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use core::mem;
use core::pin::Pin;
use futures_core::future::{FusedFuture, Future};
use futures_core::stream::{FusedStream, TryStream};
use futures_core::task::{Context, Poll};
use pin_utils::{unsafe_pinned, unsafe_unpinned};
#[derive(Debug)]
#[must_use = "futures do nothing unless you `.await` or poll them"]
pub struct TryCollect<St, C> {
stream: St,
items: C,
}
impl<St: TryStream, C: Default> TryCollect<St, C> {
unsafe_pinned!(stream: St);
unsafe_unpinned!(items: C);
pub(super) fn new(s: St) -> TryCollect<St, C> {
TryCollect {
stream: s,
items: Default::default(),
}
}
fn finish(self: Pin<&mut Self>) -> C {
mem::replace(self.items(), Default::default())
}
}
impl<St: Unpin + TryStream, C> Unpin for TryCollect<St, C> {}
impl<St, C> FusedFuture for TryCollect<St, C>
where
St: TryStream + FusedStream,
C: Default + Extend<St::Ok>,
{
fn is_terminated(&self) -> bool {
self.stream.is_terminated()
}
}
impl<St, C> Future for TryCollect<St, C>
where
St: TryStream,
C: Default + Extend<St::Ok>,
{
type Output = Result<C, St::Error>;
fn poll(
mut self: Pin<&mut Self>,
cx: &mut Context<'_>,
) -> Poll<Self::Output> {
loop {
match ready!(self.as_mut().stream().try_poll_next(cx)?) {
Some(x) => self.as_mut().items().extend(Some(x)),
None => return Poll::Ready(Ok(self.as_mut().finish())),
}
}
}
}