在匹配游戏逻辑的图块中使用STL算法

Question

I have made a tile matching game. It has a Board object that holds a vector of card objects and delegates events to them. Board event handling has following code in it:

// Counting logic-driving card states
int cardFaceUpCounter = 0;
std::vector<Card*> faceUpCards(2);

// Checking for logic-driving card states 
for (auto& card : this->boardMatrix)
{
    if (this->isCardInAnim(&card))
    {
        return;
    }
    if (this->isCardFaceUp(&card))
    {
        ++cardFaceUpCounter;
        faceUpCards[cardFaceUpCounter - 1] = &card;
    }       
}

I've just finished studying Beautiful C++ by Kate Gregory on Pluralsight. She argues that we should avoid writing loops, and should use the STL algorithm header as much as possible. I find her argument and approach very compelling, thus I have tried to refactor my latest pet project to reflect her teachings.

The example above is where I just can't see how I can use STL algorithms to both communicate the intent better and keep the performance - single loop instead of two or three loops, albeit hidden in the algorithm calls.

The second question would be if single loop efficiency can't be achieved using STL algorithms would you still prefer that approach for readability sake.

Answer 1

Here is an example of what I was thinking.

int cardFaceUpCounter = 0;
std::vector<Card*> faceUpCards(2);

if (std::any_of(boardMatrix.begin(), boardMatrix.end(), [&](auto& card) {
    if (isCardFaceUp(&card))
        faceUpCards[cardFaceUpCounter++] = &card;

    return isCardInAnim(&card);    
})) return;

Answer 2

With range-v3 , it would be something like:

std::vector<Card*> faceUpCards = this->boardMatrix
    | ranges::view::take_while([this](const auto& card){ return !isCardInAnim(&card);})
    | ranges::view::filter([this](const auto& card){ return isCardFaceUp(&card); })
    | ranges::view::transform([](auto& e){ return &e; });

With only STL, I would do something like:

auto it = std::find_if(boardMatrix.begin(), boardMatrix.end(),
                       [this](const auto& card){ return isCardInAnim(&card);});
std::vector<Card*> faceUpCards(std::distance(boardMatrix.begin(), it), nullptr);
std::transform(boardMatrix.begin(), it,
               faceUpCards.begin(),
               [](auto& card){ return &card;});
faceUpCards.erase(std::remove_if(faceUpCards.begin(), faceUpCards.end(),
                                [this](const auto& card){ return !isCardFaceUp(&card); }),
                  faceUpCards.end());