derive-io

A Rust crate that provides derive macros for implementing sync and async I/O traits on structs and enums (including Tokio, stdlib I/O, and more).

Supported traits

• #[derive(Read)]: std::io::Read
• #[derive(BufRead)]: std:io::BufRead
• #[derive(Write)]: std::io::Write
• #[derive(AsyncRead)]: tokio::io::AsyncRead
• #[derive(AsyncWrite)]: tokio::io::AsyncWrite
• #[derive(AsFileDescriptor)]:
  • std::os::fd::{AsFd, AsRawFd}
  • std::os::windows::io::{AsHandle, AsRawHandle}
• #[derive(AsSocketDescriptor)]:
  • std::os::fd::{AsFd, AsRawFd}
  • std::os::windows::io::{AsSocket, AsRawSocket}

Features

• Derive most common I/O traits for structs and enums
• Support for both named and tuple structs
• Support for enums with multiple variants
• Support for split read/write streams
• Support for generic types
• Individual methods can be overridden with custom implementations
• Support for as_ref or deref attribute on fields to delegate to the inner type
  • Note: for traits requiring a pinned-self (ie: async read/write), the holder type must be Unpin!

Tokio

use tokio::net::*;
use derive_io::{AsyncRead, AsyncWrite, AsSocketDescriptor};

#[derive(AsyncRead, AsyncWrite, AsSocketDescriptor)]
pub enum TokioStreams {
    Tcp(#[read] #[write] #[descriptor] TcpStream),
    #[cfg(unix)]
    Unix(#[read] #[write] #[descriptor] UnixStream),
    Split{ 
        #[read] #[descriptor(as_ref)] read: tokio::net::tcp::OwnedReadHalf, 
        #[write] write: tokio::net::tcp::OwnedWriteHalf,
    },
}

Generic types are supported. The generated implementations will automatically add a where clause to the impl block for each stream type.

use derive_io::{AsyncRead, AsyncWrite};

#[derive(AsyncRead, AsyncWrite)]
pub struct Generic<S> { // where S: AsyncRead + AsyncWrite
    #[read]
    #[write]
    stream: S,
}

Override one method in the write implementation:

use derive_io::{AsyncRead, AsyncWrite};

#[derive(AsyncRead, AsyncWrite)]
pub struct Override {
    #[read]
    #[write(poll_write=override_poll_write)]
    stream: tokio::net::TcpStream,
}

pub fn override_poll_write(
    stm: std::pin::Pin<&mut tokio::net::TcpStream>,
    cx: &mut std::task::Context<'_>,
    buf: &[u8],
) -> std::task::Poll<std::io::Result<usize>> {
    todo!()
}