blob: f91d26a45c96a3f8dc4577322bf84338e1148254 [file] [log] [blame]
use {Async, Poll};
use stream::Stream;
/// A combinator used to filter the results of a stream and simultaneously map
/// them to a different type.
///
/// This structure is returned by the `Stream::filter_map` method.
#[derive(Debug)]
#[must_use = "streams do nothing unless polled"]
pub struct FilterMap<S, F> {
stream: S,
f: F,
}
pub fn new<S, F, B>(s: S, f: F) -> FilterMap<S, F>
where S: Stream,
F: FnMut(S::Item) -> Option<B>,
{
FilterMap {
stream: s,
f: f,
}
}
impl<S, F> FilterMap<S, F> {
/// 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
}
}
// Forwarding impl of Sink from the underlying stream
impl<S, F> ::sink::Sink for FilterMap<S, F>
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()
}
}
impl<S, F, B> Stream for FilterMap<S, F>
where S: Stream,
F: FnMut(S::Item) -> Option<B>,
{
type Item = B;
type Error = S::Error;
fn poll(&mut self) -> Poll<Option<B>, S::Error> {
loop {
match try_ready!(self.stream.poll()) {
Some(e) => {
if let Some(e) = (self.f)(e) {
return Ok(Async::Ready(Some(e)))
}
}
None => return Ok(Async::Ready(None)),
}
}
}
}