pub struct Cursor<T> { /* private fields */ }
Expand description
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]
>
.
Implementations
sourceimpl<T> Cursor<T>
impl<T> Cursor<T>
sourcepub fn new(inner: T) -> Cursor<T>
pub fn new(inner: 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());
sourcepub fn into_inner(self) -> T
pub fn into_inner(self) -> T
Consumes this cursor, returning the underlying value.
Examples
use async_std::io::Cursor;
let buff = Cursor::new(Vec::new());
let vec = buff.into_inner();
sourcepub fn get_ref(&self) -> &T
pub fn get_ref(&self) -> &T
Gets a reference to the underlying value in this cursor.
Examples
use async_std::io::Cursor;
let buff = Cursor::new(Vec::new());
let reference = buff.get_ref();
sourcepub fn get_mut(&mut self) -> &mut T
pub fn get_mut(&mut self) -> &mut T
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());
let reference = buff.get_mut();
sourcepub fn position(&self) -> u64
pub fn position(&self) -> u64
Returns the current position of this cursor.
Examples
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);
sourcepub fn set_position(&mut self, pos: u64)
pub fn set_position(&mut self, pos: u64)
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);
Trait Implementations
sourceimpl<T> AsyncBufRead for Cursor<T> where
T: AsRef<[u8]> + Unpin,
impl<T> AsyncBufRead for Cursor<T> where
T: AsRef<[u8]> + Unpin,
sourceimpl<T> AsyncRead for Cursor<T> where
T: AsRef<[u8]> + Unpin,
impl<T> AsyncRead for Cursor<T> where
T: AsRef<[u8]> + Unpin,
sourceimpl AsyncWrite for Cursor<&mut [u8]>
impl AsyncWrite for Cursor<&mut [u8]>
sourcefn poll_write(
self: Pin<&mut Self>,
_: &mut Context<'_>,
buf: &[u8]
) -> Poll<Result<usize>>
fn poll_write(
self: Pin<&mut Self>,
_: &mut Context<'_>,
buf: &[u8]
) -> Poll<Result<usize>>
Attempt to write bytes from buf
into the object. Read more
sourcefn poll_write_vectored(
self: Pin<&mut Self>,
_: &mut Context<'_>,
bufs: &[IoSlice<'_>]
) -> Poll<Result<usize>>
fn poll_write_vectored(
self: Pin<&mut Self>,
_: &mut Context<'_>,
bufs: &[IoSlice<'_>]
) -> Poll<Result<usize>>
Attempt to write bytes from bufs
into the object using vectored
IO operations. Read more
sourceimpl AsyncWrite for Cursor<&mut Vec<u8>>
impl AsyncWrite for Cursor<&mut Vec<u8>>
sourcefn poll_write(
self: Pin<&mut Self>,
_: &mut Context<'_>,
buf: &[u8]
) -> Poll<Result<usize>>
fn poll_write(
self: Pin<&mut Self>,
_: &mut Context<'_>,
buf: &[u8]
) -> Poll<Result<usize>>
Attempt to write bytes from buf
into the object. Read more
sourcefn poll_close(self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<Result<()>>
fn poll_close(self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<Result<()>>
Attempt to close the object. Read more
sourceimpl AsyncWrite for Cursor<Vec<u8>>
impl AsyncWrite for Cursor<Vec<u8>>
sourcefn poll_write(
self: Pin<&mut Self>,
_: &mut Context<'_>,
buf: &[u8]
) -> Poll<Result<usize>>
fn poll_write(
self: Pin<&mut Self>,
_: &mut Context<'_>,
buf: &[u8]
) -> Poll<Result<usize>>
Attempt to write bytes from buf
into the object. Read more
sourcefn poll_close(self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<Result<()>>
fn poll_close(self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<Result<()>>
Attempt to close the object. Read more
Auto Trait Implementations
impl<T> RefUnwindSafe for Cursor<T> where
T: RefUnwindSafe,
impl<T> Send for Cursor<T> where
T: Send,
impl<T> Sync for Cursor<T> where
T: Sync,
impl<T> Unpin for Cursor<T> where
T: Unpin,
impl<T> UnwindSafe for Cursor<T> where
T: UnwindSafe,
Blanket Implementations
sourceimpl<R> AsyncBufReadExt for R where
R: AsyncBufRead + ?Sized,
impl<R> AsyncBufReadExt for R where
R: AsyncBufRead + ?Sized,
sourcefn fill_buf(&mut self) -> FillBuf<'_, Self>ⓘNotable traits for FillBuf<'a, R>impl<'a, R> Future for FillBuf<'a, R> where
R: AsyncBufRead + Unpin + ?Sized, type Output = Result<&'a [u8], Error>;
where
Self: Unpin,
fn fill_buf(&mut self) -> FillBuf<'_, Self>ⓘNotable traits for FillBuf<'a, R>impl<'a, R> Future for FillBuf<'a, R> where
R: AsyncBufRead + Unpin + ?Sized, type Output = Result<&'a [u8], Error>;
where
Self: Unpin,
R: AsyncBufRead + Unpin + ?Sized, type Output = Result<&'a [u8], Error>;
Returns the contents of the internal buffer, filling it with more data if empty. Read more
sourcefn read_until(
&'a mut self,
byte: u8,
buf: &'a mut Vec<u8, Global>
) -> ReadUntilFuture<'a, Self>ⓘNotable traits for ReadUntilFuture<'_, R>impl<'_, R> Future for ReadUntilFuture<'_, R> where
R: AsyncBufRead + Unpin + ?Sized, type Output = Result<usize, Error>;
where
Self: Unpin,
fn read_until(
&'a mut self,
byte: u8,
buf: &'a mut Vec<u8, Global>
) -> ReadUntilFuture<'a, Self>ⓘNotable traits for ReadUntilFuture<'_, R>impl<'_, R> Future for ReadUntilFuture<'_, R> where
R: AsyncBufRead + Unpin + ?Sized, type Output = Result<usize, Error>;
where
Self: Unpin,
R: AsyncBufRead + Unpin + ?Sized, type Output = Result<usize, Error>;
Reads all bytes and appends them into buf
until the delimiter byte
or EOF is found. Read more
sourcefn read_line(&'a mut self, buf: &'a mut String) -> ReadLineFuture<'a, Self>ⓘNotable traits for ReadLineFuture<'_, R>impl<'_, R> Future for ReadLineFuture<'_, R> where
R: AsyncBufRead + Unpin + ?Sized, type Output = Result<usize, Error>;
where
Self: Unpin,
fn read_line(&'a mut self, buf: &'a mut String) -> ReadLineFuture<'a, Self>ⓘNotable traits for ReadLineFuture<'_, R>impl<'_, R> Future for ReadLineFuture<'_, R> where
R: AsyncBufRead + Unpin + ?Sized, type Output = Result<usize, Error>;
where
Self: Unpin,
R: AsyncBufRead + Unpin + ?Sized, type Output = Result<usize, Error>;
Reads all bytes and appends them into buf
until a newline (the 0xA byte) or EOF is found. Read more
sourceimpl<R> AsyncReadExt for R where
R: AsyncRead + ?Sized,
impl<R> AsyncReadExt for R where
R: AsyncRead + ?Sized,
sourcefn read(&'a mut self, buf: &'a mut [u8]) -> ReadFuture<'a, Self>ⓘNotable traits for ReadFuture<'_, R>impl<'_, R> Future for ReadFuture<'_, R> where
R: AsyncRead + Unpin + ?Sized, type Output = Result<usize, Error>;
where
Self: Unpin,
fn read(&'a mut self, buf: &'a mut [u8]) -> ReadFuture<'a, Self>ⓘNotable traits for ReadFuture<'_, R>impl<'_, R> Future for ReadFuture<'_, R> where
R: AsyncRead + Unpin + ?Sized, type Output = Result<usize, Error>;
where
Self: Unpin,
R: AsyncRead + Unpin + ?Sized, type Output = Result<usize, Error>;
Reads some bytes from the byte stream. Read more
sourcefn read_vectored(
&'a mut self,
bufs: &'a mut [IoSliceMut<'a>]
) -> ReadVectoredFuture<'a, Self>ⓘNotable traits for ReadVectoredFuture<'_, R>impl<'_, R> Future for ReadVectoredFuture<'_, R> where
R: AsyncRead + Unpin + ?Sized, type Output = Result<usize, Error>;
where
Self: Unpin,
fn read_vectored(
&'a mut self,
bufs: &'a mut [IoSliceMut<'a>]
) -> ReadVectoredFuture<'a, Self>ⓘNotable traits for ReadVectoredFuture<'_, R>impl<'_, R> Future for ReadVectoredFuture<'_, R> where
R: AsyncRead + Unpin + ?Sized, type Output = Result<usize, Error>;
where
Self: Unpin,
R: AsyncRead + Unpin + ?Sized, type Output = Result<usize, Error>;
sourcefn read_to_end(
&'a mut self,
buf: &'a mut Vec<u8, Global>
) -> ReadToEndFuture<'a, Self>ⓘNotable traits for ReadToEndFuture<'_, R>impl<'_, R> Future for ReadToEndFuture<'_, R> where
R: AsyncRead + Unpin + ?Sized, type Output = Result<usize, Error>;
where
Self: Unpin,
fn read_to_end(
&'a mut self,
buf: &'a mut Vec<u8, Global>
) -> ReadToEndFuture<'a, Self>ⓘNotable traits for ReadToEndFuture<'_, R>impl<'_, R> Future for ReadToEndFuture<'_, R> where
R: AsyncRead + Unpin + ?Sized, type Output = Result<usize, Error>;
where
Self: Unpin,
R: AsyncRead + Unpin + ?Sized, type Output = Result<usize, Error>;
sourcefn read_to_string(
&'a mut self,
buf: &'a mut String
) -> ReadToStringFuture<'a, Self>ⓘNotable traits for ReadToStringFuture<'_, R>impl<'_, R> Future for ReadToStringFuture<'_, R> where
R: AsyncRead + Unpin + ?Sized, type Output = Result<usize, Error>;
where
Self: Unpin,
fn read_to_string(
&'a mut self,
buf: &'a mut String
) -> ReadToStringFuture<'a, Self>ⓘNotable traits for ReadToStringFuture<'_, R>impl<'_, R> Future for ReadToStringFuture<'_, R> where
R: AsyncRead + Unpin + ?Sized, type Output = Result<usize, Error>;
where
Self: Unpin,
R: AsyncRead + Unpin + ?Sized, type Output = Result<usize, Error>;
sourcefn read_exact(&'a mut self, buf: &'a mut [u8]) -> ReadExactFuture<'a, Self>ⓘNotable traits for ReadExactFuture<'_, R>impl<'_, R> Future for ReadExactFuture<'_, R> where
R: AsyncRead + Unpin + ?Sized, type Output = Result<(), Error>;
where
Self: Unpin,
fn read_exact(&'a mut self, buf: &'a mut [u8]) -> ReadExactFuture<'a, Self>ⓘNotable traits for ReadExactFuture<'_, R>impl<'_, R> Future for ReadExactFuture<'_, R> where
R: AsyncRead + Unpin + ?Sized, type Output = Result<(), Error>;
where
Self: Unpin,
R: AsyncRead + Unpin + ?Sized, type Output = Result<(), Error>;
Reads the exact number of bytes required to fill buf
. Read more
sourcefn take(self, limit: u64) -> Take<Self>
fn take(self, limit: u64) -> Take<Self>
Creates an adapter which will read at most limit
bytes from it. Read more
sourcefn chain<R>(self, next: R) -> Chain<Self, R> where
R: AsyncRead,
fn chain<R>(self, next: R) -> Chain<Self, R> where
R: AsyncRead,
Creates an adapter which will chain this stream with another. Read more
sourcefn boxed_reader<'a>(self) -> Pin<Box<dyn AsyncRead + Send + 'a, Global>>ⓘNotable traits for Pin<P>impl<P> Future for Pin<P> where
P: DerefMut,
<P as Deref>::Target: Future, type Output = <<P as Deref>::Target as Future>::Output;
where
Self: 'a + Send,
fn boxed_reader<'a>(self) -> Pin<Box<dyn AsyncRead + Send + 'a, Global>>ⓘNotable traits for Pin<P>impl<P> Future for Pin<P> where
P: DerefMut,
<P as Deref>::Target: Future, type Output = <<P as Deref>::Target as Future>::Output;
where
Self: 'a + Send,
P: DerefMut,
<P as Deref>::Target: Future, type Output = <<P as Deref>::Target as Future>::Output;
Boxes the reader and changes its type to dyn AsyncRead + Send + 'a
. Read more
sourceimpl<S> AsyncSeekExt for S where
S: AsyncSeek + ?Sized,
impl<S> AsyncSeekExt for S where
S: AsyncSeek + ?Sized,
sourceimpl<W> AsyncWriteExt for W where
W: AsyncWrite + ?Sized,
impl<W> AsyncWriteExt for W where
W: AsyncWrite + ?Sized,
sourcefn write(&'a mut self, buf: &'a [u8]) -> WriteFuture<'a, Self>ⓘNotable traits for WriteFuture<'_, W>impl<'_, W> Future for WriteFuture<'_, W> where
W: AsyncWrite + Unpin + ?Sized, type Output = Result<usize, Error>;
where
Self: Unpin,
fn write(&'a mut self, buf: &'a [u8]) -> WriteFuture<'a, Self>ⓘNotable traits for WriteFuture<'_, W>impl<'_, W> Future for WriteFuture<'_, W> where
W: AsyncWrite + Unpin + ?Sized, type Output = Result<usize, Error>;
where
Self: Unpin,
W: AsyncWrite + Unpin + ?Sized, type Output = Result<usize, Error>;
Writes some bytes into the byte stream. Read more
sourcefn write_vectored(
&'a mut self,
bufs: &'a [IoSlice<'a>]
) -> WriteVectoredFuture<'a, Self>ⓘNotable traits for WriteVectoredFuture<'_, W>impl<'_, W> Future for WriteVectoredFuture<'_, W> where
W: AsyncWrite + Unpin + ?Sized, type Output = Result<usize, Error>;
where
Self: Unpin,
fn write_vectored(
&'a mut self,
bufs: &'a [IoSlice<'a>]
) -> WriteVectoredFuture<'a, Self>ⓘNotable traits for WriteVectoredFuture<'_, W>impl<'_, W> Future for WriteVectoredFuture<'_, W> where
W: AsyncWrite + Unpin + ?Sized, type Output = Result<usize, Error>;
where
Self: Unpin,
W: AsyncWrite + Unpin + ?Sized, type Output = Result<usize, Error>;
sourcefn write_all(&'a mut self, buf: &'a [u8]) -> WriteAllFuture<'a, Self>ⓘNotable traits for WriteAllFuture<'_, W>impl<'_, W> Future for WriteAllFuture<'_, W> where
W: AsyncWrite + Unpin + ?Sized, type Output = Result<(), Error>;
where
Self: Unpin,
fn write_all(&'a mut self, buf: &'a [u8]) -> WriteAllFuture<'a, Self>ⓘNotable traits for WriteAllFuture<'_, W>impl<'_, W> Future for WriteAllFuture<'_, W> where
W: AsyncWrite + Unpin + ?Sized, type Output = Result<(), Error>;
where
Self: Unpin,
W: AsyncWrite + Unpin + ?Sized, type Output = Result<(), Error>;
Writes an entire buffer into the byte stream. Read more
sourcefn flush(&mut self) -> FlushFuture<'_, Self>ⓘNotable traits for FlushFuture<'_, W>impl<'_, W> Future for FlushFuture<'_, W> where
W: AsyncWrite + Unpin + ?Sized, type Output = Result<(), Error>;
where
Self: Unpin,
fn flush(&mut self) -> FlushFuture<'_, Self>ⓘNotable traits for FlushFuture<'_, W>impl<'_, W> Future for FlushFuture<'_, W> where
W: AsyncWrite + Unpin + ?Sized, type Output = Result<(), Error>;
where
Self: Unpin,
W: AsyncWrite + Unpin + ?Sized, type Output = Result<(), Error>;
Flushes the stream to ensure that all buffered contents reach their destination. Read more
sourcefn close(&mut self) -> CloseFuture<'_, Self>ⓘNotable traits for CloseFuture<'_, W>impl<'_, W> Future for CloseFuture<'_, W> where
W: AsyncWrite + Unpin + ?Sized, type Output = Result<(), Error>;
where
Self: Unpin,
fn close(&mut self) -> CloseFuture<'_, Self>ⓘNotable traits for CloseFuture<'_, W>impl<'_, W> Future for CloseFuture<'_, W> where
W: AsyncWrite + Unpin + ?Sized, type Output = Result<(), Error>;
where
Self: Unpin,
W: AsyncWrite + Unpin + ?Sized, type Output = Result<(), Error>;
Closes the writer. Read more
sourcefn boxed_writer<'a>(self) -> Pin<Box<dyn AsyncWrite + Send + 'a, Global>>ⓘNotable traits for Pin<P>impl<P> Future for Pin<P> where
P: DerefMut,
<P as Deref>::Target: Future, type Output = <<P as Deref>::Target as Future>::Output;
where
Self: 'a + Send,
fn boxed_writer<'a>(self) -> Pin<Box<dyn AsyncWrite + Send + 'a, Global>>ⓘNotable traits for Pin<P>impl<P> Future for Pin<P> where
P: DerefMut,
<P as Deref>::Target: Future, type Output = <<P as Deref>::Target as Future>::Output;
where
Self: 'a + Send,
P: DerefMut,
<P as Deref>::Target: Future, type Output = <<P as Deref>::Target as Future>::Output;
Boxes the writer and changes its type to dyn AsyncWrite + Send + 'a
. Read more
sourceimpl<T> BorrowMut<T> for T where
T: ?Sized,
impl<T> BorrowMut<T> for T where
T: ?Sized,
const: unstable · sourcefn borrow_mut(&mut self) -> &mut T
fn borrow_mut(&mut self) -> &mut T
Mutably borrows from an owned value. Read more
sourceimpl<T> ToOwned for T where
T: Clone,
impl<T> ToOwned for T where
T: Clone,
type Owned = T
type Owned = T
The resulting type after obtaining ownership.
sourcefn clone_into(&self, target: &mut T)
fn clone_into(&self, target: &mut T)
toowned_clone_into
)Uses borrowed data to replace owned data, usually by cloning. Read more