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use derive_new::new; use futures::{ready, Stream}; use pin_project::pin_project; use serde_closure::traits::FnMut; use std::{ pin::Pin, task::{Context, Poll} }; use super::Pipe; #[pin_project] #[derive(new)] pub struct Filter<P, F> { #[pin] pipe: P, f: F, } impl<P: Stream, F> Stream for Filter<P, F> where F: for<'a> FnMut<(&'a P::Item,), Output = bool>, { type Item = P::Item; #[inline] fn poll_next(self: Pin<&mut Self>, cx: &mut Context) -> Poll<Option<Self::Item>> { let mut self_ = self.project(); let (mut pipe, f) = (self_.pipe, &mut self_.f); Poll::Ready(loop { match ready!(pipe.as_mut().poll_next(cx)) { Some(t) if f.call_mut((&t,)) => break Some(t), Some(_) => (), None => break None, } }) } } impl<P: Pipe<Input>, F, Input> Pipe<Input> for Filter<P, F> where F: for<'a> FnMut<(&'a P::Output,), Output = bool>, { type Output = P::Output; #[inline] fn poll_next( self: Pin<&mut Self>, cx: &mut Context, mut stream: Pin<&mut impl Stream<Item = Input>>, ) -> Poll<Option<Self::Output>> { let mut self_ = self.project(); let (mut pipe, f) = (self_.pipe, &mut self_.f); Poll::Ready(loop { match ready!(pipe.as_mut().poll_next(cx, stream.as_mut())) { Some(t) if f.call_mut((&t,)) => break Some(t), Some(_) => (), None => break None, } }) } }