luaclass.lua

-- Internal register table
local _class={}

--Create an class（为了不与cocos2d-x中给出的class的名字冲突，这里创建接口改名为luaClass）
function luaClass(base)
	local superType  = type(base)
	local vtbl 		 = {}
	local class_type = {}

	class_type.ctor		= false
	class_type.__type	= 'class'
	class_type.__vtbl 	= vtbl

	--Delegate to vtbl
	_class[class_type] = vtbl
	setmetatable(class_type,{
				__newindex 	= vtbl, 
				__index 	= vtbl, 
				__call 		= function(self, ...) return self:new(...) end})

	if "class" == superType then
		--base is a class
		setmetatable(vtbl,{
				__index= function(t,k)
					local ret=_class[base][k]
					vtbl[k]=ret
					return ret
				end})

		class_type.__base	= base
		--save the top createFunc,this is used to create a object
		class_type.__createFunc = base.__createFunc
	elseif "function" == superType then
		--base is a function, used to create a userdata like cc.Node
		class_type.__createFunc = base
	elseif nil ~= base then
		--base must be a 'class' type or a 'function' type
		assert(false)
		return nil
	end
	
	function class_type:new(...)
		local obj = {}
		--
		--step1,check if are derived from userdata 
		--
		if class_type.__createFunc then
        	--如果是userdata，也就是从c++中而来，其实需要把method绑定到instance的cObject
        	local cInstance = class_type.__createFunc()
        	--相互维持引用（不用担心循环引用是否会导致gc问题，因为不会）
        	cInstance['.lua_instance'] = obj
        	obj['.c_instance'] = cInstance
        	--由userdata获得lua对象
        	function cInstance:getLuaInstance()
        		return obj
        	end
        	--由lua对象获得userdata
			function obj:getCInstance()
            	return cInstance
        	end	
		end

		obj.__base 	= class_type
		obj.__type	= 'object'

		--
		--step2,set the __index meta  method, thus object can access the class
		--
        local function lazyIndex(o, key)
			if vtbl[key] then
				return vtbl[key]
			elseif rawget(o, ".c_instance") and o['.c_instance'][key] ~= nil then
				rawset(o, key, function(self, ... ) return self:getCInstance()[key](self, ...) end)
				return o[key]
			else 
				return nil 
			end
		end
		setmetatable(obj,{ __index = lazyIndex})

		--
		--step3,construct the object
		--
		do
			local create
			create = function(c, ...)
				if c.__base then
					create(c.__base, ...)
				end
				if c.ctor then
					c.ctor(obj, ...)
				end
			end
			create(class_type,...)
		end

		--
		--step4,forbidden the new operation after construction
		--
		local function forbiddenNewIndex(o, k, v)
			--use print but not cclog or not logger, this is to reduce the dependent on other modules
			print(string.format("Warning:trying to create '%s' = '%s' in '%s', __newindex shouldnot be accessed outof ctor",
				 tostring(k), tostring(v), tostring(o)))

			rawset(o, k, v)
		end
		--not need rightnow
		--local mt = getmetatable(obj)
		--mt.__newindex = forbiddenNewIndex
		
		return obj
	end

	function class_type:super(f, ...)
		assert('object' == self.__type, 
			string.format("'self' must be a object when call super(self, '%s', ...)", tostring(f)))

		local originBase = self.__base
		--find the first f function that differ from self[f] in the inheritance chain
		local s 	= originBase
		local base 	= s.__base
		while base and s[f] == base[f] do
			s = base
			base = base.__base
		end
		
		assert(base and base[f],
			string.format("base class or function cannot be found when call .super(self, '%s', ...)", tostring(f)))
		--now base[f] is differ from self[f], but f in base also maybe inherited from base's baseClass
		while base.__base and base[f] == base.__base[f] do
			base = base.__base
		end

		-- If the base also has a baseclass, temporarily set :super to call that baseClass' methods
		-- this is to avoid stack overflow
		if base.__base then
			self.__base = base
		end

		--now, call the super function
		local result = base[f](self, ...)

		--set back
		if base.__base then
			self.__base = originBase
		end

		return result
	end

	-- 组合一个obj，把没有的接口代理到这个object中, 注意，此obj应该是lua的table
	-- 而不是c++的userdata，但是此obj可以是从c++中方法中继承出来的对象
	function class_type:compose(object)
		assert('object' == self.__type and 'object' == object.__type, 
			string.format("'self' and 'object' must be a object when call compose(self, object)", tostring(f)))

		for k, v in pairs(object.__base.__vtbl) do 
			-- 先确定是否要进行代理组合下去
			if type(v) == "function" then 
				 -- 不是以_开始，公有函数
				 -- 且在对象本身中没有这种方法
				 if string.byte(k, 1) ~= 95 and self[k] == nil then 
				 	self[k] = function(self, ...) return object[k](object, ...) end 
				 end
			end
		end
	end

	return class_type
end

--test code
--[[super = luaClass(function() return cc.Node:create() end)
	function super:ctor()
		print("super:ctor")
	end

	function super:show()
		print("super:show")
	end

	child = luaClass(super)
	function child:ctor()
		print("child:ctor")
	end

	function child:show()
		self:super('show')
		print("child:show")
	end

	local o = child:new()
	o:show()

	local t1 = os.clock()
	for i = 1, 1000000, 1 do
		o:setPosition(cc.p(1, 1))
	end
	local t2 = os.clock()
	print(t2 - t1)]]--


--test compose 

--[[obj = luaClass()
function obj:ctor()
	print("obj:ctor")
end

function obj:show()
	print("obj:show")
end



obj2 = luaClass()
function obj2:ctor()
	print("obj2:ctor")
end

function obj2:fuck()
	print("obj2:fuck")
end

local o = obj:new()
local o2 = obj2:new()

o:compose(o2)
o:fuck()]]