Module:Set

-- Derivative work of: --	(The MIT license)	Copyright (c) 2013, Wouter Scherphof (wouter.scherphof@gmail.com)	Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the "Software"), to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the following conditions:	The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software.	THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.

-- Source: https://github.com/wscherphof/lua-set/tree/master/src -- "Straightforward Set library for Lua"

local Set = {} Set.mt = {__index = Set} function Set:new(values) if getmetatable(values) == Set.mt then return values end local instance = {} if type(values) == "table" then if #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 .. 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