use std::error::Error as StdError;
use std::future::Future;
use crate::body::Body;
use crate::service::service::Service;
use crate::{Request, Response};
/// An asynchronous function from [`Request`] to [`Response`].
///
/// This is a *sealed* trait, meaning that it can not be implemented directly. Rather, it is an
/// alias for [`Service`]s that accept a [`Request`] and return a [`Future`] that resolves to a
/// [`Response`]. External callers should implement [`Service`] instead.
///
/// Rather than being generic over the request and response, this trait is generic across the
/// request [`Body`] and response [`Body`].
///
/// See the crate-level [`service`][crate::service] documentation for more information.
///
/// See [`Service`] for more information.
pub trait HttpService<ReqBody>: sealed::Sealed<ReqBody> {
/// The [`Body`] body of the [`Response`].
type ResBody: Body;
/// The error type that can occur within this [`Service`].
///
/// Note: Returning an `Error` to a hyper server, the behavior depends on the protocol. In
/// most cases, hyper will cause the connection to be abruptly aborted. In most cases, it is
/// better to return a `Response` with a 4xx or 5xx status code.
///
/// See [`Service::Error`] for more information.
type Error: Into<Box<dyn StdError + Send + Sync>>;
/// The [`Future`] returned by this [`Service`].
type Future: Future<Output = Result<Response<Self::ResBody>, Self::Error>>;
#[doc(hidden)]
fn call(&mut self, req: Request<ReqBody>) -> Self::Future;
}
impl<T, B1, B2> HttpService<B1> for T
where
T: Service<Request<B1>, Response = Response<B2>>,
B2: Body,
T::Error: Into<Box<dyn StdError + Send + Sync>>,
{
type ResBody = B2;
type Error = T::Error;
type Future = T::Future;
fn call(&mut self, req: Request<B1>) -> Self::Future {
Service::call(self, req)
}
}
impl<T, B1, B2> sealed::Sealed<B1> for T
where
T: Service<Request<B1>, Response = Response<B2>>,
B2: Body,
{
}
mod sealed {
pub trait Sealed<T> {}
}
