some cleanup and naming changes to main loop, game context boilerplate

maybe sort of better?

libretrogd/src/base/mod.rs

@@ -7,12 +7,10 @@ use crate::events::*;
 use crate::states::*;
 use crate::system::*;
 
-pub trait PrimaryState {
+pub trait CoreState {
 	fn system(&self) -> &System;
 	fn system_mut(&mut self) -> &mut System;
-}
 
-pub trait PrimaryStateWithFrameTiming: PrimaryState {
 	fn delta(&self) -> f32;
 	fn set_delta(&mut self, delta: f32);
 
@@ -25,33 +23,29 @@ pub trait PrimaryStateWithFrameTiming: PrimaryState {
 	}
 }
 
-pub trait PrimaryStateWithEvents<EventType>: PrimaryState {
+pub trait CoreStateWithEvents<EventType>: CoreState {
 	fn event_publisher(&mut self) -> &mut EventPublisher<EventType>;
 }
 
 pub trait SupportSystems {}
 
-pub trait SupportSystemsWithEvents<EventType, ContextType>: SupportSystems
-where
-	ContextType: PrimaryStateWithEvents<EventType>,
+pub trait SupportSystemsWithEvents<EventType>: SupportSystems
 {
-	fn event_listeners(&mut self) -> &mut EventListeners<EventType, ContextType>;
+	type ContextType: CoreStateWithEvents<EventType>;
+	fn event_listeners(&mut self) -> &mut EventListeners<EventType, Self::ContextType>;
 
-	fn do_events(&mut self, context: &mut ContextType) {
+	fn do_events(&mut self, context: &mut Self::ContextType) {
 		self.event_listeners().take_queue_from(context.event_publisher());
 		self.event_listeners().dispatch_queue(context);
 	}
 }
 
-pub struct App<PrimaryType, SupportType> {
-	pub primary_state: PrimaryType,
-	pub support_systems: SupportType,
-}
+pub trait AppContext {
+	type CoreType: CoreState;
+	type SupportType: SupportSystems;
 
-impl<PrimaryType, SupportType> App<PrimaryType, SupportType> {
-	pub fn new(primary_state: PrimaryType, support_systems: SupportType) -> Self {
-		App { primary_state, support_systems }
-	}
+	fn core(&mut self) -> &mut Self::CoreType;
+	fn support(&mut self) -> &mut Self::SupportType;
 }
 
 #[derive(Error, Debug)]
@@ -63,35 +57,32 @@ pub enum MainLoopError {
 	SystemError(#[from] SystemError),
 }
 
-pub fn main_loop<PrimaryType, SupportType, State>(
-	primary_state: PrimaryType,
-	support_systems: SupportType,
+pub fn main_loop<ContextType, State>(
+	mut app: ContextType,
 	initial_state: State,
 ) -> Result<(), MainLoopError>
 where
-	PrimaryType: PrimaryStateWithFrameTiming,
-	SupportType: SupportSystems,
-	State: AppState<App<PrimaryType, SupportType>> + 'static,
+	ContextType: AppContext,
+	State: AppState<ContextType> + 'static,
 {
-	let mut app = App::new(primary_state, support_systems);
 	let mut states = States::new();
 	states.push(initial_state)?;
 
 	let mut is_running = true;
-	let mut last_ticks = app.primary_state.system().ticks();
+	let mut last_ticks = app.core().system().ticks();
 
 	while is_running && !states.is_empty() {
-		app.primary_state.system_mut().do_events_with(|event| match event {
+		app.core().system_mut().do_events_with(|event| match event {
 			SystemEvent::Quit => {
 				is_running = false;
 			}
 			_ => {}
 		});
 
-		last_ticks = app.primary_state.update_frame_delta(last_ticks);
+		last_ticks = app.core().update_frame_delta(last_ticks);
 		states.update(&mut app)?;
 		states.render(&mut app);
-		app.primary_state.system_mut().display()?;
+		app.core().system_mut().display()?;
 	}
 
 	Ok(())