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This module implements FIFO queues in an efficient manner.
All operations has an amortised O(1) running time, except
len/1, reverse/1, join/2 and
split/2 that probably are O(n).
Types:
Item = term()
Q1 = Q2 = queue()
Inserts Item at the head of queue Q1. Returns
the new queue Q2.
The same as last(Q) and the opposite of
head(Q).
Types:
L = list()
Returns a queue containing the items in L, in the
same order - the head item of the list will be the head
item of the queue.
Types:
Item = term()
Q = queue()
Returns Item from the head of queue Q.
Fails with reason empty if Q is empty.
Types:
Item = term()
Q1 = Q2 = queue()
Inserts Item at the tail of queue Q1. Returns a new
queue Q2. This is the same as snoc(Q1, Item).
Types:
Item = term()
Q1 = Q2 = queue()
Inserts Item at the head of queue Q1. Returns a new
queue Q2. This is the same as cons(Item, Q1).
Types:
Item = term()
Q1 = Q2 = queue()
Returns a queue Q2 that is the result of removing
the last item from Q1. This is the opposite of
tail(Q1).
Fails with reason empty if Q1 is empty.
Types:
Q = queue()
Tests if Q is empty and returns true if so and
false otherwise.
Types:
Q1 = Q2 = Q3 = queue()
Returns a queue Q3 that is the result of joining
Q1 and Q2 with Q1 before (at the head)
Q2.
The same as init(Q1) and the opposite of
tail(Q1).
Types:
Item = term()
Q = queue()
Returns the last item of queue Q. This is the
opposite of head(Q).
Fails with reason empty if Q is empty.
Types:
Q = queue()
N = integer()
Calculates and returns the length of queue Q.
Types:
Q = queue()
Returns an empty queue.
Types:
Result = {{value, Item}, Q2} | {empty, Q1}
Q1 = Q2 = queue()
Removes the head item from the queue Q1. Returns the
tuple {{value, Item}, Q2}, where Item is the
item removed and Q2 is the new queue. If Q1 is
empty, the tuple {empty, Q1} is returned.
Types:
Result = {{value, Item}, Q2} | {empty, Q1}
Q1 = Q2 = queue()
Removes the last item from the queue Q1. Returns the
tuple {{value, Item}, Q2}, where Item is the
item removed and Q2 is the new queue. If Q1 is
empty, the tuple {empty, Q1} is returned.
Types:
Q1 = Q2 = queue()
Returns a queue Q2 that contains the items of
Q1 in the reverse order.
Types:
Item = term()
Q1 = Q2 = queue()
Inserts Item as the last item of queue Q1. Returns
the new queue Q2. This is the opposite of
cons(Item, Q1).
Types:
N = integer()
Q1 = Q2 = Q3 = queue()
Splits Q1 into a queue Q2 of length N
with items from the head end, and a queue Q3 with the
rest of the items.
Types:
Item = term()
Q1 = Q2 = queue()
Returns a queue Q2 that is the result of removing
the head item from Q1.
Fails with reason empty if Q1 is empty.
Types:
Q = queue()
Returns a list of the items in the queue, with the head item of the queue as the head of the list.