feat: get first or last (left) element with data of OneToManyUniqueBTreeMapWithData

src/one_to_many_with_data.rs

@@ -40,7 +40,7 @@ where
         old
     }
 
-    pub fn get_rights_for(&self, left: &Left) -> Option<&BTreeMap<Right, RightData>> {
+    pub fn get_rights_and_data_for(&self, left: &Left) -> Option<&BTreeMap<Right, RightData>> {
         self.left_to_rights.get(left)
     }
 
@@ -48,9 +48,17 @@ where
         self.right_to_left.get(right)
     }
 
+    pub fn first_left_and_rights_and_data(&self) -> Option<(&Left, &BTreeMap<Right, RightData>)> {
+        self.left_to_rights.first_key_value()
+    }
+
+    pub fn last_left_and_rights_and_data(&self) -> Option<(&Left, &BTreeMap<Right, RightData>)> {
+        self.left_to_rights.last_key_value()
+    }
+
     pub fn get_left_and_data_for(&self, right: &Right) -> Option<(&Left, &RightData)> {
         let left = self.right_to_left.get(right)?;
-        let rights = self.get_rights_for(left)?;
+        let rights = self.get_rights_and_data_for(left)?;
 
         let right_data = rights.get(right)?;