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use std::io;
use std::io::{Error, ErrorKind, Read};
use std::fmt;
use crate::BufferedReader;
/// Always returns EOF.
#[derive(Debug)]
pub struct EOF<C> {
cookie: C,
}
assert_send_and_sync!(EOF<C>
where C: fmt::Debug);
impl<C> fmt::Display for EOF<C> {
fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
f.debug_struct("EOF")
.finish()
}
}
impl EOF<()> {
/// Instantiates a new `EOF`.
pub fn new() -> Self {
EOF {
cookie: (),
}
}
}
impl<C> EOF<C> {
/// Instantiates a new `EOF` with a cookie.
pub fn with_cookie(cookie: C) -> Self {
EOF {
cookie,
}
}
}
impl<C> Read for EOF<C> {
fn read(&mut self, _buf: &mut [u8]) -> Result<usize, io::Error> {
return Ok(0);
}
}
impl<C: fmt::Debug + Sync + Send> BufferedReader<C> for EOF<C> {
fn buffer(&self) -> &[u8] {
return &b""[..];
}
fn data(&mut self, _amount: usize) -> Result<&[u8], io::Error> {
return Ok(&b""[..]);
}
fn consume(&mut self, amount: usize) -> &[u8] {
assert_eq!(amount, 0);
return &b""[..];
}
fn data_consume(&mut self, _amount: usize) -> Result<&[u8], io::Error> {
return Ok(&b""[..]);
}
fn data_consume_hard(&mut self, amount: usize) -> Result<&[u8], io::Error> {
if amount == 0 {
Ok(&b""[..])
} else {
Err(Error::new(ErrorKind::UnexpectedEof, "unexpected EOF"))
}
}
fn into_inner<'a>(self: Box<Self>) -> Option<Box<dyn BufferedReader<C> + 'a>>
where Self: 'a
{
return None;
}
fn get_mut(&mut self) -> Option<&mut dyn BufferedReader<C>>
{
return None;
}
fn get_ref(&self) -> Option<&dyn BufferedReader<C>>
{
return None;
}
fn cookie_set(&mut self, cookie: C) -> C {
use std::mem;
mem::replace(&mut self.cookie, cookie)
}
fn cookie_ref(&self) -> &C {
&self.cookie
}
fn cookie_mut(&mut self) -> &mut C {
&mut self.cookie
}
}
#[cfg(test)]
mod test {
use super::*;
#[test]
fn basics() {
let mut reader = EOF::new();
assert_eq!(reader.buffer(), &b""[..]);
assert_eq!(reader.data(100).unwrap(), &b""[..]);
assert_eq!(reader.buffer(), &b""[..]);
assert_eq!(reader.consume(0), &b""[..]);
assert_eq!(reader.data_hard(0).unwrap(), &b""[..]);
assert!(reader.data_hard(1).is_err());
}
}
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