Queue/Definition: Difference between revisions
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return [reader, writer]
}</syntaxhighlight>
=={{header|EasyLang}}==
A double-linked list is used, which is implemented via an expandable array.
<syntaxhighlight>
prefix qu_
global q[] head tail .
#
proc enq n . .
if tail = 0
head = 1
else
q[tail + 2] = len q[] + 1
.
q[] &= n
q[] &= tail
q[] &= 0
tail = len q[] - 2
.
func deq .
if head = 0
return 0 / 0
.
r = q[head]
old = head
head = q[head + 2]
last = len q[]
prev = q[last - 1]
if prev <> 0
q[prev + 2] = old
.
next = q[last]
if next <> 0
q[next + 1] = old
else
tail = old
.
q[old] = q[last - 2]
q[old + 1] = q[last - 1]
q[old + 2] = q[last]
len q[] -3
if head = len q[] + 1
head = old
.
if head <> 0
q[head + 1] = 0
else
tail = 0
.
return r
.
func empty .
return if head = 0
.
prefix
#
qu_enq 2
qu_enq 5
qu_enq 7
while qu_empty = 0
print qu_deq
.
</syntaxhighlight>
=={{header|EchoLisp}}==
There is no native queue type in EchoLisp. make-Q implements queues in message passing style, using vector operations. Conversions from-to lists are also provided.
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