def try_parse()

in usort/util.py [0:0]

• 15 lines of code
• 8 McCabe index (conditional complexity)

def try_parse(path: Path, data: Optional[bytes] = None) -> cst.Module:
    """
    Attempts to parse the file with all syntax versions known by LibCST.

    If parsing fails on all supported grammar versions, then raises the parser error
    from the first/newest version attempted.
    """
    if data is None:
        data = path.read_bytes()

    with timed(f"parsing {path}"):
        parse_error: Optional[cst.ParserSyntaxError] = None

        for version in cst.KNOWN_PYTHON_VERSION_STRINGS[::-1]:
            try:
                mod = cst.parse_module(
                    data, cst.PartialParserConfig(python_version=version)
                )
                return mod
            except cst.ParserSyntaxError as e:
                # keep the first error we see in case parsing fails on all versions
                if parse_error is None:
                    parse_error = e

        # not caring about existing traceback here because it's not useful for parse
        # errors, and usort_path is already going to wrap it in a custom class
        raise parse_error or Exception("unknown parse failure")