Module Belt_MutableQueue

First-in first-out queues.

This module implements queues (FIFOs), with in-place modification.

type t('a);

The type of queues containing elements of type 'a.

let make: unit => t('a);
  • returns

    a new queue, initially empty.

let clear: t('a) => unit;

Discard all elements from the queue.

let isEmpty: t('a) => bool;
  • returns

    true if the given queue is empty, false otherwise.

let fromArray: array('a) => t('a);

fromArray a is equivalent to Array.forEach a (add q a)

let add: t('a) => 'a => unit;

add q x adds the element x at the end of the queue q.

let peek: t('a) => option('a);

peekOpt q returns the first element in queue q, without removing it from the queue.

let peekUndefined: t('a) => Js.undefined('a);

peekUndefined q returns undefined if not found

let peekExn: t('a) => 'a;

peekExn q

raise an exception if q is empty

let pop: t('a) => option('a);

pop q removes and returns the first element in queue q.

let popUndefined: t('a) => Js.undefined('a);

popUndefined q removes and returns the first element in queue q. it will return undefined if it is already empty

let popExn: t('a) => 'a;

popExn q

raise an exception if q is empty

let copy: t('a) => t('a);

copy q

  • returns

    a fresh queue

let size: t('a) => int;
  • returns

    the number of elements in a queue.

let mapU: t('a) => Js.Fn.arity1(('a => 'b)) => t('b);
let map: t('a) => ('a => 'b) => t('b);
let forEachU: t('a) => Js.Fn.arity1(('a => unit)) => unit;
let forEach: t('a) => ('a => unit) => unit;

forEach q f applies f in turn to all elements of q, from the least recently entered to the most recently entered. The queue itself is unchanged.

let reduceU: t('a) => 'b => Js.Fn.arity2(('b => 'a => 'b)) => 'b;
let reduce: t('a) => 'b => ('b => 'a => 'b) => 'b;

reduce q accu f is equivalent to List.reduce l accu f, where l is the list of q's elements. The queue remains unchanged.

let transfer: t('a) => t('a) => 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 forEach (fun x -> add x q2) q1; clear q1, but runs in constant time.

let toArray: t('a) => array('a);

First added will be in the beginning of the array