BaseInstance:Clone

lib/InstanceProperty.lua

@@ -1,5 +1,6 @@
-local typeof = import("./functions/typeof")
 local assign = import("./assign")
+local cloneKey = import("./cloneKey")
+local typeof = import("./functions/typeof")
 
 local InstanceProperty = {}
 
@@ -14,6 +15,20 @@ function InstanceProperty.normal(config)
 		getDefault = function()
 			return nil
 		end,
+		clone = function(self, key)
+			local value = getmetatable(self).instance.properties[key]
+
+			if typeof(value) == "Instance" then
+				return value
+			elseif type(value) == "userdata" and typeof(value) ~= "userdata" then
+				-- Lemur implemented userdata, should have its own Clone function
+				local metatable = assert(getmetatable(value), "no metatable on cloning userdata")
+				local cloneImpl = assert(metatable[cloneKey], "no clone implementation for " .. typeof(value))
+				return cloneImpl(value)
+			end
+
+			return value
+		end,
 	}, config)
 end
 

lib/Signal.lua

@@ -5,6 +5,7 @@
 	executing an event.
 ]]
 
+local cloneKey = import("./cloneKey")
 local typeKey = import("./typeKey")
 
 local function immutableAppend(list, ...)
@@ -46,6 +47,7 @@ function Signal.new()
 	local self = newproxy(true)
 	getmetatable(self).__index = Signal
 	getmetatable(self).internal = internal
+	getmetatable(self)[cloneKey] = Signal.new
 	getmetatable(self)[typeKey] = "RBXScriptSignal"
 
 	return self

lib/cloneKey.lua

@@ -0,0 +1,13 @@
+--[[
+	This key is used to mark Roblox objects and implement Clone implementations
+
+	Use it as a key into a userdata object's metatable.
+]]
+
+local cloneKey = newproxy(true)
+
+getmetatable(cloneKey).__tostring = function()
+	return "<Lemur Clone Identifier>"
+end
+
+return cloneKey

lib/createEnum.lua

@@ -1,5 +1,10 @@
+local cloneKey = import("./cloneKey")
 local typeKey = import("./typeKey")
 
+local function cloneEnumItem(item)
+	return item
+end
+
 local function createEnumVariant(enum, variantName, variantValue)
 	local enumVariant = newproxy(true)
 
@@ -9,6 +14,7 @@ local function createEnumVariant(enum, variantName, variantValue)
 		EnumType = enum,
 	}
 
+	getmetatable(enumVariant)[cloneKey] = cloneEnumItem
 	getmetatable(enumVariant)[typeKey] = "EnumItem"
 
 	getmetatable(enumVariant).__tostring = function()

lib/createEnum_spec.lua

@@ -52,4 +52,27 @@ describe("createEnum", function()
 			tostring(variant.something)
 		end)
 	end)
+
+	it("should clone", function()
+		local BaseInstance = import("./instances/BaseInstance")
+		local InstanceProperty = import("./InstanceProperty")
+
+		local CreatableClass = BaseInstance:extend("Creatable", {
+			creatable = true,
+		})
+
+		CreatableClass.properties.Value = InstanceProperty.normal({})
+
+		local enum = createEnum("TestEnum", {
+			A = 0,
+			B = 1,
+			C = 2,
+		})
+
+		local instance = CreatableClass:new()
+		instance.Value = enum.A
+
+		local clone = instance:Clone()
+		assert.equal(clone.Value, enum.A)
+	end)
 end)

lib/instances/BaseInstance.lua

@@ -90,6 +90,10 @@ BaseInstance.properties.Parent = InstanceProperty.normal({
 
 		self:_PropagateAncestryChanged(self, value)
 	end,
+
+	clone = function()
+		return nil
+	end,
 })
 
 BaseInstance.prototype = {}
@@ -102,6 +106,29 @@ function BaseInstance.prototype:ClearAllChildren()
 	end
 end
 
+function BaseInstance.prototype:Clone()
+	local class = getmetatable(self).class
+	if not class.options.creatable then
+		error(string.format("%s cannot be cloned", class.name))
+	end
+
+	local clone = class:new()
+	local cloneProperties = getmetatable(clone).instance.properties
+	local classProperties = class.properties
+
+	for _, child in pairs(self:GetChildren()) do
+		child:Clone().Parent = clone
+	end
+
+	for propertyName, prototype in pairs(classProperties) do
+		cloneProperties[propertyName] = prototype.clone(self, propertyName)
+	end
+
+	class.postClone(clone, self)
+
+	return clone
+end
+
 function BaseInstance.prototype:FindFirstAncestor(name)
 	local level = self.Parent
 
@@ -372,6 +399,9 @@ end
 function BaseInstance:init(instance, ...)
 end
 
+function BaseInstance:postClone(old)
+end
+
 --[[
 	Create a new instance class with the given name.
 ]]

lib/instances/BaseInstance_spec.lua

@@ -1,5 +1,5 @@
-local Game = import("./Game")
 local Folder = import("./Folder")
+local Game = import("./Game")
 local typeof = import("../functions/typeof")
 
 local BaseInstance = import("./BaseInstance")
@@ -719,4 +719,99 @@ describe("instances.BaseInstance", function()
 			assert.spy(spy).was_called_with(child)
 		end)
 	end)
+
+	describe("Clone", function()
+		it("should clone the entire object", function()
+			local CreatableClass = BaseInstance:extend("Creatable", {
+				creatable = true,
+			})
+
+			local instance = CreatableClass:new()
+			instance.Name = "Alpha"
+
+			local clone = instance:Clone()
+			assert.not_equals(instance, clone)
+			assert.equal(instance.Name, "Alpha")
+			assert.equal(clone.Name, "Alpha")
+
+			clone.Name = "Beta"
+			assert.equal(instance.Name, "Alpha")
+			assert.equal(clone.Name, "Beta")
+		end)
+
+		it("should clone fresh events", function()
+			local CreatableClass = BaseInstance:extend("Creatable", {
+				creatable = true,
+			})
+
+			local instanceA = CreatableClass:new()
+			local spyA = spy.new(function() end)
+			instanceA.ChildAdded:Connect(spyA)
+
+			local instanceB = instanceA:Clone()
+			local spyB = spy.new(function() end)
+			instanceB.ChildAdded:Connect(spyB)
+
+			assert.spy(spyA).was_not_called()
+			assert.spy(spyB).was_not_called()
+
+			BaseInstance:new().Parent = instanceA
+			assert.spy(spyA).was_called()
+			assert.spy(spyB).was_not_called()
+		end)
+
+		it("should not clone the parent", function()
+			local CreatableClass = BaseInstance:extend("Creatable", {
+				creatable = true,
+			})
+
+			local instance = CreatableClass:new()
+			instance.Parent = CreatableClass:new()
+
+			local clone = instance:Clone()
+			assert.is_nil(clone.Parent)
+			assert.not_nil(instance.Parent)
+		end)
+
+		it("should clone children", function()
+			local CreatableClass = BaseInstance:extend("Creatable", {
+				creatable = true,
+			})
+
+			local parent = CreatableClass:new()
+			local child = CreatableClass:new()
+			child.Name = "Child"
+			child.Parent = parent
+
+			local clone = parent:Clone()
+			assert.equal(#clone:GetChildren(), 1)
+			assert.not_nil(clone:FindFirstChild("Child"))
+		end)
+
+		it("should not clone instance properties", function()
+			local InstanceProperty = import("../InstanceProperty")
+
+			local CreatableClass = BaseInstance:extend("Creatable", {
+				creatable = true,
+			})
+
+			CreatableClass.properties.Value = InstanceProperty.normal({})
+
+			local ref = CreatableClass:new()
+
+			local instance = CreatableClass:new()
+			instance.Value = ref
+
+			local clone = instance:Clone()
+			assert.equal(clone.Value, ref)
+			assert.equal(instance.Value, ref)
+		end)
+
+		it("should error when trying to clone a non-creatable object", function()
+			local instance = BaseInstance:new()
+			assert.has.errors(function()
+				instance:Clone()
+			end)
+		end)
+	end)
 end)

lib/instances/ModuleScript.lua

@@ -5,6 +5,10 @@ local ModuleScript = BaseInstance:extend("ModuleScript", {
 	creatable = true,
 })
 
+function ModuleScript:postClone(old)
+	getmetatable(self).instance.modulePath = getmetatable(old).instance.modulePath
+end
+
 ModuleScript.properties.Source = InstanceProperty.normal({
 	getDefault = function()
 		return ""

lib/types/Color3.lua

@@ -1,4 +1,5 @@
 local assign = import("../assign")
+local cloneKey = import("../cloneKey")
 local typeKey = import("../typeKey")
 
 local function lerpNumber(a, b, alpha)
@@ -24,6 +25,9 @@ function prototype:lerp(goal, alpha)
 end
 
 local metatable = {}
+metatable[cloneKey] = function(color3)
+	return Color3.new(color3.r, color3.g, color3.b)
+end
 metatable[typeKey] = "Color3"
 
 function metatable:__index(key)

lib/types/Color3_spec.lua

@@ -79,4 +79,24 @@ describe("types.Color3", function()
 		local type = typeof(Color3.new())
 		assert.are.equal("Color3", type)
 	end)
+
+	it("should clone", function()
+		local BaseInstance = import("../instances/BaseInstance")
+		local InstanceProperty = import("../InstanceProperty")
+
+		local CreatableClass = BaseInstance:extend("Creatable", {
+			creatable = true,
+		})
+
+		CreatableClass.properties.Value = InstanceProperty.normal({})
+
+		local color3 = Color3.new(1, 0, 0)
+
+		local instance = CreatableClass:new()
+		instance.Value = color3
+
+		local clone = instance:Clone()
+		assert.equal(clone.Value, color3)
+		assert.not_equals(getmetatable(color3), getmetatable(clone.Value))
+	end)
 end)

lib/types/Rect.lua

@@ -1,4 +1,5 @@
 local assign = import("../assign")
+local cloneKey = import("../cloneKey")
 local typeKey = import("../typeKey")
 local typeof = import("../functions/typeof")
 local Vector2 = import("./Vector2")
@@ -14,6 +15,9 @@ setmetatable(Rect, {
 local prototype = {}
 
 local metatable = {}
+metatable[cloneKey] = function(rect)
+	return Rect.new(rect.Min, rect.Max)
+end
 metatable[typeKey] = "Rect"
 
 function metatable:__index(key)

lib/types/Rect_spec.lua

@@ -81,4 +81,24 @@ describe("types.Rect", function()
 		assert.not_equals(rectA, rectB3)
 		assert.not_equals(rectA, rectB4)
 	end)
+
+	it("should clone", function()
+		local BaseInstance = import("../instances/BaseInstance")
+		local InstanceProperty = import("../InstanceProperty")
+
+		local CreatableClass = BaseInstance:extend("Creatable", {
+			creatable = true,
+		})
+
+		CreatableClass.properties.Value = InstanceProperty.normal({})
+
+		local rect = Rect.new(1, 2, 3, 4)
+
+		local instance = CreatableClass:new()
+		instance.Value = rect
+
+		local clone = instance:Clone()
+		assert.equal(clone.Value, rect)
+		assert.not_equals(getmetatable(rect), getmetatable(clone.Value))
+	end)
 end)

lib/types/UDim.lua

@@ -1,4 +1,5 @@
 local assign = import("../assign")
+local cloneKey = import("../cloneKey")
 local typeKey = import("../typeKey")
 
 local UDim = {}
@@ -12,6 +13,9 @@ setmetatable(UDim, {
 local prototype = {}
 
 local metatable = {}
+metatable[cloneKey] = function(udim)
+	return UDim.new(udim.Scale, udim.Offset)
+end
 metatable[typeKey] = "UDim"
 
 function metatable:__index(key)

lib/types/UDim2.lua

@@ -1,4 +1,5 @@
 local assign = import("../assign")
+local cloneKey = import("../cloneKey")
 local typeKey = import("../typeKey")
 local typeof = import("../functions/typeof")
 local UDim = import("./UDim")
@@ -27,6 +28,9 @@ function prototype:Lerp(goal, alpha)
 end
 
 local metatable = {}
+metatable[cloneKey] = function(udim2)
+	return UDim2.new(udim2.X.Scale, udim2.X.Offset, udim2.Y.Scale, udim2.Y.Offset)
+end
 metatable[typeKey] = "UDim2"
 
 function metatable:__index(key)