Struct std::io::Take

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

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(())
}

1.27.0source

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(())
}

1.15.0source

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(())
}

1.20.0source

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(())
}

1.20.0source

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(())
}

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 String buffer. Read more

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fn split(self, byte: u8) -> Split<Self> ⓘ
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> ⓘ
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: BorrowedCursor<'_>) -> Result<()>

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

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

1.36.0source

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

1.6.0source

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, cursor: BorrowedCursor<'_>) -> Result<()>

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

Read the exact number of bytes required to fill cursor. 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> ⓘ
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> ⓘ
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> ⓘ
where
    Self: Sized,

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

Auto Trait Implementations

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

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

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

impl<T> Unpin for Take<T>
where
    T: Unpin,

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

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>,

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.

© 2010 The Rust Project Developers
Licensed under the Apache License, Version 2.0 or the MIT license, at your option.
https://doc.rust-lang.org/std/io/struct.Take.html

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Struct std::io::Take

Implementations

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Trait Implementations

Auto Trait Implementations

Blanket Implementations