Add support for trait objects, fix hygiene

Cargo.toml

@@ -1,6 +1,6 @@
 [package]
 name = "eventbus"
-version = "0.3.2"
+version = "0.4.0"
 authors = ["SoniEx2 <endermoneymod@gmail.com>"]
 description = "Safe, fast and concurrent event system, inspired by the MinecraftForge event bus."
 keywords = ["event", "safe", "fast", "concurrent", "bus"]

src/lib.rs

@@ -22,44 +22,69 @@
 #[macro_export]
 macro_rules! register_hook {
     ($b:expr, $p:expr, $t:ty, $h:expr) => {
+        {
+            // hygiene
+            let bus: &$crate::EventBus = $b;
+            let hook = $h;
+            let pri = $p;
             {
                 static EVENT_ID: ::std::sync::atomic::AtomicUsize = std::sync::atomic::ATOMIC_USIZE_INIT;
                 static EVENT_ID_INIT: ::std::sync::Once = std::sync::ONCE_INIT;
                 // no generics allowed.
-            static DUMMY: ::std::marker::PhantomData<$t> = ::std::marker::PhantomData;
+                static DUMMY: ::std::marker::PhantomData<dyn Fn(&mut $t) + Send + Sync> = ::std::marker::PhantomData;
                 EVENT_ID_INIT.call_once(|| {
                     EVENT_ID.store($crate::get_event_id::<$t>(), std::sync::atomic::Ordering::Relaxed);
                 });
                 let id = EVENT_ID.load(std::sync::atomic::Ordering::Relaxed);
-            $crate::register::<$t, _>($b, $p, $h, id)
+                $crate::register::<$t, _>(bus, pri, hook, id)
+            }
         }
     }
 }
 
 /// Posts an event.
 ///
-/// Usage: `post!(bus, type, event)`
+/// Usage: `post_event!(bus, type, event)`
 #[macro_export]
 macro_rules! post_event {
+    // TODO allow multiple $t:ty at once and re-#[doc(hidden)] the low-level get_post_targets and
+    // get_event_id
     ($b:expr, $t:ty, $e:expr) => {
         {
-            static EVENT_ID: ::std::sync::atomic::AtomicUsize = std::sync::atomic::ATOMIC_USIZE_INIT;
-            static EVENT_ID_INIT: ::std::sync::Once = std::sync::ONCE_INIT;
+            // hygiene
+            let bus: &$crate::EventBus = $b;
+            // event setup, this may evaluate to any type.
+            let event: &mut _ = $e;
+            {
+                // it is a logic error for an event's cancellability to change based on its value.
+                static CANCELLABLE: ::std::sync::atomic::AtomicBool = ::std::sync::atomic::ATOMIC_BOOL_INIT;
+                static CANCELLABLE_INIT: ::std::sync::Once = ::std::sync::ONCE_INIT;
+                CANCELLABLE_INIT.call_once(|| {
+                    CANCELLABLE.store(<$crate::Event>::cancellable(event), std::sync::atomic::Ordering::Relaxed);
+                });
+                let cancellable = CANCELLABLE.load(std::sync::atomic::Ordering::Relaxed);
+
+                // event type setup
+                static EVENT_ID: ::std::sync::atomic::AtomicUsize = ::std::sync::atomic::ATOMIC_USIZE_INIT;
+                static EVENT_ID_INIT: ::std::sync::Once = ::std::sync::ONCE_INIT;
                 // no generics allowed.
-            static DUMMY: ::std::marker::PhantomData<$t> = ::std::marker::PhantomData;
+                static DUMMY: ::std::marker::PhantomData<dyn Fn(&mut $t) + Send + Sync> = ::std::marker::PhantomData;
                 EVENT_ID_INIT.call_once(|| {
                     EVENT_ID.store($crate::get_event_id::<$t>(), std::sync::atomic::Ordering::Relaxed);
                 });
                 let id = EVENT_ID.load(std::sync::atomic::Ordering::Relaxed);
-            let event: &mut $t = $e;
-            let handlers = $crate::get_post_targets::<$t>($b, event, id);
+
+                // handler retrieval and invokation
+                let event: &mut $t = event;
+                let handlers = $crate::get_post_targets::<$t>(bus, event, id);
                 for (_pri, fun) in handlers.iter() {
                     fun(event);
-                if <$t as $crate::Event>::cancellable() && <$t as $crate::Event>::cancelled(event) {
+                    if cancellable && <$t as $crate::Event>::cancelled(event) {
                         break;
                     }
                 }
-            <$t as $crate::Event>::cancellable() && <$t as $crate::Event>::cancelled(event)
+                cancellable && <$t as $crate::Event>::cancelled(event)
+            }
         }
     }
 }
@@ -69,7 +94,11 @@ pub trait Event: 'static {
     /// Returns whether this event is cancellable.
     ///
     /// When this is true, `cancelled` and `cancel` should also be implemented.
-    fn cancellable() -> bool {
+    ///
+    /// Note: While this method does take a `&self`, it's a logic error for an event's
+    /// cancellability to change based on its value. The `&self` is just for trait objectification.
+    /// You have been warned!
+    fn cancellable(&self) -> bool {
         false
     }
 
@@ -84,6 +113,7 @@ pub trait Event: 'static {
     ///
     /// Panics if this event is not cancellable.
     fn set_cancelled(&mut self, cancel: bool) {
+        let _ = cancel;
         panic!("not cancellable");
     }
 }
@@ -122,12 +152,12 @@ mod id_map {
     lazy_static! {
         static ref EVENT_ID_MAP: Mutex<::anymap::Map<::anymap::any::Any + Send + Sync>> = Mutex::new(::anymap::Map::new());
     }
-    struct EventId<T: Event> {
+    struct EventId<T: Event + ?Sized> {
         id: usize,
         _t: PhantomData<dyn Fn(&mut T) + Send + Sync>
     }
 
-    pub fn get_event_id<T: Event>() -> usize {
+    pub fn get_event_id<T: Event + ?Sized>() -> usize {
         static EVENT_ID_COUNT: AtomicUsize = ATOMIC_USIZE_INIT;
         let id = EVENT_ID_MAP.lock().expect("failed to allocate event id").entry::<EventId<T>>().or_insert_with(|| EventId { id: EVENT_ID_COUNT.fetch_add(1, AtomicOrdering::SeqCst), _t: PhantomData }).id;
         let handlers: Arc<Handlers<T>> = Default::default();
@@ -139,15 +169,15 @@ mod id_map {
 /// Low-level event handling function, returns the event ID for use with get_post_targets.
 ///
 /// This function is (extremely) slow!
-pub fn get_event_id<T: Event>() -> usize {
+pub fn get_event_id<T: Event + ?Sized>() -> usize {
     id_map::get_event_id::<T>()
 }
 
 type RwArcVec<T> = RwLock<Arc<Vec<T>>>;
 
-struct Handlers<T: Event>(RwArcVec<RwArcVec<(i32, Arc<dyn Fn(&mut T) + Send + Sync>)>>);
+struct Handlers<T: Event + ?Sized>(RwArcVec<RwArcVec<(i32, Arc<dyn Fn(&mut T) + Send + Sync>)>>);
 
-impl<T: Event> Default for Handlers<T> {
+impl<T: Event + ?Sized> Default for Handlers<T> {
     fn default() -> Self {
         Handlers(Default::default())
     }
@@ -165,7 +195,7 @@ lazy_static! {
 /// # Panics
 ///
 /// Panics if `id` doesn't match the given `T` (but not if the given `id` doesn't exist).
-pub fn get_post_targets<T: Event>(bus: &EventBus, event: &mut T, id: usize) -> Arc<Vec<(i32, Arc<dyn Fn(&mut T) + Send + Sync>)>> {
+pub fn get_post_targets<T: Event + ?Sized>(bus: &EventBus, _event: &mut T, id: usize) -> Arc<Vec<(i32, Arc<dyn Fn(&mut T) + Send + Sync>)>> {
     let target: Option<Arc<Vec<_>>> = HANDLERS.read().expect("failed to lock for reading").get(id).map(|arc| Arc::clone(arc))
         .map(|any| Arc::downcast::<Handlers<T>>(any).expect("Wrong id"))
         .and_then(|handlers| handlers.0.read().expect("failed to lock for reading").get(bus.id).map(|hooks| Arc::clone(&*hooks.read().expect("failed to lock for reading"))));
@@ -180,7 +210,7 @@ pub fn get_post_targets<T: Event>(bus: &EventBus, event: &mut T, id: usize) -> A
 /// # Panics
 ///
 /// Panics if `id` doesn't match the given `T`, or if `id` doesn't exist.
-pub fn register<T: Event, F: for<'a> Fn(&'a mut T) + Send + Sync + 'static>(bus: &EventBus, priority: i32, handler: F, id: usize) {
+pub fn register<T: Event + ?Sized, F: for<'a> Fn(&'a mut T) + Send + Sync + 'static>(bus: &EventBus, priority: i32, handler: F, id: usize) {
     HANDLERS.read().expect("failed to lock for reading").get(id).map(|arc| Arc::clone(arc))
         .map(|any| Arc::downcast::<Handlers<T>>(any).expect("Wrong id"))
         .map(|handlers| {

tests/compile-fail/README

@@ -0,0 +1 @@
+These are currently not being automatically tested because compiletest_rs doesn't work on stable.

tests/compile-fail/hygiene.rs

@@ -0,0 +1,18 @@
+#[macro_use]
+extern crate eventbus;
+
+use eventbus::{Event, EventBus};
+
+struct MyEvent {
+    i: i32
+}
+
+impl Event for MyEvent {
+}
+
+#[test]
+fn test_hygiene() {
+    let bus = [EventBus::new()];
+    let mut event = MyEvent { i: 3 };
+    post_event!(&bus[EVENT_ID.load(::std::sync::atomic::Ordering::Relaxed)], MyEvent, &mut event);
+}

tests/dyn_events.rs

@@ -0,0 +1,53 @@
+#[macro_use]
+extern crate eventbus;
+
+use eventbus::{Event, EventBus};
+
+trait MyEvent : Event {
+    fn get_i(&self) -> i32;
+    fn set_i(&mut self, i32);
+}
+
+struct MyEventImpl {
+    i: i32
+}
+
+impl Event for MyEventImpl {
+}
+impl MyEvent for MyEventImpl {
+    fn get_i(&self) -> i32 {
+        self.i
+    }
+    fn set_i(&mut self, i: i32) {
+        self.i = i;
+    }
+}
+
+fn add_handler(e: &mut MyEvent) {
+    /* adds 1 */
+    let i = e.get_i();
+    e.set_i(i+1);
+}
+
+fn no_handler(e: &mut MyEvent) {
+    /* does nothing */
+    let i = e.get_i();
+    e.set_i(i);
+}
+
+#[test]
+fn test_dyn_usage() {
+    let event_bus = EventBus::new();
+    //let handler_id = event_bus.register(add_handler, 0);
+    register_hook!(&event_bus, 0, dyn MyEvent, add_handler);
+    let mut event = MyEventImpl { i: 3 };
+    assert_eq!(event.i, 3);
+    post_event!(&event_bus, dyn MyEvent, &mut event);
+    assert_eq!(event.i, 4);
+    register_hook!(&event_bus, 1, dyn MyEvent, no_handler);
+    post_event!(&event_bus, dyn MyEvent, &mut event);
+    assert_eq!(event.i, 5);
+    //event_bus.unregister(handler_id);
+    post_event!(&event_bus, dyn MyEvent, &mut event);
+    //assert_eq!(event.i, 5);
+}