[Merged by Bors] - Add remove method to Map reflection trait.

crates/bevy_reflect/src/impls/std.rs

@@ -394,6 +394,12 @@ impl<K: FromReflect + Eq + Hash, V: FromReflect> Map for HashMap<K, V> {
         self.insert(key, value)
             .map(|old_value| Box::new(old_value) as Box<dyn Reflect>)
     }
+
+    fn remove(&mut self, key: &dyn Reflect) -> Option<Box<dyn Reflect>> {
+        key.downcast_ref::<K>()
+            .and_then(|key| self.remove(key))
+            .map(|value| Box::new(value) as Box<dyn Reflect>)
+    }
 }
 
 impl<K: FromReflect + Eq + Hash, V: FromReflect> Reflect for HashMap<K, V> {

crates/bevy_reflect/src/map.rs

@@ -57,6 +57,12 @@ pub trait Map: Reflect {
         key: Box<dyn Reflect>,
         value: Box<dyn Reflect>,
     ) -> Option<Box<dyn Reflect>>;
+
+    /// Removes an entry from the map.
+    ///
+    /// If the map did not have this key present, `None` is returned.
+    /// If the map did have this key present, the removed value is returned.
+    fn remove(&mut self, key: &dyn Reflect) -> Option<Box<dyn Reflect>>;
 }
 
 /// A container for compile-time map info.
@@ -246,6 +252,18 @@ impl Map for DynamicMap {
         }
     }
 
+    fn remove(&mut self, key: &dyn Reflect) -> Option<Box<dyn Reflect>> {
+        match self.indices.entry(key.reflect_hash().expect(HASH_ERROR)) {
+            Entry::Occupied(entry) => {
+                let index = *entry.get();
+                entry.remove();
+                let (_key, value) = self.values.remove(index);
+                Some(value)
+            },
+            Entry::Vacant(_) => None,
+        }
+    }
+
     fn drain(self: Box<Self>) -> Vec<(Box<dyn Reflect>, Box<dyn Reflect>)> {
         self.values
     }