53 lines
1.2 KiB
Rust
53 lines
1.2 KiB
Rust
use std::pin::Pin;
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use futures::{
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Stream,
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stream::FusedStream,
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task::{Context, Poll},
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};
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use tuwunel_core::Result;
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use super::{Cursor, State, keyval_longevity};
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use crate::keyval::KeyVal;
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pub(crate) struct ItemsRev<'a> {
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state: State<'a>,
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}
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impl<'a> From<State<'a>> for ItemsRev<'a> {
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#[inline]
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fn from(state: State<'a>) -> Self { Self { state } }
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}
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impl<'a> Cursor<'a, KeyVal<'a>> for ItemsRev<'a> {
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#[inline]
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fn state(&self) -> &State<'a> { &self.state }
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#[inline]
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fn state_mut(&mut self) -> &mut State<'a> { &mut self.state }
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#[inline]
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fn count(&self) -> (usize, Option<usize>) { self.state().count_rev() }
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#[inline]
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fn fetch(&self) -> Option<KeyVal<'a>> { self.state().fetch().map(keyval_longevity) }
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#[inline]
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fn seek(&mut self) { self.state_mut().seek_rev(); }
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}
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impl<'a> Stream for ItemsRev<'a> {
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type Item = Result<KeyVal<'a>>;
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fn poll_next(mut self: Pin<&mut Self>, _ctx: &mut Context<'_>) -> Poll<Option<Self::Item>> {
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Poll::Ready(self.seek_and_get())
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}
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fn size_hint(&self) -> (usize, Option<usize>) { self.count() }
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}
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impl FusedStream for ItemsRev<'_> {
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#[inline]
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fn is_terminated(&self) -> bool { !self.state().init && !self.state().valid() }
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}
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