add gs

RCCService2018/content/LuaPackages/RoactImpl/Config.lua

@@ -0,0 +1,146 @@
+--[[
+	Exposes an interface to set global configuration values for Roact.
+
+	Configuration can only occur once, and should only be done by an application
+	using Roact, not a library.
+
+	Any keys that aren't recognized will cause errors. Configuration is only
+	intended for configuring Roact itself, not extensions or libraries.
+
+	Configuration is expected to be set immediately after loading Roact. Setting
+	configuration values after an application starts may produce unpredictable
+	behavior.
+]]
+
+-- Every valid configuration value should be non-nil in this table.
+local defaultConfig = {
+	-- Enables storage of `debug.traceback()` values on elements for debugging.
+	["elementTracing"] = false,
+	-- Enables instrumentation of shouldUpdate and render methods for Roact components
+	["componentInstrumentation"] = false,
+}
+
+-- Build a list of valid configuration values up for debug messages.
+local defaultConfigKeys = {}
+for key in pairs(defaultConfig) do
+	table.insert(defaultConfigKeys, key)
+end
+
+--[[
+	Merges two tables together into a new table.
+]]
+local function join(a, b)
+	local new = {}
+
+	for key, value in pairs(a) do
+		new[key] = value
+	end
+
+	for key, value in pairs(b) do
+		new[key] = value
+	end
+
+	return new
+end
+
+local Config = {}
+
+function Config.new()
+	local self = {}
+
+	-- Once configuration has been set, we record a traceback.
+	-- That way, if the user mistakenly calls `set` twice, we can point to the
+	-- first place it was called.
+	self._lastConfigTraceback = nil
+
+	self._currentConfig = defaultConfig
+
+	-- We manually bind these methods here so that the Config's methods can be
+	-- used without passing in self, since they eventually get exposed on the
+	-- root Roact object.
+	self.set = function(...)
+		return Config.set(self, ...)
+	end
+
+	self.getValue = function(...)
+		return Config.getValue(self, ...)
+	end
+
+	self.reset = function(...)
+		return Config.reset(self, ...)
+	end
+
+	return self
+end
+
+function Config.set(self, configValues)
+	if self._lastConfigTraceback then
+		local message = (
+			"Global configuration can only be set once. Configuration was already set at:%s"
+		):format(
+			self._lastConfigTraceback
+		)
+
+		error(message, 3)
+	end
+
+	-- We use 3 as our traceback and error level because all of the methods are
+	-- manually bound to 'self', which creates an additional stack frame we want
+	-- to skip through.
+	self._lastConfigTraceback = debug.traceback("", 3)
+
+	-- Validate values without changing any configuration.
+	-- We only want to apply this configuration if it's valid!
+	for key, value in pairs(configValues) do
+		if defaultConfig[key] == nil then
+			local message = (
+				"Invalid global configuration key %q (type %s). Valid configuration keys are: %s"
+			):format(
+				tostring(key),
+				typeof(key),
+				table.concat(defaultConfigKeys, ", ")
+			)
+
+			error(message, 3)
+		end
+
+		-- Right now, all configuration values must be boolean.
+		if typeof(value) ~= "boolean" then
+			local message = (
+				"Invalid value %q (type %s) for global configuration key %q. Valid values are: true, false"
+			):format(
+				tostring(value),
+				typeof(value),
+				tostring(key)
+			)
+
+			error(message, 3)
+		end
+	end
+
+	-- Assign all of the (validated) configuration values in one go.
+	self._currentConfig = join(self._currentConfig, configValues)
+end
+
+function Config.getValue(self, key)
+	if defaultConfig[key] == nil then
+		local message = (
+			"Invalid global configuration key %q (type %s). Valid configuration keys are: %s"
+		):format(
+			tostring(key),
+			typeof(key),
+			table.concat(defaultConfigKeys, ", ")
+		)
+
+		error(message, 3)
+	end
+
+	return self._currentConfig[key]
+end
+
+function Config.reset(self)
+	self._lastConfigTraceback = nil
+	self._currentConfig = defaultConfig
+end
+
+return Config