1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78

// Copyright 2020 Parity Technologies (UK) Ltd.
//
// Permission is hereby granted, free of charge, to any person obtaining a
// copy of this software and associated documentation files (the "Software"),
// to deal in the Software without restriction, including without limitation
// the rights to use, copy, modify, merge, publish, distribute, sublicense,
// and/or sell copies of the Software, and to permit persons to whom the
// Software is furnished to do so, subject to the following conditions:
//
// The above copyright notice and this permission notice shall be included in
// all copies or substantial portions of the Software.
//
// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS
// OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
// FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
// DEALINGS IN THE SOFTWARE.

use async_trait::async_trait;
use futures::prelude::*;
use std::io;

/// A `Codec` defines the request and response types
/// for a request-response [`Behaviour`](crate::Behaviour) protocol or
/// protocol family and how they are encoded / decoded on an I/O stream.
#[async_trait]
pub trait Codec {
    /// The type of protocol(s) or protocol versions being negotiated.
    type Protocol: AsRef<str> + Send + Clone;
    /// The type of inbound and outbound requests.
    type Request: Send;
    /// The type of inbound and outbound responses.
    type Response: Send;

    /// Reads a request from the given I/O stream according to the
    /// negotiated protocol.
    async fn read_request<T>(
        &mut self,
        protocol: &Self::Protocol,
        io: &mut T,
    ) -> io::Result<Self::Request>
    where
        T: AsyncRead + Unpin + Send;

    /// Reads a response from the given I/O stream according to the
    /// negotiated protocol.
    async fn read_response<T>(
        &mut self,
        protocol: &Self::Protocol,
        io: &mut T,
    ) -> io::Result<Self::Response>
    where
        T: AsyncRead + Unpin + Send;

    /// Writes a request to the given I/O stream according to the
    /// negotiated protocol.
    async fn write_request<T>(
        &mut self,
        protocol: &Self::Protocol,
        io: &mut T,
        req: Self::Request,
    ) -> io::Result<()>
    where
        T: AsyncWrite + Unpin + Send;

    /// Writes a response to the given I/O stream according to the
    /// negotiated protocol.
    async fn write_response<T>(
        &mut self,
        protocol: &Self::Protocol,
        io: &mut T,
        res: Self::Response,
    ) -> io::Result<()>
    where
        T: AsyncWrite + Unpin + Send;
}