Module:Set

Documentation for this module may be created at Module:Set/doc

-- 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