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use crate::Operator;
use futures::task::{Context, Poll};
use futures::{ready, Stream};
use pin_project_lite::pin_project;
pin_project! {
#[derive(Debug, Clone, Copy)]
pub struct Operated<St, P> {
#[pin]
source: St,
op: P,
}
}
impl<St, P> Stream for Operated<St, P>
where
St: Stream,
P: Operator<St::Item>,
{
type Item = P::Output;
fn poll_next(self: std::pin::Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<Option<Self::Item>> {
let mut this = self.project();
let res = ready!(this.source.as_mut().poll_next(cx));
Poll::Ready(res.map(|x| this.op.next(x)))
}
fn size_hint(&self) -> (usize, Option<usize>) {
self.source.size_hint()
}
}
pub trait IndicatorStreamExt: Stream {
fn indicator<P>(self, op: P) -> Operated<Self, P>
where
Self: Sized,
P: Operator<Self::Item>,
{
Operated { source: self, op }
}
}
impl<St: Stream> IndicatorStreamExt for St {}