Source file state.ml

(*****************************************************************************)
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(* Copyright (c) 2018 Dynamic Ledger Solutions, Inc. <contact@tezos.com>     *)
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type t = {a : int32; b : int32}

let invariant {a; b} = Compare.Int32.(a >= 0l && b >= 0l)

let create a b =
  let st = {a; b} in
  if invariant st then Some st else None

let encoding =
  Data_encoding.conv
    (fun {a; b} -> (a, b))
    (fun (a, b) -> {a; b})
    Data_encoding.(obj2 (req "demo_a" int32) (req "demo_b" int32))

let encoding_length =
  match Data_encoding.Binary.fixed_length encoding with
  | None ->
      assert false
  | Some length ->
      length

let state_key = ["state"]

let get_state context =
  let open Lwt_syntax in
  let+ state = Context.find context state_key in
  match state with
  | None ->
      assert false
  | Some encoded_state -> (
    match Data_encoding.Binary.of_bytes_opt encoding encoded_state with
    | Some x ->
        x
    | None ->
        assert false )

let update_state context state =
  let encoded_state = Data_encoding.Binary.to_bytes_exn encoding state in
  Context.add context state_key encoded_state