Hỏi về luồng xử lý đoạn code

[Quangnguyen123 (Quang Nguyen)]

#include<iostream>

using namespace std;
 
class State{
    protected:
        State* next_a, * next_b;
        char output;
    public:
        State(State &a, State &b):next_a(&a), next_b(&b){cout << "0" << endl;}
        virtual State* transition(char)=0;
};
class State1: public State{
    public:
        State1(State &a, State &b):State(a,b){cout << "1" << endl;}
        State* transition(char);
};
class State2: public State{
    public:
        State2(State &a, State &b):State(a,b){cout << "2" << endl;}
        State* transition(char);
};
class State3: public State{
    public:
        State3(State &a, State &b):State(a,b){cout << "3" << endl;}
        State* transition(char);
};
State* State1::transition(char input){
    cout << endl << " Current state: 1";
    switch(input){
        case 'a': 
            output='y';
            cout << endl << "Output:" << output;
            cout << endl << "Next state: 1";
            return next_a;
        case 'b': 
            output='x';
            cout << endl << "Output:" << output;
            cout << endl << "Next state: 2";
            return next_b;
        default:
            cout << endl << "Undefined input";
            cout << endl << "Next state: Unchanged";
            return this;
    }
}
State* State2::transition(char input){
    cout << endl << " Current state: 2";
    switch(input){
        case 'a': 
            output='y';
            cout << endl << "Output:" << output;
            cout << endl << "Next state: 3";
            return next_a;
        case 'b': 
            output='x';
            cout << endl << "Output:" << output;
            cout << endl << "Next state: 2";
            return next_b;
        default:
            cout << endl << "Undefined input";
            cout << endl << "Next state: Unchanged";
            return this;
    }
}
State* State3::transition(char input){
    cout << endl << " Current state: 3";
    switch(input){
        case 'a': 
            output='y';
            cout << endl << "Output:" << output;
            cout << endl << "Next state: 1";
            return next_a;
        case 'b': 
            output='x';
            cout << endl << "Output:" << output;
            cout << endl << "Next state: 2";
            return next_b;
        default:
            cout << endl << "Undefined input";
            cout << endl << "Next state: Unchanged";
            return this;
    }
}

class FMS{
    State1 s1;  
    State2 s2;
    State3 s3;
    State *current;
    public:
    FMS():s1(s1,s2), s2(s3,s2), s3(s1,s3), current(&s1){cout << "5" << endl;};
    void run();
};

int main(void)
{
    FMS f1;
    
    return 0;
}

Cho mình hỏi là khi tạo ra 1 đối tượng FMS, hàm khởi tạo sẽ được gọi đến, lúc đó thì các s1 s2 s3 đã được tạo ra chữa ?

[SITUVN.gcd]

Muốn biết nó chạy theo trình tự nào thì in ra các chuỗi trong hàm dựng để biết nó đang chạy đến đâu. Chuyên nghiệp hơn thì Chế độ Gỡ lỗi (Debug Mode).