add singleton getter

src/ComponentDepot.cs

@@ -50,6 +50,11 @@ internal class ComponentDepot
 		return ref Lookup<TComponent>().Get(entityID);
 	}
 
+	public ref readonly TComponent Get<TComponent>() where TComponent : struct
+	{
+		return ref Lookup<TComponent>().Get();
+	}
+
 	public void Set<TComponent>(int entityID, in TComponent component) where TComponent : struct
 	{
 		Lookup<TComponent>().Set(entityID, component);
@@ -74,6 +79,11 @@ internal class ComponentDepot
 		}
 	}
 
+	public ref readonly Entity GetEntity<TComponent>() where TComponent : struct
+	{
+		return ref Lookup<TComponent>().FirstEntity();
+	}
+
 	public ReadOnlySpan<Entity> ReadEntities<TComponent>() where TComponent : struct
 	{
 		return Lookup<TComponent>().AllEntities();

src/ComponentStorage.cs

@@ -29,6 +29,17 @@ internal class ComponentStorage<TComponent> : ComponentStorage where TComponent
 		return ref components[entityIDToStorageIndex[entityID]];
 	}
 
+	public ref readonly TComponent Get()
+	{
+		#if DEBUG
+		if (nextID == 0)
+		{
+			throw new ArgumentOutOfRangeException("Component storage is empty!");
+		}
+		#endif
+		return ref components[0];
+	}
+
 	public void Set(int entityID, in TComponent component)
 	{
 		if (!entityIDToStorageIndex.ContainsKey(entityID))
@@ -87,4 +98,9 @@ internal class ComponentStorage<TComponent> : ComponentStorage where TComponent
 	{
 		return new ReadOnlySpan<TComponent>(components, 0, nextID);
 	}
+
+	public ref readonly Entity FirstEntity()
+	{
+		return ref storageIndexToEntities[0];
+	}
 }

src/EntityComponentReader.cs

@@ -37,8 +37,18 @@ public abstract class EntityComponentReader
 		return ComponentDepot.Some<TComponent>();
 	}
 
-	protected TComponent Get<TComponent>(in Entity entity) where TComponent : struct
+	protected ref readonly TComponent Get<TComponent>(in Entity entity) where TComponent : struct
 	{
-		return ComponentDepot.Get<TComponent>(entity.ID);
+		return ref ComponentDepot.Get<TComponent>(entity.ID);
+	}
+
+	protected ref readonly TComponent Get<TComponent>() where TComponent : struct
+	{
+		return ref ComponentDepot.Get<TComponent>();
+	}
+
+	protected ref readonly Entity GetEntity<TComponent>() where TComponent : struct
+	{
+		return ref ComponentDepot.GetEntity<TComponent>();
 	}
 }