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Add FlatMap struct

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This commit is contained in:
k-nasa 2019-10-18 10:43:21 +09:00
parent bb1416420d
commit 2dee289750
1 changed files with 37 additions and 0 deletions
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37
src/stream/stream/flatten.rs
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@ -1,8 +1,44 @@
use std::pin::Pin;
use crate::prelude::*;
use crate::stream::stream::map::Map;
use crate::stream::{IntoStream, Stream};
use crate::task::{Context, Poll};
#[allow(missing_debug_implementations)]
pub struct FlatMap<S: Stream, U: IntoStream, F> {
inner: FlattenCompat<Map<S, F, S::Item, U>, U>,
}
impl<S, U, F> FlatMap<S, U, F>
where
S: Stream,
U: IntoStream,
F: FnMut(S::Item) -> U,
{
pin_utils::unsafe_pinned!(inner: FlattenCompat<Map<S, F, S::Item, U>, U>);
pub fn new(stream: S, f: F) -> FlatMap<S, U, F> {
FlatMap {
inner: FlattenCompat::new(stream.map(f)),
}
}
}
impl<S, U, F> Stream for FlatMap<S, U, F>
where
S: Stream<Item: IntoStream<IntoStream = U, Item = U::Item>> + std::marker::Unpin,
S::Item: std::marker::Unpin,
U: Stream + std::marker::Unpin,
F: FnMut(S::Item) -> U + std::marker::Unpin,
{
type Item = U::Item;
fn poll_next(mut self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<Option<Self::Item>> {
self.as_mut().inner().poll_next(cx)
}
}
/// Real logic of both `Flatten` and `FlatMap` which simply delegate to
/// this type.
#[derive(Clone, Debug)]
@ -10,6 +46,7 @@ struct FlattenCompat<S, U> {
stream: S,
frontiter: Option<U>,
}
impl<S, U> FlattenCompat<S, U> {
pin_utils::unsafe_unpinned!(stream: S);
pin_utils::unsafe_unpinned!(frontiter: Option<U>);