[−][src]Struct async_fuse::Fuse
A fusing adapter around a value.
A Fuse<T>
is similar to Option<T>
, with the exception that it
provides and API which is more suitable for interacting with
asynchronous tasks.
For most polling operations except Fuse::poll_inner, if the value completes, the adapter will switch to an empty state and return Poll::Pending until updated again with set.
See Fuse::new for more details.
Implementations
impl<T> Fuse<Pin<Box<T>>>
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pub fn pin(value: T) -> Self
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Construct a fusing adapter around a value that is already pinned.
Examples
use async_fuse::Fuse; use std::future::Future; use tokio::time; async fn foo() -> u32 { 1 } let mut fut = Fuse::pin(foo()); assert!(!fut.is_empty()); let value = (&mut fut).await; assert!(fut.is_empty());
impl<T> Fuse<T>
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pub fn new(value: T) -> Self
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Construct a fusing adapter around a value.
Examples
use async_fuse::Fuse; use std::time::Duration; use tokio::time; let mut sleep = Fuse::new(time::sleep(Duration::from_millis(200))); tokio::pin!(sleep); tokio::select! { _ = &mut sleep => { assert!(sleep.is_empty()); sleep.set(Fuse::new(time::sleep(Duration::from_millis(200)))); } } assert!(!sleep.is_empty());
Example using an unsized trait object
use async_fuse::Fuse; use std::future::Future; use std::pin::Pin; use tokio::time; async fn foo() -> u32 { 1 } async fn bar() -> u32 { 2 } let mut fut = Fuse::<Pin<Box<dyn Future<Output = u32>>>>::new(Box::pin(foo())); let mut total = 0; while !fut.is_empty() { let value = (&mut fut).await; if value == 1 { fut.set(Box::pin(bar())); } total += value; } assert_eq!(total, 3);
pub fn set(&mut self, value: T) where
Self: Unpin,
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Self: Unpin,
Set the fused value.
Examples
use async_fuse::Fuse; use std::time::Duration; use tokio::time; let mut sleep = Fuse::new(Box::pin(time::sleep(Duration::from_millis(200)))); assert!(!sleep.is_empty()); sleep.set(Box::pin(time::sleep(Duration::from_millis(200)))); assert!(!sleep.is_empty());
Example setting an unsized trait object
use async_fuse::Fuse; use std::future::Future; use std::pin::Pin; use tokio::time; async fn foo() -> u32 { 1 } async fn bar() -> u32 { 2 } let mut fut = Fuse::<Pin<Box<dyn Future<Output = u32>>>>::empty(); assert!(fut.is_empty()); fut.set(Box::pin(foo())); assert!(!fut.is_empty()); fut.set(Box::pin(bar())); assert!(!fut.is_empty());
pub fn clear(&mut self) where
Self: Unpin,
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Self: Unpin,
Clear the fused value.
Examples
use async_fuse::Fuse; use std::time::Duration; use tokio::time; let mut sleep = Fuse::new(Box::pin(time::sleep(Duration::from_millis(200)))); assert!(!sleep.is_empty()); sleep.clear(); assert!(sleep.is_empty());
pub fn empty() -> Self
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Construct an empty fuse.
Examples
use async_fuse::Fuse; use tokio::time; let mut sleep = Fuse::<time::Sleep>::empty(); tokio::pin!(sleep); assert!(sleep.is_empty());
pub fn is_empty(&self) -> bool
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Test if the polled for value is empty.
Examples
use async_fuse::Fuse; use std::time::Duration; use tokio::time; let mut sleep = Fuse::new(time::sleep(Duration::from_millis(200))); tokio::pin!(sleep); assert!(!sleep.is_empty()); sleep.set(Fuse::empty()); assert!(sleep.is_empty());
pub fn as_inner_ref(&self) -> Option<&T>
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Access the interior value as a reference.
Examples
use async_fuse::Fuse; use std::time::Duration; use tokio::time; let mut sleep = Fuse::new(time::sleep(Duration::from_millis(200))); tokio::pin!(sleep); assert!(sleep.as_inner_ref().is_some()); sleep.set(Fuse::empty()); assert!(sleep.as_inner_ref().is_none());
pub async fn poll_inner<P, O>(self: Pin<&mut Self>, poll: P) -> O where
P: FnMut(Pin<&mut T>, &mut Context<'_>) -> Poll<O>,
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P: FnMut(Pin<&mut T>, &mut Context<'_>) -> Poll<O>,
Poll the current value with the given polling implementation.
This can be used for types which only provides a polling function.
This will never empty the underlying value.
Examples
use async_fuse::Fuse; use std::future::Future; use tokio::sync::mpsc; async fn op(n: u32) -> u32 { n } let op1 = Fuse::new(op(1)); tokio::pin!(op1); assert_eq!(op1.as_mut().poll_inner(|mut i, cx| i.poll(cx)).await, 1); assert!(!op1.is_empty()); op1.set(Fuse::new(op(2))); assert_eq!(op1.as_mut().poll_inner(|mut i, cx| i.poll(cx)).await, 2); assert!(!op1.is_empty());
pub async fn poll_future<P, O>(self: Pin<&mut Self>, poll: P) -> O where
P: FnMut(Pin<&mut T>, &mut Context<'_>) -> Poll<O>,
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P: FnMut(Pin<&mut T>, &mut Context<'_>) -> Poll<O>,
Poll the current value with the given polling implementation.
This can be used for types which only provides a polling function.
Once the underlying poll impl returns Poll::Ready
, the underlying
value will be emptied.
Examples
use async_fuse::Fuse; use std::future::Future; use tokio::sync::mpsc; async fn op(n: u32) -> u32 { n } let op1 = Fuse::new(op(1)); tokio::pin!(op1); assert_eq!(op1.as_mut().poll_future(|mut i, cx| i.poll(cx)).await, 1); assert!(op1.is_empty()); op1.set(Fuse::new(op(2))); assert!(!op1.is_empty()); assert_eq!(op1.as_mut().poll_future(|mut i, cx| i.poll(cx)).await, 2); assert!(op1.is_empty());
pub async fn poll_stream<P, O>(self: Pin<&mut Self>, poll: P) -> Option<O> where
P: FnMut(Pin<&mut T>, &mut Context<'_>) -> Poll<Option<O>>,
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P: FnMut(Pin<&mut T>, &mut Context<'_>) -> Poll<Option<O>>,
Poll the current value with the given polling implementation.
This can be used for types which only provides a polling function, or types which can be polled multiple streams. Like streams which do not provide a Stream implementation.
Will empty the fused value once the underlying poll returns
Poll::Ready(None)
.
Examples
use async_fuse::{Fuse, Stream}; use std::future::Future; use tokio::sync::mpsc; fn op(n: u32) -> impl Stream<Item = u32> { async_stream::stream! { yield n; yield n + 1; } } let op1 = Fuse::new(op(1)); tokio::pin!(op1); assert!(!op1.is_empty()); assert_eq!(op1.as_mut().poll_stream(|mut i, cx| i.poll_next(cx)).await, Some(1)); assert_eq!(op1.as_mut().poll_stream(|mut i, cx| i.poll_next(cx)).await, Some(2)); assert!(!op1.is_empty()); assert_eq!(op1.as_mut().poll_stream(|mut i, cx| i.poll_next(cx)).await, None); assert!(op1.is_empty());
pub fn as_inner_mut(&mut self) -> Option<&mut T> where
Self: Unpin,
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Self: Unpin,
Access the interior mutable value. This is only available if it implements Unpin.
Examples
use async_fuse::Fuse; let mut rx = Fuse::new(Box::pin(async { 42 })); assert!(rx.as_inner_mut().is_some());
pub fn as_pin_mut(&mut self) -> Pin<&mut Self> where
Self: Unpin,
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Self: Unpin,
Helper conversion to a pinned value.
Examples
use async_fuse::Fuse; use tokio::sync::mpsc; let (tx, rx) = mpsc::unbounded_channel::<u32>(); let mut rx = Fuse::new(rx); tx.send(42); // Manually poll the sleep. assert_eq!(rx.as_pin_mut().poll_stream(|mut i, cx| i.poll_recv(cx)).await, Some(42)); rx = Fuse::empty(); assert!(rx.is_empty());
pub async fn next(&mut self) -> Option<T::Item> where
Self: Unpin,
T: Stream,
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Self: Unpin,
T: Stream,
Poll the next value in the stream where the underlying value is unpin.
Behaves the same as [poll_stream], except that it only works for values which are Unpin.
Examples
use async_fuse::{Fuse, Stream}; use std::future::Future; use tokio::sync::mpsc; fn op(n: u32) -> impl Stream<Item = u32> { async_stream::stream! { yield n; yield n + 1; } } let mut stream = Fuse::new(Box::pin(op(1))); assert!(!stream.is_empty()); assert_eq!(stream.next().await, Some(1)); assert_eq!(stream.next().await, Some(2)); assert_eq!(stream.next().await, None); assert!(stream.is_empty());
Trait Implementations
impl<T> Default for Fuse<T>
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impl<T> From<Box<T, Global>> for Fuse<Pin<Box<T>>>
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impl<T> From<Option<Box<T, Global>>> for Fuse<Pin<Box<T>>>
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impl<T> From<Option<T>> for Fuse<T>
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impl<T> Future for Fuse<T> where
T: Future,
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T: Future,
type Output = T::Output
The type of value produced on completion.
pub fn poll(self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<Self::Output>
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impl<T> Stream for Fuse<T> where
T: Stream,
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T: Stream,
Auto Trait Implementations
impl<T> RefUnwindSafe for Fuse<T> where
T: RefUnwindSafe,
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T: RefUnwindSafe,
impl<T> Send for Fuse<T> where
T: Send,
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T: Send,
impl<T> Sync for Fuse<T> where
T: Sync,
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T: Sync,
impl<T> Unpin for Fuse<T> where
T: Unpin,
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T: Unpin,
impl<T> UnwindSafe for Fuse<T> where
T: UnwindSafe,
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T: UnwindSafe,
Blanket Implementations
impl<T> Any for T where
T: 'static + ?Sized,
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T: 'static + ?Sized,
impl<T> Borrow<T> for T where
T: ?Sized,
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T: ?Sized,
impl<T> BorrowMut<T> for T where
T: ?Sized,
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T: ?Sized,
pub fn borrow_mut(&mut self) -> &mut T
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impl<T> From<T> for T
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impl<T, U> Into<U> for T where
U: From<T>,
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U: From<T>,
impl<F> IntoFuture for F where
F: Future,
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F: Future,
type Output = <F as Future>::Output
into_future
)The output that the future will produce on completion.
type Future = F
into_future
)Which kind of future are we turning this into?
pub fn into_future(self) -> <F as IntoFuture>::Future
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impl<T, U> TryFrom<U> for T where
U: Into<T>,
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U: Into<T>,
type Error = Infallible
The type returned in the event of a conversion error.
pub fn try_from(value: U) -> Result<T, <T as TryFrom<U>>::Error>
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impl<F, T, E> TryFuture for F where
F: Future<Output = Result<T, E>> + ?Sized,
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F: Future<Output = Result<T, E>> + ?Sized,
type Ok = T
The type of successful values yielded by this future
type Error = E
The type of failures yielded by this future
pub fn try_poll(
self: Pin<&mut F>,
cx: &mut Context<'_>
) -> Poll<<F as Future>::Output>
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self: Pin<&mut F>,
cx: &mut Context<'_>
) -> Poll<<F as Future>::Output>
impl<T, U> TryInto<U> for T where
U: TryFrom<T>,
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U: TryFrom<T>,
type Error = <U as TryFrom<T>>::Error
The type returned in the event of a conversion error.
pub fn try_into(self) -> Result<U, <U as TryFrom<T>>::Error>
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impl<S, T, E> TryStream for S where
S: Stream<Item = Result<T, E>> + ?Sized,
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S: Stream<Item = Result<T, E>> + ?Sized,