refactor(ecs): make ObserveIter return EventMatch struct

3 files changed, 36 insertions, 8 deletions

diff --git a/ecs/examples/component_changed_event.rs b/ecs/examples/component_changed_event.rs
index f707255..6dde384 100644
--- a/ecs/examples/component_changed_event.rs
+++ b/ecs/examples/component_changed_event.rs
@@ -32,8 +32,12 @@ fn print_changed_greetings(observe: Observe<'_, Pair<Changed, Greeting>>)
 {
     println!("\nChanged greetings:");
 
-    for ent in &observe {
-        let Some(greeting) = ent.get::<Greeting>() else {
+    for evt_match in &observe {
+        let Some(changed_ent) = evt_match.get_entity() else {
+            continue;
+        };
+
+        let Some(greeting) = changed_ent.get::<Greeting>() else {
             unreachable!();
         };
 
diff --git a/ecs/examples/component_removed_event.rs b/ecs/examples/component_removed_event.rs
index ffa37f4..e8d1a47 100644
--- a/ecs/examples/component_removed_event.rs
+++ b/ecs/examples/component_removed_event.rs
@@ -20,8 +20,8 @@ fn eat_cheese(query: Query<(&Cheese,)>, mut actions: Actions)
 
 fn on_cheese_removed(observe: Observe<Pair<Removed, Cheese>>)
 {
-    for cheese_ent in &observe {
-        println!("Cheese entity {} was eaten", cheese_ent.uid());
+    for evt_match in &observe {
+        println!("Cheese entity {} was eaten", evt_match.id());
     }
 }
 
diff --git a/ecs/src/system/observer.rs b/ecs/src/system/observer.rs
index 1496d40..b7d84be 100644
--- a/ecs/src/system/observer.rs
+++ b/ecs/src/system/observer.rs
@@ -94,7 +94,7 @@ impl<ObservedT: Observed> Observe<'_, ObservedT>
 impl<'a, ObservedT: Observed> IntoIterator for &'a Observe<'_, ObservedT>
 {
     type IntoIter = ObserveIter<'a>;
-    type Item = EntityHandle<'a>;
+    type Item = <Self::IntoIter as Iterator>::Item;
 
     fn into_iter(self) -> Self::IntoIter
     {
@@ -110,13 +110,37 @@ pub struct ObserveIter<'observe>
 
 impl<'observe> Iterator for ObserveIter<'observe>
 {
-    type Item = EntityHandle<'observe>;
+    type Item = EventMatch<'observe>;
 
     fn next(&mut self) -> Option<Self::Item>
     {
-        let target = *self.inner.next()?;
+        let match_id = *self.inner.next()?;
 
-        self.world.get_entity(target)
+        Some(EventMatch { world: self.world, id: match_id })
+    }
+}
+
+/// A event match.
+#[derive(Debug)]
+pub struct EventMatch<'world>
+{
+    world: &'world World,
+    id: Uid,
+}
+
+impl<'world> EventMatch<'world>
+{
+    #[must_use]
+    pub fn id(&self) -> Uid
+    {
+        self.id
+    }
+
+    /// Attempts to get the entity with the id of this match.
+    #[must_use]
+    pub fn get_entity(&self) -> Option<EntityHandle<'world>>
+    {
+        self.world.get_entity(self.id)
     }
 }