def visit_decorator(self, dec: Decorator) -> None:
if dec.decorators:
decorators_to_store = dec.decorators.copy()
decorators_to_remove: List[int] = []
# the index of the last non-register decorator before finding a register decorator
# when going through decorators from top to bottom
last_non_register: Optional[int] = None
for i, d in enumerate(decorators_to_store):
impl = get_singledispatch_register_call_info(d, dec.func)
if impl is not None:
self.singledispatch_impls[impl.singledispatch_func].append(
(impl.dispatch_type, dec.func))
decorators_to_remove.append(i)
if last_non_register is not None:
# found a register decorator after a non-register decorator, which we
# don't support because we'd have to make a copy of the function before
# calling the decorator so that we can call it later, which complicates
# the implementation for something that is probably not commonly used
self.errors.error(
"Calling decorator after registering function not supported",
self.current_path,
decorators_to_store[last_non_register].line,
)
else:
if refers_to_fullname(d, 'functools.singledispatch'):
decorators_to_remove.append(i)
# make sure that we still treat the function as a singledispatch function
# even if we don't find any registered implementations (which might happen
# if all registered implementations are registered dynamically)
self.singledispatch_impls.setdefault(dec.func, [])
last_non_register = i
if decorators_to_remove:
# calling register on a function that tries to dispatch based on type annotations
# raises a TypeError because compiled functions don't have an __annotations__
# attribute
self.decorators_to_remove[dec.func] = decorators_to_remove
super().visit_decorator(dec)
