Struct async_gen::AsyncIter

pub struct AsyncIter<G> { /* private fields */ }

An async iterator over the values yielded by an underlying generator.

Example

use async_gen::{gen, AsyncIter};
use futures_core::Stream;
use futures_util::StreamExt;

fn get_async_iter() -> impl Stream<Item = i32> {
    AsyncIter::from(gen! {
        yield 1;
        yield 2;
        yield 3;
    })
}

#[tokio::main]
async fn main() {
    let it = get_async_iter();
    let v: Vec<_> = it.collect().await;
    assert_eq!(v, [1, 2, 3]);
}

Implementations

impl<G: AsyncGenerator<Return = ()>> AsyncIter<G>

pub fn poll_next( self: Pin<&mut Self>, cx: &mut Context<'_> ) -> Poll<Option<G::Yield>>

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

Return value

There are several possible return values, each indicating a distinct async iterator state:

• Poll::Pending means that this async iterator’s next value is not ready yet. Implementations will ensure that the current task will be notified when the next value may be ready.

• Poll::Ready(Some(val)) means that the async iterator has successfully produced a value, val, and may produce further values on subsequent poll_next calls.

• Poll::Ready(None) means that the async iterator has terminated, and poll_next should not be invoked again.

Panics

Once an async iterator has finished (returned Ready(None) from poll_next), calling its poll_next method again may panic, block forever, or cause other kinds of problems; the AsyncIterator trait places no requirements on the effects of such a call. However, as the poll_next method is not marked unsafe, Rust’s usual rules apply: calls must never cause undefined behavior (memory corruption, incorrect use of unsafe functions, or the like), regardless of the async iterator’s state.

Trait Implementations

impl<G: Clone> Clone for AsyncIter<G>

fn clone(&self) -> AsyncIter<G>

Returns a copy of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.

impl<G> From<G> for AsyncIter<G>

fn from(gen: G) -> Self

Converts to this type from the input type.

impl<G: AsyncGenerator<Return = ()>> Stream for AsyncIter<G>

type Item = <G as AsyncGenerator>::Yield

Values yielded by the stream.

fn poll_next( self: Pin<&mut Self>, cx: &mut Context<'_> ) -> Poll<Option<Self::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<'__pin, G> Unpin for AsyncIter<G>where __Origin<'__pin, G>: Unpin,