use crate::resources::DenoAsyncWrite;
use deno::ErrBox;
use futures::{Future, Poll};
use std::mem;
#[derive(Debug)]
pub struct Write<A, T> {
state: State<A, T>,
}
#[derive(Debug)]
enum State<A, T> {
Pending { a: A, buf: T },
Empty,
}
pub fn write<A, T>(a: A, buf: T) -> Write<A, T>
where
A: DenoAsyncWrite,
T: AsRef<[u8]>,
{
Write {
state: State::Pending { a, buf },
}
}
impl<A, T> Future for Write<A, T>
where
A: DenoAsyncWrite,
T: AsRef<[u8]>,
{
type Item = (A, T, usize);
type Error = ErrBox;
fn poll(&mut self) -> Poll<(A, T, usize), ErrBox> {
let nwritten = match self.state {
State::Pending {
ref mut a,
ref mut buf,
} => try_ready!(a.poll_write(buf.as_ref())),
State::Empty => panic!("poll a Read after it's done"),
};
match mem::replace(&mut self.state, State::Empty) {
State::Pending { a, buf } => Ok((a, buf, nwritten).into()),
State::Empty => panic!("invalid internal state"),
}
}
}