add a way to add manual dependency tuple to memos and effects

packages/signals/src/dependency.rs

@@ -0,0 +1,67 @@
+/// A dependency is a trait that can be used to determine if a effect or selector should be re-run.
+pub trait Dependency: Sized + Clone {
+    /// The output of the dependency
+    type Out: Clone + PartialEq + 'static;
+    /// Returns the output of the dependency.
+    fn out(&self) -> Self::Out;
+    /// Returns true if the dependency has changed.
+    fn changed(&self, other: &Self::Out) -> bool {
+        self.out() != *other
+    }
+}
+
+impl Dependency for () {
+    type Out = ();
+    fn out(&self) -> Self::Out {}
+}
+
+/// A dependency is a trait that can be used to determine if a effect or selector should be re-run.
+pub trait DependencyElement: 'static + PartialEq + Clone {}
+impl<T> DependencyElement for T where T: 'static + PartialEq + Clone {}
+
+impl<A: DependencyElement> Dependency for &A {
+    type Out = A;
+    fn out(&self) -> Self::Out {
+        (*self).clone()
+    }
+}
+
+macro_rules! impl_dep {
+    (
+        $($el:ident=$name:ident $other:ident,)*
+    ) => {
+        impl< $($el),* > Dependency for ($(&$el,)*)
+        where
+            $(
+                $el: DependencyElement
+            ),*
+        {
+            type Out = ($($el,)*);
+
+            fn out(&self) -> Self::Out {
+                let ($($name,)*) = self;
+                ($((*$name).clone(),)*)
+            }
+
+            fn changed(&self, other: &Self::Out) -> bool {
+                let ($($name,)*) = self;
+                let ($($other,)*) = other;
+                $(
+                    if *$name != $other {
+                        return true;
+                    }
+                )*
+                false
+            }
+        }
+    };
+}
+
+impl_dep!(A = a1 a2,);
+impl_dep!(A = a1 a2, B = b1 b2,);
+impl_dep!(A = a1 a2, B = b1 b2, C = c1 c2,);
+impl_dep!(A = a1 a2, B = b1 b2, C = c1 c2, D = d1 d2,);
+impl_dep!(A = a1 a2, B = b1 b2, C = c1 c2, D = d1 d2, E = e1 e2,);
+impl_dep!(A = a1 a2, B = b1 b2, C = c1 c2, D = d1 d2, E = e1 e2, F = f1 f2,);
+impl_dep!(A = a1 a2, B = b1 b2, C = c1 c2, D = d1 d2, E = e1 e2, F = f1 f2, G = g1 g2,);
+impl_dep!(A = a1 a2, B = b1 b2, C = c1 c2, D = d1 d2, E = e1 e2, F = f1 f2, G = g1 g2, H = h1 h2,);