72 lines
3.4 KiB
OCaml
72 lines
3.4 KiB
OCaml
(***********************************************************************)
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(* *)
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(* Caml Special Light *)
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(* *)
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(* Xavier Leroy, projet Cristal, INRIA Rocquencourt *)
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(* *)
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(* Copyright 1995 Institut National de Recherche en Informatique et *)
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(* Automatique. Distributed only by permission. *)
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(* *)
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(***********************************************************************)
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(* $Id$ *)
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(* Module [Map]: association tables over ordered types *)
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(* This module implements applicative association tables, also known as
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finite maps or dictionaries, given a total ordering function
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over the keys.
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All operations over maps are purely applicative (no side-effects).
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The implementation uses balanced binary trees, and therefore searching
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and insertion take time logarithmic in the size of the map. *)
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module type OrderedType =
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sig
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type t
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val compare: t -> t -> int
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end
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(* The input signature of the functor [Map.Make].
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[t] is the type of the map keys.
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[compare] is a total ordering function over the keys.
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This is a two-argument function [f] such that
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[f e1 e2] is zero if the keys [e1] and [e2] are equal,
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[f e1 e2] is strictly negative if [e1] is smaller than [e2],
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and [f e1 e2] is strictly positive if [e1] is greater than [e2].
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Examples: a suitable ordering function for type [int]
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is [(-)]. You can also use the generic structural comparison
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function [compare]. *)
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module type S =
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sig
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type key
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(* The type of the map keys. *)
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type 'a t
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(* The type of maps from type [key] to type ['a]. *)
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val empty: 'a t
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(* The empty map. *)
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val add: key -> 'a -> 'a t -> 'a t
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(* [add x y m] returns a map containing the same bindings as
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[m], plus a binding of [x] to [y]. If [x] was already bound
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in [m], its previous binding disappears. *)
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val find: key -> 'a t -> 'a
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(* [find x m] returns the current binding of [x] in [m],
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or raises [Not_found] if no such binding exists. *)
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val iter: (key -> 'a -> 'b) -> 'a t -> unit
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(* [iter f m] applies [f] to all bindings in map [m],
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discarding the results.
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[f] receives the key as first argument, and the associated value
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as second argument. The order in which the bindings are passed to
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[f] is unspecified. Only current bindings are presented to [f]:
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bindings hidden by more recent bindings are not passed to [f]. *)
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val fold: (key -> 'a -> 'b -> 'b) -> 'a t -> 'b -> 'b
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(* [fold f m a] computes [(f kN dN ... (f k1 d1 a)...)],
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where [k1 ... kN] are the keys of all bindings in [m],
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and [d1 ... dN] are the associated data.
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The order in which the bindings are presented to [f] is
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not specified. *)
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end
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module Make(Ord: OrderedType): (S with type key = Ord.t)
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(* Functor building an implementation of the map structure
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given a totally ordered type. *)
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