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use super::AsyncPredicate;
use crate::BoxError;
use futures_core::ready;
use pin_project::pin_project;
use std::{
future::Future,
pin::Pin,
task::{Context, Poll},
};
use tower_service::Service;
#[pin_project]
#[derive(Debug)]
pub struct AsyncResponseFuture<P, S, Request>
where
P: AsyncPredicate<Request>,
S: Service<P::Request>,
{
#[pin]
state: State<P::Future, S::Future>,
service: S,
}
opaque_future! {
pub type ResponseFuture<R, F> =
futures_util::future::Either<
futures_util::future::Ready<Result<R, crate::BoxError>>,
futures_util::future::ErrInto<F, crate::BoxError>
>;
}
#[pin_project(project = StateProj)]
#[derive(Debug)]
enum State<F, G> {
Check(#[pin] F),
WaitResponse(#[pin] G),
}
impl<P, S, Request> AsyncResponseFuture<P, S, Request>
where
P: AsyncPredicate<Request>,
S: Service<P::Request>,
S::Error: Into<BoxError>,
{
pub(crate) fn new(check: P::Future, service: S) -> Self {
Self {
state: State::Check(check),
service,
}
}
}
impl<P, S, Request> Future for AsyncResponseFuture<P, S, Request>
where
P: AsyncPredicate<Request>,
S: Service<P::Request>,
S::Error: Into<crate::BoxError>,
{
type Output = Result<S::Response, crate::BoxError>;
fn poll(self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<Self::Output> {
let mut this = self.project();
loop {
match this.state.as_mut().project() {
StateProj::Check(mut check) => {
let request = ready!(check.as_mut().poll(cx))?;
let response = this.service.call(request);
this.state.set(State::WaitResponse(response));
}
StateProj::WaitResponse(response) => {
return response.poll(cx).map_err(Into::into);
}
}
}
}
}