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use std::io;
use futures::{Future, Poll};
use {AsyncRead, AsyncWrite};
#[derive(Debug)]
pub struct Copy<R, W> {
reader: Option<R>,
read_done: bool,
writer: Option<W>,
pos: usize,
cap: usize,
amt: u64,
buf: Box<[u8]>,
}
pub fn copy<R, W>(reader: R, writer: W) -> Copy<R, W>
where R: AsyncRead,
W: AsyncWrite,
{
Copy {
reader: Some(reader),
read_done: false,
writer: Some(writer),
amt: 0,
pos: 0,
cap: 0,
buf: Box::new([0; 2048]),
}
}
impl<R, W> Future for Copy<R, W>
where R: AsyncRead,
W: AsyncWrite,
{
type Item = (u64, R, W);
type Error = io::Error;
fn poll(&mut self) -> Poll<(u64, R, W), io::Error> {
loop {
if self.pos == self.cap && !self.read_done {
let reader = self.reader.as_mut().unwrap();
let n = try_nb!(reader.read(&mut self.buf));
if n == 0 {
self.read_done = true;
} else {
self.pos = 0;
self.cap = n;
}
}
while self.pos < self.cap {
let writer = self.writer.as_mut().unwrap();
let i = try_nb!(writer.write(&self.buf[self.pos..self.cap]));
if i == 0 {
return Err(io::Error::new(io::ErrorKind::WriteZero,
"write zero byte into writer"));
} else {
self.pos += i;
self.amt += i as u64;
}
}
if self.pos == self.cap && self.read_done {
try_nb!(self.writer.as_mut().unwrap().flush());
let reader = self.reader.take().unwrap();
let writer = self.writer.take().unwrap();
return Ok((self.amt, reader, writer).into())
}
}
}
}