Function parse_python_variant_header

src/blackd/__init__.py:297–327

(value: str)

def parse_python_variant_header(value: str) -> tuple[bool, set[black.TargetVersion]]:
    if value == "pyi":
        return True, set()
    else:
        versions = set()
        for version in value.split(","):
            if version.startswith("py"):
                version = version[len("py") :]
            if "." in version:
                major_str, *rest = version.split(".")
            else:
                major_str = version[0]
                rest = [version[1:]] if len(version) > 1 else []
            try:
                major = int(major_str)
                if major not in (2, 3):
                    raise InvalidVariantHeader("major version must be 2 or 3")
                if len(rest) > 0:
                    minor = int(rest[0])
                    if major == 2:
                        raise InvalidVariantHeader("Python 2 is not supported")
                else:
                    # Default to lowest supported minor version.
                    minor = 7 if major == 2 else 3
                version_str = f"PY{major}{minor}"
                if major == 3 and not hasattr(black.TargetVersion, version_str):
                    raise InvalidVariantHeader(f"3.{minor} is not supported")
                versions.add(black.TargetVersion[version_str])
            except (KeyError, ValueError):
                raise InvalidVariantHeader("expected e.g. '3.7', 'py3.5'") from None
        return False, versions


def patched_main() -> None: