things

1 files changed, 42 insertions, 0 deletions

diff --git a/database/src/indices/key.rs b/database/src/indices/key.rs
new file mode 100644
index 0000000..ab56f76
--- /dev/null
+++ b/database/src/indices/key.rs
@@ -0,0 +1,42 @@
+/*
+    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::WriteTransaction,
+    indices::Index,
+    table::{RowNum, Table, TableNum},
+};
+use anyhow::Result;
+
+pub struct KeyIndex<T> {
+    id: TableNum,
+    key: fn(&T) -> &[u8],
+}
+
+impl<T: 'static> KeyIndex<T> {
+    pub fn new(table: &mut Table<T>, id: TableNum, key: fn(&T) -> &[u8]) -> Self {
+        table.indices.push(Box::new(Self { id, key }));
+        Self { id, key }
+    }
+    pub fn key(&self, id: RowNum, val: &T) -> Vec<u8> {
+        let mut v = Vec::new();
+        v.extend(self.id.to_be_bytes());
+        v.extend((self.key)(val));
+        v.extend(id.to_be_bytes());
+        v
+    }
+}
+impl<T: 'static> Index<T> for KeyIndex<T> {
+    fn add(&self, db: &mut dyn WriteTransaction, id: RowNum, val: &T) -> Result<()> {
+        db.set(&self.key(id, val), &[])
+    }
+    fn remove(&self, db: &mut dyn WriteTransaction, id: RowNum, val: &T) -> Result<()> {
+        db.del(&self.key(id, val))
+    }
+    fn compare(&self, before: &T, after: &T) -> bool {
+        (self.key)(before) == (self.key)(after)
+    }
+}