[storage] Add indexed access to StorageVec #165

src/storage/storage_vec.rs

@@ -31,6 +31,16 @@ impl<T: Serialize, S: Storage> StorageVec<T, S> {
         Ok(())
     }
 
+    pub(crate) fn value(&mut self, index: u64) -> Result<T, DbError> {
+        if self.size <= index {
+            return Err(DbError::Storage("index out of bounds".to_string()));
+        }
+
+        self.storage
+            .borrow_mut()
+            .value_at::<T>(self.index, Self::value_offset(index))
+    }
+
     fn reallocate(&mut self, new_capacity: u64) -> Result<(), DbError> {
         self.capacity = new_capacity;
         self.storage
@@ -81,4 +91,36 @@ mod tests {
             Ok(vec![1_i64, 3_i64, 5_i64])
         );
     }
+
+    #[test]
+    fn value() {
+        let test_file = TestFile::from("./storage_vec-value.agdb");
+        let storage = std::rc::Rc::new(std::cell::RefCell::new(
+            FileStorage::try_from(test_file.file_name().clone()).unwrap(),
+        ));
+
+        let mut vec = StorageVec::<i64>::try_from(storage).unwrap();
+        vec.push(&1).unwrap();
+        vec.push(&3).unwrap();
+        vec.push(&5).unwrap();
+
+        assert_eq!(vec.value(0), Ok(1));
+        assert_eq!(vec.value(1), Ok(3));
+        assert_eq!(vec.value(2), Ok(5));
+    }
+
+    #[test]
+    fn value_out_of_bounds() {
+        let test_file = TestFile::from("./storage_vec-value_out_of_bounds.agdb");
+        let storage = std::rc::Rc::new(std::cell::RefCell::new(
+            FileStorage::try_from(test_file.file_name().clone()).unwrap(),
+        ));
+
+        let mut vec = StorageVec::<i64>::try_from(storage).unwrap();
+
+        assert_eq!(
+            vec.value(0),
+            Err(DbError::Storage("index out of bounds".to_string()))
+        );
+    }
 }