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use std::io;
use std::fmt;
use crate::BufferedReader;
/// References a `BufferedReader`.
///
/// This is a non-owning mutable reference type for the buffered
/// reader framework. It can be used to retain ownership of the
/// reader when using interfaces that consume the reader.
#[derive(Debug)]
pub struct Mut<'a, T, C>
where
T: BufferedReader<C>,
C: Default + fmt::Debug + Sync + Send,
{
cookie: C,
reader: &'a mut T,
}
// There is a bug in assert_send_and_sync that prevents us from
// declaring multiple trait bounds on C. As a quick workaround, we
// define a local alias that combines Default and Debug for the sole
// benefit of the assert_send_and_sync macro.
mod appease_macro {
pub(crate) trait DefaultDebug: Default + std::fmt::Debug {}
assert_send_and_sync!(super::Mut<'_, T, C>
where T: crate::BufferedReader<C>,
C: DefaultDebug);
}
impl<'a, T, C> fmt::Display for Mut<'a, T, C>
where
T: BufferedReader<C>,
C: Default + fmt::Debug + Sync + Send,
{
fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
f.debug_struct("Mut")
.finish()
}
}
impl<'a, T: BufferedReader<()>> Mut<'a, T, ()> {
/// Makes a new mutable reference.
///
/// `reader` is the source to reference.
pub fn new(reader: &'a mut T) -> Self {
Self::with_cookie(reader, ())
}
}
impl<'a, T, C> Mut<'a, T, C>
where
T: BufferedReader<C>,
C: Default + fmt::Debug + Sync + Send,
{
/// Like [`Mut::new`], but sets a cookie.
///
/// The cookie can be retrieved using the [`Mut::cookie_ref`] and
/// [`Mut::cookie_mut`] methods, and set using the
/// [`Mut::cookie_set`] method.
pub fn with_cookie(reader: &'a mut T, cookie: C)
-> Mut<T, C> {
Mut {
reader,
cookie,
}
}
}
impl<'a, T, C> io::Read for Mut<'a, T, C>
where
T: BufferedReader<C>,
C: Default + fmt::Debug + Sync + Send,
{
fn read(&mut self, buf: &mut [u8]) -> Result<usize, io::Error> {
self.reader.read(buf)
}
}
impl<'a, T, C> BufferedReader<C> for Mut<'a, T, C>
where
T: BufferedReader<C>,
C: Default + fmt::Debug + Sync + Send,
{
fn buffer(&self) -> &[u8] {
self.reader.buffer()
}
fn data(&mut self, amount: usize) -> Result<&[u8], io::Error> {
self.reader.data(amount)
}
fn data_hard(&mut self, amount: usize) -> Result<&[u8], io::Error> {
self.reader.data_hard(amount)
}
fn data_eof(&mut self) -> Result<&[u8], io::Error> {
self.reader.data_eof()
}
fn consume(&mut self, amount: usize) -> &[u8] {
self.reader.consume(amount)
}
fn data_consume(&mut self, amount: usize)
-> Result<&[u8], std::io::Error> {
self.reader.data_consume(amount)
}
fn data_consume_hard(&mut self, amount: usize) -> Result<&[u8], io::Error> {
self.reader.data_consume_hard(amount)
}
fn consummated(&mut self) -> bool {
self.reader.consummated()
}
fn read_be_u16(&mut self) -> Result<u16, std::io::Error> {
self.reader.read_be_u16()
}
fn read_be_u32(&mut self) -> Result<u32, std::io::Error> {
self.reader.read_be_u32()
}
fn read_to(&mut self, terminal: u8) -> Result<&[u8], std::io::Error>
{
self.reader.read_to(terminal)
}
fn steal(&mut self, amount: usize) -> Result<Vec<u8>, std::io::Error> {
self.reader.steal(amount)
}
fn steal_eof(&mut self) -> Result<Vec<u8>, std::io::Error> {
self.reader.steal_eof()
}
fn drop_eof(&mut self) -> Result<bool, std::io::Error> {
self.reader.drop_eof()
}
fn get_mut(&mut self) -> Option<&mut dyn BufferedReader<C>> {
self.reader.get_mut()
}
fn get_ref(&self) -> Option<&dyn BufferedReader<C>> {
self.reader.get_ref()
}
/// This will always return a newly constructed [`EOF`](crate::EOF) here.
///
/// This method cannot fail, therefore we return a dummy.
fn as_boxed<'b>(self) -> Box<dyn BufferedReader<C> + 'b>
where Self: 'b
{
// We construct an EOF here, because this operation is not
// fallible.
Box::new(crate::EOF::with_cookie(C::default()))
}
/// This will always return `None`.
fn into_inner<'b>(self: Box<Self>) -> Option<Box<dyn BufferedReader<C> + 'b>>
where Self: 'b {
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 mutable_reference() {
use crate::Memory;
const DATA : &[u8] = b"01234567890123456789suffix";
let mut mem = Memory::new(DATA);
/// API that consumes the memory reader.
fn parse_ten_bytes<B: BufferedReader<()>>(mut r: B) {
let d = r.data_consume_hard(10).unwrap();
assert!(d.len() >= 10);
assert_eq!(&d[..10], &DATA[..10]);
drop(r); // We consumed the reader.
}
parse_ten_bytes(Mut::new(&mut mem));
parse_ten_bytes(Mut::new(&mut mem));
let suffix = mem.data_eof().unwrap();
assert_eq!(suffix, b"suffix");
}
}
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