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Add BufWriter::buffer method #55211

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merged 4 commits into from
Nov 15, 2018
Merged

Add BufWriter::buffer method #55211

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7eece47
Add BufWriter::buffer method
fintelia Oct 19, 2018
07d966d
Add some tests
fintelia Oct 27, 2018
40e4144
Suggested edits
fintelia Nov 1, 2018
59a0309
Fix compile errors in test
fintelia Nov 1, 2018
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48 changes: 38 additions & 10 deletions src/libstd/io/buffered.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -525,6 +525,25 @@ impl<W: Write> BufWriter<W> {
#[stable(feature = "rust1", since = "1.0.0")]
pub fn get_mut(&mut self) -> &mut W { self.inner.as_mut().unwrap() }

/// Returns a reference to the internally buffered data.
///
/// # Examples
///
/// ```no_run
/// # #![feature(bufreader_buffer)]
/// use std::io::BufWriter;
/// use std::net::TcpStream;
///
/// let buf_writer = BufWriter::new(TcpStream::connect("127.0.0.1:34254").unwrap());
///
/// // See how many bytes are currently buffered
/// let bytes_buffered = buf_writer.buffer().len();
/// ```
#[unstable(feature = "bufreader_buffer", issue = "45323")]
pub fn buffer(&self) -> &[u8] {
&self.buf
}

/// Unwraps this `BufWriter`, returning the underlying writer.
///
/// The buffer is written out before returning the writer.
Expand Down Expand Up @@ -965,31 +984,31 @@ mod tests {
let mut buf = [0, 0, 0];
let nread = reader.read(&mut buf);
assert_eq!(nread.unwrap(), 3);
let b: &[_] = &[5, 6, 7];
assert_eq!(buf, b);
assert_eq!(buf, [5, 6, 7]);
assert_eq!(reader.buffer(), []);

let mut buf = [0, 0];
let nread = reader.read(&mut buf);
assert_eq!(nread.unwrap(), 2);
let b: &[_] = &[0, 1];
assert_eq!(buf, b);
assert_eq!(buf, [0, 1]);
assert_eq!(reader.buffer(), []);

let mut buf = [0];
let nread = reader.read(&mut buf);
assert_eq!(nread.unwrap(), 1);
let b: &[_] = &[2];
assert_eq!(buf, b);
assert_eq!(buf, [2]);
assert_eq!(reader.buffer(), [3]);

let mut buf = [0, 0, 0];
let nread = reader.read(&mut buf);
assert_eq!(nread.unwrap(), 1);
let b: &[_] = &[3, 0, 0];
assert_eq!(buf, b);
assert_eq!(buf, [3, 0, 0]);
assert_eq!(reader.buffer(), []);

let nread = reader.read(&mut buf);
assert_eq!(nread.unwrap(), 1);
let b: &[_] = &[4, 0, 0];
assert_eq!(buf, b);
assert_eq!(buf, [4, 0, 0]);
assert_eq!(reader.buffer(), []);

assert_eq!(reader.read(&mut buf).unwrap(), 0);
}
Expand Down Expand Up @@ -1078,31 +1097,40 @@ mod tests {
let mut writer = BufWriter::with_capacity(2, inner);

writer.write(&[0, 1]).unwrap();
assert_eq!(writer.buffer(), []);
assert_eq!(*writer.get_ref(), [0, 1]);

writer.write(&[2]).unwrap();
assert_eq!(writer.buffer(), [2]);
assert_eq!(*writer.get_ref(), [0, 1]);

writer.write(&[3]).unwrap();
assert_eq!(writer.buffer(), [2, 3]);
assert_eq!(*writer.get_ref(), [0, 1]);

writer.flush().unwrap();
assert_eq!(writer.buffer(), []);
assert_eq!(*writer.get_ref(), [0, 1, 2, 3]);

writer.write(&[4]).unwrap();
writer.write(&[5]).unwrap();
assert_eq!(writer.buffer(), [4, 5]);
assert_eq!(*writer.get_ref(), [0, 1, 2, 3]);

writer.write(&[6]).unwrap();
assert_eq!(writer.buffer(), [6]);
assert_eq!(*writer.get_ref(), [0, 1, 2, 3, 4, 5]);

writer.write(&[7, 8]).unwrap();
assert_eq!(writer.buffer(), []);
assert_eq!(*writer.get_ref(), [0, 1, 2, 3, 4, 5, 6, 7, 8]);

writer.write(&[9, 10, 11]).unwrap();
assert_eq!(writer.buffer(), []);
assert_eq!(*writer.get_ref(), [0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11]);

writer.flush().unwrap();
assert_eq!(writer.buffer(), []);
assert_eq!(*writer.get_ref(), [0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11]);
}

Expand Down