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-rw-r--r--futures/src/subscription.rs349
1 files changed, 175 insertions, 174 deletions
diff --git a/futures/src/subscription.rs b/futures/src/subscription.rs
index 5ec39582..1a0d454d 100644
--- a/futures/src/subscription.rs
+++ b/futures/src/subscription.rs
@@ -5,11 +5,9 @@ pub use tracker::Tracker;
use crate::core::event;
use crate::core::window;
-use crate::futures::{Future, Stream};
+use crate::futures::Stream;
use crate::{BoxStream, MaybeSend};
-use futures::channel::mpsc;
-use futures::never::Never;
use std::any::TypeId;
use std::hash::Hash;
@@ -61,20 +59,66 @@ pub type Hasher = rustc_hash::FxHasher;
/// A request to listen to external events.
///
-/// Besides performing async actions on demand with `Command`, most
+/// Besides performing async actions on demand with `Task`, most
/// applications also need to listen to external events passively.
///
-/// A [`Subscription`] is normally provided to some runtime, like a `Command`,
+/// A [`Subscription`] is normally provided to some runtime, like a `Task`,
/// and it will generate events as long as the user keeps requesting it.
///
/// For instance, you can use a [`Subscription`] to listen to a `WebSocket`
/// connection, keyboard presses, mouse events, time ticks, etc.
+///
+/// # The Lifetime of a [`Subscription`]
+/// Much like a [`Future`] or a [`Stream`], a [`Subscription`] does not produce any effects
+/// on its own. For a [`Subscription`] to run, it must be returned to the iced runtime—normally
+/// in the `subscription` function of an `application` or a `daemon`.
+///
+/// When a [`Subscription`] is provided to the runtime for the first time, the runtime will
+/// start running it asynchronously. Running a [`Subscription`] consists in building its underlying
+/// [`Stream`] and executing it in an async runtime.
+///
+/// Therefore, you can think of a [`Subscription`] as a "stream builder". It simply represents a way
+/// to build a certain [`Stream`] together with some way to _identify_ it.
+///
+/// Identification is important because when a specific [`Subscription`] stops being returned to the
+/// iced runtime, the runtime will kill its associated [`Stream`]. The runtime uses the identity of a
+/// [`Subscription`] to keep track of it.
+///
+/// This way, iced allows you to declaratively __subscribe__ to particular streams of data temporarily
+/// and whenever necessary.
+///
+/// ```
+/// # mod iced {
+/// # pub mod time {
+/// # pub use iced_futures::backend::default::time::every;
+/// # pub use std::time::{Duration, Instant};
+/// # }
+/// #
+/// # pub use iced_futures::Subscription;
+/// # }
+/// use iced::time::{self, Duration, Instant};
+/// use iced::Subscription;
+///
+/// struct State {
+/// timer_enabled: bool,
+/// }
+///
+/// fn subscription(state: &State) -> Subscription<Instant> {
+/// if state.timer_enabled {
+/// time::every(Duration::from_secs(1))
+/// } else {
+/// Subscription::none()
+/// }
+/// }
+/// ```
+///
+/// [`Future`]: std::future::Future
#[must_use = "`Subscription` must be returned to runtime to take effect"]
-pub struct Subscription<Message> {
- recipes: Vec<Box<dyn Recipe<Output = Message>>>,
+pub struct Subscription<T> {
+ recipes: Vec<Box<dyn Recipe<Output = T>>>,
}
-impl<Message> Subscription<Message> {
+impl<T> Subscription<T> {
/// Returns an empty [`Subscription`] that will not produce any output.
pub fn none() -> Self {
Self {
@@ -82,19 +126,102 @@ impl<Message> Subscription<Message> {
}
}
- /// Creates a [`Subscription`] from a [`Recipe`] describing it.
- pub fn from_recipe(
- recipe: impl Recipe<Output = Message> + 'static,
- ) -> Self {
- Self {
- recipes: vec![Box::new(recipe)],
- }
+ /// Returns a [`Subscription`] that will call the given function to create and
+ /// asynchronously run the given [`Stream`].
+ ///
+ /// # Creating an asynchronous worker with bidirectional communication
+ /// You can leverage this helper to create a [`Subscription`] that spawns
+ /// an asynchronous worker in the background and establish a channel of
+ /// communication with an `iced` application.
+ ///
+ /// You can achieve this by creating an `mpsc` channel inside the closure
+ /// and returning the `Sender` as a `Message` for the `Application`:
+ ///
+ /// ```
+ /// use iced_futures::subscription::{self, Subscription};
+ /// use iced_futures::stream;
+ /// use iced_futures::futures::channel::mpsc;
+ /// use iced_futures::futures::sink::SinkExt;
+ /// use iced_futures::futures::Stream;
+ ///
+ /// pub enum Event {
+ /// Ready(mpsc::Sender<Input>),
+ /// WorkFinished,
+ /// // ...
+ /// }
+ ///
+ /// enum Input {
+ /// DoSomeWork,
+ /// // ...
+ /// }
+ ///
+ /// fn some_worker() -> impl Stream<Item = Event> {
+ /// stream::channel(100, |mut output| async move {
+ /// // Create channel
+ /// let (sender, mut receiver) = mpsc::channel(100);
+ ///
+ /// // Send the sender back to the application
+ /// output.send(Event::Ready(sender)).await;
+ ///
+ /// loop {
+ /// use iced_futures::futures::StreamExt;
+ ///
+ /// // Read next input sent from `Application`
+ /// let input = receiver.select_next_some().await;
+ ///
+ /// match input {
+ /// Input::DoSomeWork => {
+ /// // Do some async work...
+ ///
+ /// // Finally, we can optionally produce a message to tell the
+ /// // `Application` the work is done
+ /// output.send(Event::WorkFinished).await;
+ /// }
+ /// }
+ /// }
+ /// })
+ /// }
+ ///
+ /// fn subscription() -> Subscription<Event> {
+ /// Subscription::run(some_worker)
+ /// }
+ /// ```
+ ///
+ /// Check out the [`websocket`] example, which showcases this pattern to maintain a `WebSocket`
+ /// connection open.
+ ///
+ /// [`websocket`]: https://github.com/iced-rs/iced/tree/0.12/examples/websocket
+ pub fn run<S>(builder: fn() -> S) -> Self
+ where
+ S: Stream<Item = T> + MaybeSend + 'static,
+ T: 'static,
+ {
+ from_recipe(Runner {
+ id: builder,
+ spawn: move |_| builder(),
+ })
+ }
+
+ /// Returns a [`Subscription`] that will create and asynchronously run the
+ /// given [`Stream`].
+ ///
+ /// The `id` will be used to uniquely identify the [`Subscription`].
+ pub fn run_with_id<I, S>(id: I, stream: S) -> Subscription<T>
+ where
+ I: Hash + 'static,
+ S: Stream<Item = T> + MaybeSend + 'static,
+ T: 'static,
+ {
+ from_recipe(Runner {
+ id,
+ spawn: move |_| stream,
+ })
}
/// Batches all the provided subscriptions and returns the resulting
/// [`Subscription`].
pub fn batch(
- subscriptions: impl IntoIterator<Item = Subscription<Message>>,
+ subscriptions: impl IntoIterator<Item = Subscription<T>>,
) -> Self {
Self {
recipes: subscriptions
@@ -104,18 +231,13 @@ impl<Message> Subscription<Message> {
}
}
- /// Returns the different recipes of the [`Subscription`].
- pub fn into_recipes(self) -> Vec<Box<dyn Recipe<Output = Message>>> {
- self.recipes
- }
-
/// Adds a value to the [`Subscription`] context.
///
/// The value will be part of the identity of a [`Subscription`].
- pub fn with<T>(mut self, value: T) -> Subscription<(T, Message)>
+ pub fn with<A>(mut self, value: A) -> Subscription<(A, T)>
where
- Message: 'static,
- T: std::hash::Hash + Clone + Send + Sync + 'static,
+ T: 'static,
+ A: std::hash::Hash + Clone + Send + Sync + 'static,
{
Subscription {
recipes: self
@@ -123,7 +245,7 @@ impl<Message> Subscription<Message> {
.drain(..)
.map(|recipe| {
Box::new(With::new(recipe, value.clone()))
- as Box<dyn Recipe<Output = (T, Message)>>
+ as Box<dyn Recipe<Output = (A, T)>>
})
.collect(),
}
@@ -136,8 +258,8 @@ impl<Message> Subscription<Message> {
/// will panic in debug mode otherwise.
pub fn map<F, A>(mut self, f: F) -> Subscription<A>
where
- Message: 'static,
- F: Fn(Message) -> A + MaybeSend + Clone + 'static,
+ T: 'static,
+ F: Fn(T) -> A + MaybeSend + Clone + 'static,
A: 'static,
{
debug_assert!(
@@ -159,7 +281,23 @@ impl<Message> Subscription<Message> {
}
}
-impl<Message> std::fmt::Debug for Subscription<Message> {
+/// Creates a [`Subscription`] from a [`Recipe`] describing it.
+pub fn from_recipe<T>(
+ recipe: impl Recipe<Output = T> + 'static,
+) -> Subscription<T> {
+ Subscription {
+ recipes: vec![Box::new(recipe)],
+ }
+}
+
+/// Returns the different recipes of the [`Subscription`].
+pub fn into_recipes<T>(
+ subscription: Subscription<T>,
+) -> Vec<Box<dyn Recipe<Output = T>>> {
+ subscription.recipes
+}
+
+impl<T> std::fmt::Debug for Subscription<T> {
fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
f.debug_struct("Subscription").finish()
}
@@ -273,65 +411,13 @@ where
}
}
-/// Returns a [`Subscription`] that will call the given function to create and
-/// asynchronously run the given [`Stream`].
-pub fn run<S, Message>(builder: fn() -> S) -> Subscription<Message>
-where
- S: Stream<Item = Message> + MaybeSend + 'static,
- Message: 'static,
-{
- Subscription::from_recipe(Runner {
- id: builder,
- spawn: move |_| builder(),
- })
-}
-
-/// Returns a [`Subscription`] that will create and asynchronously run the
-/// given [`Stream`].
-///
-/// The `id` will be used to uniquely identify the [`Subscription`].
-pub fn run_with_id<I, S, Message>(id: I, stream: S) -> Subscription<Message>
-where
- I: Hash + 'static,
- S: Stream<Item = Message> + MaybeSend + 'static,
- Message: 'static,
-{
- Subscription::from_recipe(Runner {
- id,
- spawn: move |_| stream,
- })
-}
-
-/// Returns a [`Subscription`] that will create and asynchronously run a
-/// [`Stream`] that will call the provided closure to produce every `Message`.
-///
-/// The `id` will be used to uniquely identify the [`Subscription`].
-pub fn unfold<I, T, Fut, Message>(
- id: I,
- initial: T,
- mut f: impl FnMut(T) -> Fut + MaybeSend + Sync + 'static,
-) -> Subscription<Message>
-where
- I: Hash + 'static,
- T: MaybeSend + 'static,
- Fut: Future<Output = (Message, T)> + MaybeSend + 'static,
- Message: 'static + MaybeSend,
-{
- use futures::future::FutureExt;
-
- run_with_id(
- id,
- futures::stream::unfold(initial, move |state| f(state).map(Some)),
- )
-}
-
-pub(crate) fn filter_map<I, F, Message>(id: I, f: F) -> Subscription<Message>
+pub(crate) fn filter_map<I, F, T>(id: I, f: F) -> Subscription<T>
where
I: Hash + 'static,
- F: Fn(Event) -> Option<Message> + MaybeSend + 'static,
- Message: 'static + MaybeSend,
+ F: Fn(Event) -> Option<T> + MaybeSend + 'static,
+ T: 'static + MaybeSend,
{
- Subscription::from_recipe(Runner {
+ from_recipe(Runner {
id,
spawn: |events| {
use futures::future;
@@ -342,107 +428,22 @@ where
})
}
-/// Creates a [`Subscription`] that publishes the events sent from a [`Future`]
-/// to an [`mpsc::Sender`] with the given bounds.
-///
-/// # Creating an asynchronous worker with bidirectional communication
-/// You can leverage this helper to create a [`Subscription`] that spawns
-/// an asynchronous worker in the background and establish a channel of
-/// communication with an `iced` application.
-///
-/// You can achieve this by creating an `mpsc` channel inside the closure
-/// and returning the `Sender` as a `Message` for the `Application`:
-///
-/// ```
-/// use iced_futures::subscription::{self, Subscription};
-/// use iced_futures::futures::channel::mpsc;
-/// use iced_futures::futures::sink::SinkExt;
-///
-/// pub enum Event {
-/// Ready(mpsc::Sender<Input>),
-/// WorkFinished,
-/// // ...
-/// }
-///
-/// enum Input {
-/// DoSomeWork,
-/// // ...
-/// }
-///
-/// fn some_worker() -> Subscription<Event> {
-/// struct SomeWorker;
-///
-/// subscription::channel(std::any::TypeId::of::<SomeWorker>(), 100, |mut output| async move {
-/// // Create channel
-/// let (sender, mut receiver) = mpsc::channel(100);
-///
-/// // Send the sender back to the application
-/// output.send(Event::Ready(sender)).await;
-///
-/// loop {
-/// use iced_futures::futures::StreamExt;
-///
-/// // Read next input sent from `Application`
-/// let input = receiver.select_next_some().await;
-///
-/// match input {
-/// Input::DoSomeWork => {
-/// // Do some async work...
-///
-/// // Finally, we can optionally produce a message to tell the
-/// // `Application` the work is done
-/// output.send(Event::WorkFinished).await;
-/// }
-/// }
-/// }
-/// })
-/// }
-/// ```
-///
-/// Check out the [`websocket`] example, which showcases this pattern to maintain a `WebSocket`
-/// connection open.
-///
-/// [`websocket`]: https://github.com/iced-rs/iced/tree/0.12/examples/websocket
-pub fn channel<I, Fut, Message>(
- id: I,
- size: usize,
- f: impl FnOnce(mpsc::Sender<Message>) -> Fut + MaybeSend + 'static,
-) -> Subscription<Message>
-where
- I: Hash + 'static,
- Fut: Future<Output = Never> + MaybeSend + 'static,
- Message: 'static + MaybeSend,
-{
- use futures::stream::{self, StreamExt};
-
- Subscription::from_recipe(Runner {
- id,
- spawn: move |_| {
- let (sender, receiver) = mpsc::channel(size);
-
- let runner = stream::once(f(sender)).map(|_| unreachable!());
-
- stream::select(receiver, runner)
- },
- })
-}
-
-struct Runner<I, F, S, Message>
+struct Runner<I, F, S, T>
where
F: FnOnce(EventStream) -> S,
- S: Stream<Item = Message>,
+ S: Stream<Item = T>,
{
id: I,
spawn: F,
}
-impl<I, S, F, Message> Recipe for Runner<I, F, S, Message>
+impl<I, F, S, T> Recipe for Runner<I, F, S, T>
where
I: Hash + 'static,
F: FnOnce(EventStream) -> S,
- S: Stream<Item = Message> + MaybeSend + 'static,
+ S: Stream<Item = T> + MaybeSend + 'static,
{
- type Output = Message;
+ type Output = T;
fn hash(&self, state: &mut Hasher) {
std::any::TypeId::of::<I>().hash(state);
generated by cgit (git 2.34.1) at 2025-04-06 22:40:14 +0000