[−][src]Trait futures_lite::stream::StreamExt

pub trait StreamExt: Stream {
    fn next(&mut self) -> NextFuture<Self>ⓘ
Important traits for NextFuture<'_, T>
impl<T: Stream + Unpin + ?Sized, '_> Future for NextFuture<'_, T>    type Output = Option<T::Item>;

    where
        Self: Unpin,
    { ... }

    fn collect<C: Default + Extend<Self::Item>>(self) -> CollectFuture<Self, C>ⓘ
Important traits for CollectFuture<St, C>
impl<St, C> Future for CollectFuture<St, C> where
    St: Stream,
    C: Default + Extend<St::Item>,     type Output = C;

    where
        Self: Sized,
    { ... }

    fn try_collect<T, C: Default + Extend<T>>(self) -> TryCollectFuture<Self, C>ⓘ
Important traits for TryCollectFuture<St, C>
impl<T, E, St, C> Future for TryCollectFuture<St, C> where
    St: Stream<Item = Result<T, E>>,
    C: Default + Extend<T>,     type Output = Result<C, E>;

    where
        Self: Sized,
        Self::Item: Result<Ok = T>,
    { ... }

    fn fold<B, F>(self, init: B, f: F) -> FoldFuture<Self, F, B>ⓘ
Important traits for FoldFuture<S, F, B>
impl<S, F, B> Future for FoldFuture<S, F, B> where
    S: Stream + Sized,
    F: FnMut(B, S::Item) -> B,     type Output = B;

    where
        Self: Sized,
        F: FnMut(B, Self::Item) -> B,
    { ... }

    fn try_fold<T, E, F, B>(
        &mut self, 
        init: B, 
        f: F
    ) -> TryFoldFuture<Self, F, B>ⓘ
Important traits for TryFoldFuture<'a, S, F, B>
impl<'a, T, E, S, F, B> Future for TryFoldFuture<'a, S, F, B> where
    S: Stream + Unpin,
    S::Item: Result<Ok = T, Err = E>,
    F: FnMut(B, T) -> Result<B, E>,     type Output = Result<B, E>;

    where
        Self: Unpin + Sized,
        Self::Item: Result<Ok = T, Err = E>,
        F: FnMut(B, T) -> Result<B, E>,
    { ... }

    fn boxed(self) -> Boxed<Self::Item>
    where
        Self: Sized + Send + 'static,
    { ... }

    fn boxed_local(self) -> BoxedLocal<Self::Item>
    where
        Self: Sized + 'static,
    { ... }
}

Extension trait for Stream.

Provided methods

fn next(&mut self) -> NextFuture<Self>ⓘ

Important traits for NextFuture<'_, T>

impl<T: Stream + Unpin + ?Sized, '_> Future for NextFuture<'_, T> type Output = Option<T::Item>;
 where
    Self: Unpin, 

Retrieves the next item in the stream.

Returns None when iteration is finished. Stream implementations may choose to or not to resume iteration after that.

Examples

use futures_lite::*;

let mut s = stream::iter(1..=3);

assert_eq!(s.next().await, Some(1));
assert_eq!(s.next().await, Some(2));
assert_eq!(s.next().await, Some(3));
assert_eq!(s.next().await, None);

fn collect<C: Default + Extend<Self::Item>>(self) -> CollectFuture<Self, C>ⓘ

Important traits for CollectFuture<St, C>

impl<St, C> Future for CollectFuture<St, C> where
    St: Stream,
    C: Default + Extend<St::Item>,  type Output = C;
 where
    Self: Sized, 

Collects all items in the stream into a collection.

Examples

use futures_lite::*;

let mut s = stream::iter(1..=3);

let items: Vec<_> = s.collect().await;
assert_eq!(items, [1, 2, 3]);

fn try_collect<T, C: Default + Extend<T>>(self) -> TryCollectFuture<Self, C>ⓘ

Important traits for TryCollectFuture<St, C>

impl<T, E, St, C> Future for TryCollectFuture<St, C> where
    St: Stream<Item = Result<T, E>>,
    C: Default + Extend<T>,  type Output = Result<C, E>;
 where
    Self: Sized,
    Self::Item: Result<Ok = T>, 

Collects all items in the fallible stream into a collection.

use futures_lite::*;

let s = stream::iter(vec![Ok(1), Err(2), Ok(3)]);
let res: Result<Vec<i32>, i32> = s.try_collect().await;
assert_eq!(res, Err(2));

let s = stream::iter(vec![Ok(1), Ok(2), Ok(3)]);
let res: Result<Vec<i32>, i32> = s.try_collect().await;
assert_eq!(res, Ok(vec![1, 2, 3]));

fn fold<B, F>(self, init: B, f: F) -> FoldFuture<Self, F, B>ⓘ

Important traits for FoldFuture<S, F, B>

impl<S, F, B> Future for FoldFuture<S, F, B> where
    S: Stream + Sized,
    F: FnMut(B, S::Item) -> B,  type Output = B;
 where
    Self: Sized,
    F: FnMut(B, Self::Item) -> B, 

Accumulates a computation over the stream.

The computation begins with the accumulator value set to init then applies f to the accumulator and each item in the stream. The final accumulator value is returned.

Examples

use futures_lite::*;

let s = stream::iter(vec![1, 2, 3]);
let sum = s.fold(0, |acc, x| acc + x).await;

assert_eq!(sum, 6);

fn try_fold<T, E, F, B>(&mut self, init: B, f: F) -> TryFoldFuture<Self, F, B>ⓘ

Important traits for TryFoldFuture<'a, S, F, B>

impl<'a, T, E, S, F, B> Future for TryFoldFuture<'a, S, F, B> where
    S: Stream + Unpin,
    S::Item: Result<Ok = T, Err = E>,
    F: FnMut(B, T) -> Result<B, E>,  type Output = Result<B, E>;
 where
    Self: Unpin + Sized,
    Self::Item: Result<Ok = T, Err = E>,
    F: FnMut(B, T) -> Result<B, E>, 

Accumulates a fallible computation over the stream.

The computation begins with the accumulator value set to init then applies f to the accumulator and each item in the stream. The final accumulator value is returned, or an error if f failed the computation.

Examples

use futures_lite::*;

let mut s = stream::iter(vec![Ok(1), Ok(2), Ok(3)]);

let sum = s.try_fold(0, |acc, v| {
    if (acc + v) % 2 == 1 {
        Ok(acc + v)
    } else {
        Err("fail")
    }
})
.await;

assert_eq!(sum, Err("fail"));

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

Boxes the stream and changes its type to dyn Stream<Item = T> + Send.

Examples

use futures_lite::*;

let a = stream::once(1);
let b = stream::empty();

// Streams of different types can be stored in
// the same collection when they are boxed:
let streams = vec![a.boxed(), b.boxed()];

fn boxed_local(self) -> BoxedLocal<Self::Item> where
    Self: Sized + 'static, 

Boxes the stream and changes its type to dyn Stream<Item = T>.

Examples

use futures_lite::*;

let a = stream::once(1);
let b = stream::empty();

// Streams of different types can be stored in
// the same collection when they are boxed:
let streams = vec![a.boxed_local(), b.boxed_local()];
Loading content...

Implementors

impl<T: ?Sized> StreamExt for T where
    T: Stream, [src]

Loading content...