Struct async_std::io::Take

pub struct Take<T> { /* fields omitted */ }

Reader adaptor which limits the bytes read from an underlying reader.

This struct is generally created by calling take on a reader. Please see the documentation of take for more details.

Implementations

impl<T> Take<T>

pub fn limit(&self) -> u64

Returns the number of bytes that can be read before this instance will return EOF.

Note

This instance may reach EOF after reading fewer bytes than indicated by this method if the underlying Read instance reaches EOF.

Examples

use async_std::prelude::*;
use async_std::fs::File;

let f = File::open("foo.txt").await?;

// read at most five bytes
let handle = f.take(5);

println!("limit: {}", handle.limit());

pub fn set_limit(&mut self, limit: u64)

Sets the number of bytes that can be read before this instance will return EOF. This is the same as constructing a new Take instance, so the amount of bytes read and the previous limit value don't matter when calling this method.

Examples

use async_std::prelude::*;
use async_std::fs::File;

let f = File::open("foo.txt").await?;

// read at most five bytes
let mut handle = f.take(5);
handle.set_limit(10);

assert_eq!(handle.limit(), 10);

pub fn into_inner(self) -> T

Consumes the Take, returning the wrapped reader.

Examples

use async_std::prelude::*;
use async_std::fs::File;

let file = File::open("foo.txt").await?;

let mut buffer = [0; 5];
let mut handle = file.take(5);
handle.read(&mut buffer).await?;

let file = handle.into_inner();

pub fn get_ref(&self) -> &T

Gets a reference to the underlying reader.

Examples

use async_std::prelude::*;
use async_std::fs::File;

let file = File::open("foo.txt").await?;

let mut buffer = [0; 5];
let mut handle = file.take(5);
handle.read(&mut buffer).await?;

let file = handle.get_ref();

pub fn get_mut(&mut self) -> &mut T

Gets a mutable reference to the underlying reader.

Care should be taken to avoid modifying the internal I/O state of the underlying reader as doing so may corrupt the internal limit of this Take.

Examples

use async_std::prelude::*;
use async_std::fs::File;

let file = File::open("foo.txt").await?;

let mut buffer = [0; 5];
let mut handle = file.take(5);
handle.read(&mut buffer).await?;

let file = handle.get_mut();

Trait Implementations

impl<T: BufRead> BufRead for Take<T>

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

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

pub 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 read.

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

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

pub fn read_line<'a>(
    &'a mut self,
    buf: &'a mut String
) -> ImplFuture<Result<usize>> where
    Self: Unpin, 

Reads all bytes and appends them into buf until a newline (the 0xA byte) is reached.

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

Returns a stream over the lines of this byte stream.

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

Returns a stream over the contents of this reader split on the byte byte.

impl<T: Debug> Debug for Take<T>

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

Formats the value using the given formatter.

impl<T: Read> Read for Take<T>

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

Attempt to read from the AsyncRead into buf.

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

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

pub fn read<'a>(&'a mut self, buf: &'a mut [u8]) -> ImplFuture<Result<usize>> where
    Self: Unpin, 

Reads some bytes from the byte stream.

pub fn read_vectored<'a>(
    &'a mut self,
    bufs: &'a mut [IoSliceMut<'a>]
) -> ImplFuture<Result<usize>> where
    Self: Unpin, 

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

pub fn read_to_end<'a>(
    &'a mut self,
    buf: &'a mut Vec<u8>
) -> ImplFuture<Result<usize>> where
    Self: Unpin, 

Reads all bytes from the byte stream.

pub fn read_to_string<'a>(
    &'a mut self,
    buf: &'a mut String
) -> ImplFuture<Result<usize>> where
    Self: Unpin, 

Reads all bytes from the byte stream and appends them into a string.

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

Reads the exact number of bytes required to fill buf.

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

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

pub fn by_ref(&mut self) -> &mut Self where
    Self: Sized, 

Creates a "by reference" adaptor for this instance of Read.

pub fn bytes(self) -> Bytes<Self> where
    Self: Sized, 

Transforms this Read instance to a Stream over its bytes.

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

Creates an adaptor which will chain this stream with another.

impl<'__pin, T> Unpin for Take<T> where
    __Origin<'__pin, T>: Unpin,