Struct futures::stream::Peekable

#[must_use = "streams do nothing unless polled"]
pub struct Peekable<St> where
    St: 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<St> Peekable<St> where
    St: Stream, 

Important traits for &'_ mut F

impl<'_, F> Future for &'_ mut F where
    F: Unpin + Future + ?Sized,  type Output = <F as Future>::Output;

pub fn get_ref(&self) -> &St

Acquires a reference to the underlying stream that this combinator is pulling from.

Important traits for &'_ mut F

impl<'_, F> Future for &'_ mut F where
    F: Unpin + Future + ?Sized,  type Output = <F as Future>::Output;

pub fn get_mut(&mut self) -> &mut St

Acquires a mutable reference to the underlying stream that this combinator is pulling from.

Note that care must be taken to avoid tampering with the state of the stream which may otherwise confuse this combinator.

Important traits for Pin<P>

impl<P> Future for Pin<P> where
    P: Unpin + DerefMut,
    <P as Deref>::Target: Future,  type Output = <<P as Deref>::Target as Future>::Output;

pub fn get_pin_mut(self: Pin<&mut Peekable<St>>) -> Pin<&mut St>

Acquires a pinned mutable reference to the underlying stream that this combinator is pulling from.

Note that care must be taken to avoid tampering with the state of the stream which may otherwise confuse this combinator.

pub fn into_inner(self) -> St

Consumes this combinator, returning the underlying stream.

Note that this may discard intermediate state of this combinator, so care should be taken to avoid losing resources when this is called.

pub fn peek(
    self: Pin<&mut Peekable<St>>,
    cx: &mut Context
) -> Poll<Option<&<St as Stream>::Item>>

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, Item> Sink<Item> for Peekable<S> where
    S: Sink<Item> + Stream, 

type Error = <S as Sink<Item>>::Error

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

fn poll_ready(
    self: Pin<&mut Peekable<S>>,
    cx: &mut Context
) -> Poll<Result<(), <Peekable<S> as Sink<Item>>::Error>>

Attempts to prepare the Sink to receive a value.

fn start_send(
    self: Pin<&mut Peekable<S>>,
    item: Item
) -> Result<(), <Peekable<S> as Sink<Item>>::Error>

Begin the process of sending a value to the sink. Each call to this function must be preceded by a successful call to poll_ready which returned Poll::Ready(Ok(())).

fn poll_flush(
    self: Pin<&mut Peekable<S>>,
    cx: &mut Context
) -> Poll<Result<(), <Peekable<S> as Sink<Item>>::Error>>

Flush any remaining output from this sink.

fn poll_close(
    self: Pin<&mut Peekable<S>>,
    cx: &mut Context
) -> Poll<Result<(), <Peekable<S> as Sink<Item>>::Error>>

Flush any remaining output and close this sink, if necessary.

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

type Item = <S as Stream>::Item

Values yielded by the stream.

fn poll_next(
    self: Pin<&mut Peekable<S>>,
    cx: &mut Context
) -> Poll<Option<<Peekable<S> as Stream>::Item>>

Attempt to pull out the next value of this stream, registering the current task for wakeup if the value is not yet available, and returning None if the stream is exhausted.

fn size_hint(&self) -> (usize, Option<usize>)

Returns the bounds on the remaining length of the stream.

impl<St> FusedStream for Peekable<St> where
    St: Stream, 

fn is_terminated(&self) -> bool

Returns true if the stream should no longer be polled.

impl<St> Unpin for Peekable<St> where
    St: Unpin + Stream, 

impl<St> Debug for Peekable<St> where
    St: Debug + Stream,
    <St as Stream>::Item: Debug, 

fn fmt(&self, f: &mut Formatter) -> Result<(), Error>

Formats the value using the given formatter.