Struct futures::stream::Peekable

#[must_use = "streams do nothing unless polled"]
pub struct Peekable<S: Stream> { /* fields omitted */ }

A Stream that implements a peek method.

The peek method can be used to retrieve a reference to the next Stream::Item if available. A subsequent call to poll will return the owned item.

Methods

impl<S: Stream> Peekable<S>

fn peek(&mut self) -> Poll<Option<&S::Item>, S::Error>

Peek retrieves a reference to the next item in the stream.

This method polls the underlying stream and return either a reference to the next item if the stream is ready or passes through any errors.

Trait Implementations

impl<S> Sink for Peekable<S> where S: Sink + Stream

type SinkItem = S::SinkItem

The type of value that the sink accepts.

type SinkError = S::SinkError

The type of value produced by the sink when an error occurs.

fn start_send(&mut self,
              item: S::SinkItem)
              -> StartSend<S::SinkItem, S::SinkError>

Begin the process of sending a value to the sink.

fn poll_complete(&mut self) -> Poll<(), S::SinkError>

Make progress on all pending requests, and determine whether they have completed.

fn with<U, F, Fut>(self, f: F) -> With<Self, U, F, Fut> where F: FnMut(U) -> Fut, Fut: IntoFuture<Item=Self::SinkItem>, Fut::Error: From<Self::SinkError>, Self: Sized

Composes a function in front of the sink.

fn buffer(self, amt: usize) -> Buffer<Self> where Self: Sized

Adds a fixed-size buffer to the current sink.

fn flush(self) -> Flush<Self> where Self: Sized

A future that completes when the sink has finished processing all pending requests.

fn send(self, item: Self::SinkItem) -> Send<Self> where Self: Sized

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

fn send_all<S>(self, stream: S) -> SendAll<Self, S> where S: Stream<Item=Self::SinkItem>, Self::SinkError: From<S::Error>, Self: Sized

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

impl<S: Stream> Stream for Peekable<S>

type Item = S::Item

The type of item this stream will yield on success.

type Error = S::Error

The type of error this stream may generate.

fn poll(&mut self) -> Poll<Option<Self::Item>, Self::Error>

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

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 boxed(self) -> BoxStream<Self::Item, Self::Error> where Self: Sized + Send + 'static

Convenience function for turning this stream into a trait object.

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 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::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 for_each<F>(self, f: F) -> ForEach<Self, F> where F: FnMut(Self::Item) -> Result<(), Self::Error>, Self: Sized

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

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 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, which can be useful when you want to split ownership between tasks, or allow direct interaction between the two objects (e.g. via Sink::send_all).