superclass_iter: simplify implementation and api function signature

rbx_reflection/src/database.rs

@@ -32,19 +32,15 @@ pub struct ReflectionDatabase<'a> {
 
 pub struct SuperClassIter<'a> {
     database: &'a ReflectionDatabase<'a>,
-    descriptor: Option<&'a ClassDescriptor<'a>>,
-}
-impl<'a> SuperClassIter<'a> {
-    fn next_descriptor(&self) -> Option<&'a ClassDescriptor<'a>> {
-        let superclass = self.descriptor?.superclass.as_ref()?;
-        self.database.classes.get(superclass)
-    }
+    class_name: &'a str,
 }
 impl<'a> Iterator for SuperClassIter<'a> {
     type Item = &'a ClassDescriptor<'a>;
     fn next(&mut self) -> Option<Self::Item> {
-        let next_descriptor = self.next_descriptor();
-        std::mem::replace(&mut self.descriptor, next_descriptor)
+        let next_descriptor = self.database.classes.get(self.class_name)?;
+        // abuse empty string to create a non-class
+        self.class_name = next_descriptor.superclass.as_deref().unwrap_or("");
+        Some(next_descriptor)
     }
 }
 
@@ -79,10 +75,10 @@ impl<'a> ReflectionDatabase<'a> {
 
     /// Returns an iterator of superclasses for the provided ClassDescriptor. This
     /// iterator will start with the provided class and end with `Instance`.
-    pub fn superclasses_iter(&'a self, descriptor: &'a ClassDescriptor<'a>) -> SuperClassIter {
+    pub fn superclasses_iter(&'a self, class_name: &'a str) -> SuperClassIter {
         SuperClassIter {
             database: self,
-            descriptor: Some(descriptor),
+            class_name,
         }
     }
 

rbx_reflection_database/src/lib.rs

@@ -26,8 +26,7 @@ mod test {
     #[test]
     fn superclasses_iter_test() {
         let database = get();
-        let part_class_descriptor = database.classes.get("Part");
-        let mut iter = database.superclasses_iter(part_class_descriptor.unwrap());
+        let mut iter = database.superclasses_iter("Part");
         fn class_descriptor_eq(lhs: Option<&ClassDescriptor>, rhs: Option<&ClassDescriptor>) {
             let eq = match (lhs, rhs) {
                 (Some(lhs), Some(rhs)) => lhs.name == rhs.name,
@@ -36,7 +35,7 @@ mod test {
             };
             assert!(eq, "{:?} != {:?}", lhs, rhs);
         }
-        class_descriptor_eq(iter.next(), part_class_descriptor);
+        class_descriptor_eq(iter.next(), database.classes.get("Part"));
         class_descriptor_eq(iter.next(), database.classes.get("FormFactorPart"));
         class_descriptor_eq(iter.next(), database.classes.get("BasePart"));
         class_descriptor_eq(iter.next(), database.classes.get("PVInstance"));