feat(engine-ecs): add marker component for soles

1 files changed, 6 insertions, 1 deletions

diff --git a/engine-ecs/src/sole.rs b/engine-ecs/src/sole.rs
index 9168414..cf5283b 100644
--- a/engine-ecs/src/sole.rs
+++ b/engine-ecs/src/sole.rs
@@ -7,7 +7,7 @@ use crate::component::{
     WithAssociatedId as ComponentWithAssociatedId,
 };
 use crate::system::{Metadata as SystemMetadata, Param as SystemParam};
-use crate::World;
+use crate::{Component, World};
 
 /// A component which has a single instance in the [`World`].
 pub trait Sole: Any + IntoComponentParts + ComponentWithAssociatedId
@@ -20,6 +20,11 @@ pub trait Sole: Any + IntoComponentParts + ComponentWithAssociatedId
     fn name(&self) -> &'static str;
 }
 
+/// Marker component for the entities of soles.
+#[derive(Debug, Component)]
+#[non_exhaustive]
+pub struct Is;
+
 /// Holds a reference to a singleton component.
 #[derive(Debug)]
 pub struct Single<'world, SoleT: Sole>