Bowling Game: State Machine: Unique_Ptr: Step 33

Moving the ++frame is a trivial refactoring and the Score ends up like this:

    void AddFirstRoll            (int pins) { AddRoll(pins); }
    void AddSecondRollOfOpenFrame(int pins) { AddRoll(pins); ++frame; }
    void AddSpare(int pins)
    {
        switch (bonusRolls)
        {
        case Bonus::NoBonusRolls : score += pins;   bonusRolls = Bonus::OneBonusRoll; break;
        case Bonus::OneBonusRoll : score += pins*2; bonusRolls = Bonus::OneBonusRoll; break;
        case Bonus::TwoBonusRolls: score += pins*2; bonusRolls = Bonus::OneBonusRoll; break;
        }
        ++frame;
    }
    void AddStrike()
    {
        switch (bonusRolls)
        {
        case Bonus::NoBonusRolls        : score += 10; bonusRolls = Bonus::TwoBonusRolls;        break;
        case Bonus::OneBonusRoll        : score += 20; bonusRolls = Bonus::TwoBonusRolls;        break;
        case Bonus::TwoBonusRolls       : score += 20; bonusRolls = Bonus::TwoStrikesBonusRolls; break;
        case Bonus::TwoStrikesBonusRolls: score += 30; bonusRolls = Bonus::TwoStrikesBonusRolls; break;
        }
        ++frame;
    }
    int Score() const { return score; }
private:
    void AddRoll(int pins)
    {
        if ((frame > 10) || ((frame == 10) && (bonusRolls == Bonus::NoBonusRolls)))
            throw std::out_of_range("can't roll after game has ended");

        if (frame < 10)
            score += pins;

        switch (bonusRolls)
        {
        case Bonus::NoBonusRolls        :                                                     break;
        case Bonus::OneBonusRoll        : score += pins;   bonusRolls = Bonus::NoBonusRolls;  break;
        case Bonus::TwoBonusRolls       : score += pins;   bonusRolls = Bonus::OneBonusRoll;  break;
        case Bonus::TwoStrikesBonusRolls: score += pins*2; bonusRolls = Bonus::TwoBonusRolls; break;
        }
    }

Now, AddStrike, AddSpare and AddRoll are similar, but not identical. The similar part is that each switch statement sums in the pins knocked down in this frame plus any bonuses rolls for previous frames, and it adjusts the bonus state. In particular, AddRoll “decrements” each state back one (except for the Bonus::NoBonusRolls). The AddSpare bonus state always ends up as Bonus::OneBonusRoll but the AddStrike bonus is different.

Let’s do the easier case first: the AddSpare method. Refactor it to call the AddRoll method and then adjust the bonus state.

When you’ve done that refactoring, click next.