(**************************************************************************)
(* *)
(* OCaml *)
(* *)
(* 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 Lesser General Public License version 2.1, with the *)
(* special exception on linking described in the file LICENSE. *)
(* *)
(**************************************************************************)
(** First-in first-out queues.
This module implements queues (FIFOs), with in-place modification.
{b Warning} This module is not thread-safe: each {!Queue.t} value
must be protected from concurrent access (e.g. with a [Mutex.t]).
Failure to do so can lead to a crash.
*)
type 'a t
(** The type of queues containing elements of type ['a]. *)
exception Empty
(** Raised when {!Queue.take} or {!Queue.peek} is applied to an empty queue. *)
val create : unit -> 'a t
(** Return a new queue, initially empty. *)
val add : 'a -> 'a t -> unit
(** [add x q] adds the element [x] at the end of the queue [q]. *)
val push : 'a -> 'a t -> unit
(** [push] is a synonym for [add]. *)
val take : 'a t -> 'a
(** [take q] removes and returns the first element in queue [q],
or raises {!Empty} if the queue is empty. *)
val pop : 'a t -> 'a
(** [pop] is a synonym for [take]. *)
val peek : 'a t -> 'a
(** [peek q] returns the first element in queue [q], without removing
it from the queue, or raises {!Empty} if the queue is empty. *)
val top : 'a t -> 'a
(** [top] is a synonym for [peek]. *)
val clear : 'a t -> unit
(** Discard all elements from a queue. *)
val copy : 'a t -> 'a t
(** Return a copy of the given queue. *)
val is_empty : 'a t -> bool
(** Return [true] if the given queue is empty, [false] otherwise. *)
val length : 'a t -> int
(** Return the number of elements in a queue. *)
val iter : ('a -> unit) -> 'a t -> unit
(** [iter f q] applies [f] in turn to all elements of [q],
from the least recently entered to the most recently entered.
The queue itself is unchanged. *)
val fold : ('b -> 'a -> 'b) -> 'b -> 'a t -> 'b
(** [fold f accu q] is equivalent to [List.fold_left f accu l],
where [l] is the list of [q]'s elements. The queue remains
unchanged. *)
val transfer : 'a t -> 'a t -> unit
(** [transfer q1 q2] adds all of [q1]'s elements at the end of
the queue [q2], then clears [q1]. It is equivalent to the
sequence [iter (fun x -> add x q2) q1; clear q1], but runs
in constant time. *)
(** {6 Iterators} *)
val to_seq : 'a t -> 'a Seq.t
(** Iterate on the queue, in front-to-back order.
The behavior is not defined if the queue is modified
during the iteration.
@since 4.07 *)
val add_seq : 'a t -> 'a Seq.t -> unit
(** Add the elements from the generator to the end of the queue
@since 4.07 *)
val of_seq : 'a Seq.t -> 'a t
(** Create an array from the generator
@since 4.07 *)
|