| use crate::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`](super::StreamExt::skip) method. |
| #[must_use = "streams do nothing unless polled"] |
| pub struct Skip<St> { |
| #[pin] |
| stream: St, |
| remaining: usize, |
| } |
| } |
| |
| impl<St> fmt::Debug for Skip<St> |
| where |
| St: fmt::Debug, |
| { |
| fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result { |
| f.debug_struct("Skip") |
| .field("stream", &self.stream) |
| .finish() |
| } |
| } |
| |
| impl<St> Skip<St> { |
| pub(super) fn new(stream: St, remaining: usize) -> Self { |
| Self { stream, remaining } |
| } |
| } |
| |
| impl<St> Stream for Skip<St> |
| where |
| St: Stream, |
| { |
| type Item = St::Item; |
| |
| fn poll_next(mut self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<Option<Self::Item>> { |
| loop { |
| match ready!(self.as_mut().project().stream.poll_next(cx)) { |
| Some(e) => { |
| if self.remaining == 0 { |
| return Poll::Ready(Some(e)); |
| } |
| *self.as_mut().project().remaining -= 1; |
| } |
| None => return Poll::Ready(None), |
| } |
| } |
| } |
| |
| fn size_hint(&self) -> (usize, Option<usize>) { |
| let (lower, upper) = self.stream.size_hint(); |
| |
| let lower = lower.saturating_sub(self.remaining); |
| let upper = upper.map(|x| x.saturating_sub(self.remaining)); |
| |
| (lower, upper) |
| } |
| } |