wip: associated values store

src/runner/instance.rs

@@ -482,3 +482,58 @@ fn find_virtual_property(
 	//Transform Source property with provided function
 	(virtual_property.pointer)(variant)
 }
+
+// lazy-loaded per-instance userdata values
+// This whole thing is a bad idea and a garbage collection nightmare.
+// TODO: recreate rbx_dom_weak with my own instance type that owns this data.
+type CreateUserData=fn(&mlua::Lua)->mlua::Result<mlua::AnyUserData>;
+type LUD=phf::Map<&'static str,// Class name
+	phf::Map<&'static str,// Value name
+		CreateUserData
+	>
+>;
+static LAZY_USER_DATA:LUD=phf::phf_map!{
+	"RunService"=>phf::phf_map!{
+		"RenderStepped"=>|lua|{
+			lua.create_any_userdata(super::script_signal::ScriptSignal::new())
+		},
+	},
+};
+struct InstanceValueStore{
+	values:HashMap<Ref,
+		HashMap<&'static str,
+			mlua::AnyUserData
+		>
+	>,
+}
+struct InstanceValues<'a>{
+	named_values:&'static phf::Map<&'static str,CreateUserData>,
+	values:&'a mut HashMap<&'static str,mlua::AnyUserData>,
+}
+impl InstanceValueStore{
+	fn get_or_create_instance_values(&mut self,instance:&rbx_dom_weak::Instance)->Option<InstanceValues>{
+		LAZY_USER_DATA.get(instance.class.as_str())
+			.map(|named_values|
+				InstanceValues{
+					named_values,
+					values:self.values.entry(instance.referent())
+					.or_insert_with(||HashMap::new()),
+				}
+			)
+	}
+}
+impl InstanceValues<'_>{
+	fn get_or_create_value(&mut self,lua:&mlua::Lua,index:&str)->mlua::Result<Option<mlua::AnyUserData>>{
+		Ok(match self.named_values.get_entry(index){
+			Some((&static_index_str,&function_pointer))=>Some(
+				match self.values.entry(static_index_str){
+					Entry::Occupied(entry)=>entry.get().clone(),
+					Entry::Vacant(entry)=>entry.insert(
+						function_pointer(lua)?
+					).clone(),
+				}
+			),
+			None=>None,
+		})
+	}
+}