Struct Cursor

pub struct Cursor<T> { /* private fields */ }

A Cursor wraps an in-memory buffer and provides it with a Seek implementation.

Cursors 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]>.

Examples

We may want to write bytes to a File in our production code, but use an in-memory buffer in our tests. We can do this with Cursor:

use std::io::prelude::*;
use std::io::{self, SeekFrom};
use std::fs::File;

// a library function we've written
fn write_ten_bytes_at_end<W: Write + Seek>(mut writer: W) -> io::Result<()> {
    writer.seek(SeekFrom::End(-10))?;

    for i in 0..10 {
        writer.write(&[i])?;
    }

    // all went well
    Ok(())
}

// Here's some code that uses this library function.
//
// We might want to use a BufReader here for efficiency, but let's
// keep this example focused.
let mut file = File::create("foo.txt")?;
// First, we need to allocate 10 bytes to be able to write into.
file.set_len(10)?;

write_ten_bytes_at_end(&mut file)?;

// now let's write a test
#[test]
fn test_writes_bytes() {
    // setting up a real File is much slower than an in-memory buffer,
    // let's use a cursor instead
    use std::io::Cursor;
    let mut buff = Cursor::new(vec![0; 15]);

    write_ten_bytes_at_end(&mut buff).unwrap();

    assert_eq!(&buff.get_ref()[5..15], &[0, 1, 2, 3, 4, 5, 6, 7, 8, 9]);
}

Implementations

impl<T> Cursor<T>

pub const 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 std::io::Cursor;

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

pub fn into_inner(self) -> T

Consumes this cursor, returning the underlying value.

Examples

use std::io::Cursor;

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

let vec = buff.into_inner();

pub const fn get_ref(&self) -> &T

Gets a reference to the underlying value in this cursor.

Examples

use std::io::Cursor;

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

let reference = buff.get_ref();

pub const 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 std::io::Cursor;

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

let reference = buff.get_mut();

pub const fn position(&self) -> u64

Returns the current position of this cursor.

Examples

use std::io::Cursor;
use std::io::prelude::*;
use std::io::SeekFrom;

let mut buff = Cursor::new(vec![1, 2, 3, 4, 5]);

assert_eq!(buff.position(), 0);

buff.seek(SeekFrom::Current(2)).unwrap();
assert_eq!(buff.position(), 2);

buff.seek(SeekFrom::Current(-1)).unwrap();
assert_eq!(buff.position(), 1);

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

Sets the position of this cursor.

Examples

use 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);

impl<T> Cursor<T>

where T: AsRef<[u8]>,

pub fn split(&self) -> (&[u8], &[u8])

🔬This is a nightly-only experimental API. (cursor_split)

Splits the underlying slice at the cursor position and returns them.

Examples

#![feature(cursor_split)]
use std::io::Cursor;

let mut buff = Cursor::new(vec![1, 2, 3, 4, 5]);

assert_eq!(buff.split(), ([].as_slice(), [1, 2, 3, 4, 5].as_slice()));

buff.set_position(2);
assert_eq!(buff.split(), ([1, 2].as_slice(), [3, 4, 5].as_slice()));

buff.set_position(6);
assert_eq!(buff.split(), ([1, 2, 3, 4, 5].as_slice(), [].as_slice()));

impl<T> Cursor<T>

where T: AsMut<[u8]>,

pub fn split_mut(&mut self) -> (&mut [u8], &mut [u8])

🔬This is a nightly-only experimental API. (cursor_split)

Splits the underlying slice at the cursor position and returns them mutably.

Examples

#![feature(cursor_split)]
use std::io::Cursor;

let mut buff = Cursor::new(vec![1, 2, 3, 4, 5]);

assert_eq!(buff.split_mut(), ([].as_mut_slice(), [1, 2, 3, 4, 5].as_mut_slice()));

buff.set_position(2);
assert_eq!(buff.split_mut(), ([1, 2].as_mut_slice(), [3, 4, 5].as_mut_slice()));

buff.set_position(6);
assert_eq!(buff.split_mut(), ([1, 2, 3, 4, 5].as_mut_slice(), [].as_mut_slice()));

Trait Implementations

impl<T> AsyncBufRead for Cursor<T>

where T: AsRef<[u8]> + Unpin,

fn poll_fill_buf( self: Pin<&mut Cursor<T>>, _cx: &mut Context<'_>, ) -> Poll<Result<&[u8], Error>>

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

fn consume(self: Pin<&mut Cursor<T>>, 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.

impl<T> AsyncRead for Cursor<T>

where T: AsRef<[u8]> + Unpin,

fn poll_read( self: Pin<&mut Cursor<T>>, _cx: &mut Context<'_>, buf: &mut ReadBuf<'_>, ) -> Poll<Result<(), Error>>

Attempts to read from the AsyncRead into buf.

impl<T> AsyncSeek for Cursor<T>

where T: AsRef<[u8]> + Unpin,

fn start_seek(self: Pin<&mut Cursor<T>>, pos: SeekFrom) -> Result<(), Error>

Attempts to seek to an offset, in bytes, in a stream.

fn poll_complete( self: Pin<&mut Cursor<T>>, _: &mut Context<'_>, ) -> Poll<Result<u64, Error>>

Waits for a seek operation to complete.

impl AsyncWrite for Cursor<&mut [u8]>

fn poll_write( self: Pin<&mut Cursor<&mut [u8]>>, _: &mut Context<'_>, buf: &[u8], ) -> Poll<Result<usize, Error>>

Attempt to write bytes from buf into the object.

fn poll_write_vectored( self: Pin<&mut Cursor<&mut [u8]>>, _: &mut Context<'_>, bufs: &[IoSlice<'_>], ) -> Poll<Result<usize, Error>>

Like poll_write, except that it writes from a slice of buffers.

fn is_write_vectored(&self) -> bool

Determines if this writer has an efficient poll_write_vectored implementation.

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

Attempts to flush the object, ensuring that any buffered data reach their destination.

fn poll_shutdown( self: Pin<&mut Cursor<&mut [u8]>>, cx: &mut Context<'_>, ) -> Poll<Result<(), Error>>

Initiates or attempts to shut down this writer, returning success when the I/O connection has completely shut down.

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

fn poll_write( self: Pin<&mut Cursor<&mut Vec<u8>>>, _: &mut Context<'_>, buf: &[u8], ) -> Poll<Result<usize, Error>>

Attempt to write bytes from buf into the object.

fn poll_write_vectored( self: Pin<&mut Cursor<&mut Vec<u8>>>, _: &mut Context<'_>, bufs: &[IoSlice<'_>], ) -> Poll<Result<usize, Error>>

Like poll_write, except that it writes from a slice of buffers.

fn is_write_vectored(&self) -> bool

Determines if this writer has an efficient poll_write_vectored implementation.

fn poll_flush( self: Pin<&mut Cursor<&mut Vec<u8>>>, _: &mut Context<'_>, ) -> Poll<Result<(), Error>>

Attempts to flush the object, ensuring that any buffered data reach their destination.

fn poll_shutdown( self: Pin<&mut Cursor<&mut Vec<u8>>>, cx: &mut Context<'_>, ) -> Poll<Result<(), Error>>

Initiates or attempts to shut down this writer, returning success when the I/O connection has completely shut down.

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

fn poll_write( self: Pin<&mut Cursor<Box<[u8]>>>, _: &mut Context<'_>, buf: &[u8], ) -> Poll<Result<usize, Error>>

Attempt to write bytes from buf into the object.

fn poll_write_vectored( self: Pin<&mut Cursor<Box<[u8]>>>, _: &mut Context<'_>, bufs: &[IoSlice<'_>], ) -> Poll<Result<usize, Error>>

Like poll_write, except that it writes from a slice of buffers.

fn is_write_vectored(&self) -> bool

Determines if this writer has an efficient poll_write_vectored implementation.

fn poll_flush( self: Pin<&mut Cursor<Box<[u8]>>>, _: &mut Context<'_>, ) -> Poll<Result<(), Error>>

Attempts to flush the object, ensuring that any buffered data reach their destination.

fn poll_shutdown( self: Pin<&mut Cursor<Box<[u8]>>>, cx: &mut Context<'_>, ) -> Poll<Result<(), Error>>

Initiates or attempts to shut down this writer, returning success when the I/O connection has completely shut down.

impl AsyncWrite for Cursor<Vec<u8>>

fn poll_write( self: Pin<&mut Cursor<Vec<u8>>>, _: &mut Context<'_>, buf: &[u8], ) -> Poll<Result<usize, Error>>

Attempt to write bytes from buf into the object.

fn poll_write_vectored( self: Pin<&mut Cursor<Vec<u8>>>, _: &mut Context<'_>, bufs: &[IoSlice<'_>], ) -> Poll<Result<usize, Error>>

Like poll_write, except that it writes from a slice of buffers.

fn is_write_vectored(&self) -> bool

Determines if this writer has an efficient poll_write_vectored implementation.

fn poll_flush( self: Pin<&mut Cursor<Vec<u8>>>, _: &mut Context<'_>, ) -> Poll<Result<(), Error>>

Attempts to flush the object, ensuring that any buffered data reach their destination.

fn poll_shutdown( self: Pin<&mut Cursor<Vec<u8>>>, cx: &mut Context<'_>, ) -> Poll<Result<(), Error>>

Initiates or attempts to shut down this writer, returning success when the I/O connection has completely shut down.

impl<T> Buf for Cursor<T>

where T: AsRef<[u8]>,

fn remaining(&self) -> usize

Returns the number of bytes between the current position and the end of the buffer.

fn chunk(&self) -> &[u8]

Returns a slice starting at the current position and of length between 0 and Buf::remaining(). Note that this can return a shorter slice (this allows non-continuous internal representation).

fn advance(&mut self, cnt: usize)

Advance the internal cursor of the Buf

fn chunks_vectored<'a>(&'a self, dst: &mut [IoSlice<'a>]) -> usize

Fills dst with potentially multiple slices starting at self’s current position.

fn has_remaining(&self) -> bool

Returns true if there are any more bytes to consume

fn copy_to_slice(&mut self, dst: &mut [u8])

Copies bytes from self into dst.

fn get_u8(&mut self) -> u8

Gets an unsigned 8 bit integer from self.

fn get_i8(&mut self) -> i8

Gets a signed 8 bit integer from self.

fn get_u16(&mut self) -> u16

Gets an unsigned 16 bit integer from self in big-endian byte order.

fn get_u16_le(&mut self) -> u16

Gets an unsigned 16 bit integer from self in little-endian byte order.

fn get_u16_ne(&mut self) -> u16

Gets an unsigned 16 bit integer from self in native-endian byte order.

fn get_i16(&mut self) -> i16

Gets a signed 16 bit integer from self in big-endian byte order.

fn get_i16_le(&mut self) -> i16

Gets a signed 16 bit integer from self in little-endian byte order.

fn get_i16_ne(&mut self) -> i16

Gets a signed 16 bit integer from self in native-endian byte order.

fn get_u32(&mut self) -> u32

Gets an unsigned 32 bit integer from self in the big-endian byte order.

fn get_u32_le(&mut self) -> u32

Gets an unsigned 32 bit integer from self in the little-endian byte order.

fn get_u32_ne(&mut self) -> u32

Gets an unsigned 32 bit integer from self in native-endian byte order.

fn get_i32(&mut self) -> i32

Gets a signed 32 bit integer from self in big-endian byte order.

fn get_i32_le(&mut self) -> i32

Gets a signed 32 bit integer from self in little-endian byte order.

fn get_i32_ne(&mut self) -> i32

Gets a signed 32 bit integer from self in native-endian byte order.

fn get_u64(&mut self) -> u64

Gets an unsigned 64 bit integer from self in big-endian byte order.

fn get_u64_le(&mut self) -> u64

Gets an unsigned 64 bit integer from self in little-endian byte order.

fn get_u64_ne(&mut self) -> u64

Gets an unsigned 64 bit integer from self in native-endian byte order.

fn get_i64(&mut self) -> i64

Gets a signed 64 bit integer from self in big-endian byte order.

fn get_i64_le(&mut self) -> i64

Gets a signed 64 bit integer from self in little-endian byte order.

fn get_i64_ne(&mut self) -> i64

Gets a signed 64 bit integer from self in native-endian byte order.

fn get_u128(&mut self) -> u128

Gets an unsigned 128 bit integer from self in big-endian byte order.

fn get_u128_le(&mut self) -> u128

Gets an unsigned 128 bit integer from self in little-endian byte order.

fn get_u128_ne(&mut self) -> u128

Gets an unsigned 128 bit integer from self in native-endian byte order.

fn get_i128(&mut self) -> i128

Gets a signed 128 bit integer from self in big-endian byte order.

fn get_i128_le(&mut self) -> i128

Gets a signed 128 bit integer from self in little-endian byte order.

fn get_i128_ne(&mut self) -> i128

Gets a signed 128 bit integer from self in native-endian byte order.

fn get_uint(&mut self, nbytes: usize) -> u64

Gets an unsigned n-byte integer from self in big-endian byte order.

fn get_uint_le(&mut self, nbytes: usize) -> u64

Gets an unsigned n-byte integer from self in little-endian byte order.

fn get_uint_ne(&mut self, nbytes: usize) -> u64

Gets an unsigned n-byte integer from self in native-endian byte order.

fn get_int(&mut self, nbytes: usize) -> i64

Gets a signed n-byte integer from self in big-endian byte order.

fn get_int_le(&mut self, nbytes: usize) -> i64

Gets a signed n-byte integer from self in little-endian byte order.

fn get_int_ne(&mut self, nbytes: usize) -> i64

Gets a signed n-byte integer from self in native-endian byte order.

fn get_f32(&mut self) -> f32

Gets an IEEE754 single-precision (4 bytes) floating point number from self in big-endian byte order.

fn get_f32_le(&mut self) -> f32

Gets an IEEE754 single-precision (4 bytes) floating point number from self in little-endian byte order.

fn get_f32_ne(&mut self) -> f32

Gets an IEEE754 single-precision (4 bytes) floating point number from self in native-endian byte order.

fn get_f64(&mut self) -> f64

Gets an IEEE754 double-precision (8 bytes) floating point number from self in big-endian byte order.

fn get_f64_le(&mut self) -> f64

Gets an IEEE754 double-precision (8 bytes) floating point number from self in little-endian byte order.

fn get_f64_ne(&mut self) -> f64

Gets an IEEE754 double-precision (8 bytes) floating point number from self in native-endian byte order.

fn try_copy_to_slice(&mut self, dst: &mut [u8]) -> Result<(), TryGetError>

Copies bytes from self into dst.

fn try_get_u8(&mut self) -> Result<u8, TryGetError>

Gets an unsigned 8 bit integer from self.

fn try_get_i8(&mut self) -> Result<i8, TryGetError>

Gets a signed 8 bit integer from self.

fn try_get_u16(&mut self) -> Result<u16, TryGetError>

Gets an unsigned 16 bit integer from self in big-endian byte order.

fn try_get_u16_le(&mut self) -> Result<u16, TryGetError>

Gets an unsigned 16 bit integer from self in little-endian byte order.

fn try_get_u16_ne(&mut self) -> Result<u16, TryGetError>

Gets an unsigned 16 bit integer from self in native-endian byte order.

fn try_get_i16(&mut self) -> Result<i16, TryGetError>

Gets a signed 16 bit integer from self in big-endian byte order.

fn try_get_i16_le(&mut self) -> Result<i16, TryGetError>

Gets an signed 16 bit integer from self in little-endian byte order.

fn try_get_i16_ne(&mut self) -> Result<i16, TryGetError>

Gets a signed 16 bit integer from self in native-endian byte order.

fn try_get_u32(&mut self) -> Result<u32, TryGetError>

Gets an unsigned 32 bit integer from self in big-endian byte order.

fn try_get_u32_le(&mut self) -> Result<u32, TryGetError>

Gets an unsigned 32 bit integer from self in little-endian byte order.

fn try_get_u32_ne(&mut self) -> Result<u32, TryGetError>

Gets an unsigned 32 bit integer from self in native-endian byte order.

fn try_get_i32(&mut self) -> Result<i32, TryGetError>

Gets a signed 32 bit integer from self in big-endian byte order.

fn try_get_i32_le(&mut self) -> Result<i32, TryGetError>

Gets a signed 32 bit integer from self in little-endian byte order.

fn try_get_i32_ne(&mut self) -> Result<i32, TryGetError>

Gets a signed 32 bit integer from self in native-endian byte order.

fn try_get_u64(&mut self) -> Result<u64, TryGetError>

Gets an unsigned 64 bit integer from self in big-endian byte order.

fn try_get_u64_le(&mut self) -> Result<u64, TryGetError>

Gets an unsigned 64 bit integer from self in little-endian byte order.

fn try_get_u64_ne(&mut self) -> Result<u64, TryGetError>

Gets an unsigned 64 bit integer from self in native-endian byte order.

fn try_get_i64(&mut self) -> Result<i64, TryGetError>

Gets a signed 64 bit integer from self in big-endian byte order.

fn try_get_i64_le(&mut self) -> Result<i64, TryGetError>

Gets a signed 64 bit integer from self in little-endian byte order.

fn try_get_i64_ne(&mut self) -> Result<i64, TryGetError>

Gets a signed 64 bit integer from self in native-endian byte order.

fn try_get_u128(&mut self) -> Result<u128, TryGetError>

Gets an unsigned 128 bit integer from self in big-endian byte order.

fn try_get_u128_le(&mut self) -> Result<u128, TryGetError>

Gets an unsigned 128 bit integer from self in little-endian byte order.

fn try_get_u128_ne(&mut self) -> Result<u128, TryGetError>

Gets an unsigned 128 bit integer from self in native-endian byte order.

fn try_get_i128(&mut self) -> Result<i128, TryGetError>

Gets a signed 128 bit integer from self in big-endian byte order.

fn try_get_i128_le(&mut self) -> Result<i128, TryGetError>

Gets a signed 128 bit integer from self in little-endian byte order.

fn try_get_i128_ne(&mut self) -> Result<i128, TryGetError>

Gets a signed 128 bit integer from self in native-endian byte order.

fn try_get_uint(&mut self, nbytes: usize) -> Result<u64, TryGetError>

Gets an unsigned n-byte integer from self in big-endian byte order.

fn try_get_uint_le(&mut self, nbytes: usize) -> Result<u64, TryGetError>

Gets an unsigned n-byte integer from self in little-endian byte order.

fn try_get_uint_ne(&mut self, nbytes: usize) -> Result<u64, TryGetError>

Gets an unsigned n-byte integer from self in native-endian byte order.

fn try_get_int(&mut self, nbytes: usize) -> Result<i64, TryGetError>

Gets a signed n-byte integer from self in big-endian byte order.

fn try_get_int_le(&mut self, nbytes: usize) -> Result<i64, TryGetError>

Gets a signed n-byte integer from self in little-endian byte order.

fn try_get_int_ne(&mut self, nbytes: usize) -> Result<i64, TryGetError>

Gets a signed n-byte integer from self in native-endian byte order.

fn try_get_f32(&mut self) -> Result<f32, TryGetError>

Gets an IEEE754 single-precision (4 bytes) floating point number from self in big-endian byte order.

fn try_get_f32_le(&mut self) -> Result<f32, TryGetError>

Gets an IEEE754 single-precision (4 bytes) floating point number from self in little-endian byte order.

fn try_get_f32_ne(&mut self) -> Result<f32, TryGetError>

Gets an IEEE754 single-precision (4 bytes) floating point number from self in native-endian byte order.

fn try_get_f64(&mut self) -> Result<f64, TryGetError>

Gets an IEEE754 double-precision (8 bytes) floating point number from self in big-endian byte order.

fn try_get_f64_le(&mut self) -> Result<f64, TryGetError>

Gets an IEEE754 double-precision (8 bytes) floating point number from self in little-endian byte order.

fn try_get_f64_ne(&mut self) -> Result<f64, TryGetError>

Gets an IEEE754 double-precision (8 bytes) floating point number from self in native-endian byte order.

fn copy_to_bytes(&mut self, len: usize) -> Bytes

Consumes len bytes inside self and returns new instance of Bytes with this data.

fn take(self, limit: usize) -> Take<Self>

where Self: Sized,

Creates an adaptor which will read at most limit bytes from self.

fn chain<U>(self, next: U) -> Chain<Self, U>

where U: Buf, Self: Sized,

Creates an adaptor which will chain this buffer with another.

fn reader(self) -> Reader<Self>

where Self: Sized,

Creates an adaptor which implements the Read trait for self.

impl<T> BufRead for Cursor<T>

where T: AsRef<[u8]>,

fn fill_buf(&mut self) -> Result<&[u8], Error>

Returns the contents of the internal buffer, filling it with more data, via Read methods, if empty.

fn consume(&mut self, amt: usize)

Marks the given amount of additional bytes from the internal buffer as having been read. Subsequent calls to read only return bytes that have not been marked as read.

fn has_data_left(&mut self) -> Result<bool, Error>

🔬This is a nightly-only experimental API. (buf_read_has_data_left)

Checks if there is any data left to be read.

fn read_until(&mut self, byte: u8, buf: &mut Vec<u8>) -> Result<usize, Error>

Reads all bytes into buf until the delimiter byte or EOF is reached.

fn skip_until(&mut self, byte: u8) -> Result<usize, Error>

Skips all bytes until the delimiter byte or EOF is reached.

fn read_line(&mut self, buf: &mut String) -> Result<usize, Error>

Reads all bytes until a newline (the 0xA byte) is reached, and append them to the provided String buffer.

fn split(self, byte: u8) -> Split<Self>

where Self: Sized,

Returns an iterator over the contents of this reader split on the byte byte.

fn lines(self) -> Lines<Self>

where Self: Sized,

Returns an iterator over the lines of this reader.

impl<T> Clone for Cursor<T>

where T: Clone,

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

Returns a duplicate of the value.

fn clone_from(&mut self, other: &Cursor<T>)

Performs copy-assignment from source.

impl<T> Debug for Cursor<T>

where T: Debug,

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

Formats the value using the given formatter.

impl<T> Default for Cursor<T>

where T: Default,

fn default() -> Cursor<T>

Returns the “default value” for a type.

impl<T> PartialEq for Cursor<T>

where T: PartialEq,

fn eq(&self, other: &Cursor<T>) -> bool

Tests for self and other values to be equal, and is used by ==.

fn ne(&self, other: &Rhs) -> bool

Tests for !=. The default implementation is almost always sufficient, and should not be overridden without very good reason.

impl<T> Read for Cursor<T>

where T: AsRef<[u8]>,

fn read(&mut self, buf: &mut [u8]) -> Result<usize, Error>

Pull some bytes from this source into the specified buffer, returning how many bytes were read.

fn read_buf(&mut self, cursor: BorrowedCursor<'_>) -> Result<(), Error>

🔬This is a nightly-only experimental API. (read_buf)

Pull some bytes from this source into the specified buffer.

fn read_vectored(&mut self, bufs: &mut [IoSliceMut<'_>]) -> Result<usize, Error>

Like read, except that it reads into a slice of buffers.

fn is_read_vectored(&self) -> bool

🔬This is a nightly-only experimental API. (can_vector)

Determines if this Reader has an efficient read_vectored implementation.

fn read_exact(&mut self, buf: &mut [u8]) -> Result<(), Error>

Reads the exact number of bytes required to fill buf.

fn read_buf_exact(&mut self, cursor: BorrowedCursor<'_>) -> Result<(), Error>

🔬This is a nightly-only experimental API. (read_buf)

Reads the exact number of bytes required to fill cursor.

fn read_to_end(&mut self, buf: &mut Vec<u8>) -> Result<usize, Error>

Reads all bytes until EOF in this source, placing them into buf.

fn read_to_string(&mut self, buf: &mut String) -> Result<usize, Error>

Reads all bytes until EOF in this source, appending them to buf.

fn by_ref(&mut self) -> &mut Self

where Self: Sized,

Creates a “by reference” adaptor for this instance of Read.

fn bytes(self) -> Bytes<Self>

where Self: Sized,

Transforms this Read instance to an Iterator over its bytes.

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

where R: Read, Self: Sized,

Creates an adapter which will chain this stream with another.

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

where Self: Sized,

Creates an adapter which will read at most limit bytes from it.

impl<T> Seek for Cursor<T>

where T: AsRef<[u8]>,

fn seek(&mut self, style: SeekFrom) -> Result<u64, Error>

Seek to an offset, in bytes, in a stream.

fn stream_len(&mut self) -> Result<u64, Error>

🔬This is a nightly-only experimental API. (seek_stream_len)

Returns the length of this stream (in bytes).

fn stream_position(&mut self) -> Result<u64, Error>

Returns the current seek position from the start of the stream.

fn rewind(&mut self) -> Result<(), Error>

Rewind to the beginning of a stream.

fn seek_relative(&mut self, offset: i64) -> Result<(), Error>

Seeks relative to the current position.

impl Write for Cursor<&mut [u8]>

fn write(&mut self, buf: &[u8]) -> Result<usize, Error>

Writes a buffer into this writer, returning how many bytes were written.

fn write_vectored(&mut self, bufs: &[IoSlice<'_>]) -> Result<usize, Error>

Like write, except that it writes from a slice of buffers.

fn is_write_vectored(&self) -> bool

🔬This is a nightly-only experimental API. (can_vector)

Determines if this Writer has an efficient write_vectored implementation.

fn write_all(&mut self, buf: &[u8]) -> Result<(), Error>

Attempts to write an entire buffer into this writer.

fn write_all_vectored(&mut self, bufs: &mut [IoSlice<'_>]) -> Result<(), Error>

🔬This is a nightly-only experimental API. (write_all_vectored)

Attempts to write multiple buffers into this writer.

fn flush(&mut self) -> Result<(), Error>

Flushes this output stream, ensuring that all intermediately buffered contents reach their destination.

fn write_fmt(&mut self, args: Arguments<'_>) -> Result<(), Error>

Writes a formatted string into this writer, returning any error encountered.

fn by_ref(&mut self) -> &mut Self

where Self: Sized,

Creates a “by reference” adapter for this instance of Write.

impl<A> Write for Cursor<&mut Vec<u8, A>>

where A: Allocator,

fn write(&mut self, buf: &[u8]) -> Result<usize, Error>

Writes a buffer into this writer, returning how many bytes were written.

fn write_vectored(&mut self, bufs: &[IoSlice<'_>]) -> Result<usize, Error>

Like write, except that it writes from a slice of buffers.

fn is_write_vectored(&self) -> bool

🔬This is a nightly-only experimental API. (can_vector)

Determines if this Writer has an efficient write_vectored implementation.

fn write_all(&mut self, buf: &[u8]) -> Result<(), Error>

Attempts to write an entire buffer into this writer.

fn write_all_vectored(&mut self, bufs: &mut [IoSlice<'_>]) -> Result<(), Error>

🔬This is a nightly-only experimental API. (write_all_vectored)

Attempts to write multiple buffers into this writer.

fn flush(&mut self) -> Result<(), Error>

Flushes this output stream, ensuring that all intermediately buffered contents reach their destination.

fn write_fmt(&mut self, args: Arguments<'_>) -> Result<(), Error>

Writes a formatted string into this writer, returning any error encountered.

fn by_ref(&mut self) -> &mut Self

where Self: Sized,

Creates a “by reference” adapter for this instance of Write.

impl<const N: usize> Write for Cursor<[u8; N]>

fn write(&mut self, buf: &[u8]) -> Result<usize, Error>

Writes a buffer into this writer, returning how many bytes were written.

fn write_vectored(&mut self, bufs: &[IoSlice<'_>]) -> Result<usize, Error>

Like write, except that it writes from a slice of buffers.

fn is_write_vectored(&self) -> bool

🔬This is a nightly-only experimental API. (can_vector)

Determines if this Writer has an efficient write_vectored implementation.

fn write_all(&mut self, buf: &[u8]) -> Result<(), Error>

Attempts to write an entire buffer into this writer.

fn write_all_vectored(&mut self, bufs: &mut [IoSlice<'_>]) -> Result<(), Error>

🔬This is a nightly-only experimental API. (write_all_vectored)

Attempts to write multiple buffers into this writer.

fn flush(&mut self) -> Result<(), Error>

Flushes this output stream, ensuring that all intermediately buffered contents reach their destination.

fn write_fmt(&mut self, args: Arguments<'_>) -> Result<(), Error>

Writes a formatted string into this writer, returning any error encountered.

fn by_ref(&mut self) -> &mut Self

where Self: Sized,

Creates a “by reference” adapter for this instance of Write.

impl<A> Write for Cursor<Box<[u8], A>>

where A: Allocator,

fn write(&mut self, buf: &[u8]) -> Result<usize, Error>

Writes a buffer into this writer, returning how many bytes were written.

fn write_vectored(&mut self, bufs: &[IoSlice<'_>]) -> Result<usize, Error>

Like write, except that it writes from a slice of buffers.

fn is_write_vectored(&self) -> bool

🔬This is a nightly-only experimental API. (can_vector)

Determines if this Writer has an efficient write_vectored implementation.

fn write_all(&mut self, buf: &[u8]) -> Result<(), Error>

Attempts to write an entire buffer into this writer.

fn write_all_vectored(&mut self, bufs: &mut [IoSlice<'_>]) -> Result<(), Error>

🔬This is a nightly-only experimental API. (write_all_vectored)

Attempts to write multiple buffers into this writer.

fn flush(&mut self) -> Result<(), Error>

Flushes this output stream, ensuring that all intermediately buffered contents reach their destination.

fn write_fmt(&mut self, args: Arguments<'_>) -> Result<(), Error>

Writes a formatted string into this writer, returning any error encountered.

fn by_ref(&mut self) -> &mut Self

where Self: Sized,

Creates a “by reference” adapter for this instance of Write.

impl<A> Write for Cursor<Vec<u8, A>>

where A: Allocator,

fn write(&mut self, buf: &[u8]) -> Result<usize, Error>

Writes a buffer into this writer, returning how many bytes were written.

fn write_vectored(&mut self, bufs: &[IoSlice<'_>]) -> Result<usize, Error>

Like write, except that it writes from a slice of buffers.

fn is_write_vectored(&self) -> bool

🔬This is a nightly-only experimental API. (can_vector)

Determines if this Writer has an efficient write_vectored implementation.

fn write_all(&mut self, buf: &[u8]) -> Result<(), Error>

Attempts to write an entire buffer into this writer.

fn write_all_vectored(&mut self, bufs: &mut [IoSlice<'_>]) -> Result<(), Error>

🔬This is a nightly-only experimental API. (write_all_vectored)

Attempts to write multiple buffers into this writer.

fn flush(&mut self) -> Result<(), Error>

Flushes this output stream, ensuring that all intermediately buffered contents reach their destination.

fn write_fmt(&mut self, args: Arguments<'_>) -> Result<(), Error>

Writes a formatted string into this writer, returning any error encountered.

fn by_ref(&mut self) -> &mut Self

where Self: Sized,

Creates a “by reference” adapter for this instance of Write.

impl<T> Eq for Cursor<T>

where T: Eq,

impl<T> StructuralPartialEq for Cursor<T>