Struct futures_util::io::Cursor

impl<T> Cursor<T>

pub fn new(inner: T) -> Self

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());

pub fn into_inner(self) -> T

Consumes this cursor, returning the underlying value.

Examples

use futures::io::Cursor;

let buff = Cursor::new(Vec::new());

let vec = buff.into_inner();

pub fn get_ref(&self) -> &T

Gets a reference to the underlying value in this cursor.

Examples

use futures::io::Cursor;

let buff = Cursor::new(Vec::new());

let reference = buff.get_ref();

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 futures::io::Cursor;

let mut buff = Cursor::new(Vec::new());

let reference = buff.get_mut();

pub fn position(&self) -> u64

Returns the current position of this cursor.

Examples

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);

pub fn set_position(&mut self, pos: u64)

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);

Trait Implementations§

impl<T> AsyncBufRead for Cursor<T>where
T: AsRef<[u8]> + Unpin,

fn poll_fill_buf(
self: Pin<&mut Self>,
_: &mut Context<'_>
) -> Poll<Result<&[u8]>>

Attempt to return the contents of the internal buffer, filling it with more data from the inner reader if it is empty. Read more

fn consume(self: Pin<&mut Self>, amt: usize)

Tells this buffer that amt bytes have been consumed from the buffer, so they should no longer be returned in calls to poll_read. Read more

impl<T: AsRef<[u8]> + Unpin> AsyncRead for Cursor<T>

fn poll_read(
 self: Pin<&mut Self>,
 _cx: &mut Context<'_>,
 buf: &mut [u8]
) -> Poll<Result<usize>>

Attempt to read from the AsyncRead into buf. Read more

fn poll_read_vectored(
 self: Pin<&mut Self>,
 _: &mut Context<'_>,
 bufs: &mut [IoSliceMut<'_>]
) -> Poll<Result<usize>>

Attempt to read from the AsyncRead into bufs using vectored IO operations. Read more

impl<T> AsyncSeek for Cursor<T>where
T: AsRef<[u8]> + Unpin,

fn poll_seek(
 self: Pin<&mut Self>,
 _: &mut Context<'_>,
 pos: SeekFrom
) -> Poll<Result<u64>>

Attempt to seek to an offset, in bytes, in a stream. Read more

impl AsyncWrite for Cursor<&mut [u8]>

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

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

fn poll_flush(self: Pin<&mut Self>, _: &mut Context<'_>) -> Poll<Result<()>>

Attempt to flush the object, ensuring that any buffered data reach their destination. Read more

fn poll_close(self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<Result<()>>

Attempt to close the object. Read more

impl AsyncWrite for Cursor<&mut Vec<u8>>

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

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

fn poll_flush(self: Pin<&mut Self>, _: &mut Context<'_>) -> Poll<Result<()>>

Attempt to flush the object, ensuring that any buffered data reach their destination. Read more

fn poll_close(self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<Result<()>>

Attempt to close the object. Read more

impl AsyncWrite for Cursor<Box<[u8]>>

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

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

fn poll_flush(self: Pin<&mut Self>, _: &mut Context<'_>) -> Poll<Result<()>>

Attempt to flush the object, ensuring that any buffered data reach their destination. Read more

fn poll_close(self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<Result<()>>

Attempt to close the object. Read more

impl AsyncWrite for Cursor<Vec<u8>>

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

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

fn poll_flush(self: Pin<&mut Self>, _: &mut Context<'_>) -> Poll<Result<()>>

Attempt to flush the object, ensuring that any buffered data reach their destination. Read more

fn poll_close(self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<Result<()>>

Attempt to close the object. Read more

impl<T: Clone> Clone for Cursor<T>

fn clone(&self) -> Cursor<T>

Returns a copy of the value. Read more

1.0.0 · source§

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source. Read more

impl<T: Debug> Debug for Cursor<T>

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter. Read more

impl<T: Default> Default for Cursor<T>

fn default() -> Cursor<T>

Returns the “default value” for a type. Read more

Auto Trait Implementations§

impl<T> UnwindSafe for Cursor<T>where
T: UnwindSafe,

Blanket Implementations§

impl<T> Any for Twhere
T: 'static + ?Sized,

fn type_id(&self) -> TypeId

Gets the TypeId of self. Read more

impl<R> AsyncBufReadExt for Rwhere
R: AsyncBufRead + ?Sized,

fn fill_buf(&mut self) -> FillBuf<'_, Self> ⓘwhere
Self: Unpin,

Creates a future which will wait for a non-empty buffer to be available from this I/O object or EOF to be reached. Read more

fn consume_unpin(&mut self, amt: usize)where
Self: Unpin,

A convenience for calling AsyncBufRead::consume on Unpin IO types. Read more

fn read_until<'a>(
 &'a mut self,
 byte: u8,
 buf: &'a mut Vec<u8>
) -> ReadUntil<'a, Self> ⓘwhere
 Self: Unpin,

Creates a future which will read all the bytes associated with this I/O object into buf until the delimiter byte or EOF is reached. This method is the async equivalent to BufRead::read_until. Read more

fn read_line<'a>(&'a mut self, buf: &'a mut String) -> ReadLine<'a, Self> ⓘwhere
Self: Unpin,

Creates a future which will read all the bytes associated with this I/O object into buf until a newline (the 0xA byte) or EOF is reached, This method is the async equivalent to BufRead::read_line. Read more

fn lines(self) -> Lines<Self>where
Self: Sized,

Returns a stream over the lines of this reader. This method is the async equivalent to BufRead::lines. Read more

impl<R> AsyncReadExt for Rwhere
R: AsyncRead + ?Sized,

fn chain<R>(self, next: R) -> Chain<Self, R>where
Self: Sized,
R: AsyncRead,

Creates an adaptor which will chain this stream with another. Read more

fn read<'a>(&'a mut self, buf: &'a mut [u8]) -> Read<'a, Self> ⓘwhere
Self: Unpin,

Tries to read some bytes directly into the given buf in asynchronous manner, returning a future type. Read more

fn read_vectored<'a>(
 &'a mut self,
 bufs: &'a mut [IoSliceMut<'a>]
) -> ReadVectored<'a, Self> ⓘwhere
 Self: Unpin,

Creates a future which will read from the AsyncRead into bufs using vectored IO operations. Read more

fn read_exact<'a>(&'a mut self, buf: &'a mut [u8]) -> ReadExact<'a, Self> ⓘwhere
Self: Unpin,

Creates a future which will read exactly enough bytes to fill buf, returning an error if end of file (EOF) is hit sooner. Read more

fn read_to_end<'a>(&'a mut self, buf: &'a mut Vec<u8>) -> ReadToEnd<'a, Self> ⓘwhere
Self: Unpin,

Creates a future which will read all the bytes from this AsyncRead. Read more

fn read_to_string<'a>(
 &'a mut self,
 buf: &'a mut String
) -> ReadToString<'a, Self> ⓘwhere
 Self: Unpin,

Creates a future which will read all the bytes from this AsyncRead. Read more

fn split(self) -> (ReadHalf<Self>, WriteHalf<Self>)where
Self: AsyncWrite + Sized,

Helper method for splitting this read/write object into two halves. Read more

fn take(self, limit: u64) -> Take<Self>where
Self: Sized,

Creates an AsyncRead adapter which will read at most limit bytes from the underlying reader. Read more

impl<S> AsyncSeekExt for Swhere
S: AsyncSeek + ?Sized,

fn seek(&mut self, pos: SeekFrom) -> Seek<'_, Self> ⓘwhere
Self: Unpin,

Creates a future which will seek an IO object, and then yield the new position in the object and the object itself. Read more

fn stream_position(&mut self) -> Seek<'_, Self> ⓘwhere
Self: Unpin,

Creates a future which will return the current seek position from the start of the stream. Read more

impl<W> AsyncWriteExt for Wwhere
W: AsyncWrite + ?Sized,

fn flush(&mut self) -> Flush<'_, Self> ⓘwhere
Self: Unpin,

Creates a future which will entirely flush this AsyncWrite. Read more

fn close(&mut self) -> Close<'_, Self> ⓘwhere
Self: Unpin,

Creates a future which will entirely close this AsyncWrite.

fn write<'a>(&'a mut self, buf: &'a [u8]) -> Write<'a, Self> ⓘwhere
Self: Unpin,

Creates a future which will write bytes from buf into the object. Read more

fn write_vectored<'a>(
 &'a mut self,
 bufs: &'a [IoSlice<'a>]
) -> WriteVectored<'a, Self> ⓘwhere
 Self: Unpin,

Creates a future which will write bytes from bufs into the object using vectored IO operations. Read more

fn write_all<'a>(&'a mut self, buf: &'a [u8]) -> WriteAll<'a, Self> ⓘwhere
Self: Unpin,

Write data into this object. Read more

fn into_sink<Item: AsRef<[u8]>>(self) -> IntoSink<Self, Item>where
Self: Sized,

Allow using an AsyncWrite as a Sink<Item: AsRef<[u8]>>. Read more

impl<T> Borrow<T> for Twhere
T: ?Sized,

const: unstable · source§

fn borrow(&self) -> &T

Immutably borrows from an owned value. Read more

impl<T> BorrowMut<T> for Twhere
T: ?Sized,

const: unstable · source§

fn borrow_mut(&mut self) -> &mut T

Mutably borrows from an owned value. Read more

impl<T> From<T> for T

const: unstable · source§

fn from(t: T) -> T

Returns the argument unchanged.

impl<T, U> Into for Twhere
U: From<T>,

const: unstable · source§

fn into(self) -> U

Calls U::from(self).

That is, this conversion is whatever the implementation of From<T> for U chooses to do.

impl<T> ToOwned for Twhere
T: Clone,

type Owned = T

The resulting type after obtaining ownership.

fn to_owned(&self) -> T

Creates owned data from borrowed data, usually by cloning. Read more

fn clone_into(&self, target: &mut T)

Uses borrowed data to replace owned data, usually by cloning. Read more

impl<T, U> TryFrom for Twhere
U: Into<T>,

type Error = Infallible

The type returned in the event of a conversion error.

const: unstable · source§

fn try_from(value: U) -> Result<T, <T as TryFrom>::Error>

Performs the conversion.

impl<T, U> TryInto for Twhere
U: TryFrom<T>,