From 686958fe0c11112e412e3e6fc918b4284fb28e8c Mon Sep 17 00:00:00 2001
From: Marcus Griep <marcus@griep.us>
Date: Thu, 2 May 2019 17:21:42 -0400
Subject: [PATCH] Add reciprical compatibility layer for tower

---
 actix-tower/src/lib.rs | 387 +++++++++++++++++++++++++++++------------
 1 file changed, 275 insertions(+), 112 deletions(-)

diff --git a/actix-tower/src/lib.rs b/actix-tower/src/lib.rs
index 1e985db2..a57dad0f 100644
--- a/actix-tower/src/lib.rs
+++ b/actix-tower/src/lib.rs
@@ -6,40 +6,40 @@ use tower_service::Service as TowerService;
 
 /// Compatibility wrapper associating a `tower_service::Service` with a particular
 /// `Request` type, so that it can be used as an `actix_service::Service`.
-pub struct TowerCompat<S, R> {
+pub struct ActixCompat<S, R> {
     inner: S,
     _phantom: PhantomData<R>,
 }
 
-impl<S, R> TowerCompat<S, R> {
+impl<S, R> ActixCompat<S, R> {
     /// Wraps a `tower_service::Service` in a compatibility wrapper.
     pub fn new(inner: S) -> Self {
-        TowerCompat {
+        ActixCompat {
             inner,
             _phantom: PhantomData,
         }
     }
 }
 
-/// Extension trait for wrapping `tower_service::Service` instances for use as
+/// Extension trait for wrapping a `tower_service::Service` instance for use as
 /// an `actix_service::Service`.
 pub trait TowerServiceExt {
     /// Wraps a `tower_service::Service` in a compatibility wrapper.
-    fn compat<R>(self) -> TowerCompat<Self, R>
+    fn into_actix_service<R>(self) -> ActixCompat<Self, R>
     where
         Self: TowerService<R> + Sized;
 }
 
 impl<S> TowerServiceExt for S {
-    fn compat<R>(self) -> TowerCompat<Self, R>
+    fn into_actix_service<R>(self) -> ActixCompat<Self, R>
     where
         Self: TowerService<R> + Sized
     {
-        TowerCompat::new(self)
+        ActixCompat::new(self)
     }
 }
 
-impl<S, R> ActixService for TowerCompat<S, R>
+impl<S, R> ActixService for ActixCompat<S, R>
 where
     S: TowerService<R>,
 {
@@ -57,135 +57,298 @@ where
     }
 }
 
+/// Compatibility wrapper associating an `actix_service::Service` with a particular
+/// `Request` type, so that it can be used as a `tower_service::Service`.
+pub struct TowerCompat<S> {
+    inner: S,
+}
+
+impl<S> TowerCompat<S> {
+    /// Wraps an `actix_service::Service` in a compatibility wrapper.
+    pub fn new(inner: S) -> Self {
+        TowerCompat {
+            inner,
+        }
+    }
+}
+
+/// Extension trait for wrapping an `actix_service::Service` instance for use as
+/// a `tower_service::Service`.
+pub trait ActixServiceExt: ActixService + Sized {
+    /// Wraps a `tower_service::Service` in a compatibility wrapper.
+    fn into_tower_service(self) -> TowerCompat<Self>;
+}
+
+impl<S> ActixServiceExt for S
+where
+    S: ActixService + Sized
+{
+    fn into_tower_service(self) -> TowerCompat<Self>
+    {
+        TowerCompat::new(self)
+    }
+}
+
+impl<S> TowerService<S::Request> for TowerCompat<S>
+where
+    S: ActixService,
+{
+    type Response = S::Response;
+    type Error = S::Error;
+    type Future = S::Future;
+
+    fn poll_ready(&mut self) -> futures::Poll<(), Self::Error> {
+        ActixService::poll_ready(&mut self.inner)
+    }
+
+    fn call(&mut self, req: S::Request) -> Self::Future {
+        ActixService::call(&mut self.inner, req)
+    }
+}
+
 #[cfg(test)]
 mod tests {
-    use super::TowerServiceExt;
-    use actix_service::{Service as ActixService, ServiceExt, Transform};
-    use futures::{future::FutureResult, Async, Poll, Future};
-    use tower_service::Service as TowerService;
+    mod tower_service_into_actix_service {
+        use crate::TowerServiceExt;
+        use actix_service::{Service as ActixService, ServiceExt, Transform};
+        use futures::{future::FutureResult, Async, Poll, Future};
+        use tower_service::Service as TowerService;
 
-    struct RandomService;
-    impl<R> TowerService<R> for RandomService {
-        type Response = u32;
-        type Error = ();
-        type Future = FutureResult<Self::Response, Self::Error>;
 
-        fn poll_ready(&mut self) -> Poll<(), Self::Error> {
-            Ok(Async::Ready(()))
+        #[test]
+        fn random_service_returns_4() {
+            let mut s = RandomService.into_actix_service();
+
+            assert_eq!(Ok(Async::Ready(())), s.poll_ready());
+
+            assert_eq!(Ok(Async::Ready(4)), s.call(()).poll());
         }
 
-        fn call(&mut self, _req: R) -> Self::Future {
-            futures::finished(4)
+        #[test]
+        fn random_service_can_combine() {
+            let mut s = RandomService.into_actix_service().map(|x| x + 1);
+
+            assert_eq!(Ok(Async::Ready(())), s.poll_ready());
+
+            assert_eq!(Ok(Async::Ready(5)), s.call(()).poll());
+        }
+
+        #[test]
+        fn random_service_and_add_service_chained() {
+            let s1 = RandomService.into_actix_service();
+            let s2 = AddOneService.into_actix_service();
+            let s3 = AddOneService.into_actix_service();
+
+            let mut s = s1.and_then(s2).and_then(s3);
+
+            assert_eq!(Ok(Async::Ready(())), s.poll_ready());
+
+            assert_eq!(Ok(Async::Ready(6)), s.call(()).poll());
+        }
+
+        #[test]
+        fn random_service_and_add_service_and_ignoring_service_chained() {
+            let s1 = RandomService.into_actix_service();
+            let s2 = AddOneService.into_actix_service();
+            let s3 = AddOneService.into_actix_service();
+            let s4 = RandomService.into_actix_service();
+
+            let mut s = s1.and_then(s2).and_then(s3).and_then(s4);
+
+            assert_eq!(Ok(Async::Ready(())), s.poll_ready());
+
+            assert_eq!(Ok(Async::Ready(4)), s.call(()).poll());
+        }
+
+        #[test]
+        fn random_service_can_be_transformed_to_do_math() {
+            let transform = DoMath;
+
+            let mut s = transform.new_transform(RandomService.into_actix_service()).wait().unwrap();
+
+            assert_eq!(Ok(Async::Ready(())), s.poll_ready());
+
+            assert_eq!(Ok(Async::Ready(68)), s.call(()).poll());
+        }
+
+        struct RandomService;
+        impl<R> TowerService<R> for RandomService {
+            type Response = u32;
+            type Error = ();
+            type Future = FutureResult<Self::Response, Self::Error>;
+
+            fn poll_ready(&mut self) -> Poll<(), Self::Error> {
+                Ok(Async::Ready(()))
+            }
+
+            fn call(&mut self, _req: R) -> Self::Future {
+                futures::finished(4)
+            }
+        }
+
+        struct AddOneService;
+        impl TowerService<u32> for AddOneService {
+            type Response = u32;
+            type Error = ();
+            type Future = FutureResult<Self::Response, Self::Error>;
+
+            fn poll_ready(&mut self) -> Poll<(), Self::Error> {
+                Ok(Async::Ready(()))
+            }
+
+            fn call(&mut self, req: u32) -> Self::Future {
+                futures::finished(req + 1)
+            }
+        }
+
+        struct DoMathTransform<S>(S);
+        impl<S> ActixService for DoMathTransform<S>
+        where
+            S: ActixService<Response = u32>,
+            S::Future: 'static,
+        {
+            type Request = S::Request;
+            type Response = u32;
+            type Error = S::Error;
+            type Future = Box<dyn Future<Item = Self::Response, Error = Self::Error>>;
+
+            fn poll_ready(&mut self) -> Poll<(), Self::Error> {
+                self.0.poll_ready()
+            }
+
+            fn call(&mut self, req: Self::Request) -> Self::Future {
+                let fut = self.0.call(req).map(|x| x * 17);
+                Box::new(fut)
+            }
+        }
+
+        struct DoMath;
+        impl<S> Transform<S> for DoMath
+        where
+            S: ActixService<Response = u32>,
+            S::Future: 'static,
+        {
+            type Request = S::Request;
+            type Response = u32;
+            type Error = S::Error;
+            type Transform = DoMathTransform<S>;
+            type InitError = ();
+            type Future = FutureResult<Self::Transform, Self::InitError>;
+
+            fn new_transform(&self, service: S) -> Self::Future {
+                futures::finished(DoMathTransform(service))
+            }
         }
     }
 
-    #[test]
-    fn tower_service_as_actix_service_returns_4() {
-        let mut s = RandomService.compat();
+    mod actix_service_into_tower_service {
+        use crate::{ActixServiceExt, TowerServiceExt};
+        use actix_service::{Service as ActixService, ServiceExt};
+        use futures::{future::FutureResult, Async, Poll, Future};
+        use tower_service::Service as TowerService;
 
-        assert_eq!(Ok(Async::Ready(())), s.poll_ready());
 
-        assert_eq!(Ok(Async::Ready(4)), s.call(()).poll());
-    }
+        #[test]
+        fn random_service_returns_4() {
+            let mut s = RandomService.into_tower_service();
 
-    #[test]
-    fn tower_service_as_actix_service_can_combine() {
-        let mut s = RandomService.compat().map(|x| x + 1);
+            assert_eq!(Ok(Async::Ready(())), s.poll_ready());
 
-        assert_eq!(Ok(Async::Ready(())), s.poll_ready());
-
-        assert_eq!(Ok(Async::Ready(5)), s.call(()).poll());
-    }
-
-    struct AddOneService;
-    impl TowerService<u32> for AddOneService {
-        type Response = u32;
-        type Error = ();
-        type Future = FutureResult<Self::Response, Self::Error>;
-
-        fn poll_ready(&mut self) -> Poll<(), Self::Error> {
-            Ok(Async::Ready(()))
+            assert_eq!(Ok(Async::Ready(4)), s.call(()).poll());
         }
 
-        fn call(&mut self, req: u32) -> Self::Future {
-            futures::finished(req + 1)
-        }
-    }
+        #[test]
+        fn random_service_can_use_tower_middleware() {
+            let mut s = AddOneService::wrap(RandomService.into_tower_service()).into_actix_service();
 
-    #[test]
-    fn tower_services_as_actix_services_chained() {
-        let s1 = RandomService.compat();
-        let s2 = AddOneService.compat();
-        let s3 = AddOneService.compat();
+            assert_eq!(Ok(Async::Ready(())), s.poll_ready());
 
-        let mut s = s1.and_then(s2).and_then(s3);
-
-        assert_eq!(Ok(Async::Ready(())), s.poll_ready());
-
-        assert_eq!(Ok(Async::Ready(6)), s.call(()).poll());
-    }
-
-    #[test]
-    fn tower_services_as_actix_services_chained_2() {
-        let s1 = RandomService.compat();
-        let s2 = AddOneService.compat();
-        let s3 = AddOneService.compat();
-        let s4 = RandomService.compat();
-
-        let mut s = s1.and_then(s2).and_then(s3).and_then(s4);
-
-        assert_eq!(Ok(Async::Ready(())), s.poll_ready());
-
-        assert_eq!(Ok(Async::Ready(4)), s.call(()).poll());
-    }
-
-    struct DoMathTransform<S>(S);
-    impl<S> ActixService for DoMathTransform<S>
-    where
-        S: ActixService<Response = u32>,
-        S::Future: 'static,
-    {
-        type Request = S::Request;
-        type Response = u32;
-        type Error = S::Error;
-        type Future = Box<dyn Future<Item = Self::Response, Error = Self::Error>>;
-
-        fn poll_ready(&mut self) -> Poll<(), Self::Error> {
-            self.0.poll_ready()
+            assert_eq!(Ok(Async::Ready(5)), s.call(()).poll());
         }
 
-        fn call(&mut self, req: Self::Request) -> Self::Future {
-            let fut = self.0.call(req).map(|x| x * 17);
-            Box::new(fut)
+        #[test]
+        fn do_math_service_can_use_tower_middleware() {
+            let mut s = AddOneService::wrap(DoMathService.into_tower_service()).into_actix_service();
+
+            assert_eq!(Ok(Async::Ready(())), s.poll_ready());
+
+            assert_eq!(Ok(Async::Ready(188)), s.call(11).poll());
         }
-    }
 
-    struct DoMath;
-    impl<S> Transform<S> for DoMath
-    where
-        S: ActixService<Response = u32>,
-        S::Future: 'static,
-    {
-        type Request = S::Request;
-        type Response = u32;
-        type Error = S::Error;
-        type Transform = DoMathTransform<S>;
-        type InitError = ();
-        type Future = FutureResult<Self::Transform, Self::InitError>;
+        #[test]
+        fn random_service_and_add_service_and_ignoring_service_chained() {
+            let s1 = AddOneService::wrap(RandomService.into_tower_service()).into_actix_service();
+            let s2 = AddOneService::wrap(DoMathService.into_tower_service()).into_actix_service();
 
-        fn new_transform(&self, service: S) -> Self::Future {
-            futures::finished(DoMathTransform(service))
+            let mut s = s1.and_then(s2);
+
+            assert_eq!(Ok(Async::Ready(())), s.poll_ready());
+
+            assert_eq!(Ok(Async::Ready(86)), s.call(()).poll());
         }
-    }
 
-    #[test]
-    fn tower_service_as_actix_service_can_be_transformed() {
-        let transform = DoMath;
+        struct RandomService;
+        impl ActixService for RandomService {
+            type Request = ();
+            type Response = u32;
+            type Error = ();
+            type Future = FutureResult<Self::Response, Self::Error>;
 
-        let mut s = transform.new_transform(RandomService.compat()).wait().unwrap();
+            fn poll_ready(&mut self) -> Poll<(), Self::Error> {
+                Ok(Async::Ready(()))
+            }
 
-        assert_eq!(Ok(Async::Ready(())), s.poll_ready());
+            fn call(&mut self, _req: Self::Request) -> Self::Future {
+                futures::finished(4)
+            }
+        }
 
-        assert_eq!(Ok(Async::Ready(68)), s.call(()).poll());
-    }
+        struct AddOneService<S> {
+            inner: S
+        }
+
+        impl<S> AddOneService<S> {
+            fn wrap(inner: S) -> Self {
+                AddOneService {
+                    inner,
+                }
+            }
+        }
+
+        impl<S, R> TowerService<R> for AddOneService<S>
+        where
+            S: TowerService<R, Response = u32>,
+            S::Future: 'static,
+        {
+            type Response = u32;
+            type Error = S::Error;
+            type Future = Box<dyn Future<Item = Self::Response, Error = Self::Error>>;
+
+            fn poll_ready(&mut self) -> Poll<(), Self::Error> {
+                self.inner.poll_ready()
+            }
+
+            fn call(&mut self, req: R) -> Self::Future {
+                let fut = self.inner.call(req)
+                    .map(|x| x + 1);
+
+                Box::new(fut)
+            }
+        }
+
+        struct DoMathService;
+        impl ActixService for DoMathService {
+            type Request = u32;
+            type Response = u32;
+            type Error = ();
+            type Future = FutureResult<Self::Response, Self::Error>;
+
+            fn poll_ready(&mut self) -> Poll<(), Self::Error> {
+                Ok(Async::Ready(()))
+            }
+
+            fn call(&mut self, req: Self::Request) -> Self::Future {
+                futures::finished(req * 17)
+            }
+        }}
 }
\ No newline at end of file