Module:Middleclass

local middleclass = {

 _VERSION     = 'middleclass v3.0.1',
 _DESCRIPTION = 'Object Orientation for Lua',
 _URL         = 'https://github.com/kikito/middleclass',
 _LICENSE     = [[
   MIT LICENSE

   Copyright (c) 2011 Enrique García Cota

   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.
 ]]

}

local function _setClassDictionariesMetatables(aClass)

 local dict = aClass.__instanceDict
 dict.__index = dict

 local super = aClass.super
 if super then
   local superStatic = super.static
   setmetatable(dict, super.__instanceDict)
   setmetatable(aClass.static, { __index = function(_,k) return dict[k] or superStatic[k] end })
 else
   setmetatable(aClass.static, { __index = function(_,k) return dict[k] end })
 end

end

local function _setClassMetatable(aClass)

 setmetatable(aClass, {
   __tostring = function() return "class " .. aClass.name end,
   __index    = aClass.static,
   __newindex = aClass.__instanceDict,
   __call     = function(self, ...) return self:new(...) end
 })

end

local function _createClass(name, super)

 local aClass = { name = name, super = super, static = {}, __mixins = {}, __instanceDict={} }
 aClass.subclasses = setmetatable({}, {__mode = "k"})

 _setClassDictionariesMetatables(aClass)
 _setClassMetatable(aClass)

 return aClass

end

local function _createLookupMetamethod(aClass, name)

 return function(...)
   local method = aClass.super[name]
   assert( type(method)=='function', tostring(aClass) .. " doesn't implement metamethod '" .. name .. "'" )
   return method(...)
 end

end

local function _setClassMetamethods(aClass)

 for _,m in ipairs(aClass.__metamethods) do
   aClass[m]= _createLookupMetamethod(aClass, m)
 end

end

local function _setDefaultInitializeMethod(aClass, super)

 aClass.initialize = function(instance, ...)
   return super.initialize(instance, ...)
 end

end

local function _includeMixin(aClass, mixin)

 assert(type(mixin)=='table', "mixin must be a table")
 for name,method in pairs(mixin) do
   if name ~= "included" and name ~= "static" then aClass[name] = method end
 end
 if mixin.static then
   for name,method in pairs(mixin.static) do
     aClass.static[name] = method
   end
 end
 if type(mixin.included)=="function" then mixin:included(aClass) end
 aClass.__mixins[mixin] = true

end

local Object = _createClass("Object", nil)

Object.static.__metamethods = { '__add', '__call', '__concat', '__div', '__ipairs', '__le',

                               '__len', '__lt', '__mod', '__mul', '__pairs', '__pow', '__sub',
                               '__tostring', '__unm'}

function Object.static:allocate()

 assert(type(self) == 'table', "Make sure that you are using 'Class:allocate' instead of 'Class.allocate'")
 return setmetatable({ class = self }, self.__instanceDict)

end

function Object.static:new(...)

 local instance = self:allocate()
 instance:initialize(...)
 return instance

end

function Object.static:subclass(name)

 assert(type(self) == 'table', "Make sure that you are using 'Class:subclass' instead of 'Class.subclass'")
 assert(type(name) == "string", "You must provide a name(string) for your class")

 local subclass = _createClass(name, self)
 _setClassMetamethods(subclass)
 _setDefaultInitializeMethod(subclass, self)
 self.subclasses[subclass] = true
 self:subclassed(subclass)

 return subclass

end

function Object.static:subclassed(other) end

function Object.static:isSubclassOf(other)

 return type(other)                   == 'table' and
        type(self)                    == 'table' and
        type(self.super)              == 'table' and
        ( self.super == other or
          type(self.super.isSubclassOf) == 'function' and
          self.super:isSubclassOf(other)
        )

end

function Object.static:include( ... )

 assert(type(self) == 'table', "Make sure you that you are using 'Class:include' instead of 'Class.include'")
 for _,mixin in ipairs({...}) do _includeMixin(self, mixin) end
 return self

end

function Object.static:includes(mixin)

 return type(mixin)          == 'table' and
        type(self)           == 'table' and
        type(self.__mixins)  == 'table' and
        ( self.__mixins[mixin] or
          type(self.super)           == 'table' and
          type(self.super.includes)  == 'function' and
          self.super:includes(mixin)
        )

end

function Object:initialize() end

function Object:__tostring() return "instance of " .. tostring(self.class) end

function Object:isInstanceOf(aClass)

 return type(self)                == 'table' and
        type(self.class)          == 'table' and
        type(aClass)              == 'table' and
        ( aClass == self.class or
          type(aClass.isSubclassOf) == 'function' and
          self.class:isSubclassOf(aClass)
        )

end

function middleclass.class(name, super, ...)

 super = super or Object
 return super:subclass(name, ...)

end

middleclass.Object = Object

setmetatable(middleclass, { __call = function(_, ...) return middleclass.class(...) end })

return middleclass