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use futures::{Future, IntoFuture, Poll};
mod and_then;
mod apply;
mod cell;
mod fn_service;
mod from_err;
mod map;
mod map_err;
mod map_init_err;
mod then;
pub use self::and_then::{AndThen, AndThenNewService};
pub use self::apply::{Apply, ApplyNewService};
pub use self::fn_service::{FnNewService, FnService};
pub use self::from_err::{FromErr, FromErrNewService};
pub use self::map::{Map, MapNewService};
pub use self::map_err::{MapErr, MapErrNewService};
pub use self::map_init_err::MapInitErr;
pub use self::then::{Then, ThenNewService};
/// An asynchronous function from `Request` to a `Response`.
pub trait Service<Request> {
/// Responses given by the service.
type Response;
/// Errors produced by the service.
type Error;
/// The future response value.
type Future: Future<Item = Self::Response, Error = Self::Error>;
/// Returns `Ready` when the service is able to process requests.
///
/// If the service is at capacity, then `NotReady` is returned and the task
/// is notified when the service becomes ready again. This function is
/// expected to be called while on a task.
///
/// This is a **best effort** implementation. False positives are permitted.
/// It is permitted for the service to return `Ready` from a `poll_ready`
/// call and the next invocation of `call` results in an error.
fn poll_ready(&mut self) -> Poll<(), Self::Error>;
/// Process the request and return the response asynchronously.
///
/// This function is expected to be callable off task. As such,
/// implementations should take care to not call `poll_ready`. If the
/// service is at capacity and the request is unable to be handled, the
/// returned `Future` should resolve to an error.
///
/// Calling `call` without calling `poll_ready` is permitted. The
/// implementation must be resilient to this fact.
fn call(&mut self, req: Request) -> Self::Future;
/// Apply function to specified service and use it as a next service in
/// chain.
fn apply<T, I, F, Out, Req>(
self,
service: I,
f: F,
) -> AndThen<Self, Apply<T, F, Self::Response, Out, Req>>
where
Self: Sized,
T: Service<Req, Error = Self::Error>,
I: IntoService<T, Req>,
F: Fn(Self::Response, &mut T) -> Out,
Out: IntoFuture<Error = Self::Error>,
{
self.and_then(Apply::new(service.into_service(), f))
}
/// Call another service after call to this one has resolved successfully.
///
/// This function can be used to chain two services together and ensure that
/// the second service isn't called until call to the fist service have
/// finished. Result of the call to the first service is used as an
/// input parameter for the second service's call.
///
/// Note that this function consumes the receiving service and returns a
/// wrapped version of it.
fn and_then<F, B>(self, service: F) -> AndThen<Self, B>
where
Self: Sized,
F: IntoService<B, Self::Response>,
B: Service<Self::Response, Error = Self::Error>,
{
AndThen::new(self, service.into_service())
}
/// Map this service's error to any error implementing `From` for
/// this service`s `Error`.
///
/// Note that this function consumes the receiving service and returns a
/// wrapped version of it.
fn from_err<E>(self) -> FromErr<Self, E>
where
Self: Sized,
E: From<Self::Error>,
{
FromErr::new(self)
}
/// Chain on a computation for when a call to the service finished,
/// passing the result of the call to the next service `B`.
///
/// Note that this function consumes the receiving service and returns a
/// wrapped version of it.
fn then<B>(self, service: B) -> Then<Self, B>
where
Self: Sized,
B: Service<Result<Self::Response, Self::Error>, Error = Self::Error>,
{
Then::new(self, service)
}
/// Map this service's output to a different type, returning a new service
/// of the resulting type.
///
/// This function is similar to the `Option::map` or `Iterator::map` where
/// it will change the type of the underlying service.
///
/// Note that this function consumes the receiving service and returns a
/// wrapped version of it, similar to the existing `map` methods in the
/// standard library.
fn map<F, R>(self, f: F) -> Map<Self, F, R>
where
Self: Sized,
F: Fn(Self::Response) -> R,
{
Map::new(self, f)
}
/// Map this service's error to a different error, returning a new service.
///
/// This function is similar to the `Result::map_err` where it will change
/// the error type of the underlying service. This is useful for example to
/// ensure that services have the same error type.
///
/// Note that this function consumes the receiving service and returns a
/// wrapped version of it.
fn map_err<F, E>(self, f: F) -> MapErr<Self, F, E>
where
Self: Sized,
F: Fn(Self::Error) -> E,
{
MapErr::new(self, f)
}
}
/// Creates new `Service` values.
///
/// Acts as a service factory. This is useful for cases where new `Service`
/// values must be produced. One case is a TCP servier listener. The listner
/// accepts new TCP streams, obtains a new `Service` value using the
/// `NewService` trait, and uses that new `Service` value to process inbound
/// requests on that new TCP stream.
///
/// Request - request handled by the service
pub trait NewService<Request> {
/// Responses given by the service
type Response;
/// Errors produced by the service
type Error;
/// The `Service` value created by this factory
type Service: Service<Request, Response = Self::Response, Error = Self::Error>;
/// Errors produced while building a service.
type InitError;
/// The future of the `Service` instance.
type Future: Future<Item = Self::Service, Error = Self::InitError>;
/// Create and return a new service value asynchronously.
fn new_service(&self) -> Self::Future;
/// Apply function to specified service and use it as a next service in
/// chain.
fn apply<T, I, F, Out, Req>(
self,
service: I,
f: F,
) -> AndThenNewService<Self, ApplyNewService<T, F, Self::Response, Out, Req>>
where
Self: Sized,
T: NewService<Req, InitError = Self::InitError, Error = Self::Error>,
I: IntoNewService<T, Req>,
F: Fn(Self::Response, &mut T::Service) -> Out + Clone,
Out: IntoFuture<Error = Self::Error>,
{
self.and_then(ApplyNewService::new(service, f))
}
/// Call another service after call to this one has resolved successfully.
fn and_then<F, B>(self, new_service: F) -> AndThenNewService<Self, B>
where
Self: Sized,
F: IntoNewService<B, Self::Response>,
B: NewService<Self::Response, Error = Self::Error, InitError = Self::InitError>,
{
AndThenNewService::new(self, new_service)
}
/// `NewService` that create service to map this service's error
/// and new service's init error to any error
/// implementing `From` for this service`s `Error`.
///
/// Note that this function consumes the receiving new service and returns a
/// wrapped version of it.
fn from_err<E>(self) -> FromErrNewService<Self, E>
where
Self: Sized,
E: From<Self::Error>,
{
FromErrNewService::new(self)
}
/// Create `NewService` to chain on a computation for when a call to the
/// service finished, passing the result of the call to the next
/// service `B`.
///
/// Note that this function consumes the receiving future and returns a
/// wrapped version of it.
fn then<F, B>(self, new_service: F) -> ThenNewService<Self, B>
where
Self: Sized,
F: IntoNewService<B, Result<Self::Response, Self::Error>>,
B: NewService<
Result<Self::Response, Self::Error>,
Error = Self::Error,
InitError = Self::InitError,
>,
{
ThenNewService::new(self, new_service)
}
/// Map this service's output to a different type, returning a new service
/// of the resulting type.
fn map<F, R>(self, f: F) -> MapNewService<Self, F, R>
where
Self: Sized,
F: Fn(Self::Response) -> R,
{
MapNewService::new(self, f)
}
/// Map this service's error to a different error, returning a new service.
fn map_err<F, E>(self, f: F) -> MapErrNewService<Self, F, E>
where
Self: Sized,
F: Fn(Self::Error) -> E,
{
MapErrNewService::new(self, f)
}
/// Map this service's init error to a different error, returning a new service.
fn map_init_err<F, E>(self, f: F) -> MapInitErr<Self, F, E>
where
Self: Sized,
F: Fn(Self::InitError) -> E,
{
MapInitErr::new(self, f)
}
}
impl<'a, S, Request> Service<Request> for &'a mut S
where
S: Service<Request> + 'a,
{
type Response = S::Response;
type Error = S::Error;
type Future = S::Future;
fn poll_ready(&mut self) -> Poll<(), S::Error> {
(**self).poll_ready()
}
fn call(&mut self, request: Request) -> S::Future {
(**self).call(request)
}
}
impl<F, R, E, S, Request> NewService<Request> for F
where
F: Fn() -> R,
R: IntoFuture<Item = S, Error = E>,
S: Service<Request>,
{
type Response = S::Response;
type Error = S::Error;
type Service = S;
type InitError = E;
type Future = R::Future;
fn new_service(&self) -> Self::Future {
(*self)().into_future()
}
}
/// Trait for types that can be converted to a `Service`
pub trait IntoService<T, Request>
where
T: Service<Request>,
{
/// Convert to a `Service`
fn into_service(self) -> T;
}
/// Trait for types that can be converted to a Service
pub trait IntoNewService<T, Request>
where
T: NewService<Request>,
{
/// Convert to an `NewService`
fn into_new_service(self) -> T;
}
impl<T, Request> IntoService<T, Request> for T
where
T: Service<Request>,
{
fn into_service(self) -> T {
self
}
}
impl<T, Request> IntoNewService<T, Request> for T
where
T: NewService<Request>,
{
fn into_new_service(self) -> T {
self
}
}