Struct futures_codec::LengthCodec

pub struct LengthCodec;

A simple Codec implementation sending your data by prefixing it by its length.

Example

This codec will most likely be used wrapped in another codec like so.

use futures_codec::{Decoder, Encoder, LengthCodec};
use bytes::{Bytes, BytesMut};
use std::io::{Error, ErrorKind};

pub struct MyStringCodec(LengthCodec);

impl Encoder for MyStringCodec {
    type Item = String;
    type Error = Error;

    fn encode(&mut self, src: Self::Item, dst: &mut BytesMut) -> Result<(), Self::Error> {
        let bytes = Bytes::from(src);
        self.0.encode(bytes, dst)
    }
}

impl Decoder for MyStringCodec {
    type Item = String;
    type Error = Error;

    fn decode(&mut self, src: &mut BytesMut) -> Result<Option<Self::Item>, Self::Error> {
        match self.0.decode(src)? {
            Some(bytes) => {
                match String::from_utf8(bytes.to_vec()) {
                    Ok(string) => Ok(Some(string)),
                    Err(e) => Err(Error::new(ErrorKind::InvalidData, e))
                }
            },
            None => Ok(None),
        }
    }
}

Trait Implementations

impl Decoder for LengthCodec

type Item = Bytes

The type of items returned by decode

type Error = Error

The type of decoding errors.

fn decode(
    &mut self,
    src: &mut BytesMut
) -> Result<Option<Self::Item>, Self::Error>

Decode an item from the src BytesMut into an item

fn decode_eof(
    &mut self,
    src: &mut BytesMut
) -> Result<Option<Self::Item>, Self::Error>

Called when the input stream reaches EOF, signaling a last attempt to decode

impl Encoder for LengthCodec

type Item = Bytes

The type of items consumed by encode

type Error = Error

The type of encoding errors.

fn encode(
    &mut self,
    src: Self::Item,
    dst: &mut BytesMut
) -> Result<(), Self::Error>

Encodes an item into the BytesMut provided by dst.