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local ipairs, pairs, setmetatable, next, tostring =
ipairs, pairs, setmetatable, next, tostring;
local t_concat = table.concat;
module "set"
local set_mt = {};
function set_mt.__call(set, _, k)
return next(set._items, k);
end
function set_mt.__add(set1, set2)
return _M.union(set1, set2);
end
function set_mt.__sub(set1, set2)
return _M.difference(set1, set2);
end
function set_mt.__div(set, func)
local new_set, new_items = _M.new();
local items, new_items = set._items, new_set._items;
for item in pairs(items) do
if func(item) then
new_items[item] = true;
end
end
return new_set;
end
function set_mt.__eq(set1, set2)
local set1, set2 = set1._items, set2._items;
for item in pairs(set1) do
if not set2[item] then
return false;
end
end
for item in pairs(set2) do
if not set1[item] then
return false;
end
end
return true;
end
function set_mt.__tostring(set)
local s, items = { }, set._items;
for item in pairs(items) do
s[#s+1] = tostring(item);
end
return t_concat(s, ", ");
end
local items_mt = {};
function items_mt.__call(items, _, k)
return next(items, k);
end
function new(list)
local items = setmetatable({}, items_mt);
local set = { _items = items };
function set:add(item)
items[item] = true;
end
function set:contains(item)
return items[item];
end
function set:items()
return items;
end
function set:remove(item)
items[item] = nil;
end
function set:add_list(list)
for _, item in ipairs(list) do
items[item] = true;
end
end
function set:include(otherset)
for item in pairs(otherset) do
items[item] = true;
end
end
function set:exclude(otherset)
for item in pairs(otherset) do
items[item] = nil;
end
end
if list then
set:add_list(list);
end
return setmetatable(set, set_mt);
end
function union(set1, set2)
local set = new();
local items = set._items;
for item in pairs(set1._items) do
items[item] = true;
end
for item in pairs(set2._items) do
items[item] = true;
end
return set;
end
function difference(set1, set2)
local set = new();
local items = set._items;
for item in pairs(set1._items) do
items[item] = (not set2._items[item]) or nil;
end
return set;
end
function intersection(set1, set2)
local set = new();
local items = set._items;
set1, set2 = set1._items, set2._items;
for item in pairs(set1) do
items[item] = (not not set2[item]) or nil;
end
return set;
end
return _M;
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