Struct futures::stream::Once

#[must_use = "streams do nothing unless polled"]
pub struct Once<T, E>(_);

A stream which emits single element and then EOF.

This stream will never block and is always ready.

Trait Implementations

impl<T: Debug, E: Debug> Debug for Once<T, E>

fn fmt(&self, __arg_0: &mut Formatter) -> Result

Formats the value using the given formatter.

impl<T, E> Stream for Once<T, E>

type Item = T

The type of item this stream will yield on success.

type Error = E

The type of error this stream may generate.

fn poll(&mut self) -> Poll<Option<T>, E>

Attempt to pull out the next value of this stream, returning None if the stream is finished.

Important traits for Wait<S>

impl<S: Stream> Iterator for Wait<S> type Item = Result<S::Item, S::Error>;

fn wait(self) -> Wait<Self> where     Self: Sized,

Creates an iterator which blocks the current thread until each item of this stream is resolved.

fn into_future(self) -> StreamFuture<Self> where     Self: Sized,

Converts this stream into a Future.

fn map<U, F>(self, f: F) -> Map<Self, F> where     F: FnMut(Self::Item) -> U,     Self: Sized,

Converts a stream of type T to a stream of type U.

fn map_err<U, F>(self, f: F) -> MapErr<Self, F> where     F: FnMut(Self::Error) -> U,     Self: Sized,

Converts a stream of error type T to a stream of error type U.

fn filter<F>(self, f: F) -> Filter<Self, F> where     F: FnMut(&Self::Item) -> bool,     Self: Sized,

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

fn filter_map<F, B>(self, f: F) -> FilterMap<Self, F> where     F: FnMut(Self::Item) -> Option<B>,     Self: Sized,

Filters the values produced by this stream while simultaneously mapping them to a different type.

fn then<F, U>(self, f: F) -> Then<Self, F, U> where     F: FnMut(Result<Self::Item, Self::Error>) -> U,     U: IntoFuture,     Self: Sized,

Chain on a computation for when a value is ready, passing the resulting item to the provided closure f.

fn and_then<F, U>(self, f: F) -> AndThen<Self, F, U> where     F: FnMut(Self::Item) -> U,     U: IntoFuture<Error = Self::Error>,     Self: Sized,

Chain on a computation for when a value is ready, passing the successful results to the provided closure f.

fn or_else<F, U>(self, f: F) -> OrElse<Self, F, U> where     F: FnMut(Self::Error) -> U,     U: IntoFuture<Item = Self::Item>,     Self: Sized,

Chain on a computation for when an error happens, passing the erroneous result to the provided closure f.

fn collect(self) -> Collect<Self> where     Self: Sized,

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

fn concat2(self) -> Concat2<Self> where     Self: Sized,     Self::Item: Extend<<Self::Item as IntoIterator>::Item> + IntoIterator + Default,

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

fn concat(self) -> Concat<Self> where     Self: Sized,     Self::Item: Extend<<Self::Item as IntoIterator>::Item> + IntoIterator,

Deprecated since 0.1.14

: please use Stream::concat2 instead

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

fn fold<F, T, Fut>(self, init: T, f: F) -> Fold<Self, F, Fut, T> where     F: FnMut(T, Self::Item) -> Fut,     Fut: IntoFuture<Item = T>,     Self::Error: From<Fut::Error>,     Self: Sized,

Execute an accumulating computation over a stream, collecting all the values into one final result.

fn flatten(self) -> Flatten<Self> where     Self::Item: Stream,     <Self::Item as Stream>::Error: From<Self::Error>,     Self: Sized,

Flattens a stream of streams into just one continuous stream.

fn skip_while<P, R>(self, pred: P) -> SkipWhile<Self, P, R> where     P: FnMut(&Self::Item) -> R,     R: IntoFuture<Item = bool, Error = Self::Error>,     Self: Sized,

Skip elements on this stream while the predicate provided resolves to true.

fn take_while<P, R>(self, pred: P) -> TakeWhile<Self, P, R> where     P: FnMut(&Self::Item) -> R,     R: IntoFuture<Item = bool, Error = Self::Error>,     Self: Sized,

Take elements from this stream while the predicate provided resolves to true.

fn for_each<F, U>(self, f: F) -> ForEach<Self, F, U> where     F: FnMut(Self::Item) -> U,     U: IntoFuture<Item = (), Error = Self::Error>,     Self: Sized,

Runs this stream to completion, executing the provided closure for each element on the stream.

fn from_err<E: From<Self::Error>>(self) -> FromErr<Self, E> where     Self: Sized,

Map this stream's error to any error implementing From for this stream's Error, returning a new stream.

fn take(self, amt: u64) -> Take<Self> where     Self: Sized,

Creates a new stream of at most amt items of the underlying stream.

fn skip(self, amt: u64) -> Skip<Self> where     Self: Sized,

Creates a new stream which skips amt items of the underlying stream.

fn fuse(self) -> Fuse<Self> where     Self: Sized,

Fuse a stream such that poll will never again be called once it has finished.

fn by_ref(&mut self) -> &mut Self where     Self: Sized,

Borrows a stream, rather than consuming it.

fn catch_unwind(self) -> CatchUnwind<Self> where     Self: Sized + UnwindSafe,

Catches unwinding panics while polling the stream.

fn buffered(self, amt: usize) -> Buffered<Self> where     Self::Item: IntoFuture<Error = Self::Error>,     Self: Sized,

An adaptor for creating a buffered list of pending futures.

fn buffer_unordered(self, amt: usize) -> BufferUnordered<Self> where     Self::Item: IntoFuture<Error = Self::Error>,     Self: Sized,

An adaptor for creating a buffered list of pending futures (unordered).

fn merge<S>(self, other: S) -> Merge<Self, S> where     S: Stream<Error = Self::Error>,     Self: Sized,

Deprecated

: functionality provided by select now

An adapter for merging the output of two streams.

fn zip<S>(self, other: S) -> Zip<Self, S> where     S: Stream<Error = Self::Error>,     Self: Sized,

An adapter for zipping two streams together.

fn chain<S>(self, other: S) -> Chain<Self, S> where     S: Stream<Item = Self::Item, Error = Self::Error>,     Self: Sized,

Adapter for chaining two stream.

fn peekable(self) -> Peekable<Self> where     Self: Sized,

Creates a new stream which exposes a peek method.

fn chunks(self, capacity: usize) -> Chunks<Self> where     Self: Sized,

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

fn select<S>(self, other: S) -> Select<Self, S> where     S: Stream<Item = Self::Item, Error = Self::Error>,     Self: Sized,

Creates a stream that selects the next element from either this stream or the provided one, whichever is ready first.

fn forward<S>(self, sink: S) -> Forward<Self, S> where     S: Sink<SinkItem = Self::Item>,     Self::Error: From<S::SinkError>,     Self: Sized,

A future that completes after the given stream has been fully processed into the sink, including flushing.

fn split(self) -> (SplitSink<Self>, SplitStream<Self>) where     Self: Sink + Sized,

Splits this Stream + Sink object into separate Stream and Sink objects.

fn inspect<F>(self, f: F) -> Inspect<Self, F> where     F: FnMut(&Self::Item),     Self: Sized,

Do something with each item of this stream, afterwards passing it on.

fn inspect_err<F>(self, f: F) -> InspectErr<Self, F> where     F: FnMut(&Self::Error),     Self: Sized,

Do something with the error of this stream, afterwards passing it on.