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use core::marker::Unpin;
use core::pin::Pin;
use futures_core::stream::Stream;
use futures_core::task::{LocalWaker, Poll};
use pin_utils::{unsafe_pinned, unsafe_unpinned};
#[derive(Debug)]
#[must_use = "streams do nothing unless polled"]
pub struct Inspect<St, F> where St: Stream {
stream: St,
f: F,
}
impl<St: Stream + Unpin, F> Unpin for Inspect<St, F> {}
impl<St, F> Inspect<St, F>
where St: Stream,
F: FnMut(&St::Item) -> (),
{
unsafe_pinned!(stream: St);
unsafe_unpinned!(f: F);
pub(super) fn new(stream: St, f: F) -> Inspect<St, F> {
Inspect { stream, f }
}
pub fn get_ref(&self) -> &St {
&self.stream
}
pub fn get_mut(&mut self) -> &mut St {
&mut self.stream
}
pub fn into_inner(self) -> St {
self.stream
}
}
impl<St, F> Stream for Inspect<St, F>
where St: Stream,
F: FnMut(&St::Item),
{
type Item = St::Item;
fn poll_next(
mut self: Pin<&mut Self>,
lw: &LocalWaker
) -> Poll<Option<St::Item>> {
let item = ready!(self.stream().poll_next(lw));
Poll::Ready(item.map(|e| {
(self.f())(&e);
e
}))
}
}