Параллельное программирование на С++ в действии. Практика разработки многопоточных программ - [166]

    state = &atm::wait_for_action;
   }
  ).handle(
   [&](cancel_pressed const& msg) {
    state = &atm::done_processing;
   }
  );
 }

 void wait_for_action() {
  interface_hardware.send(display_withdrawal_options());
  incoming.wait().handle(
   [&](withdraw_pressed const& msg) {
    withdrawal_amount = msg.amount;
    bank.send(withdraw(account, msg.amount, incoming));
    state = &atm::process_withdrawal;
   }
  ).handle(
   [&](balance_pressed const& msg) {
    bank.send(get_balance(account, incoming));
    state = &atm::process_balance;
   }
  ).handle(
   [&](cancel_pressed const& msg) {
    state = &atm::done_processing;
   }
  );
 }

 void verifying_pin() {
  incoming.wait().handle(
   [&](pin_verified const& msg) {
    state = &atm::wait_for_action;
   }
  ).handle(
   [&](pin_incorrect const& msg) {
    interface_hardware.send(
     display_pin_incorrect_message());
    state = &atm::done_processing;
   }
  ).handle(
   [&](cancel_pressed const& msg) {
    state = &atm::done_processing;
   }
  );
 }

 void getting_pin() {
  incoming.wait().handle(
   [&](digit_pressed const& msg) {
    unsigned const pin_length = 4;
    pin += msg.digit;
    if (pin.length() == pin_length) {
     bank.send(verify_pin(account, pin, incoming));
     state = &atm::verifying_pin;
    }
   }
  ).handle(
   [&](clear_last_pressed const& msg) {
    if (!pin.empty()) {
     pin.pop_back();
    }
   }
  ).handle(
   [&](cancel_pressed const& msg) {
    state = &atm::done_processing;
   }
  );
 }

 void waiting_for_card() {
  interface_hardware.send(display_enter_card());
  incoming.wait().handle(
   [&](card_inserted const& msg) {
    account = msg.account;
    pin = "";
    interface_hardware.send(display_enter_pin());
    state = &atm::getting_pin;
   }
  );
 }

 void done_processing() {
  interface_hardware.send(eject_card());
  state = &atm::waiting_for_card;
 }

 atm(atm const&) = delete;
 atm& operator=(atm const&) = delete;

public:
 atm(messaging::sender bank_,
  messaging::sender interface_hardware_):
   bank(bank_), interface_hardware(interface_hardware_) {}

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

 void run() {
  state = &atm::waiting_for_card;
  try {
   for (;;) {
    (this->*state)();
   }
  } catch(messaging::close_queue const&) {
  }
 }

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

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)"