1 files changed, 45 insertions, 25 deletions

diff --git a/engine-ecs/src/component.rs b/engine-ecs/src/component.rs
index 400b12c..d424e16 100644
--- a/engine-ecs/src/component.rs
+++ b/engine-ecs/src/component.rs
@@ -3,6 +3,7 @@ use std::fmt::Debug;
 use std::ops::{Deref, DerefMut};
 
 use engine_ecs_macros::Component;
+use seq_macro::seq;
 
 use crate::event::component::Changed;
 use crate::event::Submitter as EventSubmitter;
@@ -23,13 +24,9 @@ pub mod local;
 
 pub(crate) mod storage;
 
-pub trait Component: SystemInput + Any + IntoParts
+/// A component that is not a pair and is not a sole.
+pub trait Component: WithAssociatedId + SystemInput + Any + IntoParts
 {
-    /// Returns the ID of this component.
-    fn id() -> Uid
-    where
-        Self: Sized;
-
     fn type_reflection() -> Option<&'static TypeReflection>
     where
         Self: Sized;
@@ -38,32 +35,50 @@ pub trait Component: SystemInput + Any + IntoParts
     fn name(&self) -> &'static str;
 }
 
-impl dyn Component
+pub trait WithAssociatedId
 {
-    pub fn downcast_mut<Real: 'static>(&mut self) -> Option<&mut Real>
-    {
-        (self as &mut dyn Any).downcast_mut()
-    }
+    /// Returns the ID of this component.
+    fn id() -> Uid;
+}
 
-    pub fn downcast_ref<Real: 'static>(&self) -> Option<&Real>
-    {
-        (self as &dyn Any).downcast_ref()
-    }
+/// A component that is removable from it's entity.
+///
+/// This trait is implemented for [`crate::pair::Pair`] so it does not have [`Component`]
+/// as supertrait.
+pub trait Removable: WithAssociatedId {}
 
-    pub fn is<Other: 'static>(&self) -> bool
-    {
-        (self as &dyn Any).is::<Other>()
-    }
-}
+impl<ComponentT: Component> Removable for ComponentT {}
 
-impl Debug for dyn Component
+/// Implemented by tuples of types implementing [`Removable`].
+///
+/// This trait is sealed so it cannot be implemented by types outside of this module.
+pub trait RemovableTuple: sealed::Sealed
 {
-    fn fmt(&self, formatter: &mut std::fmt::Formatter<'_>) -> std::fmt::Result
-    {
-        formatter.debug_struct("Component").finish_non_exhaustive()
-    }
+    fn ids() -> impl IntoIterator<Item = Uid>;
+}
+
+macro_rules! gen_removable_tuple_impl {
+    ($c: tt) => {
+        seq!(I in 0..=$c {
+            impl<#(RemovableT~I: Removable,)*> RemovableTuple for (#(RemovableT~I,)*)
+            {
+                fn ids() -> impl IntoIterator<Item = Uid>
+                {
+                    [#(RemovableT~I::id(),)*]
+                }
+            }
+
+            impl<#(RemovableT~I: Removable,)*> sealed::Sealed for (#(RemovableT~I,)*)
+            {
+            }
+        });
+    };
 }
 
+seq!(C in 0..=16 {
+    gen_removable_tuple_impl!(C);
+});
+
 #[derive(Debug)]
 pub struct Handle<'a, DataT: ?Sized + 'static>
 {
@@ -394,3 +409,8 @@ pub struct Info
     pub name: &'static str,
     pub is_sole: bool,
 }
+
+mod sealed
+{
+    pub trait Sealed {}
+}