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

pub trait StreamExt: Stream {
    fn next(&mut self) -> Next<Self>
    where
        Self: Unpin,
    { ... }

    fn map<T, F>(self, f: F) -> Map<Self, F>
    where
        F: FnMut(Self::Item) -> T,
        Self: Sized,
    { ... }
}
This is supported on feature="stream" only.

An extension trait for Streams that provides a variety of convenient combinator functions.

Provided methods

fn next(&mut self) -> Next<Self> where
    Self: Unpin, 

This is supported on feature="stream" only.

Creates a future that resolves to the next item in the stream.

Equivalent to:

ⓘThis example is not tested
async fn next(&mut self) -> Option<Self::Item>;

Note that because next doesn't take ownership over the stream, the Stream type must be Unpin. If you want to use next with a !Unpin stream, you'll first have to pin the stream. This can be done by boxing the stream using Box::pin or pinning it to the stack using the pin_mut! macro from the pin_utils crate.

Examples

use tokio::stream::{self, StreamExt};

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

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

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

This is supported on feature="stream" only.

Maps this stream's items to a different type, returning a new stream of the resulting type.

The provided closure is executed over all elements of this stream as they are made available. It is executed inline with calls to poll_next.

Note that this function consumes the stream passed into it and returns a wrapped version of it, similar to the existing map methods in the standard library.

Examples

use tokio::stream::{self, StreamExt};

let stream = stream::iter(1..=3);
let mut stream = stream.map(|x| x + 3);

assert_eq!(stream.next().await, Some(4));
assert_eq!(stream.next().await, Some(5));
assert_eq!(stream.next().await, Some(6));
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Implementors

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

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