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use crate::Stream;
use core::future::Future;
use core::marker::PhantomPinned;
use core::pin::Pin;
use core::task::{Context, Poll};
use pin_project_lite::pin_project;
pin_project! {
/// Future for the [`any`](super::StreamExt::any) method.
#[derive(Debug)]
#[must_use = "futures do nothing unless you `.await` or poll them"]
pub struct AnyFuture<'a, St: ?Sized, F> {
stream: &'a mut St,
f: F,
// Make this future `!Unpin` for compatibility with async trait methods.
#[pin]
_pin: PhantomPinned,
}
}
impl<'a, St: ?Sized, F> AnyFuture<'a, St, F> {
pub(super) fn new(stream: &'a mut St, f: F) -> Self {
Self {
stream,
f,
_pin: PhantomPinned,
}
}
}
impl<St, F> Future for AnyFuture<'_, St, F>
where
St: ?Sized + Stream + Unpin,
F: FnMut(St::Item) -> bool,
{
type Output = bool;
fn poll(self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<Self::Output> {
let me = self.project();
let mut stream = Pin::new(me.stream);
// Take a maximum of 32 items from the stream before yielding.
for _ in 0..32 {
match futures_core::ready!(stream.as_mut().poll_next(cx)) {
Some(v) => {
if (me.f)(v) {
return Poll::Ready(true);
}
}
None => return Poll::Ready(false),
}
}
cx.waker().wake_by_ref();
Poll::Pending
}
}