Merge #167
167: add io::cursor r=stjepang a=yoshuawuyts Adds `io::Cursor` and makes it so `io::prelude::*` behaves the way it does in std (so it can actually be implemented - though this might just have been a bug on my side??). Ref #131. Thanks! Co-authored-by: Yoshua Wuyts <yoshuawuyts@gmail.com>pull/213/head
bors[bot]
5 years ago
committed by
GitHub
commit
ff20534384
@ -0,0 +1,263 @@
|
||||
use futures_io::{AsyncBufRead, AsyncRead, AsyncSeek, AsyncWrite};
|
||||
|
||||
use std::io::{self, IoSlice, IoSliceMut, SeekFrom};
|
||||
use std::pin::Pin;
|
||||
use std::task::{Context, Poll};
|
||||
|
||||
/// A `Cursor` wraps an in-memory buffer and provides it with a
|
||||
/// [`Seek`] implementation.
|
||||
///
|
||||
/// `Cursor`s are used with in-memory buffers, anything implementing
|
||||
/// `AsRef<[u8]>`, to allow them to implement [`Read`] and/or [`Write`],
|
||||
/// allowing these buffers to be used anywhere you might use a reader or writer
|
||||
/// that does actual I/O.
|
||||
///
|
||||
/// The standard library implements some I/O traits on various types which
|
||||
/// are commonly used as a buffer, like `Cursor<`[`Vec`]`<u8>>` and
|
||||
/// `Cursor<`[`&[u8]`][bytes]`>`.
|
||||
///
|
||||
/// [`Seek`]: trait.Seek.html
|
||||
/// [`Read`]: trait.Read.html
|
||||
/// [`Write`]: trait.Write.html
|
||||
/// [`Vec`]: https://doc.rust-lang.org/std/vec/struct.Vec.html
|
||||
/// [bytes]: https://doc.rust-lang.org/std/primitive.slice.html
|
||||
/// [`File`]: struct.File.html
|
||||
#[cfg_attr(feature = "docs", doc(cfg(unstable)))]
|
||||
#[derive(Clone, Debug, Default)]
|
||||
pub struct Cursor<T> {
|
||||
inner: std::io::Cursor<T>,
|
||||
}
|
||||
|
||||
impl<T> Cursor<T> {
|
||||
/// Creates a new cursor wrapping the provided underlying in-memory buffer.
|
||||
///
|
||||
/// Cursor initial position is `0` even if underlying buffer (e.g., `Vec`)
|
||||
/// is not empty. So writing to cursor starts with overwriting `Vec`
|
||||
/// content, not with appending to it.
|
||||
///
|
||||
/// # Examples
|
||||
///
|
||||
/// ```
|
||||
/// use async_std::io::Cursor;
|
||||
///
|
||||
/// let buff = Cursor::new(Vec::new());
|
||||
/// # fn force_inference(_: &Cursor<Vec<u8>>) {}
|
||||
/// # force_inference(&buff);
|
||||
/// ```
|
||||
pub fn new(inner: T) -> Cursor<T> {
|
||||
Cursor {
|
||||
inner: std::io::Cursor::new(inner),
|
||||
}
|
||||
}
|
||||
|
||||
/// Consumes this cursor, returning the underlying value.
|
||||
///
|
||||
/// # Examples
|
||||
///
|
||||
/// ```
|
||||
/// use async_std::io::Cursor;
|
||||
///
|
||||
/// let buff = Cursor::new(Vec::new());
|
||||
/// # fn force_inference(_: &Cursor<Vec<u8>>) {}
|
||||
/// # force_inference(&buff);
|
||||
///
|
||||
/// let vec = buff.into_inner();
|
||||
/// ```
|
||||
pub fn into_inner(self) -> T {
|
||||
self.inner.into_inner()
|
||||
}
|
||||
|
||||
/// Gets a reference to the underlying value in this cursor.
|
||||
///
|
||||
/// # Examples
|
||||
///
|
||||
/// ```
|
||||
/// use async_std::io::Cursor;
|
||||
///
|
||||
/// let buff = Cursor::new(Vec::new());
|
||||
/// # fn force_inference(_: &Cursor<Vec<u8>>) {}
|
||||
/// # force_inference(&buff);
|
||||
///
|
||||
/// let reference = buff.get_ref();
|
||||
/// ```
|
||||
pub fn get_ref(&self) -> &T {
|
||||
self.inner.get_ref()
|
||||
}
|
||||
|
||||
/// Gets a mutable reference to the underlying value in this cursor.
|
||||
///
|
||||
/// Care should be taken to avoid modifying the internal I/O state of the
|
||||
/// underlying value as it may corrupt this cursor's position.
|
||||
///
|
||||
/// # Examples
|
||||
///
|
||||
/// ```
|
||||
/// use async_std::io::Cursor;
|
||||
///
|
||||
/// let mut buff = Cursor::new(Vec::new());
|
||||
/// # fn force_inference(_: &Cursor<Vec<u8>>) {}
|
||||
/// # force_inference(&buff);
|
||||
///
|
||||
/// let reference = buff.get_mut();
|
||||
/// ```
|
||||
pub fn get_mut(&mut self) -> &mut T {
|
||||
self.inner.get_mut()
|
||||
}
|
||||
|
||||
/// Returns the current position of this cursor.
|
||||
///
|
||||
/// # Examples
|
||||
///
|
||||
/// ```
|
||||
/// # fn main() -> std::io::Result<()> { async_std::task::block_on(async {
|
||||
/// #
|
||||
/// use async_std::io::Cursor;
|
||||
/// use async_std::io::prelude::*;
|
||||
/// use async_std::io::SeekFrom;
|
||||
///
|
||||
/// let mut buff = Cursor::new(vec![1, 2, 3, 4, 5]);
|
||||
///
|
||||
/// assert_eq!(buff.position(), 0);
|
||||
///
|
||||
/// buff.seek(SeekFrom::Current(2)).await?;
|
||||
/// assert_eq!(buff.position(), 2);
|
||||
///
|
||||
/// buff.seek(SeekFrom::Current(-1)).await?;
|
||||
/// assert_eq!(buff.position(), 1);
|
||||
/// #
|
||||
/// # Ok(()) }) }
|
||||
/// ```
|
||||
pub fn position(&self) -> u64 {
|
||||
self.inner.position()
|
||||
}
|
||||
|
||||
/// Sets the position of this cursor.
|
||||
///
|
||||
/// # Examples
|
||||
///
|
||||
/// ```
|
||||
/// use async_std::io::Cursor;
|
||||
///
|
||||
/// let mut buff = Cursor::new(vec![1, 2, 3, 4, 5]);
|
||||
///
|
||||
/// assert_eq!(buff.position(), 0);
|
||||
///
|
||||
/// buff.set_position(2);
|
||||
/// assert_eq!(buff.position(), 2);
|
||||
///
|
||||
/// buff.set_position(4);
|
||||
/// assert_eq!(buff.position(), 4);
|
||||
/// ```
|
||||
pub fn set_position(&mut self, pos: u64) {
|
||||
self.inner.set_position(pos)
|
||||
}
|
||||
}
|
||||
|
||||
impl<T> AsyncSeek for Cursor<T>
|
||||
where
|
||||
T: AsRef<[u8]> + Unpin,
|
||||
{
|
||||
fn poll_seek(
|
||||
mut self: Pin<&mut Self>,
|
||||
_: &mut Context<'_>,
|
||||
pos: SeekFrom,
|
||||
) -> Poll<io::Result<u64>> {
|
||||
Poll::Ready(io::Seek::seek(&mut self.inner, pos))
|
||||
}
|
||||
}
|
||||
|
||||
impl<T> AsyncRead for Cursor<T>
|
||||
where
|
||||
T: AsRef<[u8]> + Unpin,
|
||||
{
|
||||
fn poll_read(
|
||||
mut self: Pin<&mut Self>,
|
||||
_cx: &mut Context<'_>,
|
||||
buf: &mut [u8],
|
||||
) -> Poll<io::Result<usize>> {
|
||||
Poll::Ready(io::Read::read(&mut self.inner, buf))
|
||||
}
|
||||
|
||||
fn poll_read_vectored(
|
||||
mut self: Pin<&mut Self>,
|
||||
_: &mut Context<'_>,
|
||||
bufs: &mut [IoSliceMut<'_>],
|
||||
) -> Poll<io::Result<usize>> {
|
||||
Poll::Ready(io::Read::read_vectored(&mut self.inner, bufs))
|
||||
}
|
||||
}
|
||||
|
||||
impl<T> AsyncBufRead for Cursor<T>
|
||||
where
|
||||
T: AsRef<[u8]> + Unpin,
|
||||
{
|
||||
fn poll_fill_buf(self: Pin<&mut Self>, _: &mut Context<'_>) -> Poll<io::Result<&[u8]>> {
|
||||
Poll::Ready(io::BufRead::fill_buf(&mut self.get_mut().inner))
|
||||
}
|
||||
|
||||
fn consume(mut self: Pin<&mut Self>, amt: usize) {
|
||||
io::BufRead::consume(&mut self.inner, amt)
|
||||
}
|
||||
}
|
||||
|
||||
impl AsyncWrite for Cursor<&mut [u8]> {
|
||||
fn poll_write(
|
||||
mut self: Pin<&mut Self>,
|
||||
_: &mut Context<'_>,
|
||||
buf: &[u8],
|
||||
) -> Poll<io::Result<usize>> {
|
||||
Poll::Ready(io::Write::write(&mut self.inner, buf))
|
||||
}
|
||||
|
||||
fn poll_write_vectored(
|
||||
mut self: Pin<&mut Self>,
|
||||
_: &mut Context<'_>,
|
||||
bufs: &[IoSlice<'_>],
|
||||
) -> Poll<io::Result<usize>> {
|
||||
Poll::Ready(io::Write::write_vectored(&mut self.inner, bufs))
|
||||
}
|
||||
|
||||
fn poll_flush(mut self: Pin<&mut Self>, _: &mut Context<'_>) -> Poll<io::Result<()>> {
|
||||
Poll::Ready(io::Write::flush(&mut self.inner))
|
||||
}
|
||||
|
||||
fn poll_close(self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<io::Result<()>> {
|
||||
self.poll_flush(cx)
|
||||
}
|
||||
}
|
||||
|
||||
impl AsyncWrite for Cursor<&mut Vec<u8>> {
|
||||
fn poll_write(
|
||||
mut self: Pin<&mut Self>,
|
||||
_: &mut Context<'_>,
|
||||
buf: &[u8],
|
||||
) -> Poll<io::Result<usize>> {
|
||||
Poll::Ready(io::Write::write(&mut self.inner, buf))
|
||||
}
|
||||
|
||||
fn poll_close(self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<io::Result<()>> {
|
||||
self.poll_flush(cx)
|
||||
}
|
||||
|
||||
fn poll_flush(mut self: Pin<&mut Self>, _: &mut Context<'_>) -> Poll<io::Result<()>> {
|
||||
Poll::Ready(io::Write::flush(&mut self.inner))
|
||||
}
|
||||
}
|
||||
|
||||
impl AsyncWrite for Cursor<Vec<u8>> {
|
||||
fn poll_write(
|
||||
mut self: Pin<&mut Self>,
|
||||
_: &mut Context<'_>,
|
||||
buf: &[u8],
|
||||
) -> Poll<io::Result<usize>> {
|
||||
Poll::Ready(io::Write::write(&mut self.inner, buf))
|
||||
}
|
||||
|
||||
fn poll_close(self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<io::Result<()>> {
|
||||
self.poll_flush(cx)
|
||||
}
|
||||
|
||||
fn poll_flush(mut self: Pin<&mut Self>, _: &mut Context<'_>) -> Poll<io::Result<()>> {
|
||||
Poll::Ready(io::Write::flush(&mut self.inner))
|
||||
}
|
||||
}
|
||||
Loading…
Reference in New Issue