Refactor extension_trait

Author: Stjepan Glavina

src/fs/dir_builder.rs

@@ -1,8 +1,8 @@
-use std::future::Future;
 use std::path::Path;
 
 use cfg_if::cfg_if;
 
+use crate::future::Future;
 use crate::io;
 use crate::task::blocking;
 

src/fs/open_options.rs

@@ -1,9 +1,9 @@
-use std::future::Future;
 use std::path::Path;
 
 use cfg_if::cfg_if;
 
 use crate::fs::File;
+use crate::future::Future;
 use crate::io;
 use crate::task::blocking;
 

src/future/future.rs

@@ -29,7 +29,7 @@ extension_trait! {
 
         [`Waker`]: ../task/struct.Waker.html
     "#]
-    pub trait Future [FutureExt: std::future::Future] {
+    pub trait Future {
         #[doc = r#"
             The type of value produced on completion.
         "#]
@@ -101,4 +101,7 @@ extension_trait! {
         "#]
         fn poll(self: Pin<&mut Self>, cx: &mut Context) -> Poll<Self::Output>;
     }
+
+    pub trait FutureExt: std::future::Future {
+    }
 }

src/io/buf_read/mod.rs

@@ -41,7 +41,7 @@ extension_trait! {
         https://docs.rs/futures-preview/0.3.0-alpha.17/futures/io/trait.AsyncBufRead.html
         [provided methods]: #provided-methods
     "#]
-    pub trait BufRead [BufReadExt: futures_io::AsyncBufRead] {
+    pub trait BufRead {
         #[doc = r#"
             Returns the contents of the internal buffer, filling it with more data from the
             inner reader if it is empty.
@@ -64,7 +64,9 @@ extension_trait! {
             should no longer be returned in calls to `read`.
         "#]
         fn consume(self: Pin<&mut Self>, amt: usize);
+    }
 
+    pub trait BufReadExt: futures_io::AsyncBufRead {
         #[doc = r#"
             Reads all bytes into `buf` until the delimiter `byte` or EOF is reached.
 

src/io/read/mod.rs

@@ -50,7 +50,7 @@ extension_trait! {
         [`poll_read`]: #tymethod.poll_read
         [`poll_read_vectored`]: #method.poll_read_vectored
     "#]
-    pub trait Read [ReadExt: futures_io::AsyncRead] {
+    pub trait Read {
         #[doc = r#"
             Attempt to read from the `AsyncRead` into `buf`.
         "#]
@@ -70,7 +70,9 @@ extension_trait! {
         ) -> Poll<io::Result<usize>> {
             unreachable!("this impl only appears in the rendered docs")
         }
+    }
 
+    pub trait ReadExt: futures_io::AsyncRead {
         #[doc = r#"
             Reads some bytes from the byte stream.
 

src/io/seek.rs

@@ -33,7 +33,7 @@ extension_trait! {
         https://docs.rs/futures-preview/0.3.0-alpha.17/futures/io/trait.AsyncSeek.html
         [provided methods]: #provided-methods
     "#]
-    pub trait Seek [SeekExt: futures_io::AsyncSeek] {
+    pub trait Seek {
         #[doc = r#"
             Attempt to seek to an offset, in bytes, in a stream.
         "#]
@@ -42,7 +42,9 @@ extension_trait! {
             cx: &mut Context<'_>,
             pos: SeekFrom,
         ) -> Poll<io::Result<u64>>;
+    }
 
+    pub trait SeekExt: futures_io::AsyncSeek {
         #[doc = r#"
             Seeks to a new position in a byte stream.
 
@@ -70,7 +72,7 @@ extension_trait! {
         fn seek(
             &mut self,
             pos: SeekFrom,
-        ) -> impl Future<Output = io::Result<u64>> [SeekFuture<'_, Self>]
+        ) -> impl Future<Output = io::Result<u64>> + '_ [SeekFuture<'_, Self>]
         where
             Self: Unpin,
         {

src/io/write/mod.rs

@@ -47,7 +47,7 @@ extension_trait! {
         [`poll_flush`]: #tymethod.poll_flush
         [`poll_close`]: #tymethod.poll_close
     "#]
-    pub trait Write [WriteExt: futures_io::AsyncWrite] {
+    pub trait Write {
         #[doc = r#"
             Attempt to write bytes from `buf` into the object.
         "#]
@@ -78,7 +78,9 @@ extension_trait! {
             Attempt to close the object.
         "#]
         fn poll_close(self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<io::Result<()>>;
+    }
 
+    pub trait WriteExt: futures_io::AsyncWrite {
         #[doc = r#"
             Writes some bytes into the byte stream.
 

src/stream/stream/mod.rs

@@ -89,7 +89,7 @@ cfg_if! {
     if #[cfg(any(feature = "unstable", feature = "docs"))] {
         use std::pin::Pin;
 
-        use std::future::Future;
+        use crate::future::Future;
         use crate::stream::FromStream;
     }
 }
@@ -114,7 +114,7 @@ extension_trait! {
         https://docs.rs/futures-preview/0.3.0-alpha.17/futures/stream/trait.Stream.html
         [provided methods]: #provided-methods
     "#]
-    pub trait Stream [StreamExt: futures_core::stream::Stream] {
+    pub trait Stream {
         #[doc = r#"
             The type of items yielded by this stream.
         "#]
@@ -172,7 +172,9 @@ extension_trait! {
             ```
         "#]
         fn poll_next(self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<Option<Self::Item>>;
+    }
 
+    pub trait StreamExt: futures_core::stream::Stream {
         #[doc = r#"
             Advances the stream and returns the next value.
 

src/task/blocking.rs

@@ -1,13 +1,13 @@
 //! A thread pool for running blocking functions asynchronously.
 
-use std::future::Future;
 use std::sync::atomic::{AtomicU64, Ordering};
 use std::thread;
 use std::time::Duration;
 
 use crossbeam_channel::{bounded, Receiver, Sender};
 use lazy_static::lazy_static;
 
+use crate::future::Future;
 use crate::task::task::{JoinHandle, Tag};
 use crate::utils::abort_on_panic;
 

src/task/mod.rs

@@ -81,7 +81,7 @@ pub(crate) mod blocking;
 #[inline]
 pub fn blocking<F, R>(future: F) -> task::JoinHandle<R>
 where
-    F: std::future::Future<Output = R> + Send + 'static,
+    F: crate::future::Future<Output = R> + Send + 'static,
     R: Send + 'static,
 {
     blocking::spawn(future)

src/task/pool.rs

@@ -1,4 +1,3 @@
-use std::future::Future;
 use std::iter;
 use std::thread;
 
@@ -11,6 +10,7 @@ use super::task;
 use super::task_local;
 use super::worker;
 use super::{Builder, JoinHandle};
+use crate::future::Future;
 use crate::utils::abort_on_panic;
 
 /// Spawns a task.

src/task/task.rs

@@ -1,5 +1,4 @@
 use std::fmt;
-use std::future::Future;
 use std::i64;
 use std::mem;
 use std::num::NonZeroU64;
@@ -8,6 +7,7 @@ use std::sync::atomic::{AtomicU64, AtomicUsize, Ordering};
 use std::sync::Arc;
 
 use super::task_local;
+use crate::future::Future;
 use crate::task::{Context, Poll};
 
 /// A handle to a task.

src/task/task_local.rs

@@ -7,8 +7,8 @@ use std::sync::Mutex;
 use lazy_static::lazy_static;
 
 use super::worker;
+use crate::future::Future;
 use crate::utils::abort_on_panic;
-use std::future::Future;
 
 /// Declares task-local values.
 ///

src/utils.rs

@@ -36,9 +36,13 @@ macro_rules! extension_trait {
         // - `$name`: trait name that gets rendered in the docs
         // - `$ext`: name of the hidden extension trait
         // - `$base`: base trait from the `futures` crate
-        $(#[$attr:meta])*
-        pub trait $name:ident [$ext:ident: $base:path] {
-            $($body:tt)*
+        #[doc = $doc:tt]
+        pub trait $name:ident {
+            $($body_base:tt)*
+        }
+
+        pub trait $ext:ident: $base:path {
+            $($body_ext:tt)*
         }
 
         // Shim trait impls that only appear in docs.
@@ -58,21 +62,21 @@ macro_rules! extension_trait {
             pub struct ImplFuture<'a, T>(std::marker::PhantomData<&'a T>);
         }
 
-        // Render a fake trait containing all methods from the base trait and the extension trait.
+        // Render a fake trait combining the bodies of the base trait and the extension trait.
         #[cfg(feature = "docs")]
-        $(#[$attr])*
+        #[doc = $doc]
         pub trait $name {
-            extension_trait!(@doc () $($body)*);
+            extension_trait!(@doc () $($body_base)* $($body_ext)*);
         }
 
         // When not rendering docs, re-export the base trait from the futures crate.
         #[cfg(not(feature = "docs"))]
         pub use $base as $name;
 
         // The extension trait that adds methods to any type implementing the base trait.
-        $(#[$attr])*
+        /// Extension trait.
         pub trait $ext: $base {
-            extension_trait!(@ext () $($body)*);
+            extension_trait!(@ext () $($body_ext)*);
         }
 
         // Blanket implementation of the extension trait for any type implementing the base trait.
@@ -82,47 +86,15 @@ macro_rules! extension_trait {
         $(#[cfg(feature = "docs")] $imp)*
     };
 
-    // Parse an associated type.
-    (@doc ($($head:tt)*) type $name:ident; $($tail:tt)*) => {
-        extension_trait!(@doc ($($head)* type $name;) $($tail)*);
-    };
-    (@ext ($($head:tt)*) type $ident:ty; $($tail:tt)*) => {
-        extension_trait!(@ext ($($head)*) $($tail)*);
-    };
-
-    // Parse a required method.
-    (@doc ($($head:tt)*) fn $name:ident $args:tt $(-> $ret:ty)?; $($tail:tt)*) => {
-        extension_trait!(@doc ($($head)* fn $name $args $(-> $ret)?;) $($tail)*);
-    };
-    (@ext ($($head:tt)*) fn $name:ident $args:tt $(-> $ret:ty)?; $($tail:tt)*) => {
-        extension_trait!(@ext ($($head)*) $($tail)*);
-    };
-
-    // Parse a provided method that exists in the base trait.
-    (@doc ($($head:tt)*) fn $name:ident $args:tt $(-> $ret:ty)? { $($body:tt)* } $($tail:tt)*) => {
-        extension_trait!(@doc ($($head)* fn $name $args $(-> $ret)? { $($body)* }) $($tail)*);
-    };
-    (@ext ($($head:tt)*) fn $name:ident $args:tt $(-> $ret:ty)? { $($body:tt)* } $($tail:tt)*) => {
-        extension_trait!(@ext ($($head)*) $($tail)*);
-    };
-
-    // Parse the return type in an extension method where the future doesn't borrow.
-    (@doc ($($head:tt)*) -> impl Future<Output = $out:ty> [$f:ty] $($tail:tt)*) => {
-        extension_trait!(@doc ($($head)* -> owned::ImplFuture<$out>) $($tail)*);
-    };
-    (@ext ($($head:tt)*) -> impl Future<Output = $out:ty> [$f:ty] $($tail:tt)*) => {
-        extension_trait!(@ext ($($head)* -> $f) $($tail)*);
-    };
-
-    // Parse the return type in an extension method where the future borrows its environment.
-    (@doc ($($head:tt)*) -> impl Future<Output = $out:ty> + $lt:lifetime [$f:ty] $($tail:tt)*) => {
-        extension_trait!(@doc ($($head)* -> borrowed::ImplFuture<$lt, $out>) $($tail)*);
+    // Parse the return type in an extension method.
+    (@doc ($($head:tt)*) -> impl Future<Output = $out:ty> $(+ $lt:lifetime)? [$f:ty] $($tail:tt)*) => {
+        extension_trait!(@doc ($($head)* -> borrowed::ImplFuture<$($lt,)? $out>) $($tail)*);
     };
-    (@ext ($($head:tt)*) -> impl Future<Output = $out:ty> + $lt:lifetime [$f:ty] $($tail:tt)*) => {
+    (@ext ($($head:tt)*) -> impl Future<Output = $out:ty> $(+ $lt:lifetime)? [$f:ty] $($tail:tt)*) => {
         extension_trait!(@ext ($($head)* -> $f) $($tail)*);
     };
 
-    // Parse a token that doesn't fit into any of the previous patterns.
+    // Parse a token.
     (@doc ($($head:tt)*) $token:tt $($tail:tt)*) => {
         extension_trait!(@doc ($($head)* $token) $($tail)*);
     };