Параллельное программирование на С++ в действии — страница 44 из 53

};

Листинг С.8. Конечный автомат банка

class bank_machine {
 messaging::receiver incoming;
 unsigned balance;

public:
 bank_machine():
  balance(199) {}

 void done() {
  get_sender().send(messaging::close_queue());
 }

 void run() {
  try {
   for (;;) {
    incoming.wait().handle(
     [&](verify_pin const& msg) {
      if (msg.pin == "1937") {
       msg.atm_queue.send(pin_verified());
      } else {
       msg.atm_queue.send(pin_incorrect());
      }
     }
    ).handle(
     [&](withdraw const& msg) {
      if (balance >= msg.amount) {
       msg.atm_queue.send(withdraw_ok());
       balance -= msg.amount;
      } else {
       msg.atm_queue.send(withdraw_denied());
      }
     }
    ).handle(
     [&](get_balance const& msg) {
      msg.atm_queue.send(::balance(balance));
     }
    ).handle(
     [&](withdrawal_processed const& msg) {
     }
    ).handle(
     [&](cancel_withdrawal const& msg) {
     }
    );
   }
  } catch(messaging::close_queue const&) {
  }
 }

 messaging::sender get_sender() {
  return incoming;
 }
};

Листинг С.9. Конечный автомат пользовательского интерфейса

class interface_machine {
 messaging::receiver incoming;

public:
 void done() {
  get_sender().send(messaging::close_queue());
 }

 void run() {
  try {
   for (;;) {
    incoming.wait().handle (
     [&](issue_money const& msg) {
      {
       std::lock_guard lk(iom);
       std::cout << "Issuing "
<< msg.amount << std::endl;
      }
     }
    ).handle(
     [&](display_insufficient_funds const& msg) {
      {
       std::lock_guard lk(iom);
       std::cout << "Insufficient funds" << std::endl;
      }
     }
    ).handle(
     [&](display_enter_pin const& msg) {
      {
       std::lock_guard lk(iom);
       std::cout
<< "Please enter your PIN (0-9)" << std::endl;
      }
     }
    ).handle(
     [&](display_enter_card const& msg) {
      {
       std::lock_guard lk(iom);
       std::cout << "Please enter your card (I)"
<< std::endl;
      }
     }
    ).handle(
     [&](display_balance const& msg) {
      {
       std::lock_guard lk(iom);
       std::cout
<< "The balance of your account is "
<< msg.amount << std::endl;
      }
     }
    ).handle(
     [&](display_withdrawal_options const& msg) {
      {
       std::lock_guard lk(iom);
       std::cout << "Withdraw 50? (w)" << std::endl;
       std::cout << "Display Balance? (b)"
<< std::endl;
       std::cout << "Cancel? (c) " << std::endl;
      }
     }
    ).handle(
     [&](display_withdrawal_cancelled const& msg) {
      {
       std::lock_guard lk(iom);
       std::cout << "Withdrawal cancelled"
<< std::endl;
      }
     }
    ).handle(
     [&](display_pin_incorrect_message const& msg) {
      {
       std::lock_guard lk(iom);
       std::cout << "PIN incorrect" << std::endl;
      }
     }
    ).handle(
     [&](eject_card const& msg) {
      {
       std::lock_guard lk(iom);
       std::cout << "Ejecting card" << std::endl;
      }
     }
    );
   }
  } catch (messaging::close_queue&) {
  }
 }

 messaging::sender get_sender() {
  return incoming;
 }
};

Листинг С.10. Управляющая программа

int main() {
 bank_machine bank;
 interface_machine interface_hardware;

 atm machine(bank.get_sender(), interface_hardware.get_sender());

 std::thread bank_thread(&bank_machine::run, &bank);
 std::thread if_thread(&interface_machine::run,
&interface_hardware);
 std::thread atm_thread(&atm::run, &machine);

 messaging::sender atmqueue(machine.get_sender());