feat(ecs): add event loop function to world

2 files changed, 79 insertions, 13 deletions

diff --git a/ecs/src/event.rs b/ecs/src/event.rs
index 0cf6da7..01d9d80 100644
--- a/ecs/src/event.rs
+++ b/ecs/src/event.rs
@@ -2,6 +2,8 @@ use std::any::TypeId;
 use std::fmt::Debug;
 use std::hash::Hash;
 
+use seq_macro::seq;
+
 pub trait Event: Debug + 'static
 {
     fn id(&self) -> Id;
@@ -22,3 +24,49 @@ impl Id
         Self { inner: TypeId::of::<EventT>() }
     }
 }
+
+pub trait Ids
+{
+    type Iter<'a>: Iterator<Item = &'a Id>
+    where
+        Self: 'a;
+
+    fn iter(&self) -> Self::Iter<'_>;
+}
+
+/// A sequence of events.
+pub trait Sequence
+{
+    type Ids: Ids;
+
+    fn ids() -> Self::Ids;
+}
+
+macro_rules! impl_sequence {
+    ($c: tt) => {
+        seq!(I in 0..=$c {
+            impl Ids for [Id; $c + 1]
+            {
+                type Iter<'a> = std::slice::Iter<'a, Id>;
+
+                fn iter(&self) -> Self::Iter<'_> {
+                    self.into_iter()
+                }
+            }
+
+            impl<#(Event~I: Event,)*> Sequence for (#(Event~I,)*) {
+                type Ids = [Id; $c + 1];
+
+                fn ids() -> Self::Ids {
+                    [#(
+                        Id::of::<Event~I>(),
+                    )*]
+                }
+            }
+        });
+    };
+}
+
+seq!(C in 0..=64 {
+    impl_sequence!(C);
+});
diff --git a/ecs/src/lib.rs b/ecs/src/lib.rs
index 4d6e4e5..339a314 100644
--- a/ecs/src/lib.rs
+++ b/ecs/src/lib.rs
@@ -12,7 +12,7 @@ use std::vec::Drain;
 
 use crate::actions::Action;
 use crate::component::{Component, Sequence as ComponentSequence};
-use crate::event::{Event, Id as EventId};
+use crate::event::{Event, Id as EventId, Ids, Sequence as EventSequence};
 use crate::lock::{Lock, ReadGuard};
 use crate::system::{
     NoInitParamFlag as NoInitSystemParamFlag,
@@ -110,18 +110,7 @@ impl World
     /// Will panic if a system has dissapeared.
     pub fn emit(&self, event: &impl Event)
     {
-        let Some(system_indices) = self.data.events.get(&event.id()).cloned() else {
-            return;
-        };
-
-        for system_index in system_indices {
-            let system = self.systems.get(system_index).unwrap();
-
-            // SAFETY: The world data lives long enough
-            unsafe {
-                system.run(&self.data);
-            }
-        }
+        self.emit_event_by_id(event.id());
     }
 
     pub fn query<Comps>(&self) -> Query<Comps>
@@ -166,6 +155,35 @@ impl World
             }
         }
     }
+
+    pub fn event_loop<EventSeq: EventSequence>(&self)
+    {
+        let event_seq = EventSeq::ids();
+
+        loop {
+            for event_id in event_seq.iter() {
+                self.emit_event_by_id(*event_id);
+            }
+
+            self.perform_queued_actions();
+        }
+    }
+
+    fn emit_event_by_id(&self, event_id: EventId)
+    {
+        let Some(system_indices) = self.data.events.get(&event_id) else {
+            return;
+        };
+
+        for system_index in system_indices {
+            let system = self.systems.get(*system_index).unwrap();
+
+            // SAFETY: The world data lives long enough
+            unsafe {
+                system.run(&self.data);
+            }
+        }
+    }
 }
 
 #[derive(Debug, Default)]