futures_util::io

Struct Take

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pub struct Take<R> { /* private fields */ }
Available on crate feature io only.
Expand description

Reader for the take method.

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impl<R: AsyncRead> Take<R>

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pub fn limit(&self) -> u64

Returns the remaining 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 AsyncRead instance reaches EOF.

§Examples
use futures::io::{AsyncReadExt, Cursor};

let reader = Cursor::new(&b"12345678"[..]);
let mut buffer = [0; 2];

let mut take = reader.take(4);
let n = take.read(&mut buffer).await?;

assert_eq!(take.limit(), 2);
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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 futures::io::{AsyncReadExt, Cursor};

let reader = Cursor::new(&b"12345678"[..]);
let mut buffer = [0; 4];

let mut take = reader.take(4);
let n = take.read(&mut buffer).await?;

assert_eq!(n, 4);
assert_eq!(take.limit(), 0);

take.set_limit(10);
let n = take.read(&mut buffer).await?;
assert_eq!(n, 4);
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pub fn get_ref(&self) -> &R

Acquires a reference to the underlying sink or stream that this combinator is pulling from.

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

Acquires a mutable reference to the underlying sink or stream that this combinator is pulling from.

Note that care must be taken to avoid tampering with the state of the sink or stream which may otherwise confuse this combinator.

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pub fn get_pin_mut(self: Pin<&mut Self>) -> Pin<&mut R>

Acquires a pinned mutable reference to the underlying sink or stream that this combinator is pulling from.

Note that care must be taken to avoid tampering with the state of the sink or stream which may otherwise confuse this combinator.

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pub fn into_inner(self) -> R

Consumes this combinator, returning the underlying sink or stream.

Note that this may discard intermediate state of this combinator, so care should be taken to avoid losing resources when this is called.

Trait Implementations§

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impl<R: AsyncBufRead> AsyncBufRead for Take<R>

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fn poll_fill_buf( self: Pin<&mut Self>, cx: &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
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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
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impl<R: AsyncRead> AsyncRead for Take<R>

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

Attempt to read from the AsyncRead into buf. Read more
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fn poll_read_vectored( self: Pin<&mut Self>, cx: &mut Context<'_>, bufs: &mut [IoSliceMut<'_>], ) -> Poll<Result<usize, Error>>

Attempt to read from the AsyncRead into bufs using vectored IO operations. Read more
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impl<R: Debug> Debug for Take<R>

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

Formats the value using the given formatter. Read more
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impl<'__pin, R> Unpin for Take<R>
where __Origin<'__pin, R>: Unpin,

Auto Trait Implementations§

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impl<R> Freeze for Take<R>
where R: Freeze,

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impl<R> RefUnwindSafe for Take<R>
where R: RefUnwindSafe,

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impl<R> Send for Take<R>
where R: Send,

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impl<R> Sync for Take<R>
where R: Sync,

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impl<R> UnwindSafe for Take<R>
where R: UnwindSafe,

Blanket Implementations§

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

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fn type_id(&self) -> TypeId

Gets the TypeId of self. Read more
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impl<R> AsyncBufReadExt for R
where R: AsyncBufRead + ?Sized,

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

Available on crate feature io only.
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
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fn consume_unpin(&mut self, amt: usize)
where Self: Unpin,

Available on crate feature io only.
A convenience for calling AsyncBufRead::consume on Unpin IO types. Read more
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fn read_until<'a>( &'a mut self, byte: u8, buf: &'a mut Vec<u8>, ) -> ReadUntil<'a, Self>
where Self: Unpin,

Available on crate feature io only.
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
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fn read_line<'a>(&'a mut self, buf: &'a mut String) -> ReadLine<'a, Self>
where Self: Unpin,

Available on crate feature io only.
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
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fn lines(self) -> Lines<Self>
where Self: Sized,

Available on crate feature io only.
Returns a stream over the lines of this reader. This method is the async equivalent to BufRead::lines. Read more
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impl<R> AsyncReadExt for R
where R: AsyncRead + ?Sized,

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

Available on crate feature io only.
Creates an adaptor which will chain this stream with another. Read more
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fn read<'a>(&'a mut self, buf: &'a mut [u8]) -> Read<'a, Self>
where Self: Unpin,

Available on crate feature io only.
Tries to read some bytes directly into the given buf in asynchronous manner, returning a future type. Read more
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fn read_vectored<'a>( &'a mut self, bufs: &'a mut [IoSliceMut<'a>], ) -> ReadVectored<'a, Self>
where Self: Unpin,

Available on crate feature io only.
Creates a future which will read from the AsyncRead into bufs using vectored IO operations. Read more
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fn read_exact<'a>(&'a mut self, buf: &'a mut [u8]) -> ReadExact<'a, Self>
where Self: Unpin,

Available on crate feature io only.
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
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fn read_to_end<'a>(&'a mut self, buf: &'a mut Vec<u8>) -> ReadToEnd<'a, Self>
where Self: Unpin,

Available on crate feature io only.
Creates a future which will read all the bytes from this AsyncRead. Read more
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fn read_to_string<'a>( &'a mut self, buf: &'a mut String, ) -> ReadToString<'a, Self>
where Self: Unpin,

Available on crate feature io only.
Creates a future which will read all the bytes from this AsyncRead. Read more
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fn split(self) -> (ReadHalf<Self>, WriteHalf<Self>)
where Self: AsyncWrite + Sized,

Available on crate feature io only.
Helper method for splitting this read/write object into two halves. Read more
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fn take(self, limit: u64) -> Take<Self>
where Self: Sized,

Available on crate feature io only.
Creates an AsyncRead adapter which will read at most limit bytes from the underlying reader. Read more
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fn compat(self) -> Compat<Self>
where Self: Sized + Unpin,

Available on crate features io and io-compat only.
Wraps an AsyncRead in a compatibility wrapper that allows it to be used as a futures 0.1 / tokio-io 0.1 AsyncRead. If the wrapped type implements AsyncWrite as well, the result will also implement the futures 0.1 / tokio 0.1 AsyncWrite trait. Read more
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impl<T> Borrow<T> for T
where T: ?Sized,

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fn borrow(&self) -> &T

Immutably borrows from an owned value. Read more
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impl<T> BorrowMut<T> for T
where T: ?Sized,

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

Mutably borrows from an owned value. Read more
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impl<T> From<T> for T

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fn from(t: T) -> T

Returns the argument unchanged.

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

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fn into(self) -> U

Calls U::from(self).

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

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

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type Error = Infallible

The type returned in the event of a conversion error.
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fn try_from(value: U) -> Result<T, <T as TryFrom<U>>::Error>

Performs the conversion.
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impl<T, U> TryInto<U> for T
where U: TryFrom<T>,

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type Error = <U as TryFrom<T>>::Error

The type returned in the event of a conversion error.
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fn try_into(self) -> Result<U, <U as TryFrom<T>>::Error>

Performs the conversion.