feat: use alien-signals

tests/signals/issue_48.spec.luau

@@ -0,0 +1,113 @@
+local test = require("../suite").test
+local signals = require("../../packages/charm/src/signals")
+
+local computed = signals.computed
+local effect = signals.effect
+local pauseTracking = signals.pauseTracking
+local resumeTracking = signals.resumeTracking
+local signal = signals.signal
+
+type ReactionOptions<T = unknown> = {
+	fireImmediately: boolean?,
+	equals: ((a: T, b: T?) -> boolean)?,
+	onError: (error: unknown) -> ()?,
+	scheduler: (fn: () -> ()) -> ()?,
+	once: boolean?,
+}
+
+local function untracked<T>(callback: () -> T): T
+	pauseTracking()
+	local success, result = pcall(callback)
+	resumeTracking()
+	if not success then
+		error(result)
+	end
+	return result
+end
+
+local function reaction<T>(
+	dataFn: () -> T,
+	effectFn: (newValue: T, oldValue: T?) -> (),
+	options: ReactionOptions<T>?
+): () -> ()
+	local options: ReactionOptions<T> = options or {}
+	local scheduler: (() -> ()) -> () = options.scheduler or function(fn)
+		return fn()
+	end
+	local equals: (T, T?) -> boolean = options.equals or function(a, b)
+		return a == b
+	end
+	local onError = options.onError
+	local once = options.once or false
+	local fireImmediately = options.fireImmediately or false
+
+	local prevValue: T?
+	local version = 0
+
+	local tracked = computed(function()
+		local success, result = pcall(dataFn)
+		if not success then
+			untracked(function()
+				if onError then
+					onError(result)
+				end
+				return nil
+			end)
+			return prevValue
+		end
+		return result
+	end)
+
+	local dispose
+	dispose = effect(function()
+		local current = tracked()
+		if not fireImmediately and version == 0 then
+			prevValue = current
+		end
+		version += 1
+		if equals(current :: T, prevValue) then
+			return
+		end
+		local oldValue = prevValue
+		prevValue = current
+		untracked(function()
+			scheduler(function()
+				local success = pcall(effectFn, current :: T, oldValue)
+				if not success and onError then
+					onError(error)
+				end
+				if once then
+					if (fireImmediately and version > 1) or (not fireImmediately and version > 0) then
+						dispose()
+					end
+				end
+			end)
+			return nil
+		end)
+	end)
+
+	return dispose
+end
+
+test("#48", function()
+	local source = signal(0)
+	local disposeInner: () -> ()
+
+	reaction(function()
+		return source()
+	end, function(val)
+		if val == 1 then
+			disposeInner = reaction(function()
+				return source()
+			end, function() end)
+		elseif val == 2 then
+			disposeInner()
+		end
+	end)
+
+	source(1)
+	source(2)
+	source(3)
+end)
+
+return {}