bre.py 文件源码

def subfn(pattern, format, string, count=0, flags=0):  # noqa B002
    """Apply `subn` after applying backrefs."""

    is_replace = _is_replace(format)
    is_string = isinstance(format, (compat.string_type, compat.binary_type))
    if is_replace and not format.use_format:
        raise ValueError("Compiled replace is not a format object!")

    pattern = compile_search(pattern, flags)
    rflags = FORMAT if is_string else 0
    return re.subn(
        pattern, (compile_replace(pattern, format, flags=rflags) if is_replace or is_string else format),
        string, count, flags
    )