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use core::pin::Pin;
use core::task::{Context, Poll};
use completion_core::CompletionStream;
use futures_core::{ready, Stream};
use pin_project_lite::pin_project;
pin_project! {
#[derive(Debug, Clone)]
pub struct Filter<S, F> {
#[pin]
stream: S,
f: F,
}
}
impl<S, F> Filter<S, F> {
pub(crate) fn new(stream: S, f: F) -> Self {
Self { stream, f }
}
}
impl<S: CompletionStream, F: FnMut(&S::Item) -> bool> CompletionStream for Filter<S, F> {
type Item = S::Item;
unsafe fn poll_next(self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<Option<Self::Item>> {
let mut this = self.project();
loop {
match ready!(this.stream.as_mut().poll_next(cx)) {
Some(item) if (this.f)(&item) => break Poll::Ready(Some(item)),
Some(_) => {}
None => break Poll::Ready(None),
}
}
}
unsafe fn poll_cancel(self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<()> {
self.project().stream.poll_cancel(cx)
}
fn size_hint(&self) -> (usize, Option<usize>) {
let (_, high) = self.stream.size_hint();
(0, high)
}
}
impl<S, F: FnMut(&<S as CompletionStream>::Item) -> bool> Stream for Filter<S, F>
where
S: CompletionStream + Stream<Item = <S as CompletionStream>::Item>,
{
type Item = <Self as CompletionStream>::Item;
fn poll_next(self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<Option<Self::Item>> {
unsafe { CompletionStream::poll_next(self, cx) }
}
fn size_hint(&self) -> (usize, Option<usize>) {
CompletionStream::size_hint(self)
}
}
pin_project! {
#[derive(Debug, Clone)]
pub struct FilterMap<S, F> {
#[pin]
stream: S,
f: F,
}
}
impl<S, F> FilterMap<S, F> {
pub(crate) fn new(stream: S, f: F) -> Self {
Self { stream, f }
}
}
impl<S, F, T> CompletionStream for FilterMap<S, F>
where
S: CompletionStream,
F: FnMut(S::Item) -> Option<T>,
{
type Item = T;
unsafe fn poll_next(self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<Option<Self::Item>> {
let mut this = self.project();
loop {
match ready!(this.stream.as_mut().poll_next(cx)) {
Some(item) => {
if let Some(mapped) = (this.f)(item) {
break Poll::Ready(Some(mapped));
}
}
None => break Poll::Ready(None),
}
}
}
unsafe fn poll_cancel(self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<()> {
self.project().stream.poll_cancel(cx)
}
fn size_hint(&self) -> (usize, Option<usize>) {
let (_, upper) = self.stream.size_hint();
(0, upper)
}
}
impl<S, F, T> Stream for FilterMap<S, F>
where
S: CompletionStream + Stream<Item = <S as CompletionStream>::Item>,
F: FnMut(<S as CompletionStream>::Item) -> Option<T>,
{
type Item = <Self as CompletionStream>::Item;
fn poll_next(self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<Option<Self::Item>> {
unsafe { CompletionStream::poll_next(self, cx) }
}
fn size_hint(&self) -> (usize, Option<usize>) {
CompletionStream::size_hint(self)
}
}