db abstraction looks good

1 files changed, 31 insertions, 5 deletions

diff --git a/database/src/indices/key.rs b/database/src/indices/key.rs
index ab56f76..9f9511b 100644
--- a/database/src/indices/key.rs
+++ b/database/src/indices/key.rs
@@ -5,8 +5,9 @@
 */
 
 use crate::{
-    backends::WriteTransaction,
+    backends::{ReadTransaction, WriteTransaction},
     indices::Index,
+    prefix_iterator::PrefixIterator,
     table::{RowNum, Table, TableNum},
 };
 use anyhow::Result;
@@ -21,22 +22,47 @@ impl<T: 'static> KeyIndex<T> {
         table.indices.push(Box::new(Self { id, key }));
         Self { id, key }
     }
-    pub fn key(&self, id: RowNum, val: &T) -> Vec<u8> {
+    pub fn key(&self, id: RowNum, key: &[u8]) -> Vec<u8> {
         let mut v = Vec::new();
         v.extend(self.id.to_be_bytes());
-        v.extend((self.key)(val));
+        v.extend(key);
         v.extend(id.to_be_bytes());
         v
     }
+    pub fn lookup<'a>(
+        &self,
+        db: &'a dyn ReadTransaction,
+        key: &[u8],
+    ) -> Result<PrefixIterator<'a>> {
+        let mut prefix = Vec::new();
+        prefix.extend(self.id.to_be_bytes());
+        prefix.extend(key);
+        Ok(PrefixIterator {
+            inner: db.iter(&prefix, false)?,
+            prefix: prefix.into(),
+        })
+    }
 }
 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), &[])
+        db.set(&self.key(id, (self.key)(val)), &[])
     }
     fn remove(&self, db: &mut dyn WriteTransaction, id: RowNum, val: &T) -> Result<()> {
-        db.del(&self.key(id, val))
+        db.del(&self.key(id, (self.key)(val)))
     }
     fn compare(&self, before: &T, after: &T) -> bool {
         (self.key)(before) == (self.key)(after)
     }
 }
+
+// fn inc_key(key: &[u8]) -> Vec<u8> {
+//     let mut key = key.to_owned();
+//     for i in (0..key.len()).rev() {
+//         let (nv, carry) = key[i].overflowing_add(1);
+//         key[i] = nv;
+//         if !carry {
+//             break;
+//         }
+//     }
+//     key
+// }