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use std::future::Future;
use std::pin::Pin;
use std::task::{Context, Poll};
use futures_util::ready;
use pin_project::pin_project;
use super::{Combine, Filter, FilterBase, Internal, Tuple};
use crate::generic::CombinedTuples;
use crate::reject::CombineRejection;
#[derive(Clone, Copy, Debug)]
pub struct And<T, U> {
pub(super) first: T,
pub(super) second: U,
}
impl<T, U> FilterBase for And<T, U>
where
T: Filter,
T::Extract: Send,
U: Filter + Clone + Send,
<T::Extract as Tuple>::HList: Combine<<U::Extract as Tuple>::HList> + Send,
CombinedTuples<T::Extract, U::Extract>: Send,
U::Error: CombineRejection<T::Error>,
{
type Extract = CombinedTuples<T::Extract, U::Extract>;
type Error = <U::Error as CombineRejection<T::Error>>::One;
type Future = AndFuture<T, U>;
fn filter(&self, _: Internal) -> Self::Future {
AndFuture {
state: State::First(self.first.filter(Internal), self.second.clone()),
}
}
}
#[allow(missing_debug_implementations)]
#[pin_project]
pub struct AndFuture<T: Filter, U: Filter> {
#[pin]
state: State<T::Future, T::Extract, U>,
}
#[pin_project(project = StateProj)]
enum State<T, TE, U: Filter> {
First(#[pin] T, U),
Second(Option<TE>, #[pin] U::Future),
Done,
}
impl<T, U> Future for AndFuture<T, U>
where
T: Filter,
U: Filter,
<T::Extract as Tuple>::HList: Combine<<U::Extract as Tuple>::HList> + Send,
U::Error: CombineRejection<T::Error>,
{
type Output = Result<
CombinedTuples<T::Extract, U::Extract>,
<U::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, TE, U, E> Future for State<T, TE, U>
where
T: Future<Output = Result<TE, E>>,
U: Filter,
TE: Tuple,
TE::HList: Combine<<U::Extract as Tuple>::HList> + Send,
U::Error: CombineRejection<E>,
{
type Output = Result<CombinedTuples<TE, U::Extract>, <U::Error as CombineRejection<E>>::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.poll(cx))?;
let fut2 = second.filter(Internal);
self.set(State::Second(Some(ex1), fut2));
}
StateProj::Second(ex1, second) => {
let ex2 = ready!(second.poll(cx))?;
let ex3 = ex1.take().unwrap().combine(ex2);
self.set(State::Done);
return Poll::Ready(Ok(ex3));
}
StateProj::Done => panic!("polled after complete"),
}
}
}
}