feat: add super() implementation

lua/spec/class_spec.lua

@@ -8,6 +8,10 @@ describe('class', function()
 		return 'Animal'
 	end
 
+	function Animal:__tostring()
+		return self:type()
+	end
+
 	function Animal:size()
 		error('abstract')
 	end
@@ -32,6 +36,12 @@ describe('class', function()
 		return 4
 	end
 
+	local SpecialCat = Class.new(Cat)
+
+	function SpecialCat:makeSound()
+		return 'Meow'
+	end
+
 	describe('class operations', function()
 		it('base class', function ()
 			local a1 = Animal()
@@ -48,6 +58,56 @@ describe('class', function()
 		end)
 	end)
 
+	describe('super', function()
+		it('assert single proxy', function ()
+			local sc1 = SpecialCat(5)
+
+			assert.is_true(sc1:super() == sc1:super())
+		end)
+
+		it('access super methods', function ()
+			local c1 = Cat(5)
+
+			assert.equal('Animal', c1:super():type())
+			assert.error(function() return c1:super():numLegs() end)
+
+			local sc1 = SpecialCat(5)
+
+			assert.equal('Cat', sc1:super():type())
+			assert.equal(4, sc1:super():numLegs())
+			assert.error(function() return sc1:super():makeSound() end)
+		end)
+
+		it('call super metamethods', function ()
+			local c1 = Cat(5)
+
+			assert.equal('Cat', tostring(c1))
+			assert.equal('Animal', tostring(c1:super()))
+		end)
+
+		it('access instance variable from super', function ()
+			local c1 = Cat(5)
+
+			assert.equal(5, c1:super()._size)
+		end)
+
+		it('set instance variable from super', function ()
+			local c1 = Cat(5)
+
+			c1:super()._size = 20
+
+			assert.are_not_equal(5, c1._size)
+			assert.equal(20, c1._size)
+			assert.equal(20, c1:size())
+		end)
+
+		it('error if getting grandparent class', function ()
+			local sc1 = SpecialCat(5)
+
+			assert.error(function() return sc1:super():super() end, 'Cannot create proxy from a super proxy')
+		end)
+	end)
+
 	describe('instanceOf', function()
 		it('with same class', function ()
 			local c1 = Cat(5)
@@ -62,5 +122,20 @@ describe('class', function()
 			local a1 = Animal()
 			assert.is_false(Class.instanceOf(a1, Cat))
 		end)
+
+		it('with super', function ()
+			local c1 = Cat(5)
+			assert.is_true(Class.instanceOf(c1:super(), Animal))
+			assert.is_false(Class.instanceOf(c1:super(), Cat))
+		end)
+
+		it('with super of grandchild', function ()
+			local sc1 = SpecialCat(5)
+
+			local superSc1 = sc1:super()
+
+			assert.is_true(Class.instanceOf(superSc1, Cat))
+			assert.is_true(Class.instanceOf(superSc1, Animal))
+		end)
 	end)
 end)

lua/wikis/commons/Class.lua

@@ -30,6 +30,7 @@ Class.PRIVATE_FUNCTION_SPECIFIER = '_'
 ---@class BaseClass
 ---@operator call:self
 ---@field init fun(self, ...)
+---@field super fun(self: self): table
 
 ---@param base? table
 ---@param init? fun(self, ...)
@@ -51,6 +52,45 @@ function Class.new(base, init)
 
 	instance.__index = instance
 
+	instance.super = function(object)
+		if object._superProxy then
+			return object._superProxy
+		end
+		local proxy = {}
+		local proxyMT = {
+			__index = function (obj, param)
+				if param == 'super' then
+					error('Cannot create proxy from a super proxy')
+				end
+				local objVal = rawget(object, param)
+				if objVal then
+					return objVal
+				end
+				return base and base[param]
+			end,
+			_base = base,
+			_isSuperProxy = true,
+			__newindex = object,
+			__add = base and base.__add,
+			__sub = base and base.__sub,
+			__mul = base and base.__mul,
+			__div = base and base.__div,
+			__mod = base and base.__mod,
+			__pow = base and base.__pow,
+			__unm = base and base.__unm,
+			__concat = base and base.__concat,
+			__eq = base and base.__eq,
+			__lt = base and base.__lt,
+			__le = base and base.__le,
+			__pairs = base and base.__pairs,
+			__ipairs = base and base.__ipairs,
+			__tostring = base and base.__tostring,
+		}
+		setmetatable(proxy, proxyMT)
+		object._superProxy = proxy
+		return proxy
+	end
+
 	local metatable = {}
 
 	metatable.__call = function(class_tbl, ...)