1 files changed, 83 insertions, 0 deletions
diff --git a/Object.lua b/Object.lua
new file mode 100644
index 0000000..9b9080b
--- /dev/null
+++ b/Object.lua
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+local extends
+
+--- Metatable used for each class created.
+-- `__call` is an instance constructor.
+-- `__index` and `_index` are used when accessing variables inside of class and its hierarchy when accessing class itself.
+local metaclass do
+	local function _index (self, key)
+		local super = rawget(self, "__super")
+		if super then
+			local value = rawget(super, key)
+			if value ~= nil then
+				return value
+			end
+			return _index(super, key)
+		end
+	end
+	metaclass = {
+		__index = function (self, key)
+			if key == "extends" then
+				return extends
+			end
+			return _index(self, key)
+		end,
+		__call = function (self, ...)
+			local o = setmetatable({}, self)
+			self.new(o, ...)
+			return o
+		end
+	}
+end
+
+--- Method for checking if instance is of selected class.
+-- Usage: `instance:is(Object)`.
+-- Also works with classes: `Object:is(Object)`.
+local is do
+	local function _is (self, class)
+		if self then
+			if self == class then
+				return true
+			end
+			return _is(rawget(self, "__super"), class)
+		end
+	end
+	function is (self, class)
+		local mt = getmetatable(self)
+		if mt ~= metaclass then
+			return _is(mt, class)
+		end
+		return _is(self, class)
+	end
+end
+
+--- Indexing metamethod for instances.
+local index do
+	local function _index (self, key)
+		if self then
+			local value = rawget(self, key)
+			if value ~= nil then
+				return value
+			end
+			return _index(rawget(self, "__super"), key)
+		end
+	end
+	function index (self, key)
+		return _index(getmetatable(self), key)
+	end
+end
+
+--- Class creation/extension function.
+-- Class table is used as metatable for instance of that class. `Metaclass` table is used as metatable for classes.
+function extends (parent)
+	local self = setmetatable({}, metaclass)
+	rawset(self, "__class", self)
+	rawset(self, "__index", index)
+	rawset(self, "__super", parent)
+	return self
+end
+
+--- Base class used as root for class hierarchy.
+local Object = extends(nil)
+rawset(Object, "new", function () end)
+rawset(Object, "is", is)
+return Object