| use crate::stream::Stream; |
| |
| use core::fmt; |
| use core::pin::Pin; |
| use core::task::{Context, Poll}; |
| use pin_project_lite::pin_project; |
| |
| pin_project! { |
| /// Stream for the [`skip_while`](super::StreamExt::skip_while) method. |
| #[must_use = "streams do nothing unless polled"] |
| pub struct SkipWhile<St, F> { |
| #[pin] |
| stream: St, |
| predicate: Option<F>, |
| } |
| } |
| |
| impl<St, F> fmt::Debug for SkipWhile<St, F> |
| where |
| St: fmt::Debug, |
| { |
| fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result { |
| f.debug_struct("SkipWhile") |
| .field("stream", &self.stream) |
| .finish() |
| } |
| } |
| |
| impl<St, F> SkipWhile<St, F> { |
| pub(super) fn new(stream: St, predicate: F) -> Self { |
| Self { |
| stream, |
| predicate: Some(predicate), |
| } |
| } |
| } |
| |
| impl<St, F> Stream for SkipWhile<St, F> |
| where |
| St: Stream, |
| F: FnMut(&St::Item) -> bool, |
| { |
| type Item = St::Item; |
| |
| fn poll_next(self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<Option<Self::Item>> { |
| let mut this = self.project(); |
| if let Some(predicate) = this.predicate { |
| loop { |
| match ready!(this.stream.as_mut().poll_next(cx)) { |
| Some(item) => { |
| if !(predicate)(&item) { |
| *this.predicate = None; |
| return Poll::Ready(Some(item)); |
| } |
| } |
| None => return Poll::Ready(None), |
| } |
| } |
| } else { |
| this.stream.poll_next(cx) |
| } |
| } |
| |
| fn size_hint(&self) -> (usize, Option<usize>) { |
| let (lower, upper) = self.stream.size_hint(); |
| |
| if self.predicate.is_some() { |
| return (0, upper); |
| } |
| |
| (lower, upper) |
| } |
| } |