std::map and custom compare parameter

void initiateMenu()
{
    std::string selection;

    /**
     * Entry data content
     */
    struct entry {
        std::string state;
        std::string description;
        int minAuth;
        int maxAuth;
        void (*fptr)();
        bool active = false;
    };

    /**
     * Menu list
     */
    std::map<std::string, entry> entries;

    /**
     * add menu entries!
     */
    entries["KR"] = {"/",       "Customer registration",                    GUEST,      ADMIN, registerCustomer};
    entries["KL"] = {"/",       "Customer login",                           GUEST,      GUEST, loginCustomer};
    entries["KU"] = {"/",       "Customer logout",                          CUSTOMER,   ADMIN, logoutCustomer};
    entries["KS"] = {"/",       "Display my items",                         CUSTOMER,   ADMIN, displayCustomerItems};
    entries["KE"] = {"/",       "Update customers authorization access",    ADMIN,      ADMIN, setAuthorityLevel};

    /**
     * Start the program loop.
     */
    do {
        bool authenticated = customers->authenticated();
        int authorization  = authenticated ? customers->session()->returnAuth() : GUEST;

        /**
         * Display that a customer is logged in
         *  if his / her session is successfully set.
         */
        if (customers->authenticated()) {
            std::cout
                << "Logged in as: "
                << customers->session()->username()
                << std::endl;
        }

        /**
         * Print the menu, with command options.
         *
         * ROOT_STATE == /
         */
        std::cout << "------------------ MENU ------------------" << std::endl;
        for (auto & i : entries) {
            i.second.active = false;

            std::string state   = i.second.state;
            int minAuth         = i.second.minAuth;
            int maxAuth         = i.second.maxAuth;

            /**
             * If the current entry does not follow the rules for being displayed,
             *  we ignore the rest of the round and go to the next entry.
             */
            if (state != "*") {
                if (authenticated && state != customers->state()) {
                    continue;
                }

                if (!authenticated && minAuth > GUEST) {
                    continue;
                }

                if (authenticated && minAuth > authorization) {
                    continue;
                }

                if (authenticated && maxAuth < authorization) {
                    continue;
                }

                if (!authenticated && state != ROOT_STATE) {
                    continue;
                }
            }

            /**
             * prints out the menu entry: COMMAND - description
             */
            std::cout
                << i.first
                << " - "
                << i.second.description
                << std::endl;

            /**
             * let the program know which commands were displayed.
             */
            i.second.active = true;
        }

        /**
         * Retrieves the selected option as a string by the customer.
         *  The string is then converted to an enum, and
         */
        selection = getInput("Menu choice", 1, 2, true);   // Get command from user. Lengths; min: 1, max: 2. Uppercase.

        /**
         * When the returned position isn't set to the end()[index value]
         *  there was a match.
         */
        if (entries.find(selection) != entries.end()) {
            //set user state
            //TODO: add this after function pointer, and add a way for categories to use their ID in stead.
            customers->updateState(selection);

            // call function stored in entry
            (*entries.at(selection).fptr)(); //TODO: do i need to add a * in front of entries. ?
        }

    } while ( !(selection == "Q" && customers->state() == "/") );
}

/* OUTPUT
------------------ MENU ------------------
Q  - Quit current task / program
KL - Customer login
KR - Customer registration
Menu choice:
*/