Track when callbacks are invoked so that we can ensure that all screens are shown/hidden before invoking callbacks

monarch/utils/callback_tracker.lua

@@ -0,0 +1,39 @@
+local M = {}
+
+
+function M.create()
+	local instance = {}
+
+	local callback = nil
+	local callback_count = 0
+
+	--- Create a callback function and track when it is done
+	-- @return Callback function
+	function instance.track()
+		callback_count = callback_count + 1
+		return function()
+			callback_count = callback_count - 1
+			if callback_count == 0 and callback then
+				callback()
+			end
+		end
+	end
+
+	--- Call a function when all callbacks have been triggered
+	-- @param cb Function to call when all 
+	function instance.when_done(cb)
+		callback = cb
+		if callback_count == 0 then
+			callback()
+		end
+	end
+
+	return instance
+end
+
+
+return setmetatable(M, {
+	__call = function(_, ...)
+		return M.create(...)
+	end
+})