Module Queue

module Queue: sig .. end
First-in first-out queues.

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

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.