213 lines
8.0 KiB
OCaml
213 lines
8.0 KiB
OCaml
(***********************************************************************)
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(* *)
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(* OCaml *)
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(* *)
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(* Xavier Leroy, projet Cristal, INRIA Rocquencourt *)
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(* *)
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(* Copyright 1996 Institut National de Recherche en Informatique et *)
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(* en Automatique. All rights reserved. This file is distributed *)
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(* under the terms of the GNU Library General Public License, with *)
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(* the special exception on linking described in file ../LICENSE. *)
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(* *)
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(***********************************************************************)
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(** 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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For instance:
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{[
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module IntPairs =
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struct
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type t = int * int
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let compare (x0,y0) (x1,y1) =
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match Pervasives.compare x0 x1 with
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0 -> Pervasives.compare y0 y1
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| c -> c
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end
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module PairsMap = Map.Make(IntPairs)
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let m = PairsMap.(empty |> add (0,1) "hello" |> add (1,0) "world")
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]}
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This creates a new module [PairsMap], with a new type ['a PairsMap.t]
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of maps from [int * int] to ['a]. In this example, [m] contains [string]
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values so its type is [string PairsMap.t].
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*)
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module type OrderedType =
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sig
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type t
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(** The type of the map keys. *)
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val compare : t -> t -> int
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(** 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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Example: a suitable ordering function is the generic structural
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comparison function {!Pervasives.compare}. *)
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end
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(** Input signature of the functor {!Map.Make}. *)
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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 is_empty: 'a t -> bool
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(** Test whether a map is empty or not. *)
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val mem: key -> 'a t -> bool
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(** [mem x m] returns [true] if [m] contains a binding for [x],
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and [false] otherwise. *)
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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 singleton: key -> 'a -> 'a t
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(** [singleton x y] returns the one-element map that contains a binding [y]
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for [x].
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@since 3.12.0
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*)
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val remove: key -> 'a t -> 'a t
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(** [remove x m] returns a map containing the same bindings as
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[m], except for [x] which is unbound in the returned map. *)
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val merge:
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(key -> 'a option -> 'b option -> 'c option) -> 'a t -> 'b t -> 'c t
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(** [merge f m1 m2] computes a map whose keys is a subset of keys of [m1]
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and of [m2]. The presence of each such binding, and the corresponding
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value, is determined with the function [f].
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@since 3.12.0
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*)
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val compare: ('a -> 'a -> int) -> 'a t -> 'a t -> int
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(** Total ordering between maps. The first argument is a total ordering
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used to compare data associated with equal keys in the two maps. *)
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val equal: ('a -> 'a -> bool) -> 'a t -> 'a t -> bool
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(** [equal cmp m1 m2] tests whether the maps [m1] and [m2] are
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equal, that is, contain equal keys and associate them with
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equal data. [cmp] is the equality predicate used to compare
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the data associated with the keys. *)
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val iter: (key -> 'a -> unit) -> 'a t -> unit
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(** [iter f m] applies [f] to all bindings in map [m].
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[f] receives the key as first argument, and the associated value
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as second argument. The bindings are passed to [f] in increasing
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order with respect to the ordering over the type of the keys. *)
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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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(in increasing order), and [d1 ... dN] are the associated data. *)
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val for_all: (key -> 'a -> bool) -> 'a t -> bool
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(** [for_all p m] checks if all the bindings of the map
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satisfy the predicate [p].
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@since 3.12.0
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*)
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val exists: (key -> 'a -> bool) -> 'a t -> bool
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(** [exists p m] checks if at least one binding of the map
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satisfy the predicate [p].
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@since 3.12.0
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*)
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val filter: (key -> 'a -> bool) -> 'a t -> 'a t
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(** [filter p m] returns the map with all the bindings in [m]
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that satisfy predicate [p].
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@since 3.12.0
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*)
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val partition: (key -> 'a -> bool) -> 'a t -> 'a t * 'a t
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(** [partition p m] returns a pair of maps [(m1, m2)], where
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[m1] contains all the bindings of [s] that satisfy the
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predicate [p], and [m2] is the map with all the bindings of
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[s] that do not satisfy [p].
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@since 3.12.0
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*)
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val cardinal: 'a t -> int
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(** Return the number of bindings of a map.
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@since 3.12.0
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*)
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val bindings: 'a t -> (key * 'a) list
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(** Return the list of all bindings of the given map.
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The returned list is sorted in increasing order with respect
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to the ordering [Ord.compare], where [Ord] is the argument
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given to {!Map.Make}.
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@since 3.12.0
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*)
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val min_binding: 'a t -> (key * 'a)
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(** Return the smallest binding of the given map
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(with respect to the [Ord.compare] ordering), or raise
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[Not_found] if the map is empty.
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@since 3.12.0
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*)
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val max_binding: 'a t -> (key * 'a)
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(** Same as {!Map.S.min_binding}, but returns the largest binding
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of the given map.
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@since 3.12.0
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*)
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val choose: 'a t -> (key * 'a)
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(** Return one binding of the given map, or raise [Not_found] if
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the map is empty. Which binding is chosen is unspecified,
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but equal bindings will be chosen for equal maps.
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@since 3.12.0
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*)
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val split: key -> 'a t -> 'a t * 'a option * 'a t
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(** [split x m] returns a triple [(l, data, r)], where
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[l] is the map with all the bindings of [m] whose key
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is strictly less than [x];
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[r] is the map with all the bindings of [m] whose key
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is strictly greater than [x];
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[data] is [None] if [m] contains no binding for [x],
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or [Some v] if [m] binds [v] to [x].
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@since 3.12.0
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*)
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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 map: ('a -> 'b) -> 'a t -> 'b t
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(** [map f m] returns a map with same domain as [m], where the
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associated value [a] of all bindings of [m] has been
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replaced by the result of the application of [f] to [a].
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The bindings are passed to [f] in increasing order
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with respect to the ordering over the type of the keys. *)
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val mapi: (key -> 'a -> 'b) -> 'a t -> 'b t
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(** Same as {!Map.S.map}, but the function receives as arguments both the
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key and the associated value for each binding of the map. *)
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end
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(** Output signature of the functor {!Map.Make}. *)
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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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