feat(ecs): add support for entities without components

1 files changed, 48 insertions, 0 deletions

diff --git a/ecs/src/component.rs b/ecs/src/component.rs
index 85c556f..1fde5b4 100644
--- a/ecs/src/component.rs
+++ b/ecs/src/component.rs
@@ -351,3 +351,51 @@ macro_rules! inner {
 seq!(C in 0..=64 {
     inner!(C);
 });
+
+impl Sequence for ()
+{
+    type MutRefs<'component> = ();
+    type Refs<'component> = ();
+
+    fn into_vec(self) -> Vec<Box<dyn Component>>
+    {
+        Vec::new()
+    }
+
+    fn metadata() -> Vec<Metadata>
+    {
+        Vec::new()
+    }
+
+    fn added_event_ids() -> Vec<Uid>
+    {
+        Vec::new()
+    }
+
+    fn removed_event_ids() -> Vec<Uid>
+    {
+        Vec::new()
+    }
+
+    #[inline]
+    fn from_components_mut<'component>(
+        _components: &'component [EntityComponent],
+        _component_index_lookup: impl Fn(Uid) -> Option<usize>,
+        _world: &'component World,
+        _lock_component: fn(&EntityComponent) -> WriteGuard<'_, Box<dyn Component>>,
+    ) -> Self::MutRefs<'component>
+    {
+        ()
+    }
+
+    #[inline]
+    fn from_components<'component>(
+        _components: &'component [EntityComponent],
+        _component_index_lookup: impl Fn(Uid) -> Option<usize>,
+        _world: &'component World,
+        _lock_component: fn(&EntityComponent) -> ReadGuard<'_, Box<dyn Component>>,
+    ) -> Self::Refs<'component>
+    {
+        ()
+    }
+}