generalize apply combinator with transform trait

actix-service/src/fn_transform.rs

@@ -0,0 +1,123 @@
+use std::marker::PhantomData;
+
+use futures::future::{ok, FutureResult};
+use futures::{Async, IntoFuture, Poll};
+
+use super::{IntoNewTransform, IntoTransform, NewTransform, Transform};
+
+pub struct FnTransform<F, S, Req, Res>
+where
+    F: FnMut(Req, &mut S) -> Res,
+    Res: IntoFuture,
+{
+    f: F,
+    _t: PhantomData<(S, Req, Res)>,
+}
+
+impl<F, S, Req, Res> FnTransform<F, S, Req, Res>
+where
+    F: FnMut(Req, &mut S) -> Res,
+    Res: IntoFuture,
+{
+    pub fn new(f: F) -> Self {
+        FnTransform { f, _t: PhantomData }
+    }
+}
+
+impl<F, S, Req, Res> Clone for FnTransform<F, S, Req, Res>
+where
+    F: FnMut(Req, &mut S) -> Res + Clone,
+    Res: IntoFuture,
+{
+    fn clone(&self) -> Self {
+        FnTransform {
+            f: self.f.clone(),
+            _t: PhantomData,
+        }
+    }
+}
+
+impl<F, S, Req, Res> Transform<S> for FnTransform<F, S, Req, Res>
+where
+    F: FnMut(Req, &mut S) -> Res,
+    Res: IntoFuture,
+{
+    type Request = Req;
+    type Response = Res::Item;
+    type Error = Res::Error;
+    type Future = Res::Future;
+
+    fn poll_ready(&mut self) -> Poll<(), Self::Error> {
+        Ok(Async::Ready(()))
+    }
+
+    fn call(&mut self, request: Req, service: &mut S) -> Self::Future {
+        (self.f)(request, service).into_future()
+    }
+}
+
+impl<F, S, Req, Res> IntoTransform<FnTransform<F, S, Req, Res>, S> for F
+where
+    F: FnMut(Req, &mut S) -> Res,
+    Res: IntoFuture,
+{
+    fn into_transform(self) -> FnTransform<F, S, Req, Res> {
+        FnTransform::new(self)
+    }
+}
+
+pub struct FnNewTransform<F, S, Req, Out, Err>
+where
+    F: FnMut(Req, &mut S) -> Out + Clone,
+    Out: IntoFuture,
+{
+    f: F,
+    _t: PhantomData<(S, Req, Out, Err)>,
+}
+
+impl<F, S, Req, Res, Err> FnNewTransform<F, S, Req, Res, Err>
+where
+    F: FnMut(Req, &mut S) -> Res + Clone,
+    Res: IntoFuture,
+{
+    pub fn new(f: F) -> Self {
+        FnNewTransform { f, _t: PhantomData }
+    }
+}
+
+impl<F, S, Req, Res, Err> NewTransform<S> for FnNewTransform<F, S, Req, Res, Err>
+where
+    F: FnMut(Req, &mut S) -> Res + Clone,
+    Res: IntoFuture,
+{
+    type Request = Req;
+    type Response = Res::Item;
+    type Error = Res::Error;
+    type Transform = FnTransform<F, S, Req, Res>;
+    type InitError = Err;
+    type Future = FutureResult<Self::Transform, Self::InitError>;
+
+    fn new_transform(&self) -> Self::Future {
+        ok(FnTransform::new(self.f.clone()))
+    }
+}
+
+impl<F, S, Req, Res, Err> IntoNewTransform<FnNewTransform<F, S, Req, Res, Err>, S> for F
+where
+    F: FnMut(Req, &mut S) -> Res + Clone,
+    Res: IntoFuture,
+{
+    fn into_new_transform(self) -> FnNewTransform<F, S, Req, Res, Err> {
+        FnNewTransform::new(self)
+    }
+}
+
+impl<F, S, Req, Res, Err> Clone for FnNewTransform<F, S, Req, Res, Err>
+where
+    F: FnMut(Req, &mut S) -> Res + Clone,
+    Res: IntoFuture,
+{
+    fn clone(&self) -> Self {
+        Self::new(self.f.clone())
+    }
+}