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mod flush;
mod write;
mod write_all;
mod write_vectored;
use flush::FlushFuture;
use write::WriteFuture;
use write_all::WriteAllFuture;
use write_vectored::WriteVectoredFuture;
use cfg_if::cfg_if;
use crate::io::IoSlice;
cfg_if! {
if #[cfg(feature = "docs")] {
use std::pin::Pin;
use std::ops::{Deref, DerefMut};
use crate::io;
use crate::task::{Context, Poll};
#[doc(hidden)]
pub struct ImplFuture<'a, T>(std::marker::PhantomData<&'a T>);
/// Allows writing to a byte stream.
///
/// This trait is a re-export of [`futures::io::AsyncWrite`] and is an async version of
/// [`std::io::Write`].
///
/// 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
/// the prelude is imported:
///
/// ```
/// # #[allow(unused_imports)]
/// use async_std::prelude::*;
/// ```
///
/// [`std::io::Write`]: https://doc.rust-lang.org/std/io/trait.Write.html
/// [`futures::io::AsyncWrite`]:
/// https://docs.rs/futures-preview/0.3.0-alpha.17/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
pub trait Write {
/// 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>>;
/// 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!()
}
/// 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<()>>;
/// Attempt to close the object.
fn poll_close(self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<io::Result<()>>;
/// 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]) -> ImplFuture<'a, io::Result<usize>>
where
Self: Unpin,
{
unreachable!()
}
/// 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) -> ImplFuture<'_, io::Result<()>>
where
Self: Unpin,
{
unreachable!()
}
/// 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>],
) -> ImplFuture<'a, io::Result<usize>>
where
Self: Unpin,
{
unreachable!()
}
/// 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]) -> ImplFuture<'a, io::Result<()>>
where
Self: Unpin,
{
unreachable!()
}
}
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!()
}
fn poll_flush(self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<io::Result<()>> {
unreachable!()
}
fn poll_close(self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<io::Result<()>> {
unreachable!()
}
}
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!()
}
fn poll_flush(self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<io::Result<()>> {
unreachable!()
}
fn poll_close(self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<io::Result<()>> {
unreachable!()
}
}
impl<P> Write for Pin<P>
where
P: DerefMut + Unpin,
<P as Deref>::Target: Write,
{
fn poll_write(
self: Pin<&mut Self>,
cx: &mut Context<'_>,
buf: &[u8],
) -> Poll<io::Result<usize>> {
unreachable!()
}
fn poll_flush(self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<io::Result<()>> {
unreachable!()
}
fn poll_close(self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<io::Result<()>> {
unreachable!()
}
}
impl Write for Vec<u8> {
fn poll_write(
self: Pin<&mut Self>,
cx: &mut Context<'_>,
buf: &[u8],
) -> Poll<io::Result<usize>> {
unreachable!()
}
fn poll_flush(self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<io::Result<()>> {
unreachable!()
}
fn poll_close(self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<io::Result<()>> {
unreachable!()
}
}
} else {
pub use futures_io::AsyncWrite as Write;
}
}
#[doc(hidden)]
pub trait WriteExt: Write {
fn write<'a>(&'a mut self, buf: &'a [u8]) -> WriteFuture<'a, Self>
where
Self: Unpin,
{
WriteFuture { writer: self, buf }
}
fn flush(&mut self) -> FlushFuture<'_, Self>
where
Self: Unpin,
{
FlushFuture { writer: self }
}
fn write_vectored<'a>(&'a mut self, bufs: &'a [IoSlice<'a>]) -> WriteVectoredFuture<'a, Self>
where
Self: Unpin,
{
WriteVectoredFuture { writer: self, bufs }
}
fn write_all<'a>(&'a mut self, buf: &'a [u8]) -> WriteAllFuture<'a, Self>
where
Self: Unpin,
{
WriteAllFuture { writer: self, buf }
}
}
impl<T: Write + ?Sized> WriteExt for T {}