Use dict as data structure for model_modules (#1671)

Should give a slight performance improvement as we don't need to
iterate over all models declared in a file, but can lookup by name
instead.

mypy_django_plugin/django/context.py

@@ -86,15 +86,15 @@ def __init__(self, django_settings_module: str) -> None:
         self.settings = settings
 
     @cached_property
-    def model_modules(self) -> Dict[str, Set[Type[Model]]]:
+    def model_modules(self) -> Dict[str, Dict[str, Type[Model]]]:
         """All modules that contain Django models."""
-        modules: Dict[str, Set[Type[Model]]] = defaultdict(set)
+        modules: Dict[str, Dict[str, Type[Model]]] = defaultdict(dict)
         for concrete_model_cls in self.apps_registry.get_models():
-            modules[concrete_model_cls.__module__].add(concrete_model_cls)
+            modules[concrete_model_cls.__module__][concrete_model_cls.__name__] = concrete_model_cls
             # collect abstract=True models
             for model_cls in concrete_model_cls.mro()[1:]:
                 if issubclass(model_cls, Model) and hasattr(model_cls, "_meta") and model_cls._meta.abstract:
-                    modules[model_cls.__module__].add(model_cls)
+                    modules[model_cls.__module__][model_cls.__name__] = model_cls
         return modules
 
     def get_model_class_by_fullname(self, fullname: str) -> Optional[Type[Model]]:
@@ -109,10 +109,7 @@ def get_model_class_by_fullname(self, fullname: str) -> Optional[Type[Model]]:
             fullname = fullname.replace("__", ".")
 
         module, _, model_cls_name = fullname.rpartition(".")
-        for model_cls in self.model_modules.get(module, set()):
-            if model_cls.__name__ == model_cls_name:
-                return model_cls
-        return None
+        return self.model_modules.get(module, {}).get(model_cls_name)
 
     def get_model_fields(self, model_cls: Type[Model]) -> Iterator["Field[Any, Any]"]:
         for field in model_cls._meta.get_fields():

mypy_django_plugin/main.py

@@ -127,7 +127,7 @@ def get_additional_deps(self, file: MypyFile) -> List[Tuple[int, str, int]]:
             return []
         deps = set()
 
-        for model_class in defined_model_classes:
+        for model_class in defined_model_classes.values():
             for field in itertools.chain(
                 # forward relations
                 self.django_context.get_model_related_fields(model_class),