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Merge pull request #1006 from nnethercote/rm-extension_trait

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Remove `extension_trait`
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662
src/future/future/mod.rs
View file

@ -20,413 +20,269 @@ cfg_unstable_default! {
use crate::future::timeout::TimeoutFuture;
}
extension_trait! {
use core::pin::Pin;
use core::ops::{Deref, DerefMut};
use crate::task::{Context, Poll};
#[doc = r#"
A future represents an asynchronous computation.
A future is a value that may not have finished computing yet. This kind of
"asynchronous value" makes it possible for a thread to continue doing useful
work while it waits for the value to become available.
The [provided methods] do not really exist in the trait itself, but they become
available when [`FutureExt`] from the [prelude] is imported:
```
# #[allow(unused_imports)]
use async_std::prelude::*;
```
# The `poll` method
The core method of future, `poll`, *attempts* to resolve the future into a
final value. This method does not block if the value is not ready. Instead,
the current task is scheduled to be woken up when it's possible to make
further progress by `poll`ing again. The `context` passed to the `poll`
method can provide a [`Waker`], which is a handle for waking up the current
task.
When using a future, you generally won't call `poll` directly, but instead
`.await` the value.
[`Waker`]: ../task/struct.Waker.html
[provided methods]: #provided-methods
[`FutureExt`]: ../prelude/trait.FutureExt.html
[prelude]: ../prelude/index.html
"#]
pub trait Future {
#[doc = r#"
The type of value produced on completion.
"#]
type Output;
#[doc = r#"
Attempt to resolve the future to a final value, registering
the current task for wakeup if the value is not yet available.
# Return value
This function returns:
- [`Poll::Pending`] if the future is not ready yet
- [`Poll::Ready(val)`] with the result `val` of this future if it
finished successfully.
Once a future has finished, clients should not `poll` it again.
When a future is not ready yet, `poll` returns `Poll::Pending` and
stores a clone of the [`Waker`] copied from the current [`Context`].
This [`Waker`] is then woken once the future can make progress.
For example, a future waiting for a socket to become
readable would call `.clone()` on the [`Waker`] and store it.
When a signal arrives elsewhere indicating that the socket is readable,
[`Waker::wake`] is called and the socket future's task is awoken.
Once a task has been woken up, it should attempt to `poll` the future
again, which may or may not produce a final value.
Note that on multiple calls to `poll`, only the [`Waker`] from the
[`Context`] passed to the most recent call should be scheduled to
receive a wakeup.
# Runtime characteristics
Futures alone are *inert*; they must be *actively* `poll`ed to make
progress, meaning that each time the current task is woken up, it should
actively re-`poll` pending futures that it still has an interest in.
The `poll` function is not called repeatedly in a tight loop -- instead,
it should only be called when the future indicates that it is ready to
make progress (by calling `wake()`). If you're familiar with the
`poll(2)` or `select(2)` syscalls on Unix it's worth noting that futures
typically do *not* suffer the same problems of "all wakeups must poll
all events"; they are more like `epoll(4)`.
An implementation of `poll` should strive to return quickly, and should
not block. Returning quickly prevents unnecessarily clogging up
threads or event loops. If it is known ahead of time that a call to
`poll` may end up taking awhile, the work should be offloaded to a
thread pool (or something similar) to ensure that `poll` can return
quickly.
# Panics
Once a future has completed (returned `Ready` from `poll`), calling its
`poll` method again may panic, block forever, or cause other kinds of
problems; the `Future` trait places no requirements on the effects of
such a call. However, as the `poll` method is not marked `unsafe`,
Rust's usual rules apply: calls must never cause undefined behavior
(memory corruption, incorrect use of `unsafe` functions, or the like),
regardless of the future's state.
[`Poll::Pending`]: ../task/enum.Poll.html#variant.Pending
[`Poll::Ready(val)`]: ../task/enum.Poll.html#variant.Ready
[`Context`]: ../task/struct.Context.html
[`Waker`]: ../task/struct.Waker.html
[`Waker::wake`]: ../task/struct.Waker.html#method.wake
"#]
fn poll(self: Pin<&mut Self>, cx: &mut Context) -> Poll<Self::Output>;
}
#[doc = r#"
Extension methods for [`Future`].
[`Future`]: ../future/trait.Future.html
"#]
pub trait FutureExt: core::future::Future {
/// Returns a Future that delays execution for a specified time.
///
/// # Examples
///
/// ```
/// # async_std::task::block_on(async {
/// use async_std::prelude::*;
/// use async_std::future;
/// use std::time::Duration;
///
/// let a = future::ready(1).delay(Duration::from_millis(2000));
/// dbg!(a.await);
/// # })
/// ```
#[cfg(feature = "unstable")]
#[cfg_attr(feature = "docs", doc(cfg(unstable)))]
fn delay(self, dur: Duration) -> impl Future<Output = Self::Output> [DelayFuture<Self>]
where
Self: Sized,
{
DelayFuture::new(self, dur)
}
/// Flatten out the execution of this future when the result itself
/// can be converted into another future.
///
/// # Examples
///
/// ```
/// # async_std::task::block_on(async {
/// use async_std::prelude::*;
///
/// let nested_future = async { async { 1 } };
/// let future = nested_future.flatten();
/// assert_eq!(future.await, 1);
/// # })
/// ```
#[cfg(feature = "unstable")]
#[cfg_attr(feature = "docs", doc(cfg(unstable)))]
fn flatten(
self,
) -> impl Future<Output = <Self::Output as IntoFuture>::Output>
[FlattenFuture<Self, <Self::Output as IntoFuture>::Future>]
where
Self: Sized,
<Self as Future>::Output: IntoFuture,
{
FlattenFuture::new(self)
}
#[doc = r#"
Waits for one of two similarly-typed futures to complete.
Awaits multiple futures simultaneously, returning the output of the
first future that completes.
This function will return a new future which awaits for either one of both
futures to complete. If multiple futures are completed at the same time,
resolution will occur in the order that they have been passed.
Note that this function consumes all futures passed, and once a future is
completed, all other futures are dropped.
# Examples
```
# async_std::task::block_on(async {
use async_std::prelude::*;
use async_std::future;
let a = future::pending();
let b = future::ready(1u8);
let c = future::ready(2u8);
let f = a.race(b).race(c);
assert_eq!(f.await, 1u8);
# });
```
"#]
#[cfg(feature = "unstable")]
#[cfg_attr(feature = "docs", doc(cfg(unstable)))]
fn race<F>(
self,
other: F,
) -> impl Future<Output = <Self as std::future::Future>::Output> [Race<Self, F>]
where
Self: std::future::Future + Sized,
F: std::future::Future<Output = <Self as std::future::Future>::Output>,
{
Race::new(self, other)
}
#[doc = r#"
Waits for one of two similarly-typed fallible futures to complete.
Awaits multiple futures simultaneously, returning all results once complete.
`try_race` is similar to [`race`], but keeps going if a future
resolved to an error until all futures have been resolved. In which case
an error is returned.
The ordering of which value is yielded when two futures resolve
simultaneously is intentionally left unspecified.
[`race`]: #method.race
# Examples
```
# fn main() -> std::io::Result<()> { async_std::task::block_on(async {
#
use async_std::prelude::*;
use async_std::future;
use std::io::{Error, ErrorKind};
let a = future::pending::<Result<_, Error>>();
let b = future::ready(Err(Error::from(ErrorKind::Other)));
let c = future::ready(Ok(1u8));
let f = a.try_race(b).try_race(c);
assert_eq!(f.await?, 1u8);
#
# Ok(()) }) }
```
"#]
#[cfg(feature = "unstable")]
#[cfg_attr(feature = "docs", doc(cfg(unstable)))]
fn try_race<F, T, E>(
self,
other: F
) -> impl Future<Output = <Self as std::future::Future>::Output> [TryRace<Self, F>]
where
Self: std::future::Future<Output = Result<T, E>> + Sized,
F: std::future::Future<Output = <Self as std::future::Future>::Output>,
{
TryRace::new(self, other)
}
#[doc = r#"
Waits for two similarly-typed futures to complete.
Awaits multiple futures simultaneously, returning the output of the
futures once both complete.
This function returns a new future which polls both futures
concurrently.
# Examples
```
# async_std::task::block_on(async {
use async_std::prelude::*;
use async_std::future;
let a = future::ready(1u8);
let b = future::ready(2u16);
let f = a.join(b);
assert_eq!(f.await, (1u8, 2u16));
# });
```
"#]
#[cfg(any(feature = "unstable", feature = "docs"))]
#[cfg_attr(feature = "docs", doc(cfg(unstable)))]
fn join<F>(
self,
other: F
) -> impl Future<Output = (<Self as std::future::Future>::Output, <F as std::future::Future>::Output)> [Join<Self, F>]
where
Self: std::future::Future + Sized,
F: std::future::Future,
{
Join::new(self, other)
}
#[doc = r#"
Waits for two similarly-typed fallible futures to complete.
Awaits multiple futures simultaneously, returning all results once
complete.
`try_join` is similar to [`join`], but returns an error immediately
if a future resolves to an error.
[`join`]: #method.join
# Examples
```
# fn main() -> std::io::Result<()> { async_std::task::block_on(async {
#
use async_std::prelude::*;
use async_std::future;
let a = future::ready(Err::<u8, &str>("Error"));
let b = future::ready(Ok(1u8));
let f = a.try_join(b);
assert_eq!(f.await, Err("Error"));
let a = future::ready(Ok::<u8, String>(1u8));
let b = future::ready(Ok::<u16, String>(2u16));
let f = a.try_join(b);
assert_eq!(f.await, Ok((1u8, 2u16)));
#
# Ok(()) }) }
```
"#]
#[cfg(any(feature = "unstable", feature = "docs"))]
#[cfg_attr(feature = "docs", doc(cfg(unstable)))]
fn try_join<F, A, B, E>(
self,
other: F
) -> impl Future<Output = Result<(A, B), E>> [TryJoin<Self, F>]
where
Self: std::future::Future<Output = Result<A, E>> + Sized,
F: std::future::Future<Output = Result<B, E>>,
{
TryJoin::new(self, other)
}
#[doc = r#"
Waits for both the future and a timeout, if the timeout completes before
the future, it returns a TimeoutError.
# Example
```
# async_std::task::block_on(async {
#
use std::time::Duration;
use async_std::prelude::*;
use async_std::future;
let fut = future::ready(0);
let dur = Duration::from_millis(100);
let res = fut.timeout(dur).await;
assert!(res.is_ok());
let fut = future::pending::<()>();
let dur = Duration::from_millis(100);
let res = fut.timeout(dur).await;
assert!(res.is_err())
#
# });
```
"#]
#[cfg(any(all(feature = "default", feature = "unstable"), feature = "docs"))]
#[cfg_attr(feature = "docs", doc(cfg(unstable)))]
fn timeout(self, dur: Duration) -> impl Future<Output = Self::Output> [TimeoutFuture<Self>]
where Self: Sized
{
TimeoutFuture::new(self, dur)
}
}
impl<F: Future + Unpin + ?Sized> Future for Box<F> {
type Output = F::Output;
fn poll(self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<Self::Output> {
unreachable!("this impl only appears in the rendered docs")
}
}
impl<F: Future + Unpin + ?Sized> Future for &mut F {
type Output = F::Output;
fn poll(self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<Self::Output> {
unreachable!("this impl only appears in the rendered docs")
}
}
impl<P> Future for Pin<P>
pub use core::future::Future as Future;
#[doc = r#"
Extension methods for [`Future`].
[`Future`]: ../future/trait.Future.html
"#]
pub trait FutureExt: Future {
/// Returns a Future that delays execution for a specified time.
///
/// # Examples
///
/// ```
/// # async_std::task::block_on(async {
/// use async_std::prelude::*;
/// use async_std::future;
/// use std::time::Duration;
///
/// let a = future::ready(1).delay(Duration::from_millis(2000));
/// dbg!(a.await);
/// # })
/// ```
#[cfg(feature = "unstable")]
#[cfg_attr(feature = "docs", doc(cfg(unstable)))]
fn delay(self, dur: Duration) -> DelayFuture<Self>
where
P: DerefMut + Unpin,
<P as Deref>::Target: Future,
Self: Sized,
{
type Output = <<P as Deref>::Target as Future>::Output;
fn poll(self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<Self::Output> {
unreachable!("this impl only appears in the rendered docs")
}
DelayFuture::new(self, dur)
}
impl<F: Future> Future for std::panic::AssertUnwindSafe<F> {
type Output = F::Output;
/// Flatten out the execution of this future when the result itself
/// can be converted into another future.
///
/// # Examples
///
/// ```
/// # async_std::task::block_on(async {
/// use async_std::prelude::*;
///
/// let nested_future = async { async { 1 } };
/// let future = nested_future.flatten();
/// assert_eq!(future.await, 1);
/// # })
/// ```
#[cfg(feature = "unstable")]
#[cfg_attr(feature = "docs", doc(cfg(unstable)))]
fn flatten(
self,
) -> FlattenFuture<Self, <Self::Output as IntoFuture>::Future>
where
Self: Sized,
<Self as Future>::Output: IntoFuture,
{
FlattenFuture::new(self)
}
fn poll(self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<Self::Output> {
unreachable!("this impl only appears in the rendered docs")
}
#[doc = r#"
Waits for one of two similarly-typed futures to complete.
Awaits multiple futures simultaneously, returning the output of the
first future that completes.
This function will return a new future which awaits for either one of both
futures to complete. If multiple futures are completed at the same time,
resolution will occur in the order that they have been passed.
Note that this function consumes all futures passed, and once a future is
completed, all other futures are dropped.
# Examples
```
# async_std::task::block_on(async {
use async_std::prelude::*;
use async_std::future;
let a = future::pending();
let b = future::ready(1u8);
let c = future::ready(2u8);
let f = a.race(b).race(c);
assert_eq!(f.await, 1u8);
# });
```
"#]
#[cfg(feature = "unstable")]
#[cfg_attr(feature = "docs", doc(cfg(unstable)))]
fn race<F>(
self,
other: F,
) -> Race<Self, F>
where
Self: std::future::Future + Sized,
F: std::future::Future<Output = <Self as std::future::Future>::Output>,
{
Race::new(self, other)
}
#[doc = r#"
Waits for one of two similarly-typed fallible futures to complete.
Awaits multiple futures simultaneously, returning all results once complete.
`try_race` is similar to [`race`], but keeps going if a future
resolved to an error until all futures have been resolved. In which case
an error is returned.
The ordering of which value is yielded when two futures resolve
simultaneously is intentionally left unspecified.
[`race`]: #method.race
# Examples
```
# fn main() -> std::io::Result<()> { async_std::task::block_on(async {
#
use async_std::prelude::*;
use async_std::future;
use std::io::{Error, ErrorKind};
let a = future::pending::<Result<_, Error>>();
let b = future::ready(Err(Error::from(ErrorKind::Other)));
let c = future::ready(Ok(1u8));
let f = a.try_race(b).try_race(c);
assert_eq!(f.await?, 1u8);
#
# Ok(()) }) }
```
"#]
#[cfg(feature = "unstable")]
#[cfg_attr(feature = "docs", doc(cfg(unstable)))]
fn try_race<F, T, E>(
self,
other: F
) -> TryRace<Self, F>
where
Self: std::future::Future<Output = Result<T, E>> + Sized,
F: std::future::Future<Output = <Self as std::future::Future>::Output>,
{
TryRace::new(self, other)
}
#[doc = r#"
Waits for two similarly-typed futures to complete.
Awaits multiple futures simultaneously, returning the output of the
futures once both complete.
This function returns a new future which polls both futures
concurrently.
# Examples
```
# async_std::task::block_on(async {
use async_std::prelude::*;
use async_std::future;
let a = future::ready(1u8);
let b = future::ready(2u16);
let f = a.join(b);
assert_eq!(f.await, (1u8, 2u16));
# });
```
"#]
#[cfg(any(feature = "unstable", feature = "docs"))]
#[cfg_attr(feature = "docs", doc(cfg(unstable)))]
fn join<F>(
self,
other: F
) -> Join<Self, F>
where
Self: std::future::Future + Sized,
F: std::future::Future,
{
Join::new(self, other)
}
#[doc = r#"
Waits for two similarly-typed fallible futures to complete.
Awaits multiple futures simultaneously, returning all results once
complete.
`try_join` is similar to [`join`], but returns an error immediately
if a future resolves to an error.
[`join`]: #method.join
# Examples
```
# fn main() -> std::io::Result<()> { async_std::task::block_on(async {
#
use async_std::prelude::*;
use async_std::future;
let a = future::ready(Err::<u8, &str>("Error"));
let b = future::ready(Ok(1u8));
let f = a.try_join(b);
assert_eq!(f.await, Err("Error"));
let a = future::ready(Ok::<u8, String>(1u8));
let b = future::ready(Ok::<u16, String>(2u16));
let f = a.try_join(b);
assert_eq!(f.await, Ok((1u8, 2u16)));
#
# Ok(()) }) }
```
"#]
#[cfg(any(feature = "unstable", feature = "docs"))]
#[cfg_attr(feature = "docs", doc(cfg(unstable)))]
fn try_join<F, A, B, E>(
self,
other: F
) -> TryJoin<Self, F>
where
Self: std::future::Future<Output = Result<A, E>> + Sized,
F: std::future::Future<Output = Result<B, E>>,
{
TryJoin::new(self, other)
}
#[doc = r#"
Waits for both the future and a timeout, if the timeout completes before
the future, it returns a TimeoutError.
# Example
```
# async_std::task::block_on(async {
#
use std::time::Duration;
use async_std::prelude::*;
use async_std::future;
let fut = future::ready(0);
let dur = Duration::from_millis(100);
let res = fut.timeout(dur).await;
assert!(res.is_ok());
let fut = future::pending::<()>();
let dur = Duration::from_millis(100);
let res = fut.timeout(dur).await;
assert!(res.is_err())
#
# });
```
"#]
#[cfg(any(all(feature = "default", feature = "unstable"), feature = "docs"))]
#[cfg_attr(feature = "docs", doc(cfg(unstable)))]
fn timeout(self, dur: Duration) -> TimeoutFuture<Self>
where Self: Sized
{
TimeoutFuture::new(self, dur)
}
}
impl<T: Future + ?Sized> FutureExt for T {}

514
src/io/buf_read/mod.rs
View file

@ -15,332 +15,230 @@ use std::pin::Pin;
use crate::io;
use crate::task::{Context, Poll};
extension_trait! {
use std::ops::{Deref, DerefMut};
pub use futures_io::AsyncBufRead as BufRead;
#[doc = r#"
Extension methods for [`BufRead`].
[`BufRead`]: ../trait.BufRead.html
"#]
pub trait BufReadExt: BufRead {
#[doc = r#"
Allows reading from a buffered byte stream.
Reads all bytes into `buf` until the delimiter `byte` or EOF is reached.
This trait is a re-export of [`futures::io::AsyncBufRead`] and is an async version of
[`std::io::BufRead`].
This function will read bytes from the underlying stream until the delimiter or EOF
is found. Once found, all bytes up to, and including, the delimiter (if found) will
be appended to `buf`.
The [provided methods] do not really exist in the trait itself, but they become
available when [`BufReadExt`] from the [prelude] is imported:
If successful, this function will return the total number of bytes read.
```
# #[allow(unused_imports)]
use async_std::io::prelude::*;
# Examples
```no_run
# fn main() -> std::io::Result<()> { async_std::task::block_on(async {
#
use async_std::fs::File;
use async_std::io::BufReader;
use async_std::prelude::*;
let mut file = BufReader::new(File::open("a.txt").await?);
let mut buf = Vec::with_capacity(1024);
let n = file.read_until(b'\n', &mut buf).await?;
#
# Ok(()) }) }
```
[`std::io::BufRead`]: https://doc.rust-lang.org/std/io/trait.BufRead.html
[`futures::io::AsyncBufRead`]:
https://docs.rs/futures/0.3/futures/io/trait.AsyncBufRead.html
[provided methods]: #provided-methods
[`BufReadExt`]: ../io/prelude/trait.BufReadExt.html
[prelude]: ../prelude/index.html
Multiple successful calls to `read_until` append all bytes up to and including to
`buf`:
```
# fn main() -> std::io::Result<()> { async_std::task::block_on(async {
#
use async_std::io::BufReader;
use async_std::prelude::*;
let from: &[u8] = b"append\nexample\n";
let mut reader = BufReader::new(from);
let mut buf = vec![];
let mut size = reader.read_until(b'\n', &mut buf).await?;
assert_eq!(size, 7);
assert_eq!(buf, b"append\n");
size += reader.read_until(b'\n', &mut buf).await?;
assert_eq!(size, from.len());
assert_eq!(buf, from);
#
# Ok(()) }) }
```
"#]
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.
This function is a lower-level call. It needs to be paired with the [`consume`]
method to function properly. When calling this method, none of the contents will be
"read" in the sense that later calling `read` may return the same contents. As
such, [`consume`] must be called with the number of bytes that are consumed from
this buffer to ensure that the bytes are never returned twice.
[`consume`]: #tymethod.consume
An empty buffer returned indicates that the stream has reached EOF.
"#]
// TODO: write a proper doctest with `consume`
fn poll_fill_buf(self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<io::Result<&[u8]>>;
#[doc = r#"
Tells this buffer that `amt` bytes have been consumed from the buffer, so they
should no longer be returned in calls to `read`.
"#]
fn consume(self: Pin<&mut Self>, amt: usize);
}
#[doc = r#"
Extension methods for [`BufRead`].
[`BufRead`]: ../trait.BufRead.html
"#]
pub trait BufReadExt: futures_io::AsyncBufRead {
#[doc = r#"
Reads all bytes into `buf` until the delimiter `byte` or EOF is reached.
This function will read bytes from the underlying stream until the delimiter or EOF
is found. Once found, all bytes up to, and including, the delimiter (if found) will
be appended to `buf`.
If successful, this function will return the total number of bytes read.
# Examples
```no_run
# fn main() -> std::io::Result<()> { async_std::task::block_on(async {
#
use async_std::fs::File;
use async_std::io::BufReader;
use async_std::prelude::*;
let mut file = BufReader::new(File::open("a.txt").await?);
let mut buf = Vec::with_capacity(1024);
let n = file.read_until(b'\n', &mut buf).await?;
#
# Ok(()) }) }
```
Multiple successful calls to `read_until` append all bytes up to and including to
`buf`:
```
# fn main() -> std::io::Result<()> { async_std::task::block_on(async {
#
use async_std::io::BufReader;
use async_std::prelude::*;
let from: &[u8] = b"append\nexample\n";
let mut reader = BufReader::new(from);
let mut buf = vec![];
let mut size = reader.read_until(b'\n', &mut buf).await?;
assert_eq!(size, 7);
assert_eq!(buf, b"append\n");
size += reader.read_until(b'\n', &mut buf).await?;
assert_eq!(size, from.len());
assert_eq!(buf, from);
#
# Ok(()) }) }
```
"#]
fn read_until<'a>(
&'a mut self,
byte: u8,
buf: &'a mut Vec<u8>,
) -> impl Future<Output = usize> + 'a [ReadUntilFuture<'a, Self>]
where
Self: Unpin,
{
ReadUntilFuture {
reader: self,
byte,
buf,
read: 0,
}
}
#[doc = r#"
Reads all bytes and appends them into `buf` until a newline (the 0xA byte) is
reached.
This function will read bytes from the underlying stream until the newline
delimiter (the 0xA byte) or EOF is found. Once found, all bytes up to, and
including, the delimiter (if found) will be appended to `buf`.
If successful, this function will return the total number of bytes read.
If this function returns `Ok(0)`, the stream has reached EOF.
# Errors
This function has the same error semantics as [`read_until`] and will also return
an error if the read bytes are not valid UTF-8. If an I/O error is encountered then
`buf` may contain some bytes already read in the event that all data read so far
was valid UTF-8.
[`read_until`]: #method.read_until
# Examples
```no_run
# fn main() -> std::io::Result<()> { async_std::task::block_on(async {
#
use async_std::fs::File;
use async_std::io::BufReader;
use async_std::prelude::*;
let mut file = BufReader::new(File::open("a.txt").await?);
let mut buf = String::new();
file.read_line(&mut buf).await?;
#
# Ok(()) }) }
```
"#]
fn read_line<'a>(
&'a mut self,
buf: &'a mut String,
) -> impl Future<Output = io::Result<usize>> + 'a [ReadLineFuture<'a, Self>]
where
Self: Unpin,
{
ReadLineFuture {
reader: self,
bytes: unsafe { mem::replace(buf.as_mut_vec(), Vec::new()) },
buf,
read: 0,
}
}
#[doc = r#"
Returns a stream over the lines of this byte stream.
The stream returned from this function will yield instances of
[`io::Result`]`<`[`String`]`>`. Each string returned will *not* have a newline byte
(the 0xA byte) or CRLF (0xD, 0xA bytes) at the end.
[`io::Result`]: type.Result.html
[`String`]: https://doc.rust-lang.org/std/string/struct.String.html
# Examples
```no_run
# fn main() -> std::io::Result<()> { async_std::task::block_on(async {
#
use async_std::fs::File;
use async_std::io::BufReader;
use async_std::prelude::*;
let file = File::open("a.txt").await?;
let mut lines = BufReader::new(file).lines();
let mut count = 0;
while let Some(line) = lines.next().await {
line?;
count += 1;
}
#
# Ok(()) }) }
```
"#]
fn lines(self) -> Lines<Self>
where
Self: Unpin + Sized,
{
Lines {
reader: self,
buf: String::new(),
bytes: Vec::new(),
read: 0,
}
}
#[doc = r#"
Returns a stream over the contents of this reader split on the byte `byte`.
The stream returned from this function will return instances of
[`io::Result`]`<`[`Vec<u8>`]`>`. Each vector returned will *not* have
the delimiter byte at the end.
This function will yield errors whenever [`read_until`] would have
also yielded an error.
[`io::Result`]: type.Result.html
[`Vec<u8>`]: ../vec/struct.Vec.html
[`read_until`]: #method.read_until
# Examples
[`std::io::Cursor`][`Cursor`] is a type that implements `BufRead`. In
this example, we use [`Cursor`] to iterate over all hyphen delimited
segments in a byte slice
[`Cursor`]: struct.Cursor.html
```
# fn main() -> std::io::Result<()> { async_std::task::block_on(async {
#
use async_std::prelude::*;
use async_std::io;
let cursor = io::Cursor::new(b"lorem-ipsum-dolor");
let mut split_iter = cursor.split(b'-').map(|l| l.unwrap());
assert_eq!(split_iter.next().await, Some(b"lorem".to_vec()));
assert_eq!(split_iter.next().await, Some(b"ipsum".to_vec()));
assert_eq!(split_iter.next().await, Some(b"dolor".to_vec()));
assert_eq!(split_iter.next().await, None);
#
# Ok(()) }) }
```
"#]
fn split(self, byte: u8) -> Split<Self>
where
Self: Sized,
{
Split {
reader: self,
buf: Vec::new(),
delim: byte,
read: 0,
}
}
}
impl<T: BufRead + Unpin + ?Sized> BufRead for Box<T> {
fn poll_fill_buf(
self: Pin<&mut Self>,
cx: &mut Context<'_>,
) -> Poll<io::Result<&[u8]>> {
unreachable!("this impl only appears in the rendered docs")
}
fn consume(self: Pin<&mut Self>, amt: usize) {
unreachable!("this impl only appears in the rendered docs")
}
}
impl<T: BufRead + Unpin + ?Sized> BufRead for &mut T {
fn poll_fill_buf(
self: Pin<&mut Self>,
cx: &mut Context<'_>,
) -> Poll<io::Result<&[u8]>> {
unreachable!("this impl only appears in the rendered docs")
}
fn consume(self: Pin<&mut Self>, amt: usize) {
unreachable!("this impl only appears in the rendered docs")
}
}
impl<P> BufRead for Pin<P>
fn read_until<'a>(
&'a mut self,
byte: u8,
buf: &'a mut Vec<u8>,
) -> ReadUntilFuture<'a, Self>
where
P: DerefMut + Unpin,
<P as Deref>::Target: BufRead,
Self: Unpin,
{
fn poll_fill_buf(
self: Pin<&mut Self>,
cx: &mut Context<'_>,
) -> Poll<io::Result<&[u8]>> {
unreachable!("this impl only appears in the rendered docs")
}
fn consume(self: Pin<&mut Self>, amt: usize) {
unreachable!("this impl only appears in the rendered docs")
ReadUntilFuture {
reader: self,
byte,
buf,
read: 0,
}
}
impl BufRead for &[u8] {
fn poll_fill_buf(
self: Pin<&mut Self>,
cx: &mut Context<'_>,
) -> Poll<io::Result<&[u8]>> {
unreachable!()
}
#[doc = r#"
Reads all bytes and appends them into `buf` until a newline (the 0xA byte) is
reached.
fn consume(self: Pin<&mut Self>, amt: usize) {
unreachable!("this impl only appears in the rendered docs")
This function will read bytes from the underlying stream until the newline
delimiter (the 0xA byte) or EOF is found. Once found, all bytes up to, and
including, the delimiter (if found) will be appended to `buf`.
If successful, this function will return the total number of bytes read.
If this function returns `Ok(0)`, the stream has reached EOF.
# Errors
This function has the same error semantics as [`read_until`] and will also return
an error if the read bytes are not valid UTF-8. If an I/O error is encountered then
`buf` may contain some bytes already read in the event that all data read so far
was valid UTF-8.
[`read_until`]: #method.read_until
# Examples
```no_run
# fn main() -> std::io::Result<()> { async_std::task::block_on(async {
#
use async_std::fs::File;
use async_std::io::BufReader;
use async_std::prelude::*;
let mut file = BufReader::new(File::open("a.txt").await?);
let mut buf = String::new();
file.read_line(&mut buf).await?;
#
# Ok(()) }) }
```
"#]
fn read_line<'a>(
&'a mut self,
buf: &'a mut String,
) -> ReadLineFuture<'a, Self>
where
Self: Unpin,
{
ReadLineFuture {
reader: self,
bytes: unsafe { mem::replace(buf.as_mut_vec(), Vec::new()) },
buf,
read: 0,
}
}
#[doc = r#"
Returns a stream over the lines of this byte stream.
The stream returned from this function will yield instances of
[`io::Result`]`<`[`String`]`>`. Each string returned will *not* have a newline byte
(the 0xA byte) or CRLF (0xD, 0xA bytes) at the end.
[`io::Result`]: type.Result.html
[`String`]: https://doc.rust-lang.org/std/string/struct.String.html
# Examples
```no_run
# fn main() -> std::io::Result<()> { async_std::task::block_on(async {
#
use async_std::fs::File;
use async_std::io::BufReader;
use async_std::prelude::*;
let file = File::open("a.txt").await?;
let mut lines = BufReader::new(file).lines();
let mut count = 0;
while let Some(line) = lines.next().await {
line?;
count += 1;
}
#
# Ok(()) }) }
```
"#]
fn lines(self) -> Lines<Self>
where
Self: Unpin + Sized,
{
Lines {
reader: self,
buf: String::new(),
bytes: Vec::new(),
read: 0,
}
}
#[doc = r#"
Returns a stream over the contents of this reader split on the byte `byte`.
The stream returned from this function will return instances of
[`io::Result`]`<`[`Vec<u8>`]`>`. Each vector returned will *not* have
the delimiter byte at the end.
This function will yield errors whenever [`read_until`] would have
also yielded an error.
[`io::Result`]: type.Result.html
[`Vec<u8>`]: ../vec/struct.Vec.html
[`read_until`]: #method.read_until
# Examples
[`std::io::Cursor`][`Cursor`] is a type that implements `BufRead`. In
this example, we use [`Cursor`] to iterate over all hyphen delimited
segments in a byte slice
[`Cursor`]: struct.Cursor.html
```
# fn main() -> std::io::Result<()> { async_std::task::block_on(async {
#
use async_std::prelude::*;
use async_std::io;
let cursor = io::Cursor::new(b"lorem-ipsum-dolor");
let mut split_iter = cursor.split(b'-').map(|l| l.unwrap());
assert_eq!(split_iter.next().await, Some(b"lorem".to_vec()));
assert_eq!(split_iter.next().await, Some(b"ipsum".to_vec()));
assert_eq!(split_iter.next().await, Some(b"dolor".to_vec()));
assert_eq!(split_iter.next().await, None);
#
# Ok(()) }) }
```
"#]
fn split(self, byte: u8) -> Split<Self>
where
Self: Sized,
{
Split {
reader: self,
buf: Vec::new(),
delim: byte,
read: 0,
}
}
}
impl<T: BufRead + ?Sized> BufReadExt for T {}
pub fn read_until_internal<R: BufReadExt + ?Sized>(
mut reader: Pin<&mut R>,
cx: &mut Context<'_>,

751
src/io/read/mod.rs
View file

@ -21,453 +21,360 @@ pub use bytes::Bytes;
pub use chain::Chain;
pub use take::Take;
extension_trait! {
use std::pin::Pin;
use std::ops::{Deref, DerefMut};
pub use futures_io::AsyncRead as Read;
use crate::io;
use crate::task::{Context, Poll};
#[doc = r#"
Extension methods for [`Read`].
[`Read`]: ../trait.Read.html
"#]
pub trait ReadExt: Read {
#[doc = r#"
Allows reading from a byte stream.
Reads some bytes from the byte stream.
This trait is a re-export of [`futures::io::AsyncRead`] and is an async version of
[`std::io::Read`].
Returns the number of bytes read from the start of the buffer.
Methods other than [`poll_read`] and [`poll_read_vectored`] do not really exist in the
trait itself, but they become available when [`ReadExt`] from the [prelude] is imported:
If the return value is `Ok(n)`, then it must be guaranteed that
`0 <= n <= buf.len()`. A nonzero `n` value indicates that the buffer has been
filled in with `n` bytes of data. If `n` is `0`, then it can indicate one of two
scenarios:
```
# #[allow(unused_imports)]
1. This reader has reached its "end of file" and will likely no longer be able to
produce bytes. Note that this does not mean that the reader will always no
longer be able to produce bytes.
2. The buffer specified was 0 bytes in length.
# Examples
```no_run
# fn main() -> std::io::Result<()> { async_std::task::block_on(async {
#
use async_std::fs::File;
use async_std::prelude::*;
let mut file = File::open("a.txt").await?;
let mut buf = vec![0; 1024];
let n = file.read(&mut buf).await?;
#
# Ok(()) }) }
```
[`std::io::Read`]: https://doc.rust-lang.org/std/io/trait.Read.html
[`futures::io::AsyncRead`]:
https://docs.rs/futures/0.3/futures/io/trait.AsyncRead.html
[`poll_read`]: #tymethod.poll_read
[`poll_read_vectored`]: #method.poll_read_vectored
[`ReadExt`]: ../io/prelude/trait.ReadExt.html
[prelude]: ../prelude/index.html
"#]
pub trait Read {
#[doc = r#"
Attempt to read from the `AsyncRead` into `buf`.
"#]
fn poll_read(
self: Pin<&mut Self>,
cx: &mut Context<'_>,
buf: &mut [u8],
) -> Poll<io::Result<usize>>;
fn read<'a>(
&'a mut self,
buf: &'a mut [u8],
) -> ReadFuture<'a, Self>
where
Self: Unpin
{
ReadFuture { reader: self, buf }
}
#[doc = r#"
Attempt to read from the `AsyncRead` into `bufs` using vectored IO operations.
"#]
fn poll_read_vectored(
self: Pin<&mut Self>,
cx: &mut Context<'_>,
bufs: &mut [IoSliceMut<'_>],
) -> Poll<io::Result<usize>> {
unreachable!("this impl only appears in the rendered docs")
#[doc = r#"
Like [`read`], except that it reads into a slice of buffers.
Data is copied to fill each buffer in order, with the final buffer written to
possibly being only partially filled. This method must behave as a single call to
[`read`] with the buffers concatenated would.
The default implementation calls [`read`] with either the first nonempty buffer
provided, or an empty one if none exists.
[`read`]: #tymethod.read
"#]
fn read_vectored<'a>(
&'a mut self,
bufs: &'a mut [IoSliceMut<'a>],
) -> ReadVectoredFuture<'a, Self>
where
Self: Unpin,
{
ReadVectoredFuture { reader: self, bufs }
}
#[doc = r#"
Reads all bytes from the byte stream.
All bytes read from this stream will be appended to the specified buffer `buf`.
This function will continuously call [`read`] to append more data to `buf` until
[`read`] returns either `Ok(0)` or an error.
If successful, this function will return the total number of bytes read.
[`read`]: #tymethod.read
# Examples
```no_run
# fn main() -> std::io::Result<()> { async_std::task::block_on(async {
#
use async_std::fs::File;
use async_std::prelude::*;
let mut file = File::open("a.txt").await?;
let mut buf = Vec::new();
file.read_to_end(&mut buf).await?;
#
# Ok(()) }) }
```
"#]
fn read_to_end<'a>(
&'a mut self,
buf: &'a mut Vec<u8>,
) -> ReadToEndFuture<'a, Self>
where
Self: Unpin,
{
let start_len = buf.len();
ReadToEndFuture {
reader: self,
buf,
start_len,
}
}
#[doc = r#"
Extension methods for [`Read`].
Reads all bytes from the byte stream and appends them into a string.
[`Read`]: ../trait.Read.html
If successful, this function will return the number of bytes read.
If the data in this stream is not valid UTF-8 then an error will be returned and
`buf` will be left unmodified.
# Examples
```no_run
# fn main() -> std::io::Result<()> { async_std::task::block_on(async {
#
use async_std::fs::File;
use async_std::prelude::*;
let mut file = File::open("a.txt").await?;
let mut buf = String::new();
file.read_to_string(&mut buf).await?;
#
# Ok(()) }) }
```
"#]
pub trait ReadExt: futures_io::AsyncRead {
#[doc = r#"
Reads some bytes from the byte stream.
Returns the number of bytes read from the start of the buffer.
If the return value is `Ok(n)`, then it must be guaranteed that
`0 <= n <= buf.len()`. A nonzero `n` value indicates that the buffer has been
filled in with `n` bytes of data. If `n` is `0`, then it can indicate one of two
scenarios:
1. This reader has reached its "end of file" and will likely no longer be able to
produce bytes. Note that this does not mean that the reader will always no
longer be able to produce bytes.
2. The buffer specified was 0 bytes in length.
# Examples
```no_run
# fn main() -> std::io::Result<()> { async_std::task::block_on(async {
#
use async_std::fs::File;
use async_std::prelude::*;
let mut file = File::open("a.txt").await?;
let mut buf = vec![0; 1024];
let n = file.read(&mut buf).await?;
#
# Ok(()) }) }
```
"#]
fn read<'a>(
&'a mut self,
buf: &'a mut [u8],
) -> impl Future<Output = io::Result<usize>> + 'a [ReadFuture<'a, Self>]
where
Self: Unpin
{
ReadFuture { reader: self, buf }
}
#[doc = r#"
Like [`read`], except that it reads into a slice of buffers.
Data is copied to fill each buffer in order, with the final buffer written to
possibly being only partially filled. This method must behave as a single call to
[`read`] with the buffers concatenated would.
The default implementation calls [`read`] with either the first nonempty buffer
provided, or an empty one if none exists.
[`read`]: #tymethod.read
"#]
fn read_vectored<'a>(
&'a mut self,
bufs: &'a mut [IoSliceMut<'a>],
) -> impl Future<Output = io::Result<usize>> + 'a [ReadVectoredFuture<'a, Self>]
where
Self: Unpin,
{
ReadVectoredFuture { reader: self, bufs }
}
#[doc = r#"
Reads all bytes from the byte stream.
All bytes read from this stream will be appended to the specified buffer `buf`.
This function will continuously call [`read`] to append more data to `buf` until
[`read`] returns either `Ok(0)` or an error.
If successful, this function will return the total number of bytes read.
[`read`]: #tymethod.read
# Examples
```no_run
# fn main() -> std::io::Result<()> { async_std::task::block_on(async {
#
use async_std::fs::File;
use async_std::prelude::*;
let mut file = File::open("a.txt").await?;
let mut buf = Vec::new();
file.read_to_end(&mut buf).await?;
#
# Ok(()) }) }
```
"#]
fn read_to_end<'a>(
&'a mut self,
buf: &'a mut Vec<u8>,
) -> impl Future<Output = io::Result<usize>> + 'a [ReadToEndFuture<'a, Self>]
where
Self: Unpin,
{
let start_len = buf.len();
ReadToEndFuture {
reader: self,
buf,
start_len,
}
}
#[doc = r#"
Reads all bytes from the byte stream and appends them into a string.
If successful, this function will return the number of bytes read.
If the data in this stream is not valid UTF-8 then an error will be returned and
`buf` will be left unmodified.
# Examples
```no_run
# fn main() -> std::io::Result<()> { async_std::task::block_on(async {
#
use async_std::fs::File;
use async_std::prelude::*;
let mut file = File::open("a.txt").await?;
let mut buf = String::new();
file.read_to_string(&mut buf).await?;
#
# Ok(()) }) }
```
"#]
fn read_to_string<'a>(
&'a mut self,
buf: &'a mut String,
) -> impl Future<Output = io::Result<usize>> + 'a [ReadToStringFuture<'a, Self>]
where
Self: Unpin,
{
let start_len = buf.len();
ReadToStringFuture {
reader: self,
bytes: unsafe { mem::replace(buf.as_mut_vec(), Vec::new()) },
buf,
start_len,
}
}
#[doc = r#"
Reads the exact number of bytes required to fill `buf`.
This function reads as many bytes as necessary to completely fill the specified
buffer `buf`.
No guarantees are provided about the contents of `buf` when this function is
called, implementations cannot rely on any property of the contents of `buf` being
true. It is recommended that implementations only write data to `buf` instead of
reading its contents.
If this function encounters an "end of file" before completely filling the buffer,
it returns an error of the kind [`ErrorKind::UnexpectedEof`]. The contents of
`buf` are unspecified in this case.
If any other read error is encountered then this function immediately returns. The
contents of `buf` are unspecified in this case.
If this function returns an error, it is unspecified how many bytes it has read,
but it will never read more than would be necessary to completely fill the buffer.
[`ErrorKind::UnexpectedEof`]: enum.ErrorKind.html#variant.UnexpectedEof
# Examples
```no_run
# fn main() -> std::io::Result<()> { async_std::task::block_on(async {
#
use async_std::fs::File;
use async_std::prelude::*;
let mut file = File::open("a.txt").await?;
let mut buf = vec![0; 10];
file.read_exact(&mut buf).await?;
#
# Ok(()) }) }
```
"#]
fn read_exact<'a>(
&'a mut self,
buf: &'a mut [u8],
) -> impl Future<Output = io::Result<()>> + 'a [ReadExactFuture<'a, Self>]
where
Self: Unpin,
{
ReadExactFuture { reader: self, buf }
}
#[doc = r#"
Creates an adaptor which will read at most `limit` bytes from it.
This function returns a new instance of `Read` which will read at most
`limit` bytes, after which it will always return EOF ([`Ok(0)`]). Any
read errors will not count towards the number of bytes read and future
calls to [`read`] may succeed.
# Examples
[`File`]s implement `Read`:
[`File`]: ../fs/struct.File.html
[`Ok(0)`]: ../../std/result/enum.Result.html#variant.Ok
[`read`]: tymethod.read
```no_run
# fn main() -> std::io::Result<()> { async_std::task::block_on(async {
#
use async_std::io::prelude::*;
use async_std::fs::File;
let f = File::open("foo.txt").await?;
let mut buffer = [0; 5];
// read at most five bytes
let mut handle = f.take(5);
handle.read(&mut buffer).await?;
#
# Ok(()) }) }
```
"#]
fn take(self, limit: u64) -> Take<Self>
where
Self: Sized,
{
Take { inner: self, limit }
}
#[doc = r#"
Creates a "by reference" adaptor for this instance of `Read`.
The returned adaptor also implements `Read` and will simply borrow this
current reader.
# Examples
[`File`][file]s implement `Read`:
[file]: ../fs/struct.File.html
```no_run
# fn main() -> std::io::Result<()> { async_std::task::block_on(async {
#
use async_std::prelude::*;
use async_std::fs::File;
let mut f = File::open("foo.txt").await?;
let mut buffer = Vec::new();
let mut other_buffer = Vec::new();
{
let reference = f.by_ref();
// read at most 5 bytes
reference.take(5).read_to_end(&mut buffer).await?;
} // drop our &mut reference so we can use f again
// original file still usable, read the rest
f.read_to_end(&mut other_buffer).await?;
#
# Ok(()) }) }
```
"#]
fn by_ref(&mut self) -> &mut Self where Self: Sized { self }
#[doc = r#"
Transforms this `Read` instance to a `Stream` over its bytes.
The returned type implements `Stream` where the `Item` is
`Result<u8, io::Error>`.
The yielded item is `Ok` if a byte was successfully read and `Err`
otherwise. EOF is mapped to returning `None` from this iterator.
# Examples
[`File`][file]s implement `Read`:
[file]: ../fs/struct.File.html
```no_run
# fn main() -> std::io::Result<()> { async_std::task::block_on(async {
#
use async_std::prelude::*;
use async_std::fs::File;
let f = File::open("foo.txt").await?;
let mut s = f.bytes();
while let Some(byte) = s.next().await {
println!("{}", byte.unwrap());
}
#
# Ok(()) }) }
```
"#]
fn bytes(self) -> Bytes<Self> where Self: Sized {
Bytes { inner: self }
}
#[doc = r#"
Creates an adaptor which will chain this stream with another.
The returned `Read` instance will first read all bytes from this object
until EOF is encountered. Afterwards the output is equivalent to the
output of `next`.
# Examples
[`File`][file]s implement `Read`:
[file]: ../fs/struct.File.html
```no_run
# fn main() -> std::io::Result<()> { async_std::task::block_on(async {
#
use async_std::prelude::*;
use async_std::fs::File;
let f1 = File::open("foo.txt").await?;
let f2 = File::open("bar.txt").await?;
let mut handle = f1.chain(f2);
let mut buffer = String::new();
// read the value into a String. We could use any Read method here,
// this is just one example.
handle.read_to_string(&mut buffer).await?;
#
# Ok(()) }) }
```
"#]
fn chain<R: Read>(self, next: R) -> Chain<Self, R> where Self: Sized {
Chain { first: self, second: next, done_first: false }
}
}
impl<T: Read + Unpin + ?Sized> Read for Box<T> {
fn poll_read(
self: Pin<&mut Self>,
cx: &mut Context<'_>,
buf: &mut [u8],
) -> Poll<io::Result<usize>> {
unreachable!("this impl only appears in the rendered docs")
}
}
impl<T: Read + Unpin + ?Sized> Read for &mut T {
fn poll_read(
self: Pin<&mut Self>,
cx: &mut Context<'_>,
buf: &mut [u8],
) -> Poll<io::Result<usize>> {
unreachable!("this impl only appears in the rendered docs")
}
}
impl<P> Read for Pin<P>
fn read_to_string<'a>(
&'a mut self,
buf: &'a mut String,
) -> ReadToStringFuture<'a, Self>
where
P: DerefMut + Unpin,
<P as Deref>::Target: Read,
Self: Unpin,
{
fn poll_read(
self: Pin<&mut Self>,
cx: &mut Context<'_>,
buf: &mut [u8],
) -> Poll<io::Result<usize>> {
unreachable!("this impl only appears in the rendered docs")
let start_len = buf.len();
ReadToStringFuture {
reader: self,
bytes: unsafe { mem::replace(buf.as_mut_vec(), Vec::new()) },
buf,
start_len,
}
}
impl Read for &[u8] {
fn poll_read(
self: Pin<&mut Self>,
cx: &mut Context<'_>,
buf: &mut [u8],
) -> Poll<io::Result<usize>> {
unreachable!("this impl only appears in the rendered docs")
#[doc = r#"
Reads the exact number of bytes required to fill `buf`.
This function reads as many bytes as necessary to completely fill the specified
buffer `buf`.
No guarantees are provided about the contents of `buf` when this function is
called, implementations cannot rely on any property of the contents of `buf` being
true. It is recommended that implementations only write data to `buf` instead of
reading its contents.
If this function encounters an "end of file" before completely filling the buffer,
it returns an error of the kind [`ErrorKind::UnexpectedEof`]. The contents of
`buf` are unspecified in this case.
If any other read error is encountered then this function immediately returns. The
contents of `buf` are unspecified in this case.
If this function returns an error, it is unspecified how many bytes it has read,
but it will never read more than would be necessary to completely fill the buffer.
[`ErrorKind::UnexpectedEof`]: enum.ErrorKind.html#variant.UnexpectedEof
# Examples
```no_run
# fn main() -> std::io::Result<()> { async_std::task::block_on(async {
#
use async_std::fs::File;
use async_std::prelude::*;
let mut file = File::open("a.txt").await?;
let mut buf = vec![0; 10];
file.read_exact(&mut buf).await?;
#
# Ok(()) }) }
```
"#]
fn read_exact<'a>(
&'a mut self,
buf: &'a mut [u8],
) -> ReadExactFuture<'a, Self>
where
Self: Unpin,
{
ReadExactFuture { reader: self, buf }
}
#[doc = r#"
Creates an adaptor which will read at most `limit` bytes from it.
This function returns a new instance of `Read` which will read at most
`limit` bytes, after which it will always return EOF ([`Ok(0)`]). Any
read errors will not count towards the number of bytes read and future
calls to [`read`] may succeed.
# Examples
[`File`]s implement `Read`:
[`File`]: ../fs/struct.File.html
[`Ok(0)`]: ../../std/result/enum.Result.html#variant.Ok
[`read`]: tymethod.read
```no_run
# fn main() -> std::io::Result<()> { async_std::task::block_on(async {
#
use async_std::io::prelude::*;
use async_std::fs::File;
let f = File::open("foo.txt").await?;
let mut buffer = [0; 5];
// read at most five bytes
let mut handle = f.take(5);
handle.read(&mut buffer).await?;
#
# Ok(()) }) }
```
"#]
fn take(self, limit: u64) -> Take<Self>
where
Self: Sized,
{
Take { inner: self, limit }
}
#[doc = r#"
Creates a "by reference" adaptor for this instance of `Read`.
The returned adaptor also implements `Read` and will simply borrow this
current reader.
# Examples
[`File`][file]s implement `Read`:
[file]: ../fs/struct.File.html
```no_run
# fn main() -> std::io::Result<()> { async_std::task::block_on(async {
#
use async_std::prelude::*;
use async_std::fs::File;
let mut f = File::open("foo.txt").await?;
let mut buffer = Vec::new();
let mut other_buffer = Vec::new();
{
let reference = f.by_ref();
// read at most 5 bytes
reference.take(5).read_to_end(&mut buffer).await?;
} // drop our &mut reference so we can use f again
// original file still usable, read the rest
f.read_to_end(&mut other_buffer).await?;
#
# Ok(()) }) }
```
"#]
fn by_ref(&mut self) -> &mut Self where Self: Sized { self }
#[doc = r#"
Transforms this `Read` instance to a `Stream` over its bytes.
The returned type implements `Stream` where the `Item` is
`Result<u8, io::Error>`.
The yielded item is `Ok` if a byte was successfully read and `Err`
otherwise. EOF is mapped to returning `None` from this iterator.
# Examples
[`File`][file]s implement `Read`:
[file]: ../fs/struct.File.html
```no_run
# fn main() -> std::io::Result<()> { async_std::task::block_on(async {
#
use async_std::prelude::*;
use async_std::fs::File;
let f = File::open("foo.txt").await?;
let mut s = f.bytes();
while let Some(byte) = s.next().await {
println!("{}", byte.unwrap());
}
#
# Ok(()) }) }
```
"#]
fn bytes(self) -> Bytes<Self> where Self: Sized {
Bytes { inner: self }
}
#[doc = r#"
Creates an adaptor which will chain this stream with another.
The returned `Read` instance will first read all bytes from this object
until EOF is encountered. Afterwards the output is equivalent to the
output of `next`.
# Examples
[`File`][file]s implement `Read`:
[file]: ../fs/struct.File.html
```no_run
# fn main() -> std::io::Result<()> { async_std::task::block_on(async {
#
use async_std::prelude::*;
use async_std::fs::File;
let f1 = File::open("foo.txt").await?;
let f2 = File::open("bar.txt").await?;
let mut handle = f1.chain(f2);
let mut buffer = String::new();
// read the value into a String. We could use any Read method here,
// this is just one example.
handle.read_to_string(&mut buffer).await?;
#
# Ok(()) }) }
```
"#]
fn chain<R: Read>(self, next: R) -> Chain<Self, R> where Self: Sized {
Chain { first: self, second: next, done_first: false }
}
}
impl<T: Read + ?Sized> ReadExt for T {}
/// Initializes a buffer if necessary.
///
/// Currently, a buffer is always initialized because `read_initializer`

132
src/io/seek/mod.rs
View file

@ -4,117 +4,47 @@ use seek::SeekFuture;
use crate::io::SeekFrom;
extension_trait! {
use std::ops::{Deref, DerefMut};
use std::pin::Pin;
pub use futures_io::AsyncSeek as Seek;
use crate::io;
use crate::task::{Context, Poll};
#[doc = r#"
Extension methods for [`Seek`].
[`Seek`]: ../trait.Seek.html
"#]
pub trait SeekExt: Seek {
#[doc = r#"
Allows seeking through a byte stream.
Seeks to a new position in a byte stream.
This trait is a re-export of [`futures::io::AsyncSeek`] and is an async version of
[`std::io::Seek`].
Returns the new position in the byte stream.
The [provided methods] do not really exist in the trait itself, but they become
available when [`SeekExt`] the [prelude] is imported:
A seek beyond the end of stream is allowed, but behavior is defined by the
implementation.
```
# #[allow(unused_imports)]
# Examples
```no_run
# fn main() -> std::io::Result<()> { async_std::task::block_on(async {
#
use async_std::fs::File;
use async_std::io::SeekFrom;
use async_std::prelude::*;
let mut file = File::open("a.txt").await?;
let file_len = file.seek(SeekFrom::End(0)).await?;
#
# Ok(()) }) }
```
[`std::io::Seek`]: https://doc.rust-lang.org/std/io/trait.Seek.html
[`futures::io::AsyncSeek`]:
https://docs.rs/futures/0.3/futures/io/trait.AsyncSeek.html
[provided methods]: #provided-methods
[`SeekExt`]: ../io/prelude/trait.SeekExt.html
[prelude]: ../prelude/index.html
"#]
pub trait Seek {
#[doc = r#"
Attempt to seek to an offset, in bytes, in a stream.
"#]
fn poll_seek(
self: Pin<&mut Self>,
cx: &mut Context<'_>,
pos: SeekFrom,
) -> Poll<io::Result<u64>>;
}
#[doc = r#"
Extension methods for [`Seek`].
[`Seek`]: ../trait.Seek.html
"#]
pub trait SeekExt: futures_io::AsyncSeek {
#[doc = r#"
Seeks to a new position in a byte stream.
Returns the new position in the byte stream.
A seek beyond the end of stream is allowed, but behavior is defined by the
implementation.
# Examples
```no_run
# fn main() -> std::io::Result<()> { async_std::task::block_on(async {
#
use async_std::fs::File;
use async_std::io::SeekFrom;
use async_std::prelude::*;
let mut file = File::open("a.txt").await?;
let file_len = file.seek(SeekFrom::End(0)).await?;
#
# Ok(()) }) }
```
"#]
fn seek(
&mut self,
pos: SeekFrom,
) -> impl Future<Output = io::Result<u64>> + '_ [SeekFuture<'_, Self>]
where
Self: Unpin,
{
SeekFuture { seeker: self, pos }
}
}
impl<T: Seek + Unpin + ?Sized> Seek for Box<T> {
fn poll_seek(
self: Pin<&mut Self>,
cx: &mut Context<'_>,
pos: SeekFrom,
) -> Poll<io::Result<u64>> {
unreachable!("this impl only appears in the rendered docs")
}
}
impl<T: Seek + Unpin + ?Sized> Seek for &mut T {
fn poll_seek(
self: Pin<&mut Self>,
cx: &mut Context<'_>,
pos: SeekFrom,
) -> Poll<io::Result<u64>> {
unreachable!("this impl only appears in the rendered docs")
}
}
impl<P> Seek for Pin<P>
fn seek(
&mut self,
pos: SeekFrom,
) -> SeekFuture<'_, Self>
where
P: DerefMut + Unpin,
<P as Deref>::Target: Seek,
Self: Unpin,
{
fn poll_seek(
self: Pin<&mut Self>,
cx: &mut Context<'_>,
pos: SeekFrom,
) -> Poll<io::Result<u64>> {
unreachable!("this impl only appears in the rendered docs")
}
SeekFuture { seeker: self, pos }
}
}
impl<T: Seek + ?Sized> SeekExt for T {}

439
src/io/write/mod.rs
View file

@ -12,313 +12,176 @@ use write_vectored::WriteVectoredFuture;
use crate::io::{self, IoSlice};
extension_trait! {
use std::pin::Pin;
use std::ops::{Deref, DerefMut};
pub use futures_io::AsyncWrite as Write;
use crate::task::{Context, Poll};
#[doc = r#"
Extension methods for [`Write`].
[`Write`]: ../trait.Write.html
"#]
pub trait WriteExt: Write {
#[doc = r#"
Allows writing to a byte stream.
Writes some bytes into the byte stream.
This trait is a re-export of [`futures::io::AsyncWrite`] and is an async version of
[`std::io::Write`].
Returns the number of bytes written from the start of the buffer.
Methods other than [`poll_write`], [`poll_write_vectored`], [`poll_flush`], and
[`poll_close`] do not really exist in the trait itself, but they become available when
[`WriteExt`] from the [prelude] is imported:
If the return value is `Ok(n)` then it must be guaranteed that
`0 <= n <= buf.len()`. A return value of `0` typically means that the underlying
object is no longer able to accept bytes and will likely not be able to in the
future as well, or that the buffer provided is empty.
```
# #[allow(unused_imports)]
# Examples
```no_run
# fn main() -> std::io::Result<()> { async_std::task::block_on(async {
#
use async_std::fs::File;
use async_std::prelude::*;
let mut file = File::create("a.txt").await?;
let n = file.write(b"hello world").await?;
#
# Ok(()) }) }
```
[`std::io::Write`]: https://doc.rust-lang.org/std/io/trait.Write.html
[`futures::io::AsyncWrite`]:
https://docs.rs/futures/0.3/futures/io/trait.AsyncWrite.html
[`poll_write`]: #tymethod.poll_write
[`poll_write_vectored`]: #method.poll_write_vectored
[`poll_flush`]: #tymethod.poll_flush
[`poll_close`]: #tymethod.poll_close
[`WriteExt`]: ../io/prelude/trait.WriteExt.html
[prelude]: ../prelude/index.html
"#]
pub trait Write {
#[doc = r#"
Attempt to write bytes from `buf` into the object.
"#]
fn poll_write(
self: Pin<&mut Self>,
cx: &mut Context<'_>,
buf: &[u8],
) -> Poll<io::Result<usize>>;
#[doc = r#"
Attempt to write bytes from `bufs` into the object using vectored IO operations.
"#]
fn poll_write_vectored(
self: Pin<&mut Self>,
cx: &mut Context<'_>,
bufs: &[IoSlice<'_>]
) -> Poll<io::Result<usize>> {
unreachable!("this impl only appears in the rendered docs")
}
#[doc = r#"
Attempt to flush the object, ensuring that any buffered data reach
their destination.
"#]
fn poll_flush(self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<io::Result<()>>;
#[doc = r#"
Attempt to close the object.
"#]
fn poll_close(self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<io::Result<()>>;
fn write<'a>(
&'a mut self,
buf: &'a [u8],
) -> WriteFuture<'a, Self>
where
Self: Unpin,
{
WriteFuture { writer: self, buf }
}
#[doc = r#"
Extension methods for [`Write`].
Flushes the stream to ensure that all buffered contents reach their destination.
[`Write`]: ../trait.Write.html
# Examples
```no_run
# fn main() -> std::io::Result<()> { async_std::task::block_on(async {
#
use async_std::fs::File;
use async_std::prelude::*;
let mut file = File::create("a.txt").await?;
file.write_all(b"hello world").await?;
file.flush().await?;
#
# Ok(()) }) }
```
"#]
pub trait WriteExt: futures_io::AsyncWrite {
#[doc = r#"
Writes some bytes into the byte stream.
Returns the number of bytes written from the start of the buffer.
If the return value is `Ok(n)` then it must be guaranteed that
`0 <= n <= buf.len()`. A return value of `0` typically means that the underlying
object is no longer able to accept bytes and will likely not be able to in the
future as well, or that the buffer provided is empty.
# Examples
```no_run
# fn main() -> std::io::Result<()> { async_std::task::block_on(async {
#
use async_std::fs::File;
use async_std::prelude::*;
let mut file = File::create("a.txt").await?;
let n = file.write(b"hello world").await?;
#
# Ok(()) }) }
```
"#]
fn write<'a>(
&'a mut self,
buf: &'a [u8],
) -> impl Future<Output = io::Result<usize>> + 'a [WriteFuture<'a, Self>]
where
Self: Unpin,
{
WriteFuture { writer: self, buf }
}
#[doc = r#"
Flushes the stream to ensure that all buffered contents reach their destination.
# Examples
```no_run
# fn main() -> std::io::Result<()> { async_std::task::block_on(async {
#
use async_std::fs::File;
use async_std::prelude::*;
let mut file = File::create("a.txt").await?;
file.write_all(b"hello world").await?;
file.flush().await?;
#
# Ok(()) }) }
```
"#]
fn flush(&mut self) -> impl Future<Output = io::Result<()>> + '_ [FlushFuture<'_, Self>]
where
Self: Unpin,
{
FlushFuture { writer: self }
}
#[doc = r#"
Like [`write`], except that it writes from a slice of buffers.
Data is copied from each buffer in order, with the final buffer read from possibly
being only partially consumed. This method must behave as a call to [`write`] with
the buffers concatenated would.
The default implementation calls [`write`] with either the first nonempty buffer
provided, or an empty one if none exists.
[`write`]: #tymethod.write
"#]
fn write_vectored<'a>(
&'a mut self,
bufs: &'a [IoSlice<'a>],
) -> impl Future<Output = io::Result<usize>> + 'a [WriteVectoredFuture<'a, Self>]
where
Self: Unpin,
{
WriteVectoredFuture { writer: self, bufs }
}
#[doc = r#"
Writes an entire buffer into the byte stream.
This method will continuously call [`write`] until there is no more data to be
written or an error is returned. This method will not return until the entire
buffer has been successfully written or such an error occurs.
[`write`]: #tymethod.write
# Examples
```no_run
# fn main() -> std::io::Result<()> { async_std::task::block_on(async {
#
use async_std::fs::File;
use async_std::prelude::*;
let mut file = File::create("a.txt").await?;
file.write_all(b"hello world").await?;
#
# Ok(()) }) }
```
[`write`]: #tymethod.write
"#]
fn write_all<'a>(
&'a mut self,
buf: &'a [u8],
) -> impl Future<Output = io::Result<()>> + 'a [WriteAllFuture<'a, Self>]
where
Self: Unpin,
{
WriteAllFuture { writer: self, buf }
}
#[doc = r#"
Writes a formatted string into this writer, returning any error encountered.
This method will continuously call [`write`] until there is no more data to be
written or an error is returned. This future will not resolve until the entire
buffer has been successfully written or such an error occurs.
[`write`]: #tymethod.write
# Examples
```no_run
# fn main() -> std::io::Result<()> { async_std::task::block_on(async {
#
use async_std::io::prelude::*;
use async_std::fs::File;
let mut buffer = File::create("foo.txt").await?;
// this call
write!(buffer, "{:.*}", 2, 1.234567).await?;
// turns into this:
buffer.write_fmt(format_args!("{:.*}", 2, 1.234567)).await?;
#
# Ok(()) }) }
```
"#]
fn write_fmt<'a>(
&'a mut self,
fmt: std::fmt::Arguments<'_>,
) -> impl Future<Output = io::Result<()>> + 'a [WriteFmtFuture<'a, Self>]
where
Self: Unpin,
{
// In order to not have to implement an async version of `fmt` including private types
// and all, we convert `Arguments` to a `Result<Vec<u8>>` and pass that to the Future.
// Doing an owned conversion saves us from juggling references.
let mut string = String::new();
let res = std::fmt::write(&mut string, fmt)
.map(|_| string.into_bytes())
.map_err(|_| io::Error::new(io::ErrorKind::Other, "formatter error"));
WriteFmtFuture { writer: self, res: Some(res), buffer: None, amt: 0 }
}
}
impl<T: Write + Unpin + ?Sized> Write for Box<T> {
fn poll_write(
self: Pin<&mut Self>,
cx: &mut Context<'_>,
buf: &[u8],
) -> Poll<io::Result<usize>> {
unreachable!("this impl only appears in the rendered docs")
}
fn poll_flush(self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<io::Result<()>> {
unreachable!("this impl only appears in the rendered docs")
}
fn poll_close(self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<io::Result<()>> {
unreachable!("this impl only appears in the rendered docs")
}
}
impl<T: Write + Unpin + ?Sized> Write for &mut T {
fn poll_write(
self: Pin<&mut Self>,
cx: &mut Context<'_>,
buf: &[u8],
) -> Poll<io::Result<usize>> {
unreachable!("this impl only appears in the rendered docs")
}
fn poll_flush(self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<io::Result<()>> {
unreachable!("this impl only appears in the rendered docs")
}
fn poll_close(self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<io::Result<()>> {
unreachable!("this impl only appears in the rendered docs")
}
}
impl<P> Write for Pin<P>
fn flush(&mut self) -> FlushFuture<'_, Self>
where
P: DerefMut + Unpin,
<P as Deref>::Target: Write,
Self: Unpin,
{
fn poll_write(
self: Pin<&mut Self>,
cx: &mut Context<'_>,
buf: &[u8],
) -> Poll<io::Result<usize>> {
unreachable!("this impl only appears in the rendered docs")
}
fn poll_flush(self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<io::Result<()>> {
unreachable!("this impl only appears in the rendered docs")
}
fn poll_close(self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<io::Result<()>> {
unreachable!("this impl only appears in the rendered docs")
}
FlushFuture { writer: self }
}
impl Write for Vec<u8> {
fn poll_write(
self: Pin<&mut Self>,
cx: &mut Context<'_>,
buf: &[u8],
) -> Poll<io::Result<usize>> {
unreachable!("this impl only appears in the rendered docs")
}
#[doc = r#"
Like [`write`], except that it writes from a slice of buffers.
fn poll_flush(self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<io::Result<()>> {
unreachable!("this impl only appears in the rendered docs")
}
Data is copied from each buffer in order, with the final buffer read from possibly
being only partially consumed. This method must behave as a call to [`write`] with
the buffers concatenated would.
fn poll_close(self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<io::Result<()>> {
unreachable!("this impl only appears in the rendered docs")
}
The default implementation calls [`write`] with either the first nonempty buffer
provided, or an empty one if none exists.
[`write`]: #tymethod.write
"#]
fn write_vectored<'a>(
&'a mut self,
bufs: &'a [IoSlice<'a>],
) -> WriteVectoredFuture<'a, Self>
where
Self: Unpin,
{
WriteVectoredFuture { writer: self, bufs }
}
#[doc = r#"
Writes an entire buffer into the byte stream.
This method will continuously call [`write`] until there is no more data to be
written or an error is returned. This method will not return until the entire
buffer has been successfully written or such an error occurs.
[`write`]: #tymethod.write
# Examples
```no_run
# fn main() -> std::io::Result<()> { async_std::task::block_on(async {
#
use async_std::fs::File;
use async_std::prelude::*;
let mut file = File::create("a.txt").await?;
file.write_all(b"hello world").await?;
#
# Ok(()) }) }
```
[`write`]: #tymethod.write
"#]
fn write_all<'a>(
&'a mut self,
buf: &'a [u8],
) -> WriteAllFuture<'a, Self>
where
Self: Unpin,
{
WriteAllFuture { writer: self, buf }
}
#[doc = r#"
Writes a formatted string into this writer, returning any error encountered.
This method will continuously call [`write`] until there is no more data to be
written or an error is returned. This future will not resolve until the entire
buffer has been successfully written or such an error occurs.
[`write`]: #tymethod.write
# Examples
```no_run
# fn main() -> std::io::Result<()> { async_std::task::block_on(async {
#
use async_std::io::prelude::*;
use async_std::fs::File;
let mut buffer = File::create("foo.txt").await?;
// this call
write!(buffer, "{:.*}", 2, 1.234567).await?;
// turns into this:
buffer.write_fmt(format_args!("{:.*}", 2, 1.234567)).await?;
#
# Ok(()) }) }
```
"#]
fn write_fmt<'a>(
&'a mut self,
fmt: std::fmt::Arguments<'_>,
) -> WriteFmtFuture<'a, Self>
where
Self: Unpin,
{
// In order to not have to implement an async version of `fmt` including private types
// and all, we convert `Arguments` to a `Result<Vec<u8>>` and pass that to the Future.
// Doing an owned conversion saves us from juggling references.
let mut string = String::new();
let res = std::fmt::write(&mut string, fmt)
.map(|_| string.into_bytes())
.map_err(|_| io::Error::new(io::ErrorKind::Other, "formatter error"));
WriteFmtFuture { writer: self, res: Some(res), buffer: None, amt: 0 }
}
}
impl<T: Write + ?Sized> WriteExt for T {}

1
src/lib.rs
View file

@ -282,7 +282,6 @@
#![doc(test(attr(deny(rust_2018_idioms, warnings))))]
#![doc(test(attr(allow(unused_extern_crates, unused_variables))))]
#![doc(html_logo_url = "https://async.rs/images/logo--hero.svg")]
#![recursion_limit = "2048"]
extern crate alloc;

4312
src/stream/stream/mod.rs
View file

File diff suppressed because it is too large Load diff

96
src/utils.rs
View file

@ -233,99 +233,3 @@ macro_rules! cfg_default {
)*
}
}
/// Defines an extension trait for a base trait.
///
/// In generated docs, the base trait will contain methods from the extension trait. In actual
/// code, the base trait will be re-exported and the extension trait will be hidden. We then
/// re-export the extension trait from the prelude.
///
/// Inside invocations of this macro, we write a definitions that looks similar to the final
/// rendered docs, and the macro then generates all the boilerplate for us.
#[allow(unused_macros)]
#[doc(hidden)]
macro_rules! extension_trait {
(
// Interesting patterns:
// - `$name`: trait name that gets rendered in the docs
// - `$ext`: name of the hidden extension trait
// - `$base`: base trait
#[doc = $doc:tt]
pub trait $name:ident {
$($body_base:tt)*
}
#[doc = $doc_ext:tt]
pub trait $ext:ident: $base:path {
$($body_ext:tt)*
}
// Shim trait impls that only appear in docs.
$($imp:item)*
) => {
// A fake `impl Future` type that doesn't borrow.
#[allow(dead_code)]
mod owned {
#[doc(hidden)]
pub struct ImplFuture<T>(core::marker::PhantomData<T>);
}
// A fake `impl Future` type that borrows its environment.
#[allow(dead_code)]
mod borrowed {
#[doc(hidden)]
pub struct ImplFuture<'a, T>(core::marker::PhantomData<&'a T>);
}
// Render a fake trait combining the bodies of the base trait and the extension trait.
#[cfg(feature = "docs")]
#[doc = $doc]
pub trait $name {
extension_trait!(@doc [$($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.
#[doc = $doc_ext]
pub trait $ext: $name {
extension_trait!(@ext [$($body_ext)*] -> []);
}
// Blanket implementation of the extension trait for any type implementing the base trait.
impl<T: $name + ?Sized> $ext for T {}
// Shim trait impls that only appear in docs.
$(#[cfg(feature = "docs")] $imp)*
};
// Parse the return type in an extension method.
(@doc [-> impl Future<Output = $out:ty> $(+ $lt:lifetime)? [$f:ty] $($tail:tt)*] -> [$($accum:tt)*]) => {
extension_trait!(@doc [$($tail)*] -> [$($accum)* -> owned::ImplFuture<$out>]);
};
(@ext [-> impl Future<Output = $out:ty> $(+ $lt:lifetime)? [$f:ty] $($tail:tt)*] -> [$($accum:tt)*]) => {
extension_trait!(@ext [$($tail)*] -> [$($accum)* -> $f]);
};
// Parse a token.
(@doc [$token:tt $($tail:tt)*] -> [$($accum:tt)*]) => {
extension_trait!(@doc [$($tail)*] -> [$($accum)* $token]);
};
(@ext [$token:tt $($tail:tt)*] -> [$($accum:tt)*]) => {
extension_trait!(@ext [$($tail)*] -> [$($accum)* $token]);
};
// Handle the end of the token list.
(@doc [] -> [$($accum:tt)*]) => { $($accum)* };
(@ext [] -> [$($accum:tt)*]) => { $($accum)* };
// Parse imports at the beginning of the macro.
($import:item $($tail:tt)*) => {
#[cfg(feature = "docs")]
$import
extension_trait!($($tail)*);
};
}