1use bytes::BytesMut;
2use std::io;
3
4/// Trait of helper objects to write out messages as bytes, for use with
5/// [`FramedWrite`].
6///
7/// [`FramedWrite`]: crate::codec::FramedWrite
8pub trait Encoder<Item> {
9 /// The type of encoding errors.
10 ///
11 /// [`FramedWrite`] requires `Encoder`s errors to implement `From<io::Error>`
12 /// in the interest of letting it return `Error`s directly.
13 ///
14 /// [`FramedWrite`]: crate::codec::FramedWrite
15 type Error: From<io::Error>;
16
17 /// Encodes a frame into the buffer provided.
18 ///
19 /// This method will encode `item` into the byte buffer provided by `dst`.
20 /// The `dst` provided is an internal buffer of the [`FramedWrite`] instance and
21 /// will be written out when possible.
22 ///
23 /// [`FramedWrite`]: crate::codec::FramedWrite
24 fn encode(&mut self, item: Item, dst: &mut BytesMut) -> Result<(), Self::Error>;
25}
26