Class Email

sample/Extractor-Pattern.cpp:31–43

}

struct Email
{
  constexpr std::optional<std::array<std::string_view, 2>>
  operator()(std::string_view sv) const
  {
    auto const d = sv.find("@");
    if (d == std::string_view::npos)
    {
      return {};
    }
    return std::array<std::string_view, 2>{sv.substr(0, d), sv.substr(d + 1)};
  }
};

inline constexpr Email email;