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use alloc::boxed::Box;
use core::error::Error;
// use std::io;
use crate::write::internals::WriteExt;
use core::task::Poll;
use core::{pin::Pin, task::Context};
use either::Either;
use embedded_io_async::Write;
use futures::{AsyncRead, AsyncWrite, Future};
use pin_project::pin_project;
// use crate::MutexFuture;
#[pin_project]
pub struct SimpleAsyncWriter<R: Write>
where
R: embedded_io_async::Write,
{
state: internals::State<R>,
}
impl<R: Write> SimpleAsyncWriter<R> {
pub fn new(r: R) -> Self {
return Self {
state: internals::State::Idle(r),
};
}
}
type BoxFut<T> = Pin<Box<dyn Future<Output = T> + Send>>;
mod internals {
use super::*;
pub trait WriteExt: embedded_io_async::Write + Sized {
type Written: Future<Output = (Self, Result<usize, Self::Error>)>;
type Flushed: Future<Output = (Self, Result<(), Self::Error>)>;
fn get_future(
this: Pin<&mut SimpleAsyncWriter<Self>>,
buf: Option<&[u8]>,
) -> Either<Pin<Box<Self::Written>>, Pin<Box<Self::Flushed>>>;
}
impl<R: embedded_io_async::Write> WriteExt for R {
type Written = impl Future<Output = (Self, Result<usize, Self::Error>)>;
type Flushed = impl Future<Output = (Self, Result<(), Self::Error>)>;
fn get_future(
this: Pin<&mut SimpleAsyncWriter<Self>>,
buf: Option<&[u8]>,
) -> Either<Pin<Box<Self::Written>>, Pin<Box<Self::Flushed>>> {
let proj = this.project();
let mut state = State::Transitional;
std::mem::swap(proj.state, &mut state);
let buf = buf.map(|a| a.to_vec());
let mut fut = match state {
State::Idle(mut inner) => match buf {
Some(buf) => Either::Left(Box::pin(async move {
let res = inner.write(&buf).await;
(inner, res)
})),
None => Either::Right(Box::pin(async move {
let res = inner.flush().await;
(inner, res)
})),
},
State::Pending(fut) => {
// tracing::debug!("polling existing future...");
Either::Left(fut)
}
State::Transitional => unreachable!(),
State::FPending(pin) => Either::Right(pin),
};
return fut;
}
}
// pub type Written<R: Write> = impl Future<Output = (R, Result<usize, R::Error>)>;
// pub type Flushed<R: Write> = impl Future<Output = (R, Result<(), R::Error>)>;
pub enum State<R: Write> {
Idle(R),
Pending(Pin<Box<<R as WriteExt>::Written>>),
FPending(Pin<Box<<R as WriteExt>::Flushed>>),
Transitional,
}
#[cfg(feature = "futures")]
impl<R> AsyncWrite for SimpleAsyncWriter<R>
where
// new: R must now be `'static`, since it's captured
// by the future which is, itself, `'static`.
R: embedded_io_async::Write,
R::Error: Into<std::io::Error>,
{
fn poll_write(
mut self: Pin<&mut Self>,
cx: &mut Context<'_>,
buf: &[u8],
) -> Poll<std::io::Result<usize>> {
let mut fut = WriteExt::get_future(self.as_mut(), Some(buf));
let proj = self.project();
match match fut.as_mut() {
Either::Left(a) => a.as_mut().poll(cx).map(Either::Left),
Either::Right(b) => b.as_mut().poll(cx).map(Either::Right),
} {
Poll::Ready(Either::Left((inner, result))) => {
// tracing::debug!("future was ready!");
// if let Ok(n) = &result {
// let n = *n;
// // unsafe { internal_buf.set_len(n) }
// // let dst = &mut buf[..n];
// // let src = &internal_buf[..];
// // dst.copy_from_slice(src);
// } else {
// // unsafe { internal_buf.set_len(0) }
// }
*proj.state = State::Idle(inner);
Poll::Ready(result.map_err(|e| e.into()))
}
_ => {
// tracing::debug!("future was pending!");
*proj.state = match fut {
Either::Left(a) => State::Pending(a),
Either::Right(b) => State::FPending(b),
};
Poll::Pending
}
}
}
fn poll_flush(mut self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<std::io::Result<()>> {
let mut fut = WriteExt::get_future(self.as_mut(), None);
let proj = self.project();
match match fut.as_mut() {
Either::Left(a) => a.as_mut().poll(cx).map(Either::Left),
Either::Right(b) => b.as_mut().poll(cx).map(Either::Right),
} {
Poll::Ready(Either::Right((inner, result))) => {
// tracing::debug!("future was ready!");
// if let Ok(n) = &result {
// let n = *n;
// // unsafe { internal_buf.set_len(n) }
// // let dst = &mut buf[..n];
// // let src = &internal_buf[..];
// // dst.copy_from_slice(src);
// } else {
// // unsafe { internal_buf.set_len(0) }
// }
*proj.state = State::Idle(inner);
Poll::Ready(result.map_err(|e| e.into()))
}
_ => {
// tracing::debug!("future was pending!");
*proj.state = match fut {
Either::Left(a) => State::Pending(a),
Either::Right(b) => State::FPending(b),
};
Poll::Pending
}
}
}
fn poll_close(self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<std::io::Result<()>> {
return Poll::Ready(Ok(()));
}
}
}
impl<R: embedded_io_async::Write> SimpleAsyncWriter<R> {
pub fn poll_write(
mut self: Pin<&mut Self>,
cx: &mut Context<'_>,
buf: &[u8],
) -> Poll<Result<usize, R::Error>> {
let mut fut = WriteExt::get_future(self.as_mut(), Some(buf));
let proj = self.project();
match match fut.as_mut() {
Either::Left(a) => a.as_mut().poll(cx).map(Either::Left),
Either::Right(b) => b.as_mut().poll(cx).map(Either::Right),
} {
Poll::Ready(Either::Left((inner, result))) => {
// tracing::debug!("future was ready!");
// if let Ok(n) = &result {
// let n = *n;
// // unsafe { internal_buf.set_len(n) }
// // let dst = &mut buf[..n];
// // let src = &internal_buf[..];
// // dst.copy_from_slice(src);
// } else {
// // unsafe { internal_buf.set_len(0) }
// }
*proj.state = internals::State::Idle(inner);
Poll::Ready(result.map_err(|e| e.into()))
}
_ => {
// tracing::debug!("future was pending!");
*proj.state = match fut {
Either::Left(a) => internals::State::Pending(a),
Either::Right(b) => internals::State::FPending(b),
};
Poll::Pending
}
}
}
pub fn poll_flush(
mut self: Pin<&mut Self>,
cx: &mut Context<'_>,
) -> Poll<Result<(), R::Error>> {
let mut fut = WriteExt::get_future(self.as_mut(), None);
let proj = self.project();
match match fut.as_mut() {
Either::Left(a) => a.as_mut().poll(cx).map(Either::Left),
Either::Right(b) => b.as_mut().poll(cx).map(Either::Right),
} {
Poll::Ready(Either::Right((inner, result))) => {
// tracing::debug!("future was ready!");
// if let Ok(n) = &result {
// let n = *n;
// // unsafe { internal_buf.set_len(n) }
// // let dst = &mut buf[..n];
// // let src = &internal_buf[..];
// // dst.copy_from_slice(src);
// } else {
// // unsafe { internal_buf.set_len(0) }
// }
*proj.state = internals::State::Idle(inner);
Poll::Ready(result.map_err(|e| e.into()))
}
_ => {
// tracing::debug!("future was pending!");
*proj.state = match fut {
Either::Left(a) => internals::State::Pending(a),
Either::Right(b) => internals::State::FPending(b),
};
Poll::Pending
}
}
}
}