[][src]Struct futures::stream::Once

#[must_use = "streams do nothing unless polled"]
pub struct Once<Fut> { /* fields omitted */ }

A stream which emits single element and then EOF.

This stream will never block and is always ready.

Trait Implementations

impl<Fut> Unpin for Once<Fut> where
    Fut: Unpin
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impl<Fut> Stream for Once<Fut> where
    Fut: Future
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type Item = <Fut as Future>::Output

Values yielded by the stream.

impl<Fut> Debug for Once<Fut> where
    Fut: Debug
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Auto Trait Implementations

impl<Fut> Send for Once<Fut> where
    Fut: Send

impl<Fut> Sync for Once<Fut> where
    Fut: Sync

Blanket Implementations

impl<T> From for T[src]

impl<T, U> Into for T where
    U: From<T>, 
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impl<T, U> TryFrom for T where
    U: Into<T>, 
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type Error = Infallible

The type returned in the event of a conversion error.

impl<T> Borrow for T where
    T: ?Sized
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impl<T> BorrowMut for T where
    T: ?Sized
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impl<T, U> TryInto for T where
    U: TryFrom<T>, 
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type Error = <U as TryFrom<T>>::Error

The type returned in the event of a conversion error.

impl<T> Any for T where
    T: 'static + ?Sized
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impl<S, T, E> TryStream for S where
    S: Stream<Item = Result<T, E>>, 
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type Ok = T

The type of successful values yielded by this future

type Error = E

The type of failures yielded by this future

impl<T> StreamExt for T where
    T: Stream + ?Sized
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Important traits for Next<'_, St>
default fn next(&mut self) -> Next<Self> where
    Self: Unpin
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Creates a future that resolves to the next item in the stream. Read more

Important traits for StreamFuture<St>
default fn into_future(self) -> StreamFuture<Self> where
    Self: Unpin
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Converts this stream into a future of (next_item, tail_of_stream). If the stream terminates, then the next item is [None]. Read more

default fn map<T, F>(self, f: F) -> Map<Self, F> where
    F: FnMut(Self::Item) -> T, 
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Maps this stream's items to a different type, returning a new stream of the resulting type. Read more

default fn filter<Fut, F>(self, f: F) -> Filter<Self, Fut, F> where
    F: FnMut(&Self::Item) -> Fut,
    Fut: Future<Output = bool>, 
[src]

Filters the values produced by this stream according to the provided asynchronous predicate. Read more

default fn filter_map<Fut, T, F>(self, f: F) -> FilterMap<Self, Fut, F> where
    F: FnMut(Self::Item) -> Fut,
    Fut: Future<Output = Option<T>>, 
[src]

Filters the values produced by this stream while simultaneously mapping them to a different type according to the provided asynchronous closure. Read more

default fn then<Fut, F>(self, f: F) -> Then<Self, Fut, F> where
    F: FnMut(Self::Item) -> Fut,
    Fut: Future
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Computes from this stream's items new items of a different type using an asynchronous closure. Read more

Important traits for Collect<St, C>
default fn collect<C>(self) -> Collect<Self, C> where
    C: Default + Extend<Self::Item>, 
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Collect all of the values of this stream into a vector, returning a future representing the result of that computation. Read more

Important traits for Concat<St>
default fn concat(self) -> Concat<Self> where
    Self::Item: Extend<<Self::Item as IntoIterator>::Item>,
    Self::Item: IntoIterator,
    Self::Item: Default
[src]

Concatenate all items of a stream into a single extendable destination, returning a future representing the end result. Read more

Important traits for Fold<St, Fut, T, F>
default fn fold<T, Fut, F>(self, init: T, f: F) -> Fold<Self, Fut, T, F> where
    F: FnMut(T, Self::Item) -> Fut,
    Fut: Future<Output = T>, 
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Execute an accumulating asynchronous computation over a stream, collecting all the values into one final result. Read more

default fn flatten(self) -> Flatten<Self> where
    Self::Item: Stream
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Flattens a stream of streams into just one continuous stream. Read more

default fn skip_while<Fut, F>(self, f: F) -> SkipWhile<Self, Fut, F> where
    F: FnMut(&Self::Item) -> Fut,
    Fut: Future<Output = bool>, 
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Skip elements on this stream while the provided asynchronous predicate resolves to true. Read more

default fn take_while<Fut, F>(self, f: F) -> TakeWhile<Self, Fut, F> where
    F: FnMut(&Self::Item) -> Fut,
    Fut: Future<Output = bool>, 
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Take elements from this stream while the provided asynchronous predicate resolves to true. Read more

Important traits for ForEach<St, Fut, F>
default fn for_each<Fut, F>(self, f: F) -> ForEach<Self, Fut, F> where
    F: FnMut(Self::Item) -> Fut,
    Fut: Future<Output = ()>, 
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Runs this stream to completion, executing the provided asynchronous closure for each element on the stream. Read more

Important traits for ForEachConcurrent<St, Fut, F>
default fn for_each_concurrent<Fut, F, impl Into>>(
    self,
    limit: impl Into>,
    f: F
) -> ForEachConcurrent<Self, Fut, F> where
    F: FnMut(Self::Item) -> Fut,
    Fut: Future<Output = ()>,
    impl Into>: Into<Option<usize>>, 
[src]

Runs this stream to completion, executing the provided asynchronous closure for each element on the stream concurrently as elements become available. Read more

default fn take(self, n: u64) -> Take<Self>[src]

Creates a new stream of at most n items of the underlying stream. Read more

default fn skip(self, n: u64) -> Skip<Self>[src]

Creates a new stream which skips n items of the underlying stream. Read more

default fn fuse(self) -> Fuse<Self>[src]

Fuse a stream such that poll_next will never again be called once it has finished. This method can be used t turn any Stream into a FusedStream. Read more

Important traits for &'_ mut F
default fn by_ref(&mut self) -> &mut Self[src]

Borrows a stream, rather than consuming it. Read more

default fn catch_unwind(self) -> CatchUnwind<Self> where
    Self: UnwindSafe
[src]

Catches unwinding panics while polling the stream. Read more

Important traits for Pin<P>
default fn boxed(self) -> Pin<Box<Self>>[src]

Wrap the stream in a Box, pinning it.

default fn buffered(self, n: usize) -> Buffered<Self> where
    Self::Item: Future
[src]

An adaptor for creating a buffered list of pending futures. Read more

default fn buffer_unordered(self, n: usize) -> BufferUnordered<Self> where
    Self::Item: Future
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An adaptor for creating a buffered list of pending futures (unordered). Read more

default fn zip<St>(self, other: St) -> Zip<Self, St> where
    St: Stream
[src]

An adapter for zipping two streams together. Read more

default fn chain<St>(self, other: St) -> Chain<Self, St> where
    St: Stream<Item = Self::Item>, 
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Adapter for chaining two stream. Read more

default fn peekable(self) -> Peekable<Self>[src]

Creates a new stream which exposes a peek method. Read more

default fn chunks(self, capacity: usize) -> Chunks<Self>[src]

An adaptor for chunking up items of the stream inside a vector. Read more

default fn select<St>(self, other: St) -> Select<Self, St> where
    St: Stream<Item = Self::Item>, 
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This combinator will attempt to pull items from both streams. Each stream will be polled in a round-robin fashion, and whenever a stream is ready to yield an item that item is yielded. Read more

Important traits for Forward<St, Si>
default fn forward<S>(self, sink: S) -> Forward<Self, S> where
    S: Sink<Self::Ok>,
    Self: TryStream<Error = <S as Sink<Self::Ok>>::SinkError>, 
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A future that completes after the given stream has been fully processed into the sink and the sink has been flushed and closed. Read more

default fn split<Item>(self) -> (SplitSink<Self, Item>, SplitStream<Self>) where
    Self: Sink<Item>, 
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Splits this Stream + Sink object into separate Stream and Sink objects. Read more

default fn inspect<F>(self, f: F) -> Inspect<Self, F> where
    F: FnMut(&Self::Item), 
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Do something with each item of this stream, afterwards passing it on. Read more

default fn left_stream<B>(self) -> Either<Self, B> where
    B: Stream<Item = Self::Item>, 
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Wrap this stream in an Either stream, making it the left-hand variant of that Either. Read more

default fn right_stream<B>(self) -> Either<B, Self> where
    B: Stream<Item = Self::Item>, 
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Wrap this stream in an Either stream, making it the right-hand variant of that Either. Read more

default fn poll_next_unpin(
    &mut self,
    cx: &mut Context
) -> Poll<Option<Self::Item>> where
    Self: Unpin
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A convenience method for calling [Stream::poll_next] on [Unpin] stream types. Read more

Important traits for SelectNextSome<'a, St>
default fn select_next_some(&mut self) -> SelectNextSome<Self> where
    Self: Unpin + FusedStream
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Returns a [Future] that resolves when the next item in this stream is ready. Read more

impl<S> TryStreamExt for S where
    S: TryStream
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default fn err_into<E>(self) -> ErrInto<Self, E> where
    Self::Error: Into<E>, 
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Wraps the current stream in a new stream which converts the error type into the one provided. Read more

default fn map_ok<T, F>(self, f: F) -> MapOk<Self, F> where
    F: FnMut(Self::Ok) -> T, 
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Wraps the current stream in a new stream which maps the success value using the provided closure. Read more

default fn map_err<E, F>(self, f: F) -> MapErr<Self, F> where
    F: FnMut(Self::Error) -> E, 
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Wraps the current stream in a new stream which maps the error value using the provided closure. Read more

default fn into_stream(self) -> IntoStream<Self>[src]

Wraps a [TryStream] into a type that implements Stream Read more

Important traits for TryNext<'_, St>
default fn try_next(&mut self) -> TryNext<Self> where
    Self: Unpin
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Creates a future that attempts to resolve the next item in the stream. If an error is encountered before the next item, the error is returned instead. Read more

Important traits for TryForEach<St, Fut, F>
default fn try_for_each<Fut, F>(self, f: F) -> TryForEach<Self, Fut, F> where
    F: FnMut(Self::Ok) -> Fut,
    Fut: TryFuture<Ok = (), Error = Self::Error>, 
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Attempts to run this stream to completion, executing the provided asynchronous closure for each element on the stream. Read more

default fn try_skip_while<Fut, F>(self, f: F) -> TrySkipWhile<Self, Fut, F> where
    F: FnMut(&Self::Ok) -> Fut,
    Fut: TryFuture<Ok = bool, Error = Self::Error>, 
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Skip elements on this stream while the provided asynchronous predicate resolves to true. Read more

Important traits for TryForEachConcurrent<St, Fut, F>
default fn try_for_each_concurrent<Fut, F, impl Into>>(
    self,
    limit: impl Into>,
    f: F
) -> TryForEachConcurrent<Self, Fut, F> where
    F: FnMut(Self::Ok) -> Fut,
    Fut: Future<Output = Result<(), Self::Error>>,
    impl Into>: Into<Option<usize>>, 
[src]

Attempts to run this stream to completion, executing the provided asynchronous closure for each element on the stream concurrently as elements become available, exiting as soon as an error occurs. Read more

Important traits for TryCollect<St, C>
default fn try_collect<C>(self) -> TryCollect<Self, C> where
    C: Default + Extend<Self::Ok>, 
[src]

Attempt to Collect all of the values of this stream into a vector, returning a future representing the result of that computation. Read more

default fn try_filter_map<Fut, F, T>(self, f: F) -> TryFilterMap<Self, Fut, F> where
    F: FnMut(Self::Ok) -> Fut,
    Fut: TryFuture<Ok = Option<T>, Error = Self::Error>, 
[src]

Attempt to filter the values produced by this stream while simultaneously mapping them to a different type according to the provided asynchronous closure. Read more

Important traits for TryFold<St, Fut, T, F>
default fn try_fold<T, Fut, F>(self, init: T, f: F) -> TryFold<Self, Fut, T, F> where
    F: FnMut(T, Self::Ok) -> Fut,
    Fut: TryFuture<Ok = T, Error = Self::Error>, 
[src]

Attempt to execute an accumulating asynchronous computation over a stream, collecting all the values into one final result. Read more

Important traits for TryConcat<St>
default fn try_concat(self) -> TryConcat<Self> where
    Self::Ok: Extend<<Self::Ok as IntoIterator>::Item>,
    Self::Ok: IntoIterator,
    Self::Ok: Default
[src]

Attempt to concatenate all items of a stream into a single extendable destination, returning a future representing the end result. Read more

default fn try_buffer_unordered(self, n: usize) -> TryBufferUnordered<Self> where
    Self::Ok: TryFuture,
    <Self::Ok as TryFuture>::Error == Self::Error
[src]

Attempt to execute several futures from a stream concurrently. Read more

default fn try_poll_next_unpin(
    &mut self,
    cx: &mut Context
) -> Poll<Option<Result<Self::Ok, Self::Error>>> where
    Self: Unpin
[src]

A convenience method for calling [TryStream::poll_next_unpin] on [Unpin] stream types. Read more

Important traits for Compat<R>
default fn compat(self) -> Compat<Self> where
    Self: Unpin
[src]

Wraps a [TryStream] into a stream compatible with libraries using futures 0.1 Stream. Requires the compat feature to be enabled. ``` #![feature(async_await, await_macro, futures_api)] use futures::future::{FutureExt, TryFutureExt}; # let (tx, rx) = futures::channel::oneshot::channel(); Read more

default fn into_async_read(self) -> IntoAsyncRead<Self> where
    Self: TryStreamExt<Error = Error> + Unpin,
    Self::Ok: AsRef<[u8]>, 
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Adapter that converts this stream into an [AsyncRead]. Read more