pub struct Peekable<St>where
St: Stream,{ /* private fields */ }
Expand description
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.
Implementations§
source§impl<St> Peekable<St>where
St: Stream,
impl<St> Peekable<St>where
St: Stream,
sourcepub fn get_ref(&self) -> &St
pub fn get_ref(&self) -> &St
Acquires a reference to the underlying sink or stream that this combinator is pulling from.
sourcepub fn get_mut(&mut self) -> &mut St
pub fn get_mut(&mut self) -> &mut St
Acquires a mutable reference to the underlying sink or stream that this combinator is pulling from.
Note that care must be taken to avoid tampering with the state of the sink or stream which may otherwise confuse this combinator.
sourcepub fn get_pin_mut(self: Pin<&mut Peekable<St>>) -> Pin<&mut St>
pub fn get_pin_mut(self: Pin<&mut Peekable<St>>) -> Pin<&mut St>
Acquires a pinned mutable reference to the underlying sink or stream that this combinator is pulling from.
Note that care must be taken to avoid tampering with the state of the sink or stream which may otherwise confuse this combinator.
sourcepub fn into_inner(self) -> St
pub fn into_inner(self) -> St
Consumes this combinator, returning the underlying sink or stream.
Note that this may discard intermediate state of this combinator, so care should be taken to avoid losing resources when this is called.
sourcepub fn peek(self: Pin<&mut Peekable<St>>) -> Peek<'_, St> ⓘ
pub fn peek(self: Pin<&mut Peekable<St>>) -> Peek<'_, St> ⓘ
Produces a future which retrieves a reference to the next item
in the stream, or None
if the underlying stream terminates.
sourcepub fn poll_peek(
self: Pin<&mut Peekable<St>>,
cx: &mut Context<'_>,
) -> Poll<Option<&<St as Stream>::Item>>
pub fn poll_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.
sourcepub fn peek_mut(self: Pin<&mut Peekable<St>>) -> PeekMut<'_, St> ⓘ
pub fn peek_mut(self: Pin<&mut Peekable<St>>) -> PeekMut<'_, St> ⓘ
Produces a future which retrieves a mutable reference to the next item
in the stream, or None
if the underlying stream terminates.
§Examples
use futures::stream::{self, StreamExt};
use futures::pin_mut;
let stream = stream::iter(vec![1, 2, 3]).peekable();
pin_mut!(stream);
assert_eq!(stream.as_mut().peek_mut().await, Some(&mut 1));
assert_eq!(stream.as_mut().next().await, Some(1));
// Peek into the stream and modify the value which will be returned next
if let Some(p) = stream.as_mut().peek_mut().await {
if *p == 2 {
*p = 5;
}
}
assert_eq!(stream.collect::<Vec<_>>().await, vec![5, 3]);
sourcepub fn poll_peek_mut(
self: Pin<&mut Peekable<St>>,
cx: &mut Context<'_>,
) -> Poll<Option<&mut <St as Stream>::Item>>
pub fn poll_peek_mut( self: Pin<&mut Peekable<St>>, cx: &mut Context<'_>, ) -> Poll<Option<&mut <St as Stream>::Item>>
Peek retrieves a mutable reference to the next item in the stream.
sourcepub fn next_if<F>(self: Pin<&mut Peekable<St>>, func: F) -> NextIf<'_, St, F> ⓘ
pub fn next_if<F>(self: Pin<&mut Peekable<St>>, func: F) -> NextIf<'_, St, F> ⓘ
Creates a future which will consume and return the next value of this stream if a condition is true.
If func
returns true
for the next value of this stream, consume and
return it. Otherwise, return None
.
§Examples
Consume a number if it’s equal to 0.
use futures::stream::{self, StreamExt};
use futures::pin_mut;
let stream = stream::iter(0..5).peekable();
pin_mut!(stream);
// The first item of the stream is 0; consume it.
assert_eq!(stream.as_mut().next_if(|&x| x == 0).await, Some(0));
// The next item returned is now 1, so `consume` will return `false`.
assert_eq!(stream.as_mut().next_if(|&x| x == 0).await, None);
// `next_if` saves the value of the next item if it was not equal to `expected`.
assert_eq!(stream.next().await, Some(1));
Consume any number less than 10.
use futures::stream::{self, StreamExt};
use futures::pin_mut;
let stream = stream::iter(1..20).peekable();
pin_mut!(stream);
// Consume all numbers less than 10
while stream.as_mut().next_if(|&x| x < 10).await.is_some() {}
// The next value returned will be 10
assert_eq!(stream.next().await, Some(10));
sourcepub fn next_if_eq<'a, T>(
self: Pin<&'a mut Peekable<St>>,
expected: &'a T,
) -> NextIfEq<'a, St, T> ⓘ
pub fn next_if_eq<'a, T>( self: Pin<&'a mut Peekable<St>>, expected: &'a T, ) -> NextIfEq<'a, St, T> ⓘ
Creates a future which will consume and return the next item if it is
equal to expected
.
§Example
Consume a number if it’s equal to 0.
use futures::stream::{self, StreamExt};
use futures::pin_mut;
let stream = stream::iter(0..5).peekable();
pin_mut!(stream);
// The first item of the stream is 0; consume it.
assert_eq!(stream.as_mut().next_if_eq(&0).await, Some(0));
// The next item returned is now 1, so `consume` will return `false`.
assert_eq!(stream.as_mut().next_if_eq(&0).await, None);
// `next_if_eq` saves the value of the next item if it was not equal to `expected`.
assert_eq!(stream.next().await, Some(1));
Trait Implementations§
source§impl<St> FusedStream for Peekable<St>where
St: Stream,
impl<St> FusedStream for Peekable<St>where
St: Stream,
source§fn is_terminated(&self) -> bool
fn is_terminated(&self) -> bool
true
if the stream should no longer be polled.source§impl<S, Item> Sink<Item> for Peekable<S>
impl<S, Item> Sink<Item> for Peekable<S>
source§fn poll_ready(
self: Pin<&mut Peekable<S>>,
cx: &mut Context<'_>,
) -> Poll<Result<(), <Peekable<S> as Sink<Item>>::Error>>
fn poll_ready( self: Pin<&mut Peekable<S>>, cx: &mut Context<'_>, ) -> Poll<Result<(), <Peekable<S> as Sink<Item>>::Error>>
Sink
to receive a value. Read moresource§fn start_send(
self: Pin<&mut Peekable<S>>,
item: Item,
) -> Result<(), <Peekable<S> as Sink<Item>>::Error>
fn start_send( self: Pin<&mut Peekable<S>>, item: Item, ) -> Result<(), <Peekable<S> as Sink<Item>>::Error>
poll_ready
which returned Poll::Ready(Ok(()))
. Read moresource§impl<S> Stream for Peekable<S>where
S: Stream,
impl<S> Stream for Peekable<S>where
S: Stream,
source§fn poll_next(
self: Pin<&mut Peekable<S>>,
cx: &mut Context<'_>,
) -> Poll<Option<<Peekable<S> as Stream>::Item>>
fn poll_next( self: Pin<&mut Peekable<S>>, cx: &mut Context<'_>, ) -> Poll<Option<<Peekable<S> as Stream>::Item>>
None
if the stream is exhausted. Read moreimpl<'__pin, St> Unpin for Peekable<St>
Auto Trait Implementations§
impl<St> Freeze for Peekable<St>
impl<St> RefUnwindSafe for Peekable<St>
impl<St> Send for Peekable<St>
impl<St> Sync for Peekable<St>
impl<St> UnwindSafe for Peekable<St>
Blanket Implementations§
source§impl<T> BorrowMut<T> for Twhere
T: ?Sized,
impl<T> BorrowMut<T> for Twhere
T: ?Sized,
source§fn borrow_mut(&mut self) -> &mut T
fn borrow_mut(&mut self) -> &mut T
source§impl<T, Item> SinkExt<Item> for T
impl<T, Item> SinkExt<Item> for T
source§fn with<U, Fut, F, E>(self, f: F) -> With<Self, Item, U, Fut, F>
fn with<U, Fut, F, E>(self, f: F) -> With<Self, Item, U, Fut, F>
source§fn with_flat_map<U, St, F>(self, f: F) -> WithFlatMap<Self, Item, U, St, F>
fn with_flat_map<U, St, F>(self, f: F) -> WithFlatMap<Self, Item, U, St, F>
source§fn sink_map_err<E, F>(self, f: F) -> SinkMapErr<Self, F>
fn sink_map_err<E, F>(self, f: F) -> SinkMapErr<Self, F>
source§fn sink_err_into<E>(self) -> SinkErrInto<Self, Item, E>
fn sink_err_into<E>(self) -> SinkErrInto<Self, Item, E>
Into
trait. Read moresource§fn buffer(self, capacity: usize) -> Buffer<Self, Item>where
Self: Sized,
fn buffer(self, capacity: usize) -> Buffer<Self, Item>where
Self: Sized,
source§fn flush(&mut self) -> Flush<'_, Self, Item> ⓘwhere
Self: Unpin,
fn flush(&mut self) -> Flush<'_, Self, Item> ⓘwhere
Self: Unpin,
source§fn send(&mut self, item: Item) -> Send<'_, Self, Item> ⓘwhere
Self: Unpin,
fn send(&mut self, item: Item) -> Send<'_, Self, Item> ⓘwhere
Self: Unpin,
source§fn feed(&mut self, item: Item) -> Feed<'_, Self, Item> ⓘwhere
Self: Unpin,
fn feed(&mut self, item: Item) -> Feed<'_, Self, Item> ⓘwhere
Self: Unpin,
source§fn send_all<'a, St>(&'a mut self, stream: &'a mut St) -> SendAll<'a, Self, St> ⓘ
fn send_all<'a, St>(&'a mut self, stream: &'a mut St) -> SendAll<'a, Self, St> ⓘ
source§fn right_sink<Si1>(self) -> Either<Si1, Self> ⓘ
fn right_sink<Si1>(self) -> Either<Si1, Self> ⓘ
source§fn poll_ready_unpin(
&mut self,
cx: &mut Context<'_>,
) -> Poll<Result<(), Self::Error>>where
Self: Unpin,
fn poll_ready_unpin(
&mut self,
cx: &mut Context<'_>,
) -> Poll<Result<(), Self::Error>>where
Self: Unpin,
Sink::poll_ready
on Unpin
sink types.source§fn start_send_unpin(&mut self, item: Item) -> Result<(), Self::Error>where
Self: Unpin,
fn start_send_unpin(&mut self, item: Item) -> Result<(), Self::Error>where
Self: Unpin,
Sink::start_send
on Unpin
sink types.source§impl<T> StreamExt for T
impl<T> StreamExt for T
source§fn next(&mut self) -> Next<'_, Self> ⓘwhere
Self: Unpin,
fn next(&mut self) -> Next<'_, Self> ⓘwhere
Self: Unpin,
source§fn into_future(self) -> StreamFuture<Self> ⓘ
fn into_future(self) -> StreamFuture<Self> ⓘ
source§fn map<T, F>(self, f: F) -> Map<Self, F>
fn map<T, F>(self, f: F) -> Map<Self, F>
source§fn enumerate(self) -> Enumerate<Self>where
Self: Sized,
fn enumerate(self) -> Enumerate<Self>where
Self: Sized,
source§fn filter<Fut, F>(self, f: F) -> Filter<Self, Fut, F>
fn filter<Fut, F>(self, f: F) -> Filter<Self, Fut, F>
source§fn filter_map<Fut, T, F>(self, f: F) -> FilterMap<Self, Fut, F>
fn filter_map<Fut, T, F>(self, f: F) -> FilterMap<Self, Fut, F>
source§fn then<Fut, F>(self, f: F) -> Then<Self, Fut, F>
fn then<Fut, F>(self, f: F) -> Then<Self, Fut, F>
source§fn collect<C>(self) -> Collect<Self, C> ⓘ
fn collect<C>(self) -> Collect<Self, C> ⓘ
source§fn unzip<A, B, FromA, FromB>(self) -> Unzip<Self, FromA, FromB> ⓘ
fn unzip<A, B, FromA, FromB>(self) -> Unzip<Self, FromA, FromB> ⓘ
source§fn concat(self) -> Concat<Self> ⓘ
fn concat(self) -> Concat<Self> ⓘ
source§fn count(self) -> Count<Self> ⓘwhere
Self: Sized,
fn count(self) -> Count<Self> ⓘwhere
Self: Sized,
source§fn fold<T, Fut, F>(self, init: T, f: F) -> Fold<Self, Fut, T, F> ⓘ
fn fold<T, Fut, F>(self, init: T, f: F) -> Fold<Self, Fut, T, F> ⓘ
source§fn any<Fut, F>(self, f: F) -> Any<Self, Fut, F> ⓘ
fn any<Fut, F>(self, f: F) -> Any<Self, Fut, F> ⓘ
true
if any element in stream satisfied a predicate. Read moresource§fn all<Fut, F>(self, f: F) -> All<Self, Fut, F> ⓘ
fn all<Fut, F>(self, f: F) -> All<Self, Fut, F> ⓘ
true
if all element in stream satisfied a predicate. Read moresource§fn flatten(self) -> Flatten<Self>
fn flatten(self) -> Flatten<Self>
source§fn flatten_unordered(
self,
limit: impl Into<Option<usize>>,
) -> FlattenUnorderedWithFlowController<Self, ()>
fn flatten_unordered( self, limit: impl Into<Option<usize>>, ) -> FlattenUnorderedWithFlowController<Self, ()>
source§fn flat_map_unordered<U, F>(
self,
limit: impl Into<Option<usize>>,
f: F,
) -> FlatMapUnordered<Self, U, F>
fn flat_map_unordered<U, F>( self, limit: impl Into<Option<usize>>, f: F, ) -> FlatMapUnordered<Self, U, F>
StreamExt::map
but flattens nested Stream
s
and polls them concurrently, yielding items in any order, as they made
available. Read moresource§fn scan<S, B, Fut, F>(self, initial_state: S, f: F) -> Scan<Self, S, Fut, F>
fn scan<S, B, Fut, F>(self, initial_state: S, f: F) -> Scan<Self, S, Fut, F>
StreamExt::fold
that holds internal state
and produces a new stream. Read moresource§fn skip_while<Fut, F>(self, f: F) -> SkipWhile<Self, Fut, F>
fn skip_while<Fut, F>(self, f: F) -> SkipWhile<Self, Fut, F>
true
. Read moresource§fn take_while<Fut, F>(self, f: F) -> TakeWhile<Self, Fut, F>
fn take_while<Fut, F>(self, f: F) -> TakeWhile<Self, Fut, F>
true
. Read moresource§fn take_until<Fut>(self, fut: Fut) -> TakeUntil<Self, Fut>
fn take_until<Fut>(self, fut: Fut) -> TakeUntil<Self, Fut>
source§fn for_each<Fut, F>(self, f: F) -> ForEach<Self, Fut, F> ⓘ
fn for_each<Fut, F>(self, f: F) -> ForEach<Self, Fut, F> ⓘ
source§fn for_each_concurrent<Fut, F>(
self,
limit: impl Into<Option<usize>>,
f: F,
) -> ForEachConcurrent<Self, Fut, F> ⓘ
fn for_each_concurrent<Fut, F>( self, limit: impl Into<Option<usize>>, f: F, ) -> ForEachConcurrent<Self, Fut, F> ⓘ
source§fn take(self, n: usize) -> Take<Self>where
Self: Sized,
fn take(self, n: usize) -> Take<Self>where
Self: Sized,
n
items of the underlying stream. Read moresource§fn skip(self, n: usize) -> Skip<Self>where
Self: Sized,
fn skip(self, n: usize) -> Skip<Self>where
Self: Sized,
n
items of the underlying stream. Read moresource§fn catch_unwind(self) -> CatchUnwind<Self>where
Self: Sized + UnwindSafe,
fn catch_unwind(self) -> CatchUnwind<Self>where
Self: Sized + UnwindSafe,
source§fn boxed<'a>(self) -> Pin<Box<dyn Stream<Item = Self::Item> + Send + 'a>>
fn boxed<'a>(self) -> Pin<Box<dyn Stream<Item = Self::Item> + Send + 'a>>
source§fn boxed_local<'a>(self) -> Pin<Box<dyn Stream<Item = Self::Item> + 'a>>where
Self: Sized + 'a,
fn boxed_local<'a>(self) -> Pin<Box<dyn Stream<Item = Self::Item> + 'a>>where
Self: Sized + 'a,
source§fn buffered(self, n: usize) -> Buffered<Self>
fn buffered(self, n: usize) -> Buffered<Self>
source§fn buffer_unordered(self, n: usize) -> BufferUnordered<Self>
fn buffer_unordered(self, n: usize) -> BufferUnordered<Self>
source§fn zip<St>(self, other: St) -> Zip<Self, St>
fn zip<St>(self, other: St) -> Zip<Self, St>
source§fn peekable(self) -> Peekable<Self>where
Self: Sized,
fn peekable(self) -> Peekable<Self>where
Self: Sized,
peek
method. Read moresource§fn chunks(self, capacity: usize) -> Chunks<Self>where
Self: Sized,
fn chunks(self, capacity: usize) -> Chunks<Self>where
Self: Sized,
source§fn ready_chunks(self, capacity: usize) -> ReadyChunks<Self>where
Self: Sized,
fn ready_chunks(self, capacity: usize) -> ReadyChunks<Self>where
Self: Sized,
source§fn forward<S>(self, sink: S) -> Forward<Self, S> ⓘ
fn forward<S>(self, sink: S) -> Forward<Self, S> ⓘ
source§fn split<Item>(self) -> (SplitSink<Self, Item>, SplitStream<Self>)
fn split<Item>(self) -> (SplitSink<Self, Item>, SplitStream<Self>)
source§fn inspect<F>(self, f: F) -> Inspect<Self, F>
fn inspect<F>(self, f: F) -> Inspect<Self, F>
source§fn left_stream<B>(self) -> Either<Self, B> ⓘ
fn left_stream<B>(self) -> Either<Self, B> ⓘ
source§fn right_stream<B>(self) -> Either<B, Self> ⓘ
fn right_stream<B>(self) -> Either<B, Self> ⓘ
source§fn poll_next_unpin(&mut self, cx: &mut Context<'_>) -> Poll<Option<Self::Item>>where
Self: Unpin,
fn poll_next_unpin(&mut self, cx: &mut Context<'_>) -> Poll<Option<Self::Item>>where
Self: Unpin,
Stream::poll_next
on Unpin
stream types.source§fn select_next_some(&mut self) -> SelectNextSome<'_, Self> ⓘwhere
Self: Unpin + FusedStream,
fn select_next_some(&mut self) -> SelectNextSome<'_, Self> ⓘwhere
Self: Unpin + FusedStream,
source§impl<S> TryStreamExt for S
impl<S> TryStreamExt for S
source§fn err_into<E>(self) -> ErrInto<Self, E>
fn err_into<E>(self) -> ErrInto<Self, E>
source§fn map_ok<T, F>(self, f: F) -> MapOk<Self, F>
fn map_ok<T, F>(self, f: F) -> MapOk<Self, F>
source§fn map_err<E, F>(self, f: F) -> MapErr<Self, F>
fn map_err<E, F>(self, f: F) -> MapErr<Self, F>
source§fn and_then<Fut, F>(self, f: F) -> AndThen<Self, Fut, F>
fn and_then<Fut, F>(self, f: F) -> AndThen<Self, Fut, F>
f
. Read moresource§fn or_else<Fut, F>(self, f: F) -> OrElse<Self, Fut, F>
fn or_else<Fut, F>(self, f: F) -> OrElse<Self, Fut, F>
f
. Read moresource§fn inspect_ok<F>(self, f: F) -> InspectOk<Self, F>
fn inspect_ok<F>(self, f: F) -> InspectOk<Self, F>
source§fn inspect_err<F>(self, f: F) -> InspectErr<Self, F>
fn inspect_err<F>(self, f: F) -> InspectErr<Self, F>
source§fn into_stream(self) -> IntoStream<Self>where
Self: Sized,
fn into_stream(self) -> IntoStream<Self>where
Self: Sized,
source§fn try_next(&mut self) -> TryNext<'_, Self> ⓘwhere
Self: Unpin,
fn try_next(&mut self) -> TryNext<'_, Self> ⓘwhere
Self: Unpin,
source§fn try_for_each<Fut, F>(self, f: F) -> TryForEach<Self, Fut, F> ⓘ
fn try_for_each<Fut, F>(self, f: F) -> TryForEach<Self, Fut, F> ⓘ
source§fn try_skip_while<Fut, F>(self, f: F) -> TrySkipWhile<Self, Fut, F>
fn try_skip_while<Fut, F>(self, f: F) -> TrySkipWhile<Self, Fut, F>
true
. Read moresource§fn try_take_while<Fut, F>(self, f: F) -> TryTakeWhile<Self, Fut, F>
fn try_take_while<Fut, F>(self, f: F) -> TryTakeWhile<Self, Fut, F>
true
. Read moresource§fn try_for_each_concurrent<Fut, F>(
self,
limit: impl Into<Option<usize>>,
f: F,
) -> TryForEachConcurrent<Self, Fut, F> ⓘ
fn try_for_each_concurrent<Fut, F>( self, limit: impl Into<Option<usize>>, f: F, ) -> TryForEachConcurrent<Self, Fut, F> ⓘ
source§fn try_collect<C>(self) -> TryCollect<Self, C> ⓘ
fn try_collect<C>(self) -> TryCollect<Self, C> ⓘ
source§fn try_chunks(self, capacity: usize) -> TryChunks<Self>where
Self: Sized,
fn try_chunks(self, capacity: usize) -> TryChunks<Self>where
Self: Sized,
source§fn try_ready_chunks(self, capacity: usize) -> TryReadyChunks<Self>where
Self: Sized,
fn try_ready_chunks(self, capacity: usize) -> TryReadyChunks<Self>where
Self: Sized,
source§fn try_filter<Fut, F>(self, f: F) -> TryFilter<Self, Fut, F>
fn try_filter<Fut, F>(self, f: F) -> TryFilter<Self, Fut, F>
source§fn try_filter_map<Fut, F, T>(self, f: F) -> TryFilterMap<Self, Fut, F>
fn try_filter_map<Fut, F, T>(self, f: F) -> TryFilterMap<Self, Fut, F>
source§fn try_flatten_unordered(
self,
limit: impl Into<Option<usize>>,
) -> TryFlattenUnordered<Self>
fn try_flatten_unordered( self, limit: impl Into<Option<usize>>, ) -> TryFlattenUnordered<Self>
source§fn try_flatten(self) -> TryFlatten<Self>
fn try_flatten(self) -> TryFlatten<Self>
source§fn try_fold<T, Fut, F>(self, init: T, f: F) -> TryFold<Self, Fut, T, F> ⓘ
fn try_fold<T, Fut, F>(self, init: T, f: F) -> TryFold<Self, Fut, T, F> ⓘ
source§fn try_concat(self) -> TryConcat<Self> ⓘ
fn try_concat(self) -> TryConcat<Self> ⓘ
source§fn try_buffer_unordered(self, n: usize) -> TryBufferUnordered<Self>
fn try_buffer_unordered(self, n: usize) -> TryBufferUnordered<Self>
source§fn try_buffered(self, n: usize) -> TryBuffered<Self>
fn try_buffered(self, n: usize) -> TryBuffered<Self>
source§fn try_poll_next_unpin(
&mut self,
cx: &mut Context<'_>,
) -> Poll<Option<Result<Self::Ok, Self::Error>>>where
Self: Unpin,
fn try_poll_next_unpin(
&mut self,
cx: &mut Context<'_>,
) -> Poll<Option<Result<Self::Ok, Self::Error>>>where
Self: Unpin,
TryStream::try_poll_next
on Unpin
stream types.source§fn into_async_read(self) -> IntoAsyncRead<Self>
fn into_async_read(self) -> IntoAsyncRead<Self>
AsyncBufRead
. Read moresource§fn try_all<Fut, F>(self, f: F) -> TryAll<Self, Fut, F> ⓘ
fn try_all<Fut, F>(self, f: F) -> TryAll<Self, Fut, F> ⓘ
Err
is encountered or if an Ok
item is found
that does not satisfy the predicate. Read more