Struct std::io::Take

1.0.0 · source ·

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

Expand description

Reader adapter 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

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impl<T> Take<T>

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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 std::io;
use std::io::prelude::*;
use std::fs::File;
fn main() -> io::Result<()> {
 let f = File::open("foo.txt")?;
 // read at most five bytes
 let handle = f.take(5);
 println!("limit: {}", handle.limit());
 Ok(())
}

Run

1.27.0 · source

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 std::io;
use std::io::prelude::*;
use std::fs::File;
fn main() -> io::Result<()> {
 let f = File::open("foo.txt")?;
 // read at most five bytes
 let mut handle = f.take(5);
 handle.set_limit(10);
 assert_eq!(handle.limit(), 10);
 Ok(())
}

Run

1.15.0 · source

pub fn into_inner(self) -> T

Consumes the Take, returning the wrapped reader.

Examples

use std::io;
use std::io::prelude::*;
use std::fs::File;
fn main() -> io::Result<()> {
 let mut file = File::open("foo.txt")?;
 let mut buffer = [0; 5];
 let mut handle = file.take(5);
 handle.read(&mut buffer)?;
 let file = handle.into_inner();
 Ok(())
}

Run

1.20.0 · source

pub fn get_ref(&self) -> &T

Gets a reference to the underlying reader.

Examples

use std::io;
use std::io::prelude::*;
use std::fs::File;
fn main() -> io::Result<()> {
 let mut file = File::open("foo.txt")?;
 let mut buffer = [0; 5];
 let mut handle = file.take(5);
 handle.read(&mut buffer)?;
 let file = handle.get_ref();
 Ok(())
}

Run

1.20.0 · source

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 std::io;
use std::io::prelude::*;
use std::fs::File;
fn main() -> io::Result<()> {
 let mut file = File::open("foo.txt")?;
 let mut buffer = [0; 5];
 let mut handle = file.take(5);
 handle.read(&mut buffer)?;
 let file = handle.get_mut();
 Ok(())
}

Run

Trait Implementations

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impl<T: BufRead> BufRead for Take<T>

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

Returns 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(&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. Read more

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

🔬 This is a nightly-only experimental API. (buf_read_has_data_left #86423)

Check if the underlying Read has any data left to be read. Read more

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

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

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

Read all bytes until a newline (the 0xA byte) is reached, and append them to the provided buffer. You do not need to clear the buffer before appending. Read more

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fn split(self, byte: u8) -> Split<Self>iNotable traits for Split<B>impl<B: BufRead> Iterator for Split<B> type Item = Result<Vec<u8>>; where
Self: Sized,

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

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fn lines(self) -> Lines<Self>iNotable traits for Lines<B>impl<B: BufRead> Iterator for Lines<B> type Item = Result<String>; where
Self: Sized,

Returns an iterator over the lines of this reader. Read more

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impl<T: Debug> Debug for Take<T>

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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<T: Read> Read for Take<T>

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

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

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fn read_buf(&mut self, buf: &mut ReadBuf<'_>) -> Result<()>

🔬 This is a nightly-only experimental API. (read_buf #78485)

Pull some bytes from this source into the specified buffer. Read more

1.36.0 · source

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

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

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fn is_read_vectored(&self) -> bool

🔬 This is a nightly-only experimental API. (can_vector #69941)

Determines if this Reader has an efficient read_vectored implementation. Read more

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

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

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

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

1.6.0 · source

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

Read the exact number of bytes required to fill buf. Read more

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fn read_buf_exact(&mut self, buf: &mut ReadBuf<'_>) -> Result<()>

🔬 This is a nightly-only experimental API. (read_buf #78485)

Read the exact number of bytes required to fill buf. Read more

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

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

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fn bytes(self) -> Bytes<Self>iNotable traits for Bytes<R>impl<R: Read> Iterator for Bytes<R> type Item = Result<u8>; where
Self: Sized,

Transforms this Read instance to an Iterator over its bytes. Read more

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fn chain<R: Read>(self, next: R) -> Chain<Self, R>iNotable traits for Chain<T, U>impl<T: Read, U: Read> Read for Chain<T, U> where
Self: Sized,

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

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fn take(self, limit: u64) -> Take<Self>iNotable traits for Take<T>impl<T: Read> Read for Take<T> where
Self: Sized,

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