Make GuiData more lean

exp_gui/module/data.lua

@@ -6,15 +6,20 @@ This is not limited to GUI element definitions but this is the most common use c
 local ExpUtil = require("modules/exp_util")
 local Storage = require("modules/exp_util/storage")
 
---- @type table<string, ExpGui.GuiData>
+--- @type table<string, ExpGui.GuiData_Raw>
+local scope_data = {}
+
+--- @type table<string, ExpGui.GuiData_Internal>
 local registered_scopes = {}
 
 --- @type table<uint, uint> Reg -> Player Index
 local registration_numbers = {}
 local reg_obj = script.register_on_object_destroyed
 
---- @type table<string, [table<uint, table<uint, any>>, table<uint, any>, table<uint, any>, table]>
-local scope_data = {}
+--- @alias DataKey LuaGuiElement | LuaPlayer | LuaForce
+--- @alias DataKeys "element_data" | "player_data" | "force_data" | "global_data"
+local DataKeys = ExpUtil.enum{ "element_data", "player_data", "force_data", "global_data" }
+local DataKeysConcat = table.concat(DataKeys, ", ")
 
 Storage.register({
     scope_data = scope_data,
@@ -24,10 +29,10 @@ Storage.register({
     for scope, data in pairs(tbl.scope_data) do
         local proxy = registered_scopes[scope]
         if proxy then
-            proxy.element_data = data[1]
-            proxy.player_data = data[2]
-            proxy.force_data = data[3]
-            proxy.global_data = data[4]
+            rawset(proxy, "_raw", data)
+            for k, v in pairs(data) do
+                rawset(proxy, k, v)
+            end
         end
     end
 end)
@@ -37,43 +42,68 @@ local GuiData = {
     _scopes = registered_scopes,
 }
 
---- @alias DataKey LuaGuiElement | LuaPlayer | LuaForce
+--- @class ExpGui.GuiData_Raw
+--- @field element_data table<uint, table<uint, any>?>?
+--- @field player_data table<uint, any>?
+--- @field force_data table<uint, any>?
+--- @field global_data table?
+-- This class has no prototype methods
+-- Keep this in sync with DataKeys to block arbitrary strings
 
---- @class ExpGui.GuiData: table<DataKey, any>
+--- @class ExpGui.GuiData_Internal
 --- @field _scope string
---- @field _owner any
+--- @field _raw ExpGui.GuiData_Raw
+-- This class has no prototype methods
+-- Do add keys to _raw without also referencing scope_data
+
+--- @class ExpGui.GuiData: table
 --- @field element_data table<uint, table<uint, any>>
 --- @field player_data table<uint, any>
 --- @field force_data table<uint, any>
 --- @field global_data table
 -- This class has no prototype methods
+-- Same as raw but __index ensures the values exist
 
 GuiData._metatable = {
     __class = "GuiData",
 }
 
-Storage.register_metatable(GuiData._metatable.__class, GuiData._metatable)
-
 --- Return the index for a given key
---- @param self ExpGui.GuiData
---- @param key DataKey
+--- @param self ExpGui.GuiData_Internal
+--- @param key DataKeys | DataKey
 --- @return any
 function GuiData._metatable.__index(self, key)
+    if type(key) == "string" then
+        -- This is only called when the key does not exist, ie it is not in storage
+        -- Once created, these tables are never removed as they are likely to be used again
+        assert(DataKeys[key], "Valid keys are: " .. DataKeysConcat)
+        local value = {}
+        self._raw[key] = value
+        rawset(self, key, value)
+        scope_data[self._scope] = self._raw
+        return value
+    end
+
+    -- Check a given child table based on the object type
     assert(type(key) == "userdata", "Index type '" .. ExpUtil.get_class_name(key) .. "' given to GuiData. Must be of type userdata.")
     local object_name = key.object_name
     if object_name == "LuaGuiElement" then
-        local player_elements = self.element_data[key.player_index]
+        local data = self._raw.element_data
+        local player_elements = data and data[key.player_index]
         return player_elements and player_elements[key.index]
     elseif object_name == "LuaPlayer" then
-        return self.player_data[key.index]
+        local data = self._raw.player_data
+        return data and data[key.index]
     elseif object_name == "LuaForce" then
-        return self.force_data[key.index]
+        local data = self._raw.force_data
+        return data and data[key.index]
     else
         error("Unsupported object class '" .. object_name .. "' given as index to GuiData.")
     end
 end
 
 --- Set the value index of a given key
+-- Internal type is not used here to allow for creation of storage
 --- @param self ExpGui.GuiData
 --- @param key DataKey
 --- @param value unknown
@@ -81,10 +111,11 @@ function GuiData._metatable.__newindex(self, key, value)
     assert(type(key) == "userdata", "Index type '" .. ExpUtil.get_class_name(key) .. "' given to GuiData. Must be of type userdata.")
     local object_name = key.object_name
     if object_name == "LuaGuiElement" then
-        local player_elements = self.element_data[key.player_index]
+        local data = self.element_data
+        local player_elements = data[key.player_index]
         if not player_elements then
             player_elements = {}
-            self.element_data[key.player_index] = player_elements
+            data[key.player_index] = player_elements
         end
         player_elements[key.index] = value
         registration_numbers[reg_obj(key)] = key.player_index
@@ -106,20 +137,11 @@ function GuiData.create(scope)
 
     local instance = {
         _scope = scope,
-        element_data = {},
-        player_data = {},
-        force_data = {},
-        global_data = {},
-    }
-
-    scope_data[scope] = {
-        instance.element_data,
-        instance.player_data,
-        instance.force_data,
-        instance.global_data,
+        _raw = {},
     }
 
     GuiData._scopes[scope] = instance
+    --- @cast instance ExpGui.GuiData
     return setmetatable(instance, GuiData._metatable)
 end
 
@@ -127,7 +149,7 @@ end
 --- @param scope string
 --- @return ExpGui.GuiData
 function GuiData.get(scope)
-    return GuiData._scopes[scope]
+    return GuiData._scopes[scope] --[[ @as ExpGui.GuiData ]]
 end
 
 --- Used to clean up data from destroyed elements
@@ -140,9 +162,13 @@ local function on_object_destroyed(event)
     registration_numbers[event.registration_number] = nil
 
     for _, scope in pairs(registered_scopes) do
-        local player_elements = scope.element_data[player_index]
+        local data = scope._raw.element_data
+        local player_elements = data and data[player_index]
         if player_elements then
             player_elements[element_index] = nil
+            if not next(player_elements) then
+                data[player_index] = nil
+            end
         end
     end
 end
@@ -152,7 +178,10 @@ end
 local function on_player_removed(event)
     local player_index = event.player_index
     for _, scope in pairs(registered_scopes) do
-        scope.player_data[player_index] = nil
+        local data = scope._raw.player_data
+        if data then
+            data[player_index] = nil
+        end
     end
 end
 
@@ -161,7 +190,10 @@ end
 local function on_forces_merged(event)
     local force_index = event.source_index
     for _, scope in pairs(registered_scopes) do
-        scope.force_data[force_index] = nil
+        local data = scope._raw.force_data
+        if data then
+            data[force_index] = nil
+        end
     end
 end