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(***********************************************************************)
(* *)
(* Objective Caml *)
(* *)
(* Xavier Leroy, projet Cristal, INRIA Rocquencourt *)
(* *)
(* Copyright 1996 Institut National de Recherche en Informatique et *)
(* en Automatique. All rights reserved. This file is distributed *)
(* under the terms of the GNU Library General Public License. *)
(* *)
(***********************************************************************)
(* $Id$ *)
(* Module [Map]: association tables over ordered types *)
(* This module implements applicative association tables, also known as
finite maps or dictionaries, given a total ordering function
over the keys.
All operations over maps are purely applicative (no side-effects).
The implementation uses balanced binary trees, and therefore searching
and insertion take time logarithmic in the size of the map. *)
module type OrderedType =
sig
type t
val compare: t -> t -> int
end
(* The input signature of the functor [Map.Make].
[t] is the type of the map keys.
[compare] is a total ordering function over the keys.
This is a two-argument function [f] such that
[f e1 e2] is zero if the keys [e1] and [e2] are equal,
[f e1 e2] is strictly negative if [e1] is smaller than [e2],
and [f e1 e2] is strictly positive if [e1] is greater than [e2].
Example: a suitable ordering function is
the generic structural comparison function [compare]. *)
module type S =
sig
type key
(* The type of the map keys. *)
type (+'a) t
(* The type of maps from type [key] to type ['a]. *)
val empty: 'a t
(* The empty map. *)
val add: key:key -> data:'a -> 'a t -> 'a t
(* [add x y m] returns a map containing the same bindings as
[m], plus a binding of [x] to [y]. If [x] was already bound
in [m], its previous binding disappears. *)
val find: key -> 'a t -> 'a
(* [find x m] returns the current binding of [x] in [m],
or raises [Not_found] if no such binding exists. *)
val remove: key -> 'a t -> 'a t
(* [remove x m] returns a map containing the same bindings as
[m], except for [x] which is unbound in the returned map. *)
val mem: key -> 'a t -> bool
(* [mem x m] returns [true] if [m] contains a binding for [x],
and [false] otherwise. *)
val iter: f:(key:key -> data:'a -> unit) -> 'a t -> unit
(* [iter f m] applies [f] to all bindings in map [m].
[f] receives the key as first argument, and the associated value
as second argument. The order in which the bindings are passed to
[f] is unspecified. Only current bindings are presented to [f]:
bindings hidden by more recent bindings are not passed to [f]. *)
val map: f:('a -> 'b) -> 'a t -> 'b t
(* [map f m] returns a map with same domain as [m], where the
associated value [a] of all bindings of [m] has been
replaced by the result of the application of [f] to [a].
The order in which the associated values are passed to [f]
is unspecified. *)
val mapi: f:(key -> 'a -> 'b) -> 'a t -> 'b t
(* Same as [map], but the function receives as arguments both the
key and the associated value for each binding of the map. *)
val fold: f:(key:key -> data:'a -> 'b -> 'b) -> 'a t -> init:'b -> 'b
(* [fold f m a] computes [(f kN dN ... (f k1 d1 a)...)],
where [k1 ... kN] are the keys of all bindings in [m],
and [d1 ... dN] are the associated data.
The order in which the bindings are presented to [f] is
unspecified. *)
end
module Make(Ord: OrderedType): (S with type key = Ord.t)
(* Functor building an implementation of the map structure
given a totally ordered type. *)
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