blob: e7869cc198b67c9a2d605e2845aa786953ec505f [file] [log] [blame]
use std::io;
use std::mem;
use futures::{Poll, Future};
use AsyncRead;
/// A future which can be used to easily read the entire contents of a stream
/// into a vector.
///
/// Created by the [`read_to_end`] function.
///
/// [`read_to_end`]: fn.read_to_end.html
#[derive(Debug)]
pub struct ReadToEnd<A> {
state: State<A>,
}
#[derive(Debug)]
enum State<A> {
Reading {
a: A,
buf: Vec<u8>,
},
Empty,
}
/// Creates a future which will read all the bytes associated with the I/O
/// object `A` into the buffer provided.
///
/// In the case of an error the buffer and the object will be discarded, with
/// the error yielded. In the case of success both the object and the buffer
/// will be returned, with all data read from the stream appended to the buffer.
pub fn read_to_end<A>(a: A, buf: Vec<u8>) -> ReadToEnd<A>
where A: AsyncRead,
{
ReadToEnd {
state: State::Reading {
a: a,
buf: buf,
}
}
}
impl<A> Future for ReadToEnd<A>
where A: AsyncRead,
{
type Item = (A, Vec<u8>);
type Error = io::Error;
fn poll(&mut self) -> Poll<(A, Vec<u8>), io::Error> {
match self.state {
State::Reading { ref mut a, ref mut buf } => {
// If we get `Ok`, then we know the stream hit EOF and we're done. If we
// hit "would block" then all the read data so far is in our buffer, and
// otherwise we propagate errors
try_nb!(a.read_to_end(buf));
},
State::Empty => panic!("poll ReadToEnd after it's done"),
}
match mem::replace(&mut self.state, State::Empty) {
State::Reading { a, buf } => Ok((a, buf).into()),
State::Empty => unreachable!(),
}
}
}