(**************************************************************************)
(* *)
(* Copyright (C) Jean-Christophe Filliatre *)
(* *)
(* This software is free software; you can redistribute it and/or *)
(* modify it under the terms of the GNU Library General Public *)
(* License version 2.1, with the special exception on linking *)
(* described in file LICENSE. *)
(* *)
(* This software is distributed in the hope that it will be useful, *)
(* but WITHOUT ANY WARRANTY; without even the implied warranty of *)
(* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. *)
(* *)
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(*s Hash tables for hash consing.
Hash consed values are of the
following type [hash_consed]. The field [tag] contains a unique
integer (for values hash consed with the same table). The field
[hkey] contains the hash key of the value (without modulo) for
possible use in other hash tables (and internally when hash
consing tables are resized). The field [node] contains the value
itself.
Hash consing tables are using weak pointers, so that values that are no
more referenced from anywhere else can be erased by the GC. *)
type 'a hash_consed = private {
hkey : int;
tag : int;
node : 'a }
(*s Generic part, using ocaml generic equality and hash function. *)
type 'a t
val create : int -> 'a t
(** [create n] creates an empty table of initial size [n]. The table
will grow as needed. *)
val clear : 'a t -> unit
(** Removes all elements from the table. *)
val hashcons : 'a t -> 'a -> 'a hash_consed
(** [hashcons t n] hash-cons the value [n] using table [t] i.e. returns
any existing value in [t] equal to [n], if any; otherwise, allocates
a new one hash-consed value of node [n] and returns it.
As a consequence the returned value is physically equal to
any equal value already hash-consed using table [t]. *)
val iter : ('a hash_consed -> unit) -> 'a t -> unit
(** [iter f t] iterates [f] over all elements of [t]. *)
val stats : 'a t -> int * int * int * int * int * int
(** Return statistics on the table. The numbers are, in order:
table length, number of entries, sum of bucket lengths,
smallest bucket length, median bucket length, biggest bucket length. *)
(*s Functorial interface. *)
module type HashedType =
sig
type t
val equal : t -> t -> bool
val hash : t -> int
end
module type S =
sig
type key
type t
val create : int -> t
val clear : t -> unit
val hashcons : t -> key -> key hash_consed
val iter : (key hash_consed -> unit) -> t -> unit
val stats : t -> int * int * int * int * int * int
end
module Make(H : HashedType) : (S with type key = H.t)