(dirty) iteration

Author: uint

docs-test-gen/templates/storey-container-impl.tpl

@@ -112,25 +112,6 @@ where
     }
 }
 
-impl<V> IterableStorable for MyMap<V>
-where
-    V: IterableStorable,
-    <V as IterableStorable>::KeyDecodeError: std::fmt::Display,
-{
-    type Key = (u32, V::Key);
-    type KeyDecodeError = ();
-    type Value = V::Value;
-    type ValueDecodeError = V::ValueDecodeError;
-
-    fn decode_key(key: &[u8]) -> Result<Self::Key, ()> {
-        todo!()
-    }
-
-    fn decode_value(value: &[u8]) -> Result<Self::Value, Self::ValueDecodeError> {
-        V::decode_value(value)
-    }
-}
-
 impl<V, S> MyMapAccess<V, S>
 where
     V: Storable,

src/pages/storey/container-impl/my-map.mdx

@@ -205,21 +205,9 @@ assert_eq!(access.entry(2).get().unwrap(), Some(200));
 
 # Iteration
 
-To be continued...
+While we have a functional collection by now, we can't perform iteration yet. Instead of trying to implement iteration on our own, there are benefits to using abstractions `storey` provides. This means implementing `IterableStorable` for `MyMap`.
 
-| Associated type    | Details                                                                                                                   |
-| ------------------ | ------------------------------------------------------------------------------------------------------------------------- |
-| `Key`              | The key type to be returned by iterators. Here a tuple of `u32` and the key type of the inner container.                  |
-| `KeyDecodeError`   | The error to be returned on invalid key data. Here we don't care, so we use `()`. In production, use a proper error type. |
-| `Value`            | The value type to be returned by iterators. Here it's delegated to the inner container.                                   |
-| `ValueDecodeError` | The error type for invalid value data. Delegated to the inner container.                                                  |
-
-The methods: | Method | Function |
-|----------------|-----------------------------------------------------------------------------| |
-`decode_value` | Used for iteration. This is how the framework knows how to decode values given raw
-data. |
-
-```
+```rust template="storey-container-impl"
 impl<V> IterableStorable for MyMap<V>
 where
     V: IterableStorable,
@@ -231,7 +219,16 @@ where
     type ValueDecodeError = V::ValueDecodeError;
 
     fn decode_key(key: &[u8]) -> Result<Self::Key, ()> {
-        todo!()
+        if key.len() < 4 {
+            return Err(());
+        }
+
+        let key_arr = key[0..4].try_into().map_err(|_| ())?;
+        let this_key = u32::from_le_bytes(key_arr);
+
+        let rest = V::decode_key(&key[4..]).map_err(|_| ())?;
+
+        Ok((this_key, rest))
     }
 
     fn decode_value(value: &[u8]) -> Result<Self::Value, Self::ValueDecodeError> {
@@ -240,6 +237,21 @@ where
 }
 ```
 
+Alright. Let's dive into the trait items!
+
+| Associated type    | Details                                                                                                                   |
+| ------------------ | ------------------------------------------------------------------------------------------------------------------------- |
+| `Key`              | The key type to be returned by iterators. Here a tuple of `u32` and the key type of the inner container.                  |
+| `KeyDecodeError`   | The error to be returned on invalid key data. Here we don't care, so we use `()`. In production, use a proper error type. |
+| `Value`            | The value type to be returned by iterators. Here it's delegated to the inner container.                                   |
+| `ValueDecodeError` | The error type for invalid value data. Delegated to the inner container.                                                  |
+
+| Method | Function |
+|----------------|-----------------------------------------------------------------------------|
+| `decode_key` | This is how the framework knows how to decode keys given raw bytes. |
+| `decode_value` | This is how the framework knows how to decode values given raw bytes. In this case, we delegate to the inner collection. |
+
+
 [`Item`]: /storey/containers/item
 [`Map`]: /storey/containers/map
 [`Storable`]: https://docs.rs/storey/latest/storey/containers/trait.Storable.html