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Use our own io::Cursor #1943
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Use our own io::Cursor #1943
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,238 @@ | ||
| use futures_core::task::{Context, Poll}; | ||
| #[cfg(feature = "read_initializer")] | ||
| use futures_io::Initializer; | ||
| use futures_io::{AsyncBufRead, AsyncRead, AsyncSeek, AsyncWrite, IoSlice, IoSliceMut, SeekFrom}; | ||
| use std::io; | ||
| use std::pin::Pin; | ||
|
|
||
| /// A `Cursor` wraps an in-memory buffer and provides it with a | ||
| /// [`AsyncSeek`] implementation. | ||
| /// | ||
| /// `Cursor`s are used with in-memory buffers, anything implementing | ||
| /// `AsRef<[u8]>`, to allow them to implement [`AsyncRead`] and/or [`AsyncWrite`], | ||
| /// 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]`>`. | ||
| /// | ||
| /// [`AsyncSeek`]: trait.AsyncSeek.html | ||
| /// [`AsyncRead`]: trait.AsyncRead.html | ||
| /// [`AsyncWrite`]: trait.AsyncWrite.html | ||
| /// [bytes]: https://doc.rust-lang.org/std/primitive.slice.html | ||
| #[derive(Clone, Debug, Default)] | ||
| pub struct Cursor<T> { | ||
| inner: 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 futures::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: io::Cursor::new(inner), | ||
| } | ||
| } | ||
|
|
||
| /// Consumes this cursor, returning the underlying value. | ||
| /// | ||
| /// # Examples | ||
| /// | ||
| /// ``` | ||
| /// use futures::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 futures::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 futures::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 | ||
| /// | ||
| /// ``` | ||
| /// # futures::executor::block_on(async { | ||
| /// use futures::io::{AsyncSeekExt, Cursor, 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::<(), Box<dyn std::error::Error>>(()) }).unwrap(); | ||
| /// ``` | ||
| pub fn position(&self) -> u64 { | ||
| self.inner.position() | ||
| } | ||
|
|
||
| /// Sets the position of this cursor. | ||
| /// | ||
| /// # Examples | ||
| /// | ||
| /// ``` | ||
| /// use futures::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: AsRef<[u8]> + Unpin> AsyncRead for Cursor<T> { | ||
| #[cfg(feature = "read_initializer")] | ||
| #[inline] | ||
| unsafe fn initializer(&self) -> Initializer { | ||
| io::Read::initializer(&self.inner) | ||
| } | ||
|
|
||
| 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) | ||
| } | ||
| } | ||
|
|
||
| macro_rules! delegate_async_write_to_stdio { | ||
| () => { | ||
| 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 [u8]> { | ||
| delegate_async_write_to_stdio!(); | ||
| } | ||
|
|
||
| impl AsyncWrite for Cursor<&mut Vec<u8>> { | ||
| delegate_async_write_to_stdio!(); | ||
| } | ||
|
|
||
| impl AsyncWrite for Cursor<Vec<u8>> { | ||
| delegate_async_write_to_stdio!(); | ||
| } | ||
|
|
||
| impl AsyncWrite for Cursor<Box<[u8]>> { | ||
| delegate_async_write_to_stdio!(); | ||
| } | ||
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As there is not enough time, it is implemented as a newtype, but it can be optimized later.