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use core::fmt;
use core::pin::Pin;
use futures_core::stream::{FusedStream, Stream};
use futures_core::task::{Context, Poll};
#[cfg(feature = "sink")]
use futures_sink::Sink;
use pin_project::{pin_project, project};
use crate::fns::FnMut1;
#[pin_project]
#[must_use = "streams do nothing unless polled"]
pub struct Map<St, F> {
#[pin]
stream: St,
f: F,
}
impl<St, F> fmt::Debug for Map<St, F>
where
St: fmt::Debug,
{
fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
f.debug_struct("Map")
.field("stream", &self.stream)
.finish()
}
}
impl<St, F> Map<St, F> {
pub(crate) fn new(stream: St, f: F) -> Map<St, F> {
Map { stream, f }
}
delegate_access_inner!(stream, St, ());
}
impl<St, F> FusedStream for Map<St, F>
where St: FusedStream,
F: FnMut1<St::Item>,
{
fn is_terminated(&self) -> bool {
self.stream.is_terminated()
}
}
impl<St, F> Stream for Map<St, F>
where St: Stream,
F: FnMut1<St::Item>,
{
type Item = F::Output;
#[project]
fn poll_next(
self: Pin<&mut Self>,
cx: &mut Context<'_>,
) -> Poll<Option<Self::Item>> {
#[project]
let Map { stream, f } = self.project();
let res = ready!(stream.poll_next(cx));
Poll::Ready(res.map(|x| f.call_mut(x)))
}
fn size_hint(&self) -> (usize, Option<usize>) {
self.stream.size_hint()
}
}
#[cfg(feature = "sink")]
impl<St, F, Item> Sink<Item> for Map<St, F>
where St: Stream + Sink<Item>,
F: FnMut1<St::Item>,
{
type Error = St::Error;
delegate_sink!(stream, Item);
}