Merge pull request #1 from mykmelez/iter-from-result

Have iter_from/iter_dup_from return a Result

src/cursor.rs

@@ -61,9 +61,9 @@ pub trait Cursor<'txn> {
     /// For databases with duplicate data items (`DatabaseFlags::DUP_SORT`), the
     /// duplicate data items of each key will be returned before moving on to
     /// the next key.
-    fn iter_from<K>(&mut self, key: K) -> Iter<'txn> where K: AsRef<[u8]> {
-        self.get(Some(key.as_ref()), None, ffi::MDB_SET_RANGE).unwrap();
-        Iter::new(self.cursor(), ffi::MDB_GET_CURRENT, ffi::MDB_NEXT)
+    fn iter_from<K>(&mut self, key: K) -> Result<Iter<'txn>> where K: AsRef<[u8]> {
+        try!(self.get(Some(key.as_ref()), None, ffi::MDB_SET_RANGE));
+        Ok(Iter::new(self.cursor(), ffi::MDB_GET_CURRENT, ffi::MDB_NEXT))
     }
 
     /// Iterate over duplicate database items. The iterator will begin with the
@@ -82,9 +82,9 @@ pub trait Cursor<'txn> {
 
     /// Iterate over duplicate items in the database starting from the given
     /// key. Each item will be returned as an iterator of its duplicates.
-    fn iter_dup_from<K>(&mut self, key: &K) -> IterDup<'txn> where K: AsRef<[u8]> {
-        self.get(Some(key.as_ref()), None, ffi::MDB_SET_RANGE).unwrap();
-        IterDup::new(self.cursor(), ffi::MDB_GET_CURRENT)
+    fn iter_dup_from<K>(&mut self, key: &K) -> Result<IterDup<'txn>> where K: AsRef<[u8]> {
+        try!(self.get(Some(key.as_ref()), None, ffi::MDB_SET_RANGE));
+        Ok(IterDup::new(self.cursor(), ffi::MDB_GET_CURRENT))
     }
 
     /// Iterate over the duplicates of the item in the database with the given
@@ -424,7 +424,8 @@ mod test {
 
         let items: Vec<(&[u8], &[u8])> = vec!((b"key1", b"val1"),
                                               (b"key2", b"val2"),
-                                              (b"key3", b"val3"));
+                                              (b"key3", b"val3"),
+                                              (b"key5", b"val5"));
 
         {
             let mut txn = env.begin_rw_txn().unwrap();
@@ -445,7 +446,12 @@ mod test {
         assert_eq!(items, cursor.iter_start().collect::<Vec<_>>());
 
         assert_eq!(items.clone().into_iter().skip(1).collect::<Vec<_>>(),
-                   cursor.iter_from(b"key2").collect::<Vec<_>>());
+                   cursor.iter_from(b"key2").unwrap().collect::<Vec<_>>());
+
+        assert_eq!(items.clone().into_iter().skip(3).collect::<Vec<_>>(),
+                   cursor.iter_from(b"key4").unwrap().collect::<Vec<_>>());
+
+        assert!(cursor.iter_from(b"key6").is_err());
     }
 
     #[test]
@@ -462,7 +468,10 @@ mod test {
                                               (b"b", b"3"),
                                               (b"c", b"1"),
                                               (b"c", b"2"),
-                                              (b"c", b"3"));
+                                              (b"c", b"3"),
+                                              (b"e", b"1"),
+                                              (b"e", b"2"),
+                                              (b"e", b"3"));
 
         {
             let mut txn = env.begin_rw_txn().unwrap();
@@ -484,14 +493,18 @@ mod test {
                    cursor.iter_dup_start().flat_map(|x| x).collect::<Vec<(&[u8], &[u8])>>());
 
         assert_eq!(items.clone().into_iter().skip(3).collect::<Vec<(&[u8], &[u8])>>(),
-                   cursor.iter_dup_from(b"b").flat_map(|x| x).collect::<Vec<_>>());
+                   cursor.iter_dup_from(b"b").unwrap().flat_map(|x| x).collect::<Vec<_>>());
 
         assert_eq!(items.clone().into_iter().skip(3).collect::<Vec<(&[u8], &[u8])>>(),
-                   cursor.iter_dup_from(b"ab").flat_map(|x| x).collect::<Vec<_>>());
+                   cursor.iter_dup_from(b"ab").unwrap().flat_map(|x| x).collect::<Vec<_>>());
+
+        assert_eq!(items.clone().into_iter().skip(9).collect::<Vec<(&[u8], &[u8])>>(),
+                   cursor.iter_dup_from(b"d").unwrap().flat_map(|x| x).collect::<Vec<_>>());
 
         assert_eq!(items.clone().into_iter().skip(3).take(3).collect::<Vec<(&[u8], &[u8])>>(),
                    cursor.iter_dup_of(b"b").unwrap().collect::<Vec<_>>());
 
+        assert!(cursor.iter_dup_from(b"foo").is_err());
         assert!(cursor.iter_dup_of(b"foo").is_err());
     }