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, Stream}; 6 use futures_core::task::{Context, Poll}; 7 use pin_project_lite::pin_project; 8 9 pin_project! { 10 /// Future for the [`collect`](super::StreamExt::collect) method. 11 #[derive(Debug)] 12 #[must_use = "futures do nothing unless you `.await` or poll them"] 13 pub struct Collect<St, C> { 14 #[pin] 15 stream: St, 16 collection: C, 17 } 18 } 19 20 impl<St: Stream, C: Default> Collect<St, C> { finish(self: Pin<&mut Self>) -> C21 fn finish(self: Pin<&mut Self>) -> C { 22 mem::take(self.project().collection) 23 } 24 new(stream: St) -> Self25 pub(super) fn new(stream: St) -> Self { 26 Self { stream, collection: Default::default() } 27 } 28 } 29 30 impl<St, C> FusedFuture for Collect<St, C> 31 where 32 St: FusedStream, 33 C: Default + Extend<St::Item>, 34 { is_terminated(&self) -> bool35 fn is_terminated(&self) -> bool { 36 self.stream.is_terminated() 37 } 38 } 39 40 impl<St, C> Future for Collect<St, C> 41 where 42 St: Stream, 43 C: Default + Extend<St::Item>, 44 { 45 type Output = C; 46 poll(mut self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<C>47 fn poll(mut self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<C> { 48 let mut this = self.as_mut().project(); 49 loop { 50 match ready!(this.stream.as_mut().poll_next(cx)) { 51 Some(e) => this.collection.extend(Some(e)), 52 None => return Poll::Ready(self.finish()), 53 } 54 } 55 } 56 } 57