blob: d000f1b9c12fe01d089ecf48d430b6acd2a31942 [file] [log] [blame]
use std::io;
use std::mem;
use futures::{Poll, Future};
use AsyncWrite;
/// A future used to write the entire contents of some data to a stream.
///
/// This is created by the [`write_all`] top-level method.
///
/// [`write_all`]: fn.write_all.html
#[derive(Debug)]
pub struct WriteAll<A, T> {
state: State<A, T>,
}
#[derive(Debug)]
enum State<A, T> {
Writing {
a: A,
buf: T,
pos: usize,
},
Empty,
}
/// Creates a future that will write the entire contents of the buffer `buf` to
/// the stream `a` provided.
///
/// The returned future will not return until all the data has been written, and
/// the future will resolve to the stream as well as the buffer (for reuse if
/// needed).
///
/// Any error which happens during writing will cause both the stream and the
/// buffer to get destroyed.
///
/// The `buf` parameter here only requires the `AsRef<[u8]>` trait, which should
/// be broadly applicable to accepting data which can be converted to a slice.
/// The `Window` struct is also available in this crate to provide a different
/// window into a slice if necessary.
pub fn write_all<A, T>(a: A, buf: T) -> WriteAll<A, T>
where A: AsyncWrite,
T: AsRef<[u8]>,
{
WriteAll {
state: State::Writing {
a: a,
buf: buf,
pos: 0,
},
}
}
fn zero_write() -> io::Error {
io::Error::new(io::ErrorKind::WriteZero, "zero-length write")
}
impl<A, T> Future for WriteAll<A, T>
where A: AsyncWrite,
T: AsRef<[u8]>,
{
type Item = (A, T);
type Error = io::Error;
fn poll(&mut self) -> Poll<(A, T), io::Error> {
match self.state {
State::Writing { ref mut a, ref buf, ref mut pos } => {
let buf = buf.as_ref();
while *pos < buf.len() {
let n = try_nb!(a.write(&buf[*pos..]));
*pos += n;
if n == 0 {
return Err(zero_write())
}
}
}
State::Empty => panic!("poll a WriteAll after it's done"),
}
match mem::replace(&mut self.state, State::Empty) {
State::Writing { a, buf, .. } => Ok((a, buf).into()),
State::Empty => panic!(),
}
}
}