(*
copyright (c) 2013-2014, simon cruanes
all rights reserved.

redistribution and use in source and binary forms, with or without
modification, are permitted provided that the following conditions are met:

redistributions of source code must retain the above copyright notice, this
list of conditions and the following disclaimer.  redistributions in binary
form must reproduce the above copyright notice, this list of conditions and the
following disclaimer in the documentation and/or other materials provided with
the distribution.

THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND
ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE
FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*)

(** {1 Hash Table with Heterogeneous Keys}

From https://github.com/mjambon/mixtbl , thanks to him.
Example:

{[
let inj_int = Mixtbl.access () ;;

let tbl = Mixtbl.create 10 ;;

OUnit.assert_equal None (Mixtbl.get ~inj:inj_int tbl "a");;

Mixtbl.set inj_int tbl "a" 1;;

OUnit.assert_equal (Some 1) (Mixtbl.get ~inj:inj_int tbl "a");;

let inj_string = Mixtbl.access () ;;

Mixtbl.set inj_string tbl "b" "Hello";

OUnit.assert_equal (Some "Hello") (Mixtbl.get inj_string tbl "b");;
OUnit.assert_equal None (Mixtbl.get inj_string tbl "a");;
OUnit.assert_equal (Some 1) (Mixtbl.get inj_int tbl "a");;
Mixtbl.set inj_string tbl "a" "Bye";;

OUnit.assert_equal None (Mixtbl.get inj_int tbl "a");;
OUnit.assert_equal (Some "Bye") (Mixtbl.get inj_string tbl "a");;
]}

@since 0.6 *)

type 'a t
(** A hash table containing values of different types.
    The type parameter ['a] represents the type of the keys. *)

type 'b injection
(** An accessor for values of type 'b in any table. Values put
    in the table using an key can only be retrieved using this
    very same key. *)

val create : int -> 'a t
(** [create n] creates a hash table of initial size [n]. *)

val create_inj : unit -> 'b injection
(** Return a value that works for a given type of values.  This function is
    normally called once for each type of value.  Several keys may be
    created for the same type, but a value set with a given setter can only be
    retrieved with the matching getter.  The same key can be reused
    across multiple tables (although not in a thread-safe way). *)

val get : inj:'b injection -> 'a t  -> 'a -> 'b option
(** Get the value corresponding to this key, if it exists and
    belongs to the same key *)

val set : inj:'b injection -> 'a t -> 'a -> 'b -> unit
(** Bind the key to the value, using [inj] *)

val find : inj:'b injection -> 'a t -> 'a -> 'b
(** Find the value for the given key, which must be of the right type.
    raises Not_found if either the key is not found, or if its value
    doesn't belong to the right type *)

val length : 'a t -> int
(** Number of bindings *)

val clear : 'a t -> unit
(** Clear content of the hashtable *)

val remove : 'a t -> 'a -> unit
(** Remove the binding for this key *)

val copy : 'a t -> 'a t
(** Copy of the table *)

val mem : inj:_ injection-> 'a t -> 'a -> bool
(** Is the given key in the table, with the right type? *)

val iter_keys : 'a t -> ('a -> unit) -> unit
(** Iterate on the keys of this table *)

val fold_keys : 'a t -> 'b -> ('b -> 'a -> 'b) -> 'b
(** Fold over the keys *)

(** {2 Iterators} *)

type 'a sequence = ('a -> unit) -> unit

val keys_seq : 'a t -> 'a sequence
(** All the keys *)

val bindings_of : inj:'b injection -> 'a t -> ('a * 'b) sequence
(** All the bindings that come from the corresponding injection *)

type value =
  | Value : ('b injection -> 'b option) -> value

val bindings : 'a t -> ('a *  value) sequence
(** Iterate on all bindings *)