Minetest-WorldEditAdditions/worldeditadditions/utils/queue.lua
2021-07-30 19:57:16 +01:00

57 lines
1.1 KiB
Lua

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--- A Queue implementation, taken & adapted from https://www.lua.org/pil/11.4.html
-- @submodule worldeditadditions.utils.queue
local Queue = {}
Queue.__index = Queue
function Queue.new()
local result = { first = 0, last = -1, items = {} }
setmetatable(result, Queue)
return result
end
function Queue:enqueue(value)
local new_last = self.last + 1
self.last = new_last
self.items[new_last] = value
return new_last
end
function Queue:contains(value)
for i=self.first,self.last do
if self.items[i] == value then
return true
end
end
return false
end
function Queue:is_empty()
return self.first > self.last
end
function Queue:remove_index(index)
self.items[index] = nil
end
function Queue:dequeue()
if Queue.is_empty(self) then
error("Error: The self is empty!")
end
local first = self.first
-- Find the next non-nil item
local value
while value == nil do
if first >= self.last then return nil end
value = self.items[first]
self.items[first] = nil -- Help the garbage collector out
first = first + 1
end
self.first = first
return value
end
return Queue