Take in alloc::io - Rust
Description: Reader adapter which limits the bytes read from an underlying reader.

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## Take

# Struct Take

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    #[non_exhaustive]pub struct Take<T> { /* private fields */ }

🔬This is a nightly-only experimental API. (`alloc_io` #154046)
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>

1.0.0 · Source

#### 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(())
    }

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#### pub fn position(&self) -> u64

🔬This is a nightly-only experimental API. (`seek_io_take_position` #97227)

Returns the number of bytes read so far.

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(())
    }

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(())
    }

1.20.0 · Source

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

Gets a 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_ref();
        Ok(())
    }

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(())
    }

## Trait Implementations§

1.0.0 · Source§

### impl<T> Debug for Take<T>
where T: Debug,

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

Formats the value using the given formatter. Read more

## Auto Trait Implementations§

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### impl<T> Freeze for Take<T>
where T: Freeze,

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

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

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

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

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### impl<T> UnsafeUnpin for Take<T>
where T: UnsafeUnpin,

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### 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>,

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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.