blob: e39c31f34811c772921aa77983464e9dc675bd8e [file] [log] [blame]
use {Poll, Async};
use stream::Stream;
/// A stream which "fuse"s a stream once it's terminated.
///
/// Normally streams can behave unpredictably when used after they have already
/// finished, but `Fuse` continues to return `None` from `poll` forever when
/// finished.
#[derive(Debug)]
#[must_use = "streams do nothing unless polled"]
pub struct Fuse<S> {
stream: S,
done: bool,
}
// Forwarding impl of Sink from the underlying stream
impl<S> ::sink::Sink for Fuse<S>
where S: ::sink::Sink
{
type SinkItem = S::SinkItem;
type SinkError = S::SinkError;
fn start_send(&mut self, item: S::SinkItem) -> ::StartSend<S::SinkItem, S::SinkError> {
self.stream.start_send(item)
}
fn poll_complete(&mut self) -> Poll<(), S::SinkError> {
self.stream.poll_complete()
}
fn close(&mut self) -> Poll<(), S::SinkError> {
self.stream.close()
}
}
pub fn new<S: Stream>(s: S) -> Fuse<S> {
Fuse { stream: s, done: false }
}
impl<S: Stream> Stream for Fuse<S> {
type Item = S::Item;
type Error = S::Error;
fn poll(&mut self) -> Poll<Option<S::Item>, S::Error> {
if self.done {
Ok(Async::Ready(None))
} else {
let r = self.stream.poll();
if let Ok(Async::Ready(None)) = r {
self.done = true;
}
r
}
}
}
impl<S> Fuse<S> {
/// Returns whether the underlying stream has finished or not.
///
/// If this method returns `true`, then all future calls to poll are
/// guaranteed to return `None`. If this returns `false`, then the
/// underlying stream is still in use.
pub fn is_done(&self) -> bool {
self.done
}
/// Acquires a reference to the underlying stream that this combinator is
/// pulling from.
pub fn get_ref(&self) -> &S {
&self.stream
}
/// Acquires a mutable reference to the underlying stream that this
/// combinator is pulling from.
///
/// Note that care must be taken to avoid tampering with the state of the
/// stream which may otherwise confuse this combinator.
pub fn get_mut(&mut self) -> &mut S {
&mut self.stream
}
/// Consumes this combinator, returning the underlying stream.
///
/// Note that this may discard intermediate state of this combinator, so
/// care should be taken to avoid losing resources when this is called.
pub fn into_inner(self) -> S {
self.stream
}
}