51 lines
1.2 KiB
Rust
51 lines
1.2 KiB
Rust
use std::{convert, pin::Pin, sync::Arc};
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use conduwuit::Result;
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use futures::{
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stream::FusedStream,
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task::{Context, Poll},
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Stream,
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};
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use rocksdb::{ColumnFamily, ReadOptions};
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use super::{keyval_longevity, Cursor, From, State};
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use crate::{keyval::KeyVal, Engine};
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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> ItemsRev<'a> {
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pub(crate) fn new(db: &'a Arc<Engine>, cf: &'a Arc<ColumnFamily>, opts: ReadOptions) -> Self {
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Self { state: State::new(db, cf, opts) }
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}
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}
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impl<'a> convert::From<State<'a>> for ItemsRev<'a> {
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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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fn state(&self) -> &State<'a> { &self.state }
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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.seek_rev(); }
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#[inline]
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fn init(self, from: From<'a>) -> Self { Self { state: self.state.init_rev(from) } }
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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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}
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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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