1Queue(3)                         OCaml library                        Queue(3)
2
3
4

NAME

6       Queue - First-in first-out queues.
7

Module

9       Module   Queue
10

Documentation

12       Module Queue
13        : sig end
14
15
16       First-in first-out queues.
17
18       This module implements queues (FIFOs), with in-place modification.
19
20
21       Alert  unsynchronized_access.   Unsynchronized accesses to queues are a
22       programming error.
23
24
25
26
27
28
29
30       Unsynchronized accesses
31
32       Unsynchronized accesses to a queue may lead to an invalid queue  state.
33       Thus,  concurrent accesses to queues must be synchronized (for instance
34       with a Mutex.t ).
35
36       type 'a t
37
38
39       The type of queues containing elements of type 'a .
40
41
42
43       exception Empty
44
45
46       Raised when Queue.take or Queue.peek is applied to an empty queue.
47
48
49
50       val create : unit -> 'a t
51
52       Return a new queue, initially empty.
53
54
55
56       val add : 'a -> 'a t -> unit
57
58
59       add x q adds the element x at the end of the queue q .
60
61
62
63       val push : 'a -> 'a t -> unit
64
65
66       push is a synonym for add .
67
68
69
70       val take : 'a t -> 'a
71
72
73       take q removes and returns the first element in queue  q  ,  or  raises
74       Queue.Empty if the queue is empty.
75
76
77
78       val take_opt : 'a t -> 'a option
79
80
81       take_opt  q  removes  and returns the first element in queue q , or re‐
82       turns None if the queue is empty.
83
84
85       Since 4.08
86
87
88
89       val pop : 'a t -> 'a
90
91
92       pop is a synonym for take .
93
94
95
96       val peek : 'a t -> 'a
97
98
99       peek q returns the first element in queue q , without removing it  from
100       the queue, or raises Queue.Empty if the queue is empty.
101
102
103
104       val peek_opt : 'a t -> 'a option
105
106
107       peek_opt  q  returns the first element in queue q , without removing it
108       from the queue, or returns None if the queue is empty.
109
110
111       Since 4.08
112
113
114
115       val top : 'a t -> 'a
116
117
118       top is a synonym for peek .
119
120
121
122       val clear : 'a t -> unit
123
124       Discard all elements from a queue.
125
126
127
128       val copy : 'a t -> 'a t
129
130       Return a copy of the given queue.
131
132
133
134       val is_empty : 'a t -> bool
135
136       Return true if the given queue is empty, false otherwise.
137
138
139
140       val length : 'a t -> int
141
142       Return the number of elements in a queue.
143
144
145
146       val iter : ('a -> unit) -> 'a t -> unit
147
148
149       iter f q applies f in turn to all elements of q , from  the  least  re‐
150       cently  entered  to the most recently entered.  The queue itself is un‐
151       changed.
152
153
154
155       val fold : ('b -> 'a -> 'b) -> 'b -> 'a t -> 'b
156
157
158       fold f accu q is equivalent to List.fold_left f accu l , where l is the
159       list of q 's elements. The queue remains unchanged.
160
161
162
163       val transfer : 'a t -> 'a t -> unit
164
165
166       transfer  q1 q2 adds all of q1 's elements at the end of the queue q2 ,
167       then clears q1 . It is equivalent to the sequence iter (fun x -> add  x
168       q2) q1; clear q1 , but runs in constant time.
169
170
171
172
173   Iterators
174       val to_seq : 'a t -> 'a Seq.t
175
176       Iterate  on  the  queue,  in  front-to-back order.  The behavior is not
177       specified if the queue is modified during the iteration.
178
179
180       Since 4.07
181
182
183
184       val add_seq : 'a t -> 'a Seq.t -> unit
185
186       Add the elements from a sequence to the end of the queue.
187
188
189       Since 4.07
190
191
192
193       val of_seq : 'a Seq.t -> 'a t
194
195       Create a queue from a sequence.
196
197
198       Since 4.07
199
200
201
202
203
204OCamldoc                          2023-07-20                          Queue(3)