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Address TODO in visitor type checking using mapping of CSTNode to valid return types.

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Jennifer Taylor 2019-10-15 13:25:22 -07:00 • committed by Jennifer Taylor
parent 704fe2bc3a
commit 0de26fc769
1 changed files with 6 additions and 16 deletions
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22
libcst/matchers/_visitors.py
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@ -37,6 +37,7 @@ from libcst.matchers._matcher_base import (
OneOf,
matches,
)
from libcst.matchers._return_types import TYPED_FUNCTION_RETURN_MAPPING
_CSTNodeT = TypeVar("_CSTNodeT", bound=cst.CSTNode)
@ -58,11 +59,11 @@ def _get_possible_match_classes(matcher: BaseMatcherNode) -> List[Type[cst.CSTNo
return [getattr(cst, matcher.__class__.__name__)]
def _get_possible_annotated_classes(annotation: Type[object]) -> List[Type[object]]:
def _get_possible_annotated_classes(annotation: object) -> List[Type[object]]:
if getattr(annotation, "__origin__", None) is Union:
return getattr(annotation, "__args__", [])
else:
return [annotation]
return [cast(Type[object], annotation)]
def _get_valid_leave_annotations_for_classes(
@ -75,20 +76,9 @@ def _get_valid_leave_annotations_for_classes(
# all possible valid return annotations. Its not really possible for us (or
# pyre) to fully enforce return types given the presence of OneOf/AllOf matchers, so
# we do the best we can by taking a union of all valid return annotations.
# TODO: We could possibly teach LibCST codegen to generate a mapping of class
# to valid leave annotations when it generates leave_<Node> methods, but for
# now this is functionally identical. That would get rid of the need to provide
# a namespace here, as well as a gross getattr on the CSTTransformer class.
meth = getattr(cst.CSTTransformer, f"leave_{cls.__name__}")
namespace: Dict[str, object] = {
**{x: getattr(cst, x) for x in dir(cst)},
"cst": cst,
"libcst": cst,
}
type_hints = get_type_hints(meth, namespace, namespace)
if "return" in type_hints:
retval.update(_get_possible_annotated_classes(type_hints["return"]))
retval.update(
_get_possible_annotated_classes(TYPED_FUNCTION_RETURN_MAPPING[cls])
)
return retval