IVR Call flow State Machine

Question

i'm trying to implement a state machine that can handle the flow of the calls inside an IVR using the Boost Statechart Library, but im very green on C++ and need a hand with some basics.

Lets say my call flow looks this: (focus on first 2 states USR_checkSubscription & USR_checkBalance)

My question is simple but i just can find on how to make it work! I know that the initial state will be USR_checkSubscription, but when i enter that state, how can i go to other states depending on stuff i make there, lets say i want to go to State "USR_checkBalance" if i have a variable with value=1.

This is my SM_callModel.cpp

#include "SM_callModel.h"
using namespace std;
namespace sc = boost::statechart;
namespace mpl = boost::mpl;
// States definition
struct USR_checkSubscription;
struct USR_checkBalance;
struct MNU_welcomeSubscribed;
struct MNU_mainMenu;
struct MNU_selectLeague;
struct MNU_menu1Content;
struct USR_selectSubscription;
struct USR_waitingForNumber;
struct USR_wrongNumber;
struct USR_confirmSubscription;
struct USR_chargeUser;
struct USR_inssuficientBalance;
struct USR_selectTopUp;
struct USR_endCall;
// Events definition
struct EvSubscribed : sc::event< EvSubscribed> {};
struct EvNotSubscribed : sc::event< EvNotSubscribed > {};
struct EvPressNumberNotSubscribed : sc::event< EvPressNumberNotSubscribed > {};
struct EvBalance : sc::event< EvBalance > {};
struct EvNoBalance : sc::event< EvNoBalance > {};
struct EvPressNumber : sc::event< EvPressNumber > {};
struct EvGoToConfirmSubscription : sc::event< EvGoToConfirmSubscription > {};
struct EvGoToChargeUser : sc::event< EvGoToChargeUser > {};
struct EvNotCharged : sc::event< EvNotCharged > {};
struct EvGoToMainMenu : sc::event< EvGoToMainMenu > {};
struct EvMenu1 : sc::event< EvMenu1 > {};
struct EvGoToMenu1Content : sc::event< EvGoToMenu1Content > {};
struct EvWrongNumber : sc::event< EvWrongNumber > {};
struct EvNoTime : sc::event< EvNoTime > {};
struct EvReturn : sc::event< EvReturn > {};
struct EvEndCall : sc::event< EvEndCall > {};
struct VoiceSM : sc::state_machine< VoiceSM, USR_checkSubscription > {};// The initialization state
VoiceSM VSM;
/* Check user subscription status */
struct USR_checkSubscription : sc::simple_state< USR_checkSubscription, VoiceSM>
{
    USR_checkSubscription() {
        // Check if user is subscribed via WebService (lets say it returns as subscribed = 1)
        int subscribed = 1;
        //HOW CAN I GO TO "EvSubscribed" OR "EvNotSubscribed" DEPENDING ON THE VARIABLE SUBSCRIBED???
        cout << "User is subscribed 1/0 n" << endl;
    }
    ~USR_checkSubscription() {}
    typedef mpl::list<
    sc::transition< EvSubscribed, USR_checkBalance >, // if is subscribed then go to USR_checkBalance
    sc::transition< EvNotSubscribed, USR_selectSubscription > > reactions; // if is not subscribed go to USR_selectSubscription
};
/* Check user current balance */
struct USR_checkBalance : sc::simple_state< USR_checkBalance, VoiceSM>
{
    USR_checkBalance() {
        // Check balance with web service
        cout << "User has balance Y/N? n" << endl;
    }
    ~USR_checkBalance() {}
    typedef mpl::list<
    sc::transition< EvBalance, MNU_welcomeSubscribed >,
    sc::transition< EvNoBalance, USR_selectTopUp > > reactions;
};
/* User press 1 to get 15 minutes to his account */
struct USR_selectTopUp : sc::simple_state< USR_selectTopUp, VoiceSM>
{
    USR_selectTopUp() {
        // Check balance with web service
        cout << "User selected 15 minutes n" << endl;
    }
    ~USR_selectTopUp() {}
    typedef mpl::list<
    sc::transition< EvGoToChargeUser, USR_chargeUser >,
    sc::transition< EvNoTime, USR_waitingForNumber >,
    sc::transition< EvWrongNumber, USR_wrongNumber > > reactions;
};
/* Play welcome audio for subscribed users */
struct MNU_welcomeSubscribed : sc::simple_state< MNU_welcomeSubscribed, VoiceSM>
{
    MNU_welcomeSubscribed() {
        // Check balance with web service
        cout << "Welcome user xxxxxx n" << endl;
    }
    ~MNU_welcomeSubscribed() {}
    typedef sc::transition< EvGoToMainMenu, MNU_mainMenu > reactions;
};
/* Play audio when user didn't digit anything */
struct USR_waitingForNumber : sc::simple_state< USR_waitingForNumber, VoiceSM>
{
    USR_waitingForNumber() {
        // Check balance with web service
        cout << "User didn't press any digit, its being redirected n" << endl;
    }
    ~USR_waitingForNumber() {}
    typedef sc::transition< EvGoToMainMenu, MNU_mainMenu > reactions;
};
/* Play audio when user inputs a wrong number */
struct USR_wrongNumber : sc::simple_state< USR_wrongNumber, VoiceSM>
{
    USR_wrongNumber() {
        // Counter ++
        // Get previous activity and then go back???
        cout << "User pressed the wrong number, try again n" << endl;
    }
    ~USR_wrongNumber() {}
    typedef sc::transition< EvGoToMainMenu, MNU_mainMenu > reactions;
};
/* Check user current balance */
struct USR_selectSubscription : sc::simple_state< USR_selectSubscription, VoiceSM>
{
    USR_selectSubscription() {
        // Select 1 or 2 for type of subscription
        cout << "User selected 1 or 2 n" << endl;
    }
    ~USR_selectSubscription() {}
    typedef mpl::list<
    sc::transition< EvGoToConfirmSubscription, USR_confirmSubscription >,
    sc::transition< EvNoTime, USR_waitingForNumber >,
    sc::transition< EvWrongNumber, USR_wrongNumber > > reactions;
};
/* Confirm user subscription */
struct USR_confirmSubscription : sc::simple_state< USR_confirmSubscription, VoiceSM>
{
    USR_confirmSubscription() {
        // Select 1 or 2 for type of subscription
        cout << "Press 1 or 2 to select  n" << endl;
    }
    ~USR_confirmSubscription() {}
    typedef mpl::list<
    sc::transition< EvGoToChargeUser, USR_chargeUser >,
    sc::transition< EvNoTime, USR_waitingForNumber >,
    sc::transition< EvWrongNumber, USR_wrongNumber > > reactions;
};
/* Charge the user */
struct USR_chargeUser : sc::simple_state< USR_chargeUser, VoiceSM>
{
    USR_chargeUser() {
        // Connect to web service to charge user depending on type of subscription
        cout << "Press 1 or 2 to select  n" << endl;
    }
    ~USR_chargeUser() {}
    typedef mpl::list<
    sc::transition< EvGoToMainMenu, MNU_mainMenu >,
    sc::transition< EvNotCharged, USR_inssuficientBalance >,
    sc::transition< EvNoTime, USR_waitingForNumber >,
    sc::transition< EvWrongNumber, USR_wrongNumber > > reactions;
};
/* User has no balance, end the call */
struct USR_inssuficientBalance : sc::simple_state< USR_inssuficientBalance, VoiceSM>
{
    USR_inssuficientBalance() {
        // Play audio of inssuficient balance and end call
        cout << "User doesn't have enough balance, end call.  n" << endl;
    }
    ~USR_inssuficientBalance() {}
    typedef sc::transition< EvEndCall, USR_endCall > reactions;
};
/* Play audio with main menu and wait for user input */
struct MNU_mainMenu : sc::simple_state< MNU_mainMenu, VoiceSM>
{
    MNU_mainMenu() {
        cout << "Press 1 - 8 from the menu  n" << endl;
    }
    ~MNU_mainMenu() {}
    typedef mpl::list<
    sc::transition< EvMenu1, MNU_selectLeague >,
    sc::transition< EvNoTime, USR_waitingForNumber >,
    sc::transition< EvWrongNumber, USR_wrongNumber > > reactions;
};
/* Select League (Liga Americana/Nacional) wait for 1 or 2 digits */
struct MNU_selectLeague : sc::simple_state< MNU_selectLeague, VoiceSM>
{
    MNU_selectLeague() {
        cout << "Select a league  n" << endl;
    }
    ~MNU_selectLeague() {}
    typedef mpl::list<
    sc::transition< EvGoToMenu1Content, MNU_menu1Content >,
    sc::transition< EvNoTime, USR_waitingForNumber >,
    sc::transition< EvWrongNumber, USR_wrongNumber > > reactions;
};
/* Menu 1 Content */
struct MNU_menu1Content : sc::simple_state< MNU_menu1Content, VoiceSM>
{
    MNU_menu1Content() {
        cout << "Content for menu 1 n" << endl;
    }
    ~MNU_menu1Content() {}
    typedef sc::transition< EvGoToMenu1Content, MNU_menu1Content > reactions;
};
int main()
{
    VSM.initiate();
    return 0;
}

Answer 1

Solved it! (with some friend help) so i was attempting to access the outer context of a simple_state from its constructor.

This assert fails when an attempt is made to access an outer context from a constructor of a state that is not a subtype of state<>. To correct this, derive from state<> instead of simple_state<>.

So in others words i needed to implement state<> instead of simple_state<>.

Here is some coding of how it needs to be

#include <boost/statechart/state.hpp>

struct state_1 : sc::state< state_1, DU >
{
    int suscription = 1;

    state_1( my_context ctx ) : my_base( ctx )
    {
        if (suscription == 1){
            cout<<"Going to event yes \n"<<endl;
            post_event( EvYes() );

        } else {
            post_event( EvNo() );
        }

    }
    typedef mpl::list< // Reaction to Events
    sc::transition< EvYes, state_4 >,
    sc::transition< EvNo, state_2 > > reactions;
};