def regex_text(self) -> str:
        """
        Return regex text (yet to be compiled) for this drug.
        """
        if self._regex_text is None:
            possibilities = []  # type: List[str]
            for p in list(set(self.all_generics + self.alternatives)):
                if self.add_preceding_word_boundary and not p.startswith(WB):
                    p = WB + p
                if self.add_preceding_wildcards and not p.startswith(WILDCARD):
                    p = WILDCARD + p
                if self.add_following_wildcards and not p.endswith(WILDCARD):
                    p = p + WILDCARD
                possibilities.append(p)
            self._regex_text = "|".join("(?:" + x + ")" for x in possibilities)
        return self._regex_text
Return regex text (yet to be compiled) for this drug.