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use std::future::Future;
use std::pin::Pin;
use std::task::{Context, Poll};
use futures_util::{ready, TryFuture};
use pin_project::pin_project;
use super::{Filter, FilterBase, Func, Internal};
use crate::reject::CombineRejection;
#[derive(Clone, Copy, Debug)]
pub struct AndThen<T, F> {
pub(super) filter: T,
pub(super) callback: F,
}
impl<T, F> FilterBase for AndThen<T, F>
where
T: Filter,
F: Func<T::Extract> + Clone + Send,
F::Output: TryFuture + Send,
<F::Output as TryFuture>::Error: CombineRejection<T::Error>,
{
type Extract = (<F::Output as TryFuture>::Ok,);
type Error = <<F::Output as TryFuture>::Error as CombineRejection<T::Error>>::One;
type Future = AndThenFuture<T, F>;
#[inline]
fn filter(&self, _: Internal) -> Self::Future {
AndThenFuture {
state: State::First(self.filter.filter(Internal), self.callback.clone()),
}
}
}
#[allow(missing_debug_implementations)]
#[pin_project]
pub struct AndThenFuture<T, F>
where
T: Filter,
F: Func<T::Extract>,
F::Output: TryFuture + Send,
<F::Output as TryFuture>::Error: CombineRejection<T::Error>,
{
#[pin]
state: State<T::Future, F>,
}
#[pin_project(project = StateProj)]
enum State<T, F>
where
T: TryFuture,
F: Func<T::Ok>,
F::Output: TryFuture + Send,
<F::Output as TryFuture>::Error: CombineRejection<T::Error>,
{
First(#[pin] T, F),
Second(#[pin] F::Output),
Done,
}
impl<T, F> Future for AndThenFuture<T, F>
where
T: Filter,
F: Func<T::Extract>,
F::Output: TryFuture + Send,
<F::Output as TryFuture>::Error: CombineRejection<T::Error>,
{
type Output = Result<
(<F::Output as TryFuture>::Ok,),
<<F::Output as TryFuture>::Error as CombineRejection<T::Error>>::One,
>;
fn poll(self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<Self::Output> {
self.project().state.poll(cx)
}
}
impl<T, F> Future for State<T, F>
where
T: TryFuture,
F: Func<T::Ok>,
F::Output: TryFuture + Send,
<F::Output as TryFuture>::Error: CombineRejection<T::Error>,
{
type Output = Result<
(<F::Output as TryFuture>::Ok,),
<<F::Output as TryFuture>::Error as CombineRejection<T::Error>>::One,
>;
fn poll(mut self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<Self::Output> {
loop {
match self.as_mut().project() {
StateProj::First(first, second) => {
let ex1 = ready!(first.try_poll(cx))?;
let fut2 = second.call(ex1);
self.set(State::Second(fut2));
}
StateProj::Second(second) => {
let ex2 = match ready!(second.try_poll(cx)) {
Ok(item) => Ok((item,)),
Err(err) => Err(From::from(err)),
};
self.set(State::Done);
return Poll::Ready(ex2);
}
StateProj::Done => panic!("polled after complete"),
}
}
}
}