# 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(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 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
```rust
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.
```rust
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:
```rust
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!()
}
```