def _get_localpart(alias: RoomAlias) -> str:
if len(alias) == 0:
raise ValueError("Alias is empty")
elif alias[0] != "#":
raise ValueError("Aliases start with #")
try:
sep = alias.index(":")
except ValueError as e:
raise ValueError("Alias must contain domain separator") from e
if sep == len(alias) - 1:
raise ValueError("Alias must contain domain")
return alias[1:sep]
def alias(self) -> Optional[RoomAlias]:
if not self.username:
return None
return RoomAlias(f"#{self.alias_localpart}:{self.hs_domain}")