Draft websocket example 🎉

native/src/subscription.rs

@@ -2,7 +2,6 @@
 use crate::event::{self, Event};
 use crate::Hasher;
 
-use iced_futures::futures::channel::mpsc;
 use iced_futures::futures::{self, Future, Stream};
 use iced_futures::BoxStream;
 
@@ -59,21 +58,9 @@ pub fn events_with<Message>(
 where
     Message: 'static + Send,
 {
-    #[derive(Debug, Clone, Copy, Hash)]
-    struct Events(u64);
-
-    let hash = {
-        use std::hash::Hasher as _;
-
-        let mut hasher = Hasher::default();
-
-        f.hash(&mut hasher);
-
-        hasher.finish()
-    };
-
     Subscription::from_recipe(Runner {
-        initial: Events(hash),
+        id: f,
+        initial: (),
         spawn: move |_, events| {
             use futures::future;
             use futures::stream::StreamExt;
@@ -89,16 +76,19 @@ where
 /// [`Stream`] returned by the provided closure.
 ///
 /// The `initial` state will be used to uniquely identify the [`Subscription`].
-pub fn run<T, S, Message>(
+pub fn run<I, T, S, Message>(
+    id: I,
     initial: T,
     f: impl FnOnce(T) -> S + 'static,
 ) -> Subscription<Message>
 where
-    Message: 'static,
-    T: Clone + Hash + 'static,
+    I: Hash + 'static,
+    T: 'static,
     S: Stream<Item = Message> + Send + 'static,
+    Message: 'static,
 {
     Subscription::from_recipe(Runner {
+        id,
         initial,
         spawn: move |initial, _| f(initial),
     })
@@ -108,79 +98,41 @@ where
 /// [`Stream`] that will call the provided closure to produce every `Message`.
 ///
 /// The `initial` state will be used to uniquely identify the [`Subscription`].
-pub fn unfold<T, Fut, Message>(
+pub fn unfold<I, T, Fut, Message>(
+    id: I,
     initial: T,
     mut f: impl FnMut(T) -> Fut + Send + Sync + 'static,
 ) -> Subscription<Message>
 where
-    Message: 'static,
-    T: Clone + Hash + Send + 'static,
-    Fut: Future<Output = (Message, T)> + Send + 'static,
+    I: Hash + 'static,
+    T: Send + 'static,
+    Fut: Future<Output = (Option<Message>, T)> + Send + 'static,
+    Message: 'static + Send,
 {
-    use futures::future::FutureExt;
-
-    run(initial, move |initial| {
-        futures::stream::unfold(initial, move |state| f(state).map(Some))
-    })
-}
-
-/// Returns a [`Subscription`] that will open a channel and asynchronously run a
-/// [`Stream`] that will call the provided closure to produce every `Message`.
-///
-/// When the [`Subscription`] starts, an `on_ready` message will be produced
-/// containing the [`mpsc::Sender`] end of the channel, which can be used by
-/// the parent application to send `Input` to the running [`Subscription`].
-///
-/// The provided closure should use the [`mpsc::Receiver`] argument to await for
-/// any `Input`.
-///
-/// This function is really useful to create asynchronous workers with
-/// bidirectional communication with a parent application.
-///
-/// The `initial` state will be used to uniquely identify the [`Subscription`].
-pub fn worker<T, Fut, Message, Input>(
-    initial: T,
-    on_ready: impl FnOnce(mpsc::Sender<Input>) -> Message + 'static,
-    f: impl FnMut(T, &mut mpsc::Receiver<Input>) -> Fut + Send + Sync + 'static,
-) -> Subscription<Message>
-where
-    T: Clone + Hash + Send + 'static,
-    Fut: Future<Output = (Message, T)> + Send + 'static,
-    Message: Send + 'static,
-    Input: Send + 'static,
-{
-    use futures::future;
+    use futures::future::{self, FutureExt};
     use futures::stream::StreamExt;
 
-    run(initial, move |initial| {
-        let (sender, receiver) = mpsc::channel(100);
-
-        futures::stream::once(future::ready(on_ready(sender))).chain(
-            futures::stream::unfold(
-                (f, initial, receiver),
-                move |(mut f, state, mut receiver)| async {
-                    let (message, state) = f(state, &mut receiver).await;
-
-                    Some((message, (f, state, receiver)))
-                },
-            ),
-        )
+    run(id, initial, move |initial| {
+        futures::stream::unfold(initial, move |state| f(state).map(Some))
+            .filter_map(future::ready)
     })
 }
 
-struct Runner<T, F, S, Message>
+struct Runner<I, T, F, S, Message>
 where
     F: FnOnce(T, EventStream) -> S,
     S: Stream<Item = Message>,
 {
+    id: I,
     initial: T,
     spawn: F,
 }
 
-impl<T, S, F, Message> Recipe<Hasher, (Event, event::Status)>
-    for Runner<T, F, S, Message>
+impl<I, T, S, F, Message> Recipe<Hasher, (Event, event::Status)>
+    for Runner<I, T, F, S, Message>
 where
-    T: Clone + Hash + 'static,
+    I: Hash + 'static,
+    T: 'static,
     F: FnOnce(T, EventStream) -> S,
     S: Stream<Item = Message> + Send + 'static,
 {
@@ -189,7 +141,7 @@ where
     fn hash(&self, state: &mut Hasher) {
         std::any::TypeId::of::<T>().hash(state);
 
-        self.initial.hash(state);
+        self.id.hash(state);
     }
 
     fn stream(self: Box<Self>, input: EventStream) -> BoxStream<Self::Output> {