Struct FnStream

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

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.

Note FnStream is only Send but not Sync because generator is a boxed future that is Send and returns () as output when it is done.

Examples

use aws_smithy_async::future::pagination_stream::fn_stream::FnStream;
let mut 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> FnStream<Item>

pub fn new<T>(generator: T) -> Self

where T: FnOnce(Sender<Item>) -> Pin<Box<dyn Future<Output = ()> + Send + 'static>>,

Creates a new function based stream driven by generator.

For examples, see the documentation for FnStream

pub async fn next(&mut self) -> Option<Item>

where Self: Unpin,

Consumes and returns the next Item from this stream.

pub async fn collect<T: Collectable<Item>>(self) -> T

Consumes this stream and gathers elements into a collection.

impl<T, E> FnStream<Result<T, E>>

pub async fn try_next(&mut self) -> Result<Option<T>, E>

Yields the next item in the stream or returns an error if an error is encountered.

pub async fn try_collect(self) -> Result<Vec<T>, E>

Convenience method for .collect::<Result<Vec<_>, _>().

Trait Implementations

impl<Item> Debug for FnStream<Item>

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.

impl<'__pin, Item> Unpin for FnStream<Item>

where __Origin<'__pin, Item>: Unpin,