Trait std::io::BufReadUnstable
[-] [+]
[src]
pub trait BufRead: Read { fn fill_buf(&mut self) -> Result<&[u8]>; fn consume(&mut self, amt: usize); fn read_until(&mut self, byte: u8, buf: &mut Vec<u8>) -> Result<()> { ... } fn read_line(&mut self, buf: &mut String) -> Result<()> { ... } }
A Buffer is a type of reader which has some form of internal buffering to allow certain kinds of reading operations to be more optimized than others.
This type extends the Read
trait with a few methods that are not
possible to reasonably implement with purely a read interface.
Required Methods
fn fill_buf(&mut self) -> Result<&[u8]>
Fills the internal buffer of this object, returning the buffer contents.
None of the contents will be "read" in the sense that later calling
read
may return the same contents.
The consume
function must be called with the number of bytes that are
consumed from this buffer returned to ensure that the bytes are never
returned twice.
An empty buffer returned indicates that the stream has reached EOF.
Errors
This function will return an I/O error if the underlying reader was read, but returned an error.
fn consume(&mut self, amt: usize)
Tells this buffer that amt
bytes have been consumed from the buffer,
so they should no longer be returned in calls to read
.
Provided Methods
fn read_until(&mut self, byte: u8, buf: &mut Vec<u8>) -> Result<()>
Read all bytes until the delimiter byte
is reached.
This function will continue to read (and buffer) bytes from the
underlying stream until the delimiter or EOF is found. Once found, all
bytes up to, and including, the delimiter (if found) will be appended to
buf
.
If this buffered reader is currently at EOF, then this function will not
place any more bytes into buf
and will return Ok(())
.
Errors
This function will ignore all instances of ErrorKind::Interrupted
and
will otherwise return any errors returned by fill_buf
.
If an I/O error is encountered then all bytes read so far will be
present in buf
and its length will have been adjusted appropriately.
fn read_line(&mut self, buf: &mut String) -> Result<()>
Read all bytes until a newline byte (the 0xA byte) is reached.
This function will continue to read (and buffer) bytes from the
underlying stream until the newline delimiter (the 0xA byte) or EOF is
found. Once found, all bytes up to, and including, the delimiter (if
found) will be appended to buf
.
If this reader is currently at EOF then this function will not modify
buf
and will return Ok(())
.
Errors
This function has the same error semantics as read_until
and will also
return an error if the read bytes are not valid UTF-8. If an I/O error
is encountered then buf
may contain some bytes already read in the
event that all data read so far was valid UTF-8.
Implementors
impl<R: Read> BufRead for BufReader<R>
impl<S: Read + Write> BufRead for BufStream<S>
impl<'a> BufRead for Cursor<&'a [u8]>
impl<'a> BufRead for Cursor<&'a mut [u8]>
impl<'a> BufRead for Cursor<Vec<u8>>
impl<'a, B: BufRead + ?Sized> BufRead for &'a mut B
impl<B: BufRead + ?Sized> BufRead for Box<B>
impl<'a> BufRead for &'a [u8]