add gs

RCCService2018/content/LuaPackages/RoactImpl/SingleEventManager.lua

@@ -0,0 +1,145 @@
+--[[
+	An interface to have one event listener at a time on an event.
+
+	One listener can be registered per SingleEventManager/Instance/Event triple.
+
+	For example:
+
+		myManager:connect(myPart, "Touched", touchedListener)
+		myManager:connect(myPart, "Touched", otherTouchedListener)
+
+	If myPart is touched, only `otherTouchedListener` will fire, because the
+	first listener was disconnected during the second connect call.
+
+	The hooks provided by SingleEventManager pass the associated Roblox object
+	as the first parameter to the callback. This differs from normal
+	Roblox events.
+]]
+
+local SingleEventManager = {}
+
+SingleEventManager.__index = SingleEventManager
+
+local function createHook(rbx, key, method)
+	local hook = {
+		method = method,
+		connection = rbx[key]:Connect(function(...)
+			method(rbx, ...)
+		end)
+	}
+
+	return hook
+end
+
+local function createChangeHook(rbx, key, method)
+	local hook = {
+		method = method,
+		connection = rbx:GetPropertyChangedSignal(key):Connect(function(...)
+			method(rbx, ...)
+		end)
+	}
+
+	return hook
+end
+
+local function formatChangeKey(key)
+	return ("!PropertyChangeEvent:%s"):format(key)
+end
+
+function SingleEventManager.new()
+	local self = {}
+
+	self._hookCache = {}
+
+	setmetatable(self, SingleEventManager)
+
+	return self
+end
+
+function SingleEventManager:connect(rbx, key, method)
+	local rbxHooks = self._hookCache[rbx]
+
+	if rbxHooks then
+		local existingHook = rbxHooks[key]
+
+		if existingHook then
+			if existingHook.method == method then
+				return
+			end
+
+			existingHook.connection:Disconnect()
+		end
+
+		rbxHooks[key] = createHook(rbx, key, method)
+	else
+		rbxHooks = {}
+		rbxHooks[key] = createHook(rbx, key, method)
+
+		self._hookCache[rbx] = rbxHooks
+	end
+end
+
+function SingleEventManager:connectProperty(rbx, key, method)
+	local rbxHooks = self._hookCache[rbx]
+	local formattedKey = formatChangeKey(key)
+
+	if rbxHooks then
+		local existingHook = rbxHooks[formattedKey]
+
+		if existingHook then
+			if existingHook.method == method then
+				return
+			end
+
+			existingHook.connection:Disconnect()
+		end
+
+		rbxHooks[formattedKey] = createChangeHook(rbx, key, method)
+	else
+		rbxHooks = {}
+		rbxHooks[formattedKey] = createChangeHook(rbx, key, method)
+
+		self._hookCache[rbx] = rbxHooks
+	end
+end
+
+function SingleEventManager:disconnect(rbx, key)
+	local rbxHooks = self._hookCache[rbx]
+
+	if not rbxHooks then
+		return
+	end
+
+	local existingHook = rbxHooks[key]
+
+	if not existingHook then
+		return
+	end
+
+	existingHook.connection:Disconnect()
+	rbxHooks[key] = nil
+
+	if next(rbxHooks) == nil then
+		self._hookCache[rbx] = nil
+	end
+end
+
+function SingleEventManager:disconnectProperty(rbx, key)
+	self:disconnect(rbx, formatChangeKey(key))
+end
+
+function SingleEventManager:disconnectAll(rbx)
+	local rbxHooks = self._hookCache[rbx]
+
+	if not rbxHooks then
+		return
+	end
+
+	for _, hook in pairs(rbxHooks) do
+		hook.connection:Disconnect()
+	end
+
+	self._hookCache[rbx] = nil
+end
+
+return SingleEventManager