blob: a47c4b5e938eb26e04f6214ebe74cc6b13dc1ee9 [file] [log] [blame]
use futures_core::future::Future;
use futures_core::stream::TryStream;
use futures_core::task::{LocalWaker, Poll};
use pin_utils::{unsafe_pinned, unsafe_unpinned};
use std::marker::Unpin;
use std::mem;
use std::pin::Pin;
use std::prelude::v1::*;
/// A future which attempts to collect all of the values of a stream.
///
/// This future is created by the `Stream::try_collect` method.
#[derive(Debug)]
#[must_use = "streams do nothing unless polled"]
pub struct TryCollect<St, C> where St: TryStream {
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(mut self: Pin<&mut Self>) -> C {
mem::replace(self.items(), Default::default())
}
}
impl<St: Unpin + TryStream, C> Unpin for TryCollect<St, C> {}
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>,
lw: &LocalWaker,
) -> Poll<Self::Output> {
loop {
match ready!(self.stream().try_poll_next(lw)) {
Some(Ok(x)) => self.items().extend(Some(x)),
Some(Err(e)) => return Poll::Ready(Err(e)),
None => return Poll::Ready(Ok(self.finish())),
}
}
}
}