blob: 9fd2ef24067826a07b9530c37737de2dcb31d0e3 [file] [log] [blame]
use core::marker::Unpin;
use core::pin::PinMut;
use futures_core::stream::Stream;
use futures_core::task::{self, Poll};
use pin_utils::{unsafe_pinned, unsafe_unpinned};
/// A stream combinator which will change the type of a stream from one
/// type to another.
///
/// This is produced by the `Stream::map` method.
#[derive(Debug)]
#[must_use = "streams do nothing unless polled"]
pub struct Map<St, F> {
stream: St,
f: F,
}
impl<St: Unpin, F> Unpin for Map<St, F> {}
impl<St, T, F> Map<St, F>
where St: Stream,
F: FnMut(St::Item) -> T,
{
unsafe_pinned!(stream: St);
unsafe_unpinned!(f: F);
pub(super) fn new(stream: St, f: F) -> Map<St, F> {
Map { stream, f }
}
/// Acquires a reference to the underlying stream that this combinator is
/// pulling from.
pub fn get_ref(&self) -> &St {
&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 St {
&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) -> St {
self.stream
}
}
impl<St, F, T> Stream for Map<St, F>
where St: Stream,
F: FnMut(St::Item) -> T,
{
type Item = T;
fn poll_next(
mut self: PinMut<Self>,
cx: &mut task::Context
) -> Poll<Option<T>> {
let option = ready!(self.stream().poll_next(cx));
Poll::Ready(option.map(self.f()))
}
}
/* TODO
// Forwarding impl of Sink from the underlying stream
impl<S, F> Sink for Map<S, F>
where S: Sink
{
type SinkItem = S::SinkItem;
type SinkError = S::SinkError;
delegate_sink!(stream);
}
*/