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No need for a custom impl for FromIter for DoubleEndedStream

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This commit is contained in:
Felipe Sere 2019-12-12 20:46:03 +01:00
parent b0038e11be
commit 182fe6896f
3 changed files with 9 additions and 59 deletions
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57
src/stream/double_ended_stream/from_iter.rs
View file

@ -1,57 +0,0 @@
use crate::stream::Stream;
use std::pin::Pin;
use std::task::{Context, Poll};
use crate::stream::DoubleEndedStream;
/// A double-ended stream that was created from iterator.
///
/// This stream is created by the [`from_iter`] function.
/// See it documentation for more.
///
/// [`from_iter`]: fn.from_iter.html
#[derive(Debug)]
pub struct FromIter<T> {
inner: Vec<T>,
}
/// Converts an iterator into a double-ended stream.
///
/// # Examples
///
/// ```
/// # async_std::task::block_on(async {
/// #
/// use async_std::stream::double_ended_stream::{self, DoubleEndedStream};
///
/// let mut s = double_ended_stream::from_iter(vec![0, 1, 2, 3]);
///
/// assert_eq!(s.next_back().await, Some(3));
/// assert_eq!(s.next_back().await, Some(2));
/// assert_eq!(s.next_back().await, Some(1));
/// assert_eq!(s.next_back().await, Some(0));
/// assert_eq!(s.next_back().await, None);
/// #
/// # })
/// ```
pub fn from_iter<I: IntoIterator>(iter: I) -> FromIter<I::Item> {
FromIter { inner: iter.into_iter().collect() }
}
impl<T> Unpin for FromIter<T> {}
impl<T> Stream for FromIter<T> {
type Item = T;
fn poll_next(mut self: Pin<&mut Self>, _cx: &mut Context<'_>) -> Poll<Option<Self::Item>> {
if self.inner.len() > 0 {
return Poll::Ready(Some(self.inner.remove(0)));
}
return Poll::Ready(None);
}
}
impl<T> DoubleEndedStream for FromIter<T> {
fn poll_next_back(mut self: Pin<&mut Self>, _cx: &mut Context<'_>) -> Poll<Option<Self::Item>> {
Poll::Ready(self.inner.pop())
}
}

2
src/stream/double_ended_stream/mod.rs
View file

@ -3,14 +3,12 @@ use crate::stream::Stream;
use std::pin::Pin;
use std::task::{Context, Poll};
mod from_iter;
mod next_back;
mod nth_back;
mod rfind;
mod rfold;
mod try_rfold;
pub use from_iter::{from_iter, FromIter};
use next_back::NextBackFuture;
use nth_back::NthBackFuture;
use rfind::RFindFuture;

9
src/stream/from_iter.rs
View file

@ -3,6 +3,8 @@ use std::pin::Pin;
use pin_project_lite::pin_project;
use crate::stream::Stream;
#[cfg(feature = "unstable")]
use crate::stream::double_ended_stream::DoubleEndedStream;
use crate::task::{Context, Poll};
pin_project! {
@ -51,3 +53,10 @@ impl<I: Iterator> Stream for FromIter<I> {
Poll::Ready(self.iter.next())
}
}
#[cfg(feature = "unstable")]
impl<T: DoubleEndedIterator> DoubleEndedStream for FromIter<T> {
fn poll_next_back(mut self: Pin<&mut Self>, _cx: &mut Context<'_>) -> Poll<Option<T::Item>> {
Poll::Ready(self.iter.next_back())
}
}