use std::fmt;
use std::future::Future;
use std::pin::Pin;
use std::task::{Context, Poll};
use futures_core::ready;
use pin_project_lite::pin_project;
use super::error::Overloaded;
pin_project! {
pub struct ResponseFuture<F> {
#[pin]
state: ResponseState<F>,
}
}
pin_project! {
#[project = ResponseStateProj]
enum ResponseState<F> {
Called {
#[pin]
fut: F
},
Overloaded,
}
}
impl<F> ResponseFuture<F> {
pub(crate) fn called(fut: F) -> Self {
ResponseFuture {
state: ResponseState::Called { fut },
}
}
pub(crate) fn overloaded() -> Self {
ResponseFuture {
state: ResponseState::Overloaded,
}
}
}
impl<F, T, E> Future for ResponseFuture<F>
where
F: Future<Output = Result<T, E>>,
E: Into<crate::BoxError>,
{
type Output = Result<T, crate::BoxError>;
fn poll(self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<Self::Output> {
match self.project().state.project() {
ResponseStateProj::Called { fut } => {
Poll::Ready(ready!(fut.poll(cx)).map_err(Into::into))
}
ResponseStateProj::Overloaded => Poll::Ready(Err(Overloaded::new().into())),
}
}
}
impl<F> fmt::Debug for ResponseFuture<F>
where
F: fmt::Debug,
{
fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
f.write_str("ResponseFuture")
}
}