1Queue(3)                         OCaml library                        Queue(3)
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NAME

6       Queue - First-in first-out queues.
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Module

9       Module   Queue
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Documentation

12       Module Queue
13        : sig end
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16       First-in first-out queues.
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18       This module implements queues (FIFOs), with in-place modification.
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20       Warning This module is not thread-safe: each Queue.t value must be pro‐
21       tected from concurrent access (e.g. with a Mutex.t ).  Failure to do so
22       can lead to a crash.
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28       type 'a t
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31       The type of queues containing elements of type 'a .
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35       exception Empty
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38       Raised when Queue.take or Queue.peek is applied to an empty queue.
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42       val create : unit -> 'a t
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44       Return a new queue, initially empty.
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48       val add : 'a -> 'a t -> unit
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51       add x q adds the element x at the end of the queue q .
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55       val push : 'a -> 'a t -> unit
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58       push is a synonym for add .
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62       val take : 'a t -> 'a
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65       take  q  removes  and  returns the first element in queue q , or raises
66       Queue.Empty if the queue is empty.
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70       val take_opt : 'a t -> 'a option
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73       take_opt q removes and returns the first element in queue q  ,  or  re‐
74       turns None if the queue is empty.
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77       Since 4.08
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81       val pop : 'a t -> 'a
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84       pop is a synonym for take .
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88       val peek : 'a t -> 'a
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91       peek  q returns the first element in queue q , without removing it from
92       the queue, or raises Queue.Empty if the queue is empty.
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96       val peek_opt : 'a t -> 'a option
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99       peek_opt q returns the first element in queue q , without  removing  it
100       from the queue, or returns None if the queue is empty.
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103       Since 4.08
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107       val top : 'a t -> 'a
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110       top is a synonym for peek .
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114       val clear : 'a t -> unit
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116       Discard all elements from a queue.
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120       val copy : 'a t -> 'a t
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122       Return a copy of the given queue.
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126       val is_empty : 'a t -> bool
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128       Return true if the given queue is empty, false otherwise.
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132       val length : 'a t -> int
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134       Return the number of elements in a queue.
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138       val iter : ('a -> unit) -> 'a t -> unit
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141       iter  f  q  applies f in turn to all elements of q , from the least re‐
142       cently entered to the most recently entered.  The queue itself  is  un‐
143       changed.
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147       val fold : ('b -> 'a -> 'b) -> 'b -> 'a t -> 'b
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150       fold f accu q is equivalent to List.fold_left f accu l , where l is the
151       list of q 's elements. The queue remains unchanged.
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155       val transfer : 'a t -> 'a t -> unit
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158       transfer q1 q2 adds all of q1 's elements at the end of the queue q2  ,
159       then  clears q1 . It is equivalent to the sequence iter (fun x -> add x
160       q2) q1; clear q1 , but runs in constant time.
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165   Iterators
166       val to_seq : 'a t -> 'a Seq.t
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168       Iterate on the queue, in front-to-back order.  The behavior is not  de‐
169       fined if the queue is modified during the iteration.
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172       Since 4.07
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176       val add_seq : 'a t -> 'a Seq.t -> unit
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178       Add the elements from a sequence to the end of the queue.
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181       Since 4.07
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185       val of_seq : 'a Seq.t -> 'a t
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187       Create a queue from a sequence.
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190       Since 4.07
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196OCamldoc                          2022-02-04                          Queue(3)