roblox_emulator: refactor nil instances

lib/roblox_emulator/src/context.rs

@@ -13,24 +13,15 @@ pub enum ServicesError{
 pub struct Services{
 	pub(crate) game:Ref,
 	pub(crate) workspace:Ref,
-	pub(crate) nil:Ref,
 }
 
 impl Services{
-	fn get_or_create_services(dom:&mut WeakDom)->Result<Services,ServicesError>{
+	fn find_services(dom:&WeakDom)->Result<Services,ServicesError>{
-		let game=dom.root_ref();
-		// error if workspace does not exist
-		let workspace=*dom.root().children().iter().find(|&&r|
-			dom.get_by_ref(r).is_some_and(|instance|instance.class=="Workspace")
-		).ok_or(ServicesError::WorkspaceNotFound)?;
-		// the root nil instance does not have a parent
-		let nil=dom.insert(Ref::none(),InstanceBuilder::new("Nil")
-			.with_referent(<Ref as std::str::FromStr>::from_str("ffffffffffffffffffffffffffffffff").unwrap())
-		);
 		Ok(Services{
-			game,
+			workspace:*dom.root().children().iter().find(|&&r|
-			workspace,
+				dom.get_by_ref(r).is_some_and(|instance|instance.class=="Workspace")
-			nil,
+			).ok_or(ServicesError::WorkspaceNotFound)?,
+			game:dom.root_ref(),
 		})
 	}
 }
@@ -42,8 +33,8 @@ pub struct Context{
 }
 
 impl Context{
-	pub fn from_place(mut dom:WeakDom)->Result<Context,ServicesError>{
+	pub fn from_place(dom:WeakDom)->Result<Context,ServicesError>{
-		let services=Services::get_or_create_services(&mut dom)?;
+		let services=Services::find_services(&dom)?;
 		Ok(Self{dom,services})
 	}
 	pub fn script_singleton(source:String)->(Context,crate::runner::instance::Instance){
@@ -106,15 +97,9 @@ impl Context{
 			game.properties.insert(static_ustr("workspace"),rbx_types::Variant::Ref(workspace));
 			game.properties.insert(static_ustr("Workspace"),rbx_types::Variant::Ref(workspace));
 		}
-
 		dom.insert(game,InstanceBuilder::new("Lighting"));
 
-		// the root nil instance does not have a parent
+		let services=Services{game,workspace};
-		let nil=dom.insert(Ref::none(),InstanceBuilder::new("Nil")
-			.with_referent(<Ref as std::str::FromStr>::from_str("ffffffffffffffffffffffffffffffff").unwrap())
-		);
-
-		let services=Services{game,workspace,nil};
 		Self{dom,services}
 	}
 }

lib/roblox_emulator/src/runner/instance/instance.rs

@@ -22,9 +22,9 @@ pub fn set_globals(lua:&mlua::Lua,globals:&mlua::Table)->Result<(),mlua::Error>{
 	table.raw_set("new",
 		lua.create_function(|lua,(class_name,parent):(mlua::String,Option<Instance>)|{
 			let class_name_str=&*class_name.to_str()?;
-			let parent=parent.unwrap_or(Instance::nil());
+			let parent_ref=parent.map_or(Ref::none(),|instance|instance.referent);
 			dom_mut(lua,|dom|{
-				Ok(Instance::new_unchecked(dom.insert(parent.referent,InstanceBuilder::new(class_name_str))))
+				Ok(Instance::new_unchecked(dom.insert(parent_ref,InstanceBuilder::new(class_name_str))))
 			})
 		})?
 	)?;
@@ -107,16 +107,7 @@ impl Instance{
 		Self{referent}
 	}
 	pub fn new(referent:Ref)->Option<Self>{
-		match referent=="ffffffffffffffffffffffffffffffff".parse().unwrap(){
+		referent.is_some().then_some(Self{referent})
-			true=>None,
-			false=>Some(Self{referent})
-		}
-	}
-	// Using a sentinel value as a ref for nil instances because global variables are hard.
-	pub fn nil()->Self{
-		Self{
-			referent:"ffffffffffffffffffffffffffffffff".parse().unwrap()
-		}
 	}
 	pub fn get<'a>(&self,dom:&'a WeakDom)->mlua::Result<&'a rbx_dom_weak::Instance>{
 		dom.get_by_ref(self.referent).ok_or_else(||mlua::Error::runtime("Instance missing"))
@@ -137,10 +128,10 @@ impl mlua::UserData for Instance{
 		}
 		fields.add_field_method_get("parent",get_parent);
 		fields.add_field_method_get("Parent",get_parent);
-		fn set_parent(lua:&mlua::Lua,this:&mut Instance,val:Option<Instance>)->mlua::Result<()>{
+		fn set_parent(lua:&mlua::Lua,this:&mut Instance,new_parent:Option<Instance>)->mlua::Result<()>{
-			let parent=val.unwrap_or(Instance::nil());
+			let parent_ref=new_parent.map_or(Ref::none(),|instance|instance.referent);
 			dom_mut(lua,|dom|{
-				dom.transfer_within(this.referent,parent.referent);
+				dom.transfer_within(this.referent,parent_ref);
 				Ok(())
 			})
 		}
@@ -171,7 +162,6 @@ impl mlua::UserData for Instance{
 		fn clone(lua:&mlua::Lua,this:&Instance,_:())->mlua::Result<Instance>{
 			dom_mut(lua,|dom|{
 				let instance_ref=dom.clone_within(this.referent);
-				dom.transfer_within(instance_ref,Instance::nil().referent);
 				Ok(Instance::new_unchecked(instance_ref))
 			})
 		}
@@ -271,7 +261,7 @@ impl mlua::UserData for Instance{
 		methods.add_method("IsA",is_a);
 		methods.add_method("Destroy",|lua,this,()|
 			dom_mut(lua,|dom|{
-				dom.transfer_within(this.referent,Instance::nil().referent);
+				dom.transfer_within(this.referent,Ref::none());
 				Ok(())
 			})
 		);