things

1 files changed, 70 insertions, 0 deletions

diff --git a/database/src/iterator.rs b/database/src/iterator.rs
new file mode 100644
index 0000000..2db349b
--- /dev/null
+++ b/database/src/iterator.rs
@@ -0,0 +1,70 @@
+/*
+    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
+                }
+            }
+        }
+    }
+}