1 use core::mem; 2 use core::pin::Pin; 3 use futures_core::future::{FusedFuture, Future}; 4 use futures_core::ready; 5 use futures_core::stream::{FusedStream, TryStream}; 6 use futures_core::task::{Context, Poll}; 7 use pin_project_lite::pin_project; 8 9 pin_project! { 10 /// Future for the [`try_collect`](super::TryStreamExt::try_collect) method. 11 #[derive(Debug)] 12 #[must_use = "futures do nothing unless you `.await` or poll them"] 13 pub struct TryCollect<St, C> { 14 #[pin] 15 stream: St, 16 items: C, 17 } 18 } 19 20 impl<St: TryStream, C: Default> TryCollect<St, C> { new(s: St) -> Self21 pub(super) fn new(s: St) -> Self { 22 Self { 23 stream: s, 24 items: Default::default(), 25 } 26 } 27 } 28 29 impl<St, C> FusedFuture for TryCollect<St, C> 30 where 31 St: TryStream + FusedStream, 32 C: Default + Extend<St::Ok>, 33 { is_terminated(&self) -> bool34 fn is_terminated(&self) -> bool { 35 self.stream.is_terminated() 36 } 37 } 38 39 impl<St, C> Future for TryCollect<St, C> 40 where 41 St: TryStream, 42 C: Default + Extend<St::Ok>, 43 { 44 type Output = Result<C, St::Error>; 45 poll( self: Pin<&mut Self>, cx: &mut Context<'_>, ) -> Poll<Self::Output>46 fn poll( 47 self: Pin<&mut Self>, 48 cx: &mut Context<'_>, 49 ) -> Poll<Self::Output> { 50 let mut this = self.project(); 51 Poll::Ready(Ok(loop { 52 match ready!(this.stream.as_mut().try_poll_next(cx)?) { 53 Some(x) => this.items.extend(Some(x)), 54 None => break mem::replace(this.items, Default::default()), 55 } 56 })) 57 } 58 } 59