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local Set = {}
Set.mt = {__index = Set}
function Set:new(values)
local instance = {}
local isSet if getmetatable(values) == Set.mt then isSet = true end
if type(values) == "table" then
if not isSet and #values > 0 then
for _,v in ipairs(values) do
instance[v] = true
end
else
for k in pairs(values) do
instance[k] = true
end
end
elseif values ~= nil then
instance = {[values] = true}
end
return setmetatable(instance, Set.mt)
end
function Set:add(e)
if e ~= nil then self[e] = true end
return self
end
function Set:remove(e)
if e ~= nil then self[e] = nil end
return self
end
function Set:anelement()
for e in pairs(self) do
return e
end
end
-- Union
Set.mt.__add = function (a, b)
local res, a, b = Set:new(), Set:new(a), Set:new(b)
for k in pairs(a) do res[k] = true end
for k in pairs(b) do res[k] = true end
return res
end
-- Subtraction
Set.mt.__sub = function (a, b)
local res, a, b = Set:new(), Set:new(a), Set:new(b)
for k in pairs(a) do res[k] = true end
for k in pairs(b) do res[k] = nil end
return res
end
-- Intersection
Set.mt.__mul = function (a, b)
local res, a, b = Set:new(), Set:new(a), Set:new(b)
for k in pairs(a) do
res[k] = b[k]
end
return res
end
-- String representation
Set.mt.__tostring = function (set)
local s = "{"
local sep = ""
for k in pairs(set) do
s = s .. sep .. tostring(k)
sep = ", "
end
return s .. "}"
end
function Set:len()
local num = 0
for _ in pairs(self) do
num = num + 1
end
return num
end
function Set:tolist()
local res = {}
for k in pairs(self) do
table.insert(res, k)
end
return res
end
return Set |