embassy-futures: add select 5 and 6

embassy-futures/src/select.rs

@@ -188,6 +188,169 @@ where
 
 // ====================================================================
 
+/// Result for [`select5`].
+#[derive(Debug, Clone)]
+#[cfg_attr(feature = "defmt", derive(defmt::Format))]
+pub enum Either5<A, B, C, D, E> {
+    /// First future finished first.
+    First(A),
+    /// Second future finished first.
+    Second(B),
+    /// Third future finished first.
+    Third(C),
+    /// Fourth future finished first.
+    Fourth(D),
+    /// Fifth future finished first.
+    Fifth(E),
+}
+
+/// Same as [`select`], but with more futures.
+pub fn select5<A, B, C, D, E>(a: A, b: B, c: C, d: D, e: E) -> Select5<A, B, C, D, E>
+where
+    A: Future,
+    B: Future,
+    C: Future,
+    D: Future,
+    E: Future,
+{
+    Select5 { a, b, c, d, e }
+}
+
+/// Future for the [`select5`] function.
+#[derive(Debug)]
+#[must_use = "futures do nothing unless you `.await` or poll them"]
+pub struct Select5<A, B, C, D, E> {
+    a: A,
+    b: B,
+    c: C,
+    d: D,
+    e: E,
+}
+
+impl<A, B, C, D, E> Future for Select5<A, B, C, D, E>
+where
+    A: Future,
+    B: Future,
+    C: Future,
+    D: Future,
+    E: Future,
+{
+    type Output = Either5<A::Output, B::Output, C::Output, D::Output, E::Output>;
+
+    fn poll(self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<Self::Output> {
+        let this = unsafe { self.get_unchecked_mut() };
+        let a = unsafe { Pin::new_unchecked(&mut this.a) };
+        let b = unsafe { Pin::new_unchecked(&mut this.b) };
+        let c = unsafe { Pin::new_unchecked(&mut this.c) };
+        let d = unsafe { Pin::new_unchecked(&mut this.d) };
+        let e = unsafe { Pin::new_unchecked(&mut this.e) };
+        if let Poll::Ready(x) = a.poll(cx) {
+            return Poll::Ready(Either5::First(x));
+        }
+        if let Poll::Ready(x) = b.poll(cx) {
+            return Poll::Ready(Either5::Second(x));
+        }
+        if let Poll::Ready(x) = c.poll(cx) {
+            return Poll::Ready(Either5::Third(x));
+        }
+        if let Poll::Ready(x) = d.poll(cx) {
+            return Poll::Ready(Either5::Fourth(x));
+        }
+        if let Poll::Ready(x) = e.poll(cx) {
+            return Poll::Ready(Either5::Fifth(x));
+        }
+        Poll::Pending
+    }
+}
+
+// ====================================================================
+
+/// Result for [`select6`].
+#[derive(Debug, Clone)]
+#[cfg_attr(feature = "defmt", derive(defmt::Format))]
+pub enum Either6<A, B, C, D, E, F> {
+    /// First future finished first.
+    First(A),
+    /// Second future finished first.
+    Second(B),
+    /// Third future finished first.
+    Third(C),
+    /// Fourth future finished first.
+    Fourth(D),
+    /// Fifth future finished first.
+    Fifth(E),
+    /// Sixth future finished first.
+    Sixth(F),
+}
+
+/// Same as [`select`], but with more futures.
+pub fn select6<A, B, C, D, E, F>(a: A, b: B, c: C, d: D, e: E, f: F) -> Select6<A, B, C, D, E, F>
+where
+    A: Future,
+    B: Future,
+    C: Future,
+    D: Future,
+    E: Future,
+    F: Future,
+{
+    Select6 { a, b, c, d, e, f }
+}
+
+/// Future for the [`select6`] function.
+#[derive(Debug)]
+#[must_use = "futures do nothing unless you `.await` or poll them"]
+pub struct Select6<A, B, C, D, E, F> {
+    a: A,
+    b: B,
+    c: C,
+    d: D,
+    e: E,
+    f: F,
+}
+
+impl<A, B, C, D, E, F> Future for Select6<A, B, C, D, E, F>
+where
+    A: Future,
+    B: Future,
+    C: Future,
+    D: Future,
+    E: Future,
+    F: Future,
+{
+    type Output = Either6<A::Output, B::Output, C::Output, D::Output, E::Output, F::Output>;
+
+    fn poll(self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<Self::Output> {
+        let this = unsafe { self.get_unchecked_mut() };
+        let a = unsafe { Pin::new_unchecked(&mut this.a) };
+        let b = unsafe { Pin::new_unchecked(&mut this.b) };
+        let c = unsafe { Pin::new_unchecked(&mut this.c) };
+        let d = unsafe { Pin::new_unchecked(&mut this.d) };
+        let e = unsafe { Pin::new_unchecked(&mut this.e) };
+        let f = unsafe { Pin::new_unchecked(&mut this.f) };
+        if let Poll::Ready(x) = a.poll(cx) {
+            return Poll::Ready(Either6::First(x));
+        }
+        if let Poll::Ready(x) = b.poll(cx) {
+            return Poll::Ready(Either6::Second(x));
+        }
+        if let Poll::Ready(x) = c.poll(cx) {
+            return Poll::Ready(Either6::Third(x));
+        }
+        if let Poll::Ready(x) = d.poll(cx) {
+            return Poll::Ready(Either6::Fourth(x));
+        }
+        if let Poll::Ready(x) = e.poll(cx) {
+            return Poll::Ready(Either6::Fifth(x));
+        }
+        if let Poll::Ready(x) = f.poll(cx) {
+            return Poll::Ready(Either6::Sixth(x));
+        }
+        Poll::Pending
+    }
+}
+
+// ====================================================================
+
 /// Future for the [`select_array`] function.
 #[derive(Debug)]
 #[must_use = "futures do nothing unless you `.await` or poll them"]