Macro allochronic_util::select

select!() { /* proc-macro */ }

Polls all passed Futures or Streams until one is ready and returns it. Prioritizes by order.

Raw-mode

If the complete item is unspecified, Futures and Streams will be pulled beyond exhaustion. If a high priority item is exhausted and select! is being used in a loop, it will continuously return the same result, which might be unintended.

Fused-mode

If the complete item is specified, all polled items have to implement FusedFuture or FusedStream, for Streams this will unwrap the Option. The complete item will be executed once all items have been exhausted. Items will not be pulled beyond exhaustion.

Examples

Raw-mode:

use futures_util::stream;
use allochronic_util::select;

let mut stream1 = stream::iter(1..=3);
let mut stream2 = stream::iter(4..=6);
let mut stream3 = stream::iter(7..=9);

let mut counter = 0;

while let Some(result) = select![
	result: &mut stream1 => result,
	result: &mut stream2 => result,
	result: &mut stream3 => result,
] {
	counter += 1;
	assert_eq!(counter, result);
}

// this loop will only reach the number of three, because it will abort after the first stream
// is exhausted
assert_eq!(counter, 3);

Fused-mode:

use futures_util::stream::{self, StreamExt};
use allochronic_util::select;

let mut stream1 = stream::iter(1..=3).fuse();
let mut stream2 = stream::iter(4..=6).fuse();
let mut stream3 = stream::iter(7..=9).fuse();

let mut counter = 0;

while let Some(result) = select![
	result: &mut stream1 => Some(result),
	result: &mut stream2 => Some(result),
	result: &mut stream3 => Some(result),
	complete => None,
] {
	counter += 1;
	assert_eq!(counter, result);
}

assert_eq!(counter, 9);