Source file `tree.ml`

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(*****************************************************************************)
(*                                                                           *)
(* Open Source License                                                       *)
(* Copyright (c) 2022 TriliTech <contact@trili.tech>                         *)
(* Copyright (c) 2022 Nomadic Labs <contact@nomadic-labs.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.                                                 *)
(*                                                                           *)
(*****************************************************************************)

type tree_instance = ..

type key = string list

type value = bytes

exception Incorrect_tree_type

module type S = sig
  type tree

  val select : tree_instance -> tree

  val wrap : tree -> tree_instance

  val remove : tree -> key -> tree Lwt.t

  val add : tree -> key -> value -> tree Lwt.t

  val add_tree : tree -> key -> tree -> tree Lwt.t

  val find : tree -> key -> value option Lwt.t

  val find_tree : tree -> key -> tree option Lwt.t

  val hash : tree -> Context_hash.t

  val length : tree -> key -> int Lwt.t

  val list :
    tree -> ?offset:int -> ?length:int -> key -> (string * tree) list Lwt.t
end

type 'tree backend = (module S with type tree = 'tree)

let select : type tree. tree backend -> tree_instance -> tree =
 fun (module T) tree -> T.select tree

let wrap : type tree. tree backend -> tree -> tree_instance =
 fun (module T) tree -> T.wrap tree

let remove : type tree. tree backend -> tree -> key -> tree Lwt.t =
 fun (module T) tree key -> T.remove tree key

let add : type tree. tree backend -> tree -> key -> value -> tree Lwt.t =
 fun (module T) tree key value -> T.add tree key value

let add_tree : type tree. tree backend -> tree -> key -> tree -> tree Lwt.t =
 fun (module T) tree key subtree -> T.add_tree tree key subtree

let find : type tree. tree backend -> tree -> key -> value option Lwt.t =
 fun (module T) tree key -> T.find tree key

let find_tree : type tree. tree backend -> tree -> key -> tree option Lwt.t =
 fun (module T) tree key -> T.find_tree tree key

let hash : type tree. tree backend -> tree -> Context_hash.t =
 fun (module T) tree -> T.hash tree

let length : type tree. tree backend -> tree -> key -> int Lwt.t =
 fun (module T) tree key -> T.length tree key

let list :
    type tree.
    tree backend ->
    tree ->
    ?offset:int ->
    ?length:int ->
    key ->
    (string * tree) list Lwt.t =
 fun (module T) tree ?offset ?length key -> T.list tree ?offset ?length key

type wrapped_tree = Wrapped_tree : 'tree * 'tree backend -> wrapped_tree

type tree_instance += Wrapped of wrapped_tree

module Wrapped : S with type tree = wrapped_tree = struct
  type tree = wrapped_tree

  let remove (Wrapped_tree (t, b)) key =
    let open Lwt.Syntax in
    let+ t = remove b t key in
    Wrapped_tree (t, b)

  let add (Wrapped_tree (t, b)) key v =
    let open Lwt.Syntax in
    let+ t = add b t key v in
    Wrapped_tree (t, b)

  let add_tree (Wrapped_tree (t, b)) key (Wrapped_tree (t', b')) =
    let open Lwt.Syntax in
    let t' = select b (wrap b' t') in
    let+ t = add_tree b t key t' in
    Wrapped_tree (t, b)

  let find_tree (Wrapped_tree (t, b)) key =
    let open Lwt.Syntax in
    let+ t' = find_tree b t key in
    match t' with Some t' -> Some (Wrapped_tree (t', b)) | None -> None

  let length (Wrapped_tree (t, b)) key = length b t key

  let list (Wrapped_tree (t, b)) ?offset ?length key =
    let open Lwt.Syntax in
    let+ list = list b t ?offset ?length key in
    List.rev
    @@ List.rev_map (fun (step, tree) -> (step, Wrapped_tree (tree, b))) list

  let find (Wrapped_tree (t, b)) key = find b t key

  let hash (Wrapped_tree (t, b)) = hash b t

  let select = function
    | Wrapped (Wrapped_tree (_, _) as wt) -> wt
    | _ -> raise Incorrect_tree_type

  let wrap t = Wrapped t
end