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How to Implement a Queue in Lua Programming?
There are different approaches one can take to declare a queue in Lua; the most basic one is to make use of the tables and repeat function, and take two variables that will help us to insert and delete elements from the queue.
Example
Consider the code shown below −
queue = {}
queue.first = 0
queue.last = -1
queue.data = {}
function insert(q, val)
q.last = q.last + 1
q.data[q.last] = val
end
function remove(q)
if (q.first > q.last) then
rval = -1
else
print("remove: q.data[q.first]= ", q.data[q.first], " q.first= ", q.first)
local rval = q.data[q.first]
print("remove: rval= ", rval)
q.data[q.first] = nil
q.first = q.first + 1
print("remove: q.first= ", q.first)
end
return rval
end
insert(queue,"a")
insert(queue,"b")
insert(queue,"c")
for i,v in ipairs(queue.data) do
print(i, v)
end
repeat
local x = remove(queue)
print("list item= ", x)
until (queue.first > queue.last)Output
1 b 2 c remove: q.data[q.first]= a q.first= 0 remove: rval= a remove: q.first= 1 list item= nil remove: q.data[q.first]= b q.first= 1 remove: rval= b remove: q.first= 2 list item= nil remove: q.data[q.first]= c q.first= 2 remove: rval= c remove: q.first= 3 list item= nil
Updated on: 19-Jul-2021
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