Struct aws_smithy_async::future::fn_stream::FnStream

pub struct FnStream<Item, F> { /* private fields */ }

Utility to drive a stream with an async function and a channel.

The closure is passed a reference to a Sender which acts as a rendezvous channel. Messages sent to the sender will be emitted to the stream. Because the stream is 1-bounded, the function will not proceed until the stream is read.

This utility is used by generated paginators to generate a stream of paginated results.

If tx.send returns an error, the function MUST return immediately.

Examples

use tokio_stream::StreamExt;
use aws_smithy_async::future::fn_stream::FnStream;
let stream = FnStream::new(|tx| Box::pin(async move {
    if let Err(_) = tx.send("Hello!").await {
        return;
    }
    if let Err(_) = tx.send("Goodbye!").await {
        return;
    }
}));
assert_eq!(stream.collect::<Vec<_>>().await, vec!["Hello!", "Goodbye!"]);

Implementations

impl<Item, F> FnStream<Item, F>

pub fn new<T>(generator: T) -> Selfwhere T: FnOnce(Sender<Item>) -> F,

Creates a new function based stream driven by generator.

For examples, see the documentation for FnStream

Trait Implementations

impl<Item, F> Stream for FnStream<Item, F>where F: Future<Output = ()>,

type Item = Item

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, Item, F> Unpin for FnStream<Item, F>where __Origin<'__pin, Item, F>: Unpin,