Trait tk_bufstream::Decode
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[src]
pub trait Decode: Sized { type Item; fn decode(&mut self, buf: &mut Buf) -> Result<Option<Self::Item>, Error>; fn done(&mut self, buf: &mut Buf) -> Result<Self::Item> { ... } }
Decoding of a frame from an internal buffer.
This trait is used when constructing an instance of Framed
. It defines how
to decode the incoming bytes on a stream to the specified type of frame for
that framed I/O stream.
The primary method of this trait, decode
, attempts to decode a
frame from a buffer of bytes. It has the option of returning NotReady
,
indicating that more bytes need to be read before decoding can
continue.
Associated Types
type Item
Decoded message
Required Methods
fn decode(&mut self, buf: &mut Buf) -> Result<Option<Self::Item>, Error>
Attempts to decode a frame from the provided buffer of bytes.
This method is called by Framed
whenever bytes are ready to be parsed.
The provided buffer of bytes is what's been read so far, and this
instance of Decode
can determine whether an entire frame is in the
buffer and is ready to be returned.
If an entire frame is available, then this instance will remove those bytes from the buffer provided and return them as a decoded frame. Note that removing bytes from the provided buffer doesn't always necessarily copy the bytes, so this should be an efficient operation in most circumstances.
If the bytes look valid, but a frame isn't fully available yet, then
Ok(None)
is returned. This indicates to the Framed
instance that
it needs to read some more bytes before calling this method again.
Finally, if the bytes in the buffer are malformed then an error is
returned indicating why. This informs Framed
that the stream is now
corrupt and should be terminated.
Provided Methods
fn done(&mut self, buf: &mut Buf) -> Result<Self::Item>
A default method available to be called when there are no more bytes available to be read from the underlying I/O.
This method defaults to calling decode
and returns an error if
Ok(None)
is returned. Typically this doesn't need to be implemented
unless the framing protocol differs near the end of the stream.