(***********************************************************************)
(*                                                                     *)
(*                               TAToo                                 *)
(*                                                                     *)
(*                     Kim Nguyen, LRI UMR8623                         *)
(*                   Université Paris-Sud & CNRS                       *)
(*                                                                     *)
(*  Copyright 2010-2012 Université Paris-Sud and Centre National de la *)
(*  Recherche Scientifique. All rights reserved.  This file is         *)
(*  distributed under the terms of the GNU Lesser General Public       *)
(*  License, with the special exception on linking described in file   *)
(*  ../LICENSE.                                                        *)
(*                                                                     *)
(***********************************************************************)

include Hcons_sig

module type TableBuilder =
  functor
    (H : Common_sig.HashedType) ->
      Common_sig.HashSet with type data = H.t

module Builder (TB : TableBuilder) (H : Common_sig.HashedType) =
struct
  type data = H.t
  type t = { id   : Uid.t;
             hash : int;
             node : data }
  let uid_make = ref (Uid.make_maker())
  let node t = t.node
  let uid t = t.id
  let hash t = t.hash
  let equal t1 t2 = t1 == t2
  module HN =
  struct
    type _t = t
    type t = _t
    let hash = hash
    let equal x y = x == y || H.equal x.node y.node
  end
  module T = TB(HN)

  let pool = T.create 101
  let init () =
    T.clear pool;
    uid_make := Uid.make_maker ()
  let dummy x = { id = Uid.dummy; hash = H.hash x; node = x }

  let make x =
    let cell = dummy x in
    try
      T.find pool cell
    with
    | Not_found ->
      let cell = { cell with id = !uid_make(); } in
      T.add pool cell;
      cell
end

module Make = Builder (Misc.HashSet)
module Weak = Builder (Weak.Make)

module PosInt =
struct
  type data = int
  type t = int
  let make v =
    if v < 0 then raise (Invalid_argument "Hcons.PosInt.make")
    else v

  let node v = v

  let hash v = v

  let uid v = Uid.of_int v
  let dummy _ = ~-1
  let equal x y = x == y

  let init () = ()
end