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use core::pin::Pin;
use pin_project_lite::pin_project;
use crate::stream::Stream;
use crate::task::{Context, Poll};
pin_project! {
#[derive(Clone, Debug)]
pub struct Take<S> {
#[pin]
pub(crate) stream: S,
pub(crate) remaining: usize,
}
}
impl<S> Take<S> {
pub(super) fn new(stream: S, remaining: usize) -> Self {
Self {
stream,
remaining,
}
}
}
impl<S: Stream> Stream for Take<S> {
type Item = S::Item;
fn poll_next(self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<Option<S::Item>> {
let this = self.project();
if *this.remaining == 0 {
Poll::Ready(None)
} else {
let next = futures_core::ready!(this.stream.poll_next(cx));
match next {
Some(_) => *this.remaining -= 1,
None => *this.remaining = 0,
}
Poll::Ready(next)
}
}
}