Struct iowrap::Eof

pub struct Eof<R: Read> { /* private fields */ }

Track whether a stream has hit the end of file.

This allows slightly nicer code when reading lots of items using an uncooperative api, or when you want an UnexpectedEof only after the first byte. It also simplifies determining the last chunk when processing input in fixed-size chunks.

Eof::eof() and – for consistency – the Read implementation of Eof ignore ErrorKind::Interrupted errors and retry the operation.

Example

use std::io;
use std::io::Read;
use std::fs::File;
use iowrap::Eof;

fn load() -> io::Result<Vec<u64>> {
  let mut ret = Vec::new();
  let mut file = Eof::new(File::open("foo.bin")?);
  while !file.eof()? {
    ret.push(third_party::parse_thing(&mut file));
  }
  Ok(ret)
}

mod third_party {
  use std::io::Read;
  pub fn parse_thing<R: Read>(mut from: R) -> u64 {
    let mut buf = [0u8; 8];
    from.read_exact(&mut buf).unwrap();
    u64::from(buf[0]) // oops!
  }
}

Implementations

impl<R: Read> Eof<R>

pub fn new(inner: R) -> Self

pub fn eof(&mut self) -> Result<bool>

Test if we are at the end of the stream. If false, then a proceeding read() will always succeed.

pub fn held_state(&self) -> Option<u8>

The buffered value, which we read while checking for EOF.

pub fn get_ref(&self) -> &R

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

pub fn into_inner(self) -> R

Trait Implementations

impl<R: Read> Read for Eof<R>

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

For consistency with eof(), this implementation retries the operation on ErrorKind::Interrupted errors.

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

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

fn is_read_vectored(&self) -> bool

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

Determines if this Reader has an efficient read_vectored implementation.

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

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

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

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

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

Read the exact number of bytes required to fill buf.

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

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

Pull some bytes from this source into the specified buffer.

fn read_buf_exact(&mut self, cursor: BorrowedCursor<'_>) -> Result<(), Error>

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

Read the exact number of bytes required to fill cursor.

fn by_ref(&mut self) -> &mut Self

where Self: Sized,

Creates a “by reference” adaptor for this instance of Read.

fn bytes(self) -> Bytes<Self>

where Self: Sized,

Transforms this Read instance to an Iterator over its bytes.

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

where R: Read, Self: Sized,

Creates an adapter which will chain this stream with another.

fn take(self, limit: u64) -> Take<Self>

where Self: Sized,

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