Remove poll*with_context functions

taiki-e · Apr 24, 2020 · b124ec7 · b124ec7
1 parent 3060c18
commit b124ec7
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Showing 2 changed files with 30 additions and 28 deletions.
diff --git a/futures-async-stream-macro/src/visitor.rs b/futures-async-stream-macro/src/visitor.rs
@@ -106,9 +106,9 @@ impl Visitor {
                 }
                 Stream | TryStream => {
                     quote! {
-                        match unsafe { ::futures_async_stream::stream::poll_next_with_context(
+                        match unsafe { ::futures_async_stream::stream::Stream::poll_next(
                             ::futures_async_stream::reexport::pin::Pin::as_mut(&mut __pinned),
-                            __task_context,
+                            ::futures_async_stream::future::get_context(__task_context),
                         ) } {
                             ::futures_async_stream::reexport::task::Poll::Ready(
                                 ::futures_async_stream::reexport::option::Option::Some(e),
@@ -191,19 +191,31 @@ impl Visitor {
             return;
         }
 
+        // Desugar `<base>.await` into:
+        //
+        // {
+        //     let mut __pinned = <base>;
+        //     loop {
+        //         if let Poll::Ready(result) = unsafe { Future::poll(
+        //             Pin::new_unchecked(&mut __pinned),
+        //             get_context(__task_context),
+        //         ) } {
+        //             break result;
+        //         }
+        //         __task_context = yield Poll::Pending;
+        //     }
+        // }
         if let Expr::Await(ExprAwait { base, await_token, .. }) = expr {
             *expr = syn::parse2(quote_spanned! { await_token.span() => {
                 let mut __pinned = #base;
                 loop {
-                    if let ::futures_async_stream::reexport::task::Poll::Ready(x) =
-                        unsafe { ::futures_async_stream::future::poll_with_context(
-                            ::futures_async_stream::reexport::pin::Pin::new_unchecked(&mut __pinned),
-                            __task_context,
-                        )}
-                    {
-                        break x;
+                    if let ::futures_async_stream::reexport::task::Poll::Ready(result) =
+                    unsafe { ::futures_async_stream::future::Future::poll(
+                        ::futures_async_stream::reexport::pin::Pin::new_unchecked(&mut __pinned),
+                        ::futures_async_stream::future::get_context(__task_context),
+                    ) } {
+                        break result;
                     }
-
                     __task_context = yield ::futures_async_stream::reexport::task::Poll::Pending;
                 }
             }})

diff --git a/src/lib.rs b/src/lib.rs
@@ -234,14 +234,16 @@ pub use futures_async_stream_macro::async_try_stream_block;
 #[doc(hidden)]
 pub mod future {
     use core::{
-        future::Future,
         ops::{Generator, GeneratorState},
         pin::Pin,
         ptr::NonNull,
         task::{Context, Poll},
     };
     use pin_project::pin_project;
 
+    #[doc(hidden)]
+    pub use core::future::Future;
+
     /// This type is needed because:
     ///
     /// a) Generators cannot implement `for<'a, 'b> Generator<&'a mut Context<'b>>`, so we need to pass
@@ -293,11 +295,8 @@ pub mod future {
     }
 
     #[doc(hidden)]
-    pub unsafe fn poll_with_context<F>(f: Pin<&mut F>, mut cx: ResumeTy) -> Poll<F::Output>
-    where
-        F: Future,
-    {
-        F::poll(f, cx.0.as_mut())
+    pub unsafe fn get_context<'a, 'b>(cx: ResumeTy) -> &'a mut Context<'b> {
+        &mut *cx.0.as_ptr().cast()
     }
 }
 
@@ -312,11 +311,13 @@ pub mod stream {
         ptr::NonNull,
         task::{Context, Poll},
     };
-    use futures_core::stream::Stream;
     use pin_project::pin_project;
 
     use super::future::ResumeTy;
 
+    #[doc(hidden)]
+    pub use futures_core::stream::Stream;
+
     /// Wrap a generator in a stream.
     ///
     /// This function returns a `GenStream` underneath, but hides it in `impl Trait` to give
@@ -352,17 +353,6 @@ pub mod stream {
         }
     }
 
-    #[doc(hidden)]
-    pub unsafe fn poll_next_with_context<S>(
-        s: Pin<&mut S>,
-        mut cx: ResumeTy,
-    ) -> Poll<Option<S::Item>>
-    where
-        S: Stream,
-    {
-        S::poll_next(s, cx.0.as_mut())
-    }
-
     // This is equivalent to the `futures::stream::StreamExt::next` method.
     // But we want to make this crate dependency as small as possible, so we define our `next` function.
     #[doc(hidden)]