Module Base.QueueSource

A queue implemented with an array.

The implementation will grow the array as necessary. The array will never automatically be shrunk, but the size can be interrogated and set with capacity and set_capacity.

Iteration functions (iter, fold, map, concat_map, filter, filter_map, filter_inplace, and some functions from Container.S1) will raise if the queue is modified during iteration.

Also see Linked_queue, which has different performance characteristics.

Sourcemodule type S = sig ... end
Sourcetype 'a t
Sourceval compare : ('a -> 'a -> int) -> 'a t -> 'a t -> int
Sourceval compare__local : ('a -> 'a -> int) -> 'a t -> 'a t -> int
Sourceval globalize : ('a -> 'a) -> 'a t -> 'a t
include S with type 'a t := 'a t
include Sexplib0.Sexpable.S1 with type 'a t := 'a t
Sourceval t_of_sexp : (Sexplib0.Sexp.t -> 'a) -> Sexplib0.Sexp.t -> 'a t
Sourceval sexp_of_t : ('a -> Sexplib0.Sexp.t) -> 'a t -> Sexplib0.Sexp.t
include Indexed_container.S1 with type 'a t := 'a t
include Container.S1 with type 'a t := 'a t
Sourceval mem : 'a t -> 'a -> equal:('a -> 'a -> bool) -> bool

Checks whether the provided element is there, using equal.

Sourceval length : 'a t -> int
Sourceval is_empty : 'a t -> bool
Sourceval iter : 'a t -> f:('a -> unit) -> unit
Sourceval fold : 'a t -> init:'acc -> f:('acc -> 'a -> 'acc) -> 'acc

fold t ~init ~f returns f (... f (f (f init e1) e2) e3 ...) en, where e1..en are the elements of t

Sourceval fold_result : 'a t -> init:'acc -> f:('acc -> 'a -> ('acc, 'e) Result.t) -> ('acc, 'e) Result.t

fold_result t ~init ~f is a short-circuiting version of fold that runs in the Result monad. If f returns an Error _, that value is returned without any additional invocations of f.

Sourceval fold_until : 'a t -> init:'acc -> f:('acc -> 'a -> ('acc, 'final) Container.Continue_or_stop.t) -> finish:('acc -> 'final) -> 'final

fold_until t ~init ~f ~finish is a short-circuiting version of fold. If f returns Stop _ the computation ceases and results in that value. If f returns Continue _, the fold will proceed. If f never returns Stop _, the final result is computed by finish.

Example:

  type maybe_negative =
    | Found_negative of int
    | All_nonnegative of { sum : int }

  (** [first_neg_or_sum list] returns the first negative number in [list], if any,
      otherwise returns the sum of the list. *)
  let first_neg_or_sum =
    List.fold_until ~init:0
      ~f:(fun sum x ->
        if x < 0
        then Stop (Found_negative x)
        else Continue (sum + x))
      ~finish:(fun sum -> All_nonnegative { sum })
  ;;

  let x = first_neg_or_sum [1; 2; 3; 4; 5]
  val x : maybe_negative = All_nonnegative {sum = 15}

  let y = first_neg_or_sum [1; 2; -3; 4; 5]
  val y : maybe_negative = Found_negative -3
Sourceval exists : 'a t -> f:('a -> bool) -> bool

Returns true if and only if there exists an element for which the provided function evaluates to true. This is a short-circuiting operation.

Sourceval for_all : 'a t -> f:('a -> bool) -> bool

Returns true if and only if the provided function evaluates to true for all elements. This is a short-circuiting operation.

Sourceval count : 'a t -> f:('a -> bool) -> int

Returns the number of elements for which the provided function evaluates to true.

Returns the sum of f i for all i in the container.

Sourceval sum : (module Container.Summable with type t = 'sum) -> 'a t -> f:('a -> 'sum) -> 'sum
Sourceval find : 'a t -> f:('a -> bool) -> 'a option

Returns as an option the first element for which f evaluates to true.

Sourceval find_map : 'a t -> f:('a -> 'b option) -> 'b option

Returns the first evaluation of f that returns Some, and returns None if there is no such element.

Sourceval to_list : 'a t -> 'a list
Sourceval to_array : 'a t -> 'a array
Sourceval min_elt : 'a t -> compare:('a -> 'a -> int) -> 'a option

Returns a minimum (resp maximum) element from the collection using the provided compare function, or None if the collection is empty. In case of a tie, the first element encountered while traversing the collection is returned. The implementation uses fold so it has the same complexity as fold.

Sourceval max_elt : 'a t -> compare:('a -> 'a -> int) -> 'a option

These are all like their equivalents in Container except that an index starting at 0 is added as the first argument to f.

Sourceval foldi : 'a t -> init:_ -> f:(int -> _ -> 'a -> _) -> _
Sourceval iteri : 'a t -> f:(int -> 'a -> unit) -> unit
Sourceval existsi : 'a t -> f:(int -> 'a -> bool) -> bool
Sourceval for_alli : 'a t -> f:(int -> 'a -> bool) -> bool
Sourceval counti : 'a t -> f:(int -> 'a -> bool) -> int
Sourceval findi : 'a t -> f:(int -> 'a -> bool) -> (int * 'a) option
Sourceval find_mapi : 'a t -> f:(int -> 'a -> 'b option) -> 'b option
Sourceval singleton : 'a -> 'a t

singleton a returns a queue with one element.

Sourceval of_list : 'a list -> 'a t

of_list list returns a queue t with the elements of list in the same order as the elements of list (i.e. the first element of t is the first element of the list).

Sourceval of_array : 'a array -> 'a t
Sourceval init : int -> f:(int -> 'a) -> 'a t

init n ~f is equivalent to of_list (List.init n ~f).

Sourceval enqueue : 'a t -> 'a -> unit

enqueue t a adds a to the end of t.

Sourceval enqueue_all : 'a t -> 'a list -> unit

enqueue_all t list adds all elements in list to t in order of list.

Sourceval dequeue : 'a t -> 'a option

dequeue t removes and returns the front element of t, if any.

Sourceval dequeue_exn : 'a t -> 'a
Sourceval dequeue_and_ignore_exn : 'a t -> unit

dequeue_and_ignore_exn t removes the front element of t, or raises if the queue is empty.

Sourceval drain : 'a t -> f:('a -> unit) -> while_:('a -> bool) -> unit

drain t ~f ~while_ repeatedly calls while_ on the head of t, and if it returns true then dequeues it and calls f on it. It stops when t is empty or while_ returns false. A common use case is tracking the sum of data in a recent time interval: t contains timestamped data, while_ checks for elements with an old timestamp, and f subtracts data from the sum.

Sourceval peek : 'a t -> 'a option

peek t returns but does not remove the front element of t, if any.

Sourceval peek_exn : 'a t -> 'a
Sourceval clear : _ t -> unit

clear t discards all elements from t.

Sourceval copy : 'a t -> 'a t

copy t returns a copy of t.

Sourceval map : 'a t -> f:('a -> 'b) -> 'b t
Sourceval mapi : 'a t -> f:(int -> 'a -> 'b) -> 'b t
Sourceval concat_map : 'a t -> f:('a -> 'b list) -> 'b t

Creates a new queue with elements equal to List.concat_map ~f (to_list t).

Sourceval concat_mapi : 'a t -> f:(int -> 'a -> 'b list) -> 'b t
Sourceval filter_map : 'a t -> f:('a -> 'b option) -> 'b t

filter_map creates a new queue with elements equal to List.filter_map ~f (to_list t).

Sourceval filter_mapi : 'a t -> f:(int -> 'a -> 'b option) -> 'b t
Sourceval filter : 'a t -> f:('a -> bool) -> 'a t

filter is like filter_map, except with List.filter.

Sourceval filteri : 'a t -> f:(int -> 'a -> bool) -> 'a t
Sourceval filter_inplace : 'a t -> f:('a -> bool) -> unit

filter_inplace t ~f removes all elements of t that don't satisfy f. If f raises, t is unchanged. This is inplace in that it modifies t; however, it uses space linear in the final length of t.

Sourceval filteri_inplace : 'a t -> f:(int -> 'a -> bool) -> unit
include Equal.S1 with type 'a t := 'a t
Sourceval equal : 'a Equal.equal -> 'a t Equal.equal
Sourceval equal__local : ('a -> 'a -> bool) -> 'a t -> 'a t -> bool
include Invariant.S1 with type 'a t := 'a t
Sourceval invariant : ('a -> unit) -> 'a t -> unit
Sourceval create : ?capacity:int -> unit -> _ t

Create an empty queue.

Sourceval last : 'a t -> 'a option

last t returns the most recently enqueued element in t, if any.

Sourceval last_exn : 'a t -> 'a
Sourceval enqueue_front : 'a t -> 'a -> unit

Add an element to the front of the queue, as opposed to enqueue which adds to the back of the queue.

Sourceval dequeue_back : 'a t -> 'a option

dequeue_back t removes and returns the back element of t, if any.

Sourceval dequeue_back_exn : 'a t -> 'a
Sourceval peek_back : 'a t -> 'a option

peek_back t returns but does not remove the back element of t, if any.

Sourceval peek_back_exn : 'a t -> 'a
Sourceval blit_transfer : src:'a t -> dst:'a t -> ?len:int -> unit -> unit

Transfers up to len elements from the front of src to the end of dst, removing them from src. It is an error if len < 0.

Aside from a call to set_capacity dst if needed, runs in O(len) time

Sourceval get : 'a t -> int -> 'a

get t i returns the i'th element in t, where the 0'th element is at the front of t and the length t - 1 element is at the back.

Sourceval set : 'a t -> int -> 'a -> unit
Sourceval capacity : _ t -> int

Returns the current length of the backing array.

Sourceval set_capacity : _ t -> int -> unit

set_capacity t c sets the capacity of t's backing array to at least max c (length t). If t's capacity changes, then this involves allocating a new backing array and copying the queue elements over. set_capacity may decrease the capacity of t, if c < capacity t.

Sourcemodule Iteration : sig ... end

Use Iteration to implement iteration functions that guard against mutation.