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use core::pin::Pin;
use futures_core::stream::{FusedStream, Stream};
use futures_core::task::{Context, Poll};
use futures_sink::Sink;
use pin_utils::{unsafe_pinned, unsafe_unpinned};
#[derive(Debug)]
#[must_use = "streams do nothing unless polled"]
pub struct Map<St, F> {
stream: St,
f: F,
}
impl<St: Unpin, F> Unpin for Map<St, F> {}
impl<St, T, F> Map<St, F>
where St: Stream,
F: FnMut(St::Item) -> T,
{
unsafe_pinned!(stream: St);
unsafe_unpinned!(f: F);
pub(super) fn new(stream: St, f: F) -> Map<St, F> {
Map { 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: FusedStream, F> FusedStream for Map<St, F> {
fn is_terminated(&self) -> bool {
self.stream.is_terminated()
}
}
impl<St, F, T> Stream for Map<St, F>
where St: Stream,
F: FnMut(St::Item) -> T,
{
type Item = T;
fn poll_next(
mut self: Pin<&mut Self>,
cx: &mut Context<'_>,
) -> Poll<Option<T>> {
let option = ready!(self.as_mut().stream().poll_next(cx));
Poll::Ready(option.map(self.as_mut().f()))
}
}
impl<S, F, T, Item> Sink<Item> for Map<S, F>
where S: Stream + Sink<Item>,
F: FnMut(S::Item) -> T,
{
type SinkError = S::SinkError;
delegate_sink!(stream, Item);
}