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std: Destabilize io::BufStream

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As pointed out in #17136 the semantics of a `BufStream` aren't always what one
expects, and it looks like other [languages like C#][c-sharp] implement a
buffered stream with only one underlying buffer. For now this commit
destabilizes the primitive in the `std::io` module to give us some more time in
figuring out what to do with it.

[c-sharp]: https://msdn.microsoft.com/en-us/library/system.io.bufferedstream%28v=vs.110%29.aspx

[breaking-change]
This commit is contained in:
Alex Crichton 2015-04-30 15:45:48 -07:00
parent e962870420
commit db477eef72
1 changed files with 18 additions and 10 deletions
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28
src/libstd/io/buffered.rs
View file

@ -432,15 +432,19 @@ impl<W: Read + Write> Read for InternalBufWriter<W> {
/// infrequent calls to `read` and `write` on the underlying `Read+Write`.
///
/// The output buffer will be written out when this stream is dropped.
#[stable(feature = "rust1", since = "1.0.0")]
#[unstable(feature = "buf_stream",
reason = "unsure about semantics of buffering two directions, \
leading to issues like #17136")]
pub struct BufStream<S: Write> {
inner: BufReader<InternalBufWriter<S>>
}
#[unstable(feature = "buf_stream",
reason = "unsure about semantics of buffering two directions, \
leading to issues like #17136")]
impl<S: Read + Write> BufStream<S> {
/// Creates a new buffered stream with explicitly listed capacities for the
/// reader/writer buffer.
#[stable(feature = "rust1", since = "1.0.0")]
pub fn with_capacities(reader_cap: usize, writer_cap: usize, inner: S)
-> BufStream<S> {
let writer = BufWriter::with_capacity(writer_cap, inner);
@ -451,13 +455,11 @@ impl<S: Read + Write> BufStream<S> {
/// Creates a new buffered stream with the default reader/writer buffer
/// capacities.
#[stable(feature = "rust1", since = "1.0.0")]
pub fn new(inner: S) -> BufStream<S> {
BufStream::with_capacities(DEFAULT_BUF_SIZE, DEFAULT_BUF_SIZE, inner)
}
/// Gets a reference to the underlying stream.
#[stable(feature = "rust1", since = "1.0.0")]
pub fn get_ref(&self) -> &S {
let InternalBufWriter(ref w) = self.inner.inner;
w.get_ref()
@ -469,7 +471,6 @@ impl<S: Read + Write> BufStream<S> {
///
/// It is inadvisable to read directly from or write directly to the
/// underlying stream.
#[stable(feature = "rust1", since = "1.0.0")]
pub fn get_mut(&mut self) -> &mut S {
let InternalBufWriter(ref mut w) = self.inner.inner;
w.get_mut()
@ -479,7 +480,6 @@ impl<S: Read + Write> BufStream<S> {
///
/// The internal write buffer is written out before returning the stream.
/// Any leftover data in the read buffer is lost.
#[stable(feature = "rust1", since = "1.0.0")]
pub fn into_inner(self) -> Result<S, IntoInnerError<BufStream<S>>> {
let BufReader { inner: InternalBufWriter(w), buf, pos, cap } = self.inner;
w.into_inner().map_err(|IntoInnerError(w, e)| {
@ -490,20 +490,26 @@ impl<S: Read + Write> BufStream<S> {
}
}
#[stable(feature = "rust1", since = "1.0.0")]
#[unstable(feature = "buf_stream",
reason = "unsure about semantics of buffering two directions, \
leading to issues like #17136")]
impl<S: Read + Write> BufRead for BufStream<S> {
fn fill_buf(&mut self) -> io::Result<&[u8]> { self.inner.fill_buf() }
fn consume(&mut self, amt: usize) { self.inner.consume(amt) }
}
#[stable(feature = "rust1", since = "1.0.0")]
#[unstable(feature = "buf_stream",
reason = "unsure about semantics of buffering two directions, \
leading to issues like #17136")]
impl<S: Read + Write> Read for BufStream<S> {
fn read(&mut self, buf: &mut [u8]) -> io::Result<usize> {
self.inner.read(buf)
}
}
#[stable(feature = "rust1", since = "1.0.0")]
#[unstable(feature = "buf_stream",
reason = "unsure about semantics of buffering two directions, \
leading to issues like #17136")]
impl<S: Read + Write> Write for BufStream<S> {
fn write(&mut self, buf: &[u8]) -> io::Result<usize> {
self.inner.inner.get_mut().write(buf)
@ -513,7 +519,9 @@ impl<S: Read + Write> Write for BufStream<S> {
}
}
#[stable(feature = "rust1", since = "1.0.0")]
#[unstable(feature = "buf_stream",
reason = "unsure about semantics of buffering two directions, \
leading to issues like #17136")]
impl<S: Write> fmt::Debug for BufStream<S> where S: fmt::Debug {
fn fmt(&self, fmt: &mut fmt::Formatter) -> fmt::Result {
let reader = &self.inner;