109 lines
3.8 KiB
OCaml
109 lines
3.8 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. *)
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(* *)
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(* All rights reserved. This file is distributed under the terms of *)
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(* the GNU Lesser General Public License version 2.1, with the *)
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(* special exception on linking described in the file LICENSE. *)
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(* *)
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(**************************************************************************)
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(** First-in first-out queues.
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This module implements queues (FIFOs), with in-place modification.
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{b Warning} This module is not thread-safe: each {!Queue.t} value
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must be protected from concurrent access (e.g. with a [Mutex.t]).
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Failure to do so can lead to a crash.
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*)
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type !'a t
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(** The type of queues containing elements of type ['a]. *)
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exception Empty
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(** Raised when {!Queue.take} or {!Queue.peek} is applied to an empty queue. *)
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val create : unit -> 'a t
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(** Return a new queue, initially empty. *)
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val add : 'a -> 'a t -> unit
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(** [add x q] adds the element [x] at the end of the queue [q]. *)
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val push : 'a -> 'a t -> unit
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(** [push] is a synonym for [add]. *)
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val take : 'a t -> 'a
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(** [take q] removes and returns the first element in queue [q],
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or raises {!Empty} if the queue is empty. *)
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val take_opt : 'a t -> 'a option
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(** [take_opt q] removes and returns the first element in queue [q],
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or returns [None] if the queue is empty.
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@since 4.08 *)
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val pop : 'a t -> 'a
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(** [pop] is a synonym for [take]. *)
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val peek : 'a t -> 'a
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(** [peek q] returns the first element in queue [q], without removing
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it from the queue, or raises {!Empty} if the queue is empty. *)
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val peek_opt : 'a t -> 'a option
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(** [peek_opt q] returns the first element in queue [q], without removing
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it from the queue, or returns [None] if the queue is empty.
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@since 4.08 *)
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val top : 'a t -> 'a
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(** [top] is a synonym for [peek]. *)
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val clear : 'a t -> unit
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(** Discard all elements from a queue. *)
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val copy : 'a t -> 'a t
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(** Return a copy of the given queue. *)
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val is_empty : 'a t -> bool
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(** Return [true] if the given queue is empty, [false] otherwise. *)
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val length : 'a t -> int
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(** Return the number of elements in a queue. *)
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val iter : ('a -> unit) -> 'a t -> unit
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(** [iter f q] applies [f] in turn to all elements of [q],
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from the least recently entered to the most recently entered.
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The queue itself is unchanged. *)
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val fold : ('b -> 'a -> 'b) -> 'b -> 'a t -> 'b
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(** [fold f accu q] is equivalent to [List.fold_left f accu l],
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where [l] is the list of [q]'s elements. The queue remains
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unchanged. *)
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val transfer : 'a t -> 'a t -> unit
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(** [transfer q1 q2] adds all of [q1]'s elements at the end of
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the queue [q2], then clears [q1]. It is equivalent to the
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sequence [iter (fun x -> add x q2) q1; clear q1], but runs
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in constant time. *)
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(** {1 Iterators} *)
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val to_seq : 'a t -> 'a Seq.t
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(** Iterate on the queue, in front-to-back order.
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The behavior is not defined if the queue is modified
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during the iteration.
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@since 4.07 *)
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val add_seq : 'a t -> 'a Seq.t -> unit
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(** Add the elements from the generator to the end of the queue
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@since 4.07 *)
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val of_seq : 'a Seq.t -> 'a t
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(** Create a queue from the generator
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@since 4.07 *)
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