Struct std::io::Take
pub struct Take<T> { /* fields omitted */ }
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
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 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(()) }
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(()) }
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(()) }
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(()) }
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
impl<T: BufRead> BufRead for Take<T>
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
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
fn has_data_left(&mut self) -> Result<bool>
buf_read_has_data_left
#86423)recently added
Check if the underlying Read
has any data left to be read. Read more
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
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. Read more
impl<B: BufRead> Iterator for Split<B> type Item = Result<Vec<u8>>;
Returns an iterator over the contents of this reader split on the byte byte
. Read more
impl<B: BufRead> Iterator for Lines<B> type Item = Result<String>;
Returns an iterator over the lines of this reader. Read more
impl<T: Debug> Debug for Take<T>
fn fmt(&self, f: &mut Formatter<'_>) -> Result
Formats the value using the given formatter. Read more
impl<T: Read> Read for Take<T>
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
unsafe fn initializer(&self) -> Initializer
Determines if this Read
er can work with buffers of uninitialized memory. Read more
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
fn read_vectored(&mut self, bufs: &mut [IoSliceMut<'_>]) -> Result<usize>
Like read
, except that it reads into a slice of buffers. Read more
fn is_read_vectored(&self) -> bool
Determines if this Read
er has an efficient read_vectored
implementation. Read more
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
fn read_exact(&mut self, buf: &mut [u8]) -> Result<()>
Read the exact number of bytes required to fill buf
. Read more
Creates a “by reference” adapter for this instance of Read
. Read more
impl<R: Read> Iterator for Bytes<R> type Item = Result<u8>;
impl<T: Read, U: Read> Read for Chain<T, U>
Creates an adapter which will chain this stream with another. Read more
impl<T: Read> Read for Take<T>
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
impl<T> From<T> for T
pub fn from(t: T) -> T
Performs the conversion.
pub fn into(self) -> U
Performs the conversion.
type Error = Infallible
The type returned in the event of a conversion error.
pub fn try_from(value: U) -> Result<T, <T as TryFrom<U>>::Error>
Performs the conversion.
type Error = <U as TryFrom<T>>::Error
The type returned in the event of a conversion error.
pub 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