| exception Not_found -> None
| v -> Some (f v)
end
| _ -> raise DecoderError
let fieldDefault s default f =
fieldOptional s f
|> map (function
| None -> default
| Some s -> s)
let tuple1 a = function
| `Tuple [w]
| `List [w] -> a w
| _ -> raise DecoderError
let tuple2 a b = function
| `Tuple [w ; x]
| `List [w ; x] -> (a w, b x)
| _ -> raise DecoderError
let tuple3 a b c = function
| `Tuple [w; x; y]
| `List [w; x; y] -> (a w, b x, c y)
| _ -> raise DecoderError
let tuple4 a b c d = function
| `Tuple [w; x; y; z]
| `List [w; x; y; z] -> (a w, b x, c y, d z)
| _ -> raise DecoderError
let enum l = function
| `Variant (s, None)
| `String s ->
begin match List.assoc s l with
| exception Not_found -> raise DecoderError
| `Single a -> a
| `Decode _ -> raise DecoderError
end
| `Variant (s, Some args)
| `List [`String s; args] ->
begin match List.assoc s l with
| exception Not_found -> raise DecoderError
| `Single _ -> raise DecoderError
| `Decode d -> decode d args
end
| _ -> raise DecoderError
let option_as_constr f =
enum
[ "None", `Single None
; "Some", `Decode (map (fun x -> Some x) f)
]
let nullable f = function
| `Null -> None
| x -> Some (f x)
let adapter (normalize: Json.t -> Json.t) (reader: 'a t) json =
reader (normalize json)