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use core::fmt;
use core::pin::Pin;
use futures_core::stream::{FusedStream, Stream};
use futures_core::task::{Context, Poll};
#[cfg(feature = "sink")]
use futures_sink::Sink;
use pin_utils::{unsafe_pinned, unsafe_unpinned};
/// Stream for the [`map`](super::StreamExt::map) method.
#[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, F> fmt::Debug for Map<St, F>
where
St: fmt::Debug,
{
fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
f.debug_struct("Map")
.field("stream", &self.stream)
.finish()
}
}
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
}
/// Acquires a pinned 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_pin_mut(self: Pin<&mut Self>) -> Pin<&mut St> {
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> FusedStream for Map<St, F>
where St: FusedStream,
F: FnMut(St::Item) -> T,
{
fn is_terminated(&self) -> bool {
self.stream.is_terminated()
}
}
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: Pin<&mut Self>,
cx: &mut Context<'_>,
) -> Poll<Option<T>> {
self.as_mut()
.stream()
.poll_next(cx)
.map(|opt| opt.map(|x| self.as_mut().f()(x)))
}
fn size_hint(&self) -> (usize, Option<usize>) {
self.stream.size_hint()
}
}
// Forwarding impl of Sink from the underlying stream
#[cfg(feature = "sink")]
impl<S, F, T, Item> Sink<Item> for Map<S, F>
where S: Stream + Sink<Item>,
F: FnMut(S::Item) -> T,
{
type Error = S::Error;
delegate_sink!(stream, Item);
}
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