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/*
This file is part of jellything (https://codeberg.org/metamuffin/jellything)
which is licensed under the GNU Affero General Public License (version 3); see /COPYING.
Copyright (C) 2025 metamuffin <metamuffin.org>
*/
use crate::backends::ReadTransaction;
use anyhow::Result;
use std::{borrow::Cow, ops::Range};
pub struct PrefixIterator<'a> {
db: &'a dyn ReadTransaction,
prefix: &'a [u8],
cursor: Cow<'a, [u8]>,
}
impl Iterator for PrefixIterator<'_> {
type Item = Result<Vec<u8>>;
fn next(&mut self) -> Option<Self::Item> {
match self.db.next(&self.cursor) {
Err(e) => Some(Err(e)),
Ok(None) => None,
Ok(Some(next)) => {
if next.starts_with(self.prefix) {
self.cursor = next.clone().into();
Some(Ok(next))
} else {
None
}
}
}
}
}
pub struct RangeIterator<'a> {
db: &'a dyn ReadTransaction,
range: Range<Cow<'a, [u8]>>,
}
impl Iterator for RangeIterator<'_> {
type Item = Result<Vec<u8>>;
fn next(&mut self) -> Option<Self::Item> {
match self.db.next(&self.range.start) {
Err(e) => Some(Err(e)),
Ok(None) => None,
Ok(Some(next)) => {
if next.as_slice() < self.range.end.as_ref() {
self.range.start = next.clone().into();
Some(Ok(next))
} else {
None
}
}
}
}
}
impl DoubleEndedIterator for RangeIterator<'_> {
fn next_back(&mut self) -> Option<Self::Item> {
match self.db.prev(&self.range.end) {
Err(e) => Some(Err(e)),
Ok(None) => None,
Ok(Some(prev)) => {
if prev.as_slice() >= self.range.start.as_ref() {
self.range.end = prev.clone().into();
Some(Ok(prev))
} else {
None
}
}
}
}
}
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