package core_kernel

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package core_kernel
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module Key : Core_kernel.Hashtbl.Key_plain with type t = t
type 'a t

A hash-queue, where the values are of type 'a.

val sexp_of_t : ('a -> Ppx_sexp_conv_lib.Sexp.t) -> 'a t -> Ppx_sexp_conv_lib.Sexp.t
include Core_kernel.Container.S1 with type 'a t := 'a t
val length : 'a t -> int
val is_empty : 'a t -> bool
val iter : 'a t -> f:('a -> unit) -> unit
val fold : 'a t -> init:'accum -> f:('accum -> 'a -> 'accum) -> 'accum

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

val fold_result : 'a t -> init:'accum -> f:('accum -> 'a -> ('accum, 'e) Base.Result.t) -> ('accum, 'e) Base.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.

val fold_until : 'a t -> init:'accum -> f:('accum -> 'a -> ('accum, 'final) Base__.Container_intf.Continue_or_stop.t) -> finish:('accum -> '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
val 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.

val 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.

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

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

val sum : (module Base__.Container_intf.Summable with type t = 'sum) -> 'a t -> f:('a -> 'sum) -> 'sum

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

val find : 'a t -> f:('a -> bool) -> 'a option

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

val 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.

val to_list : 'a t -> 'a list
val to_array : 'a t -> 'a array
val 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.

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

invariant t checks the invariants of the queue.

val invariant : 'a t -> Base.Unit.t
val create : ?growth_allowed:Base.Bool.t -> ?size:Base.Int.t -> Base.Unit.t -> 'a t

create () returns an empty queue. The arguments growth_allowed and size are referring to the underlying hashtable.

  • parameter growth_allowed

    defaults to true

  • parameter size

    initial size -- default to 16

val clear : 'a t -> Base.Unit.t

Clears the queue.

Finding elements

val mem : 'a t -> Key.t -> Base.Bool.t

mem q k returns true iff there is some (k, v) in the queue.

val lookup : 'a t -> Key.t -> 'a Base.Option.t

lookup t k returns the value of the key-value pair in the queue with key k, if there is one.

val lookup_exn : 'a t -> Key.t -> 'a

Adding, removing, and replacing elements

Note that even the non-*_exn versions can raise, but only if there is an ongoing iteration.

val enqueue : 'a t -> [ `back | `front ] -> Key.t -> 'a -> [ `Ok | `Key_already_present ]

enqueue t back_or_front k v adds the key-value pair (k, v) to the front or back of the queue, returning `Ok if the pair was added, or `Key_already_present if there is already a (k, v') in the queue.

val enqueue_exn : 'a t -> [ `back | `front ] -> Key.t -> 'a -> Base.Unit.t

Like enqueue, but it raises in the `Key_already_present case

val enqueue_back : 'a t -> Key.t -> 'a -> [ `Ok | `Key_already_present ]

See enqueue. enqueue_back t k v is the same as enqueue t `back k v

val enqueue_back_exn : 'a t -> Key.t -> 'a -> Base.Unit.t

See enqueue_exn. enqueue_back_exn t k v is the same as enqueue_exn t `back k v

val enqueue_front : 'a t -> Key.t -> 'a -> [ `Ok | `Key_already_present ]

See enqueue. enqueue_front t k v is the same as enqueue t `front k v

val enqueue_front_exn : 'a t -> Key.t -> 'a -> Base.Unit.t

See enqueue_exn. enqueue_front_exn t k v is the same as enqueue_exn t `front k v

val lookup_and_move_to_back : 'a t -> Key.t -> 'a Base.Option.t

lookup_and_move_to_back finds the key-value pair (k, v) and moves it to the back of the queue if it exists, otherwise returning None.

The _exn versions of these functions raise if key-value pair does not exist.

val lookup_and_move_to_back_exn : 'a t -> Key.t -> 'a

Like lookup_and_move_to_back, but raises instead of returning an option

val lookup_and_move_to_front : 'a t -> Key.t -> 'a Base.Option.t

Like lookup_and_move_to_back, but moves element to the front of the queue

val lookup_and_move_to_front_exn : 'a t -> Key.t -> 'a

Like lookup_and_move_to_front, but raises instead of returning an option

val first : 'a t -> 'a Base.Option.t

first t returns the front element of the queue, without removing it.

val first_with_key : 'a t -> (Key.t * 'a) Base.Option.t

first_with_key t returns the front element of the queue and its key, without removing it.

val keys : 'a t -> Key.t Base.List.t

keys t returns the keys in the order of the queue.

val dequeue : 'a t -> [ `back | `front ] -> 'a Base.Option.t

dequeue t front_or_back returns the front or back element of the queue.

val dequeue_exn : 'a t -> [ `back | `front ] -> 'a

Like dequeue, but it raises if the queue is empty.

val dequeue_back : 'a t -> 'a Base.Option.t

dequeue_back t returns the back element of the queue.

val dequeue_back_exn : 'a t -> 'a

Like dequeue_back, but it raises if the queue is empty.

val dequeue_front : 'a t -> 'a Base.Option.t

dequeue_front t returns the front element of the queue.

val dequeue_front_exn : 'a t -> 'a

Like dequeue_front, but it raises if the queue is empty.

val dequeue_with_key : 'a t -> [ `back | `front ] -> (Key.t * 'a) Base.Option.t

dequeue_with_key t returns the front or back element of the queue and its key.

val dequeue_with_key_exn : 'a t -> [ `back | `front ] -> Key.t * 'a

Like dequeue_with_key, but it raises if the queue is empty.

val dequeue_back_with_key : 'a t -> (Key.t * 'a) Base.Option.t

dequeue_back_with_key t returns the back element of the queue and its key.

val dequeue_back_with_key_exn : 'a t -> Key.t * 'a

Like dequeue_back_with_key, but it raises if the queue is empty.

val dequeue_front_with_key : 'a t -> (Key.t * 'a) Base.Option.t

dequeue_front_with_key t returns the front element of the queue and its key.

val dequeue_front_with_key_exn : 'a t -> Key.t * 'a

Like dequeue_front_with_key, but it raises if the queue is empty.

val dequeue_all : 'a t -> f:('a -> Base.Unit.t) -> Base.Unit.t

dequeue_all t ~f dequeues every element of the queue and applies f to each one. The dequeue order is from front to back.

val remove : 'a t -> Key.t -> [ `Ok | `No_such_key ]

remove q k removes the key-value pair with key k from the queue.

val remove_exn : 'a t -> Key.t -> Base.Unit.t
val replace : 'a t -> Key.t -> 'a -> [ `Ok | `No_such_key ]

replace q k v changes the value of key k in the queue to v.

val replace_exn : 'a t -> Key.t -> 'a -> Base.Unit.t
val drop : ?n:Base.Int.t -> 'a t -> [ `back | `front ] -> Base.Unit.t

drop ?n q back_or_front drops n elements (default 1) from the back or front of the queue. If the queue has fewer than n elements then it is cleared.

val drop_front : ?n:Base.Int.t -> 'a t -> Base.Unit.t

Equivalent to drop ?n q `front.

val drop_back : ?n:Base.Int.t -> 'a t -> Base.Unit.t

Equivalent to drop ?n q `back.

Iterating over elements

val iteri : 'a t -> f:(key:Key.t -> data:'a -> Base.Unit.t) -> Base.Unit.t

iter t ~f applies f to each key and element of the queue.

val foldi : 'a t -> init:'b -> f:('b -> key:Key.t -> data:'a -> 'b) -> 'b
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