QT container, with specified order and no repetitions

Question

I need somthing similar to QSet, but I need the items to be saved on the order I inserted them

is there such thing?

Answer 1

Maybe a QList or a QVector could help.

QList<QString> stringList;
//By the way, Qt provides QStringList as a typedef for QList<QString>
stringList.append("A");
stringList.append("B");

qDebug() << stringList.at(0); //A
qDebug() << stringList.at(1); //B

Answer 2

I am not aware of anything like that out of the box in neither Qt nor STL. Boost has something like that I think but it is not that hard to do this yourself.

You could do a wrapper around QHash like this:

template<typename T>
class MySet : QHash<T, int>
{
public:
    using QHash<T, int>::QHash;

    QVector<T> values() //this 'hides' the base QHash::values() of QHash
    {
        QVector<T> vec(count());

        for(auto it = cbegin(); it != end(); ++it)
        {
            vec[it.value()] = it.key();
        }

        return vec;
    }

    void insert(const T &value)
    {
        if(!contains(value))
        {
            insert(value, m_Data.count());
        }
    }
};

The usage is quite similar to QSet:

MySet<QString> set;
set.insert("1");
set.insert("2");
set.insert("3");
qDebug() << set.values();

And that prints the values in order. If you need more complete support like iterators also iterating in your desired order you would have to reimplement more functionality but the gist of it would be the same. After all QSet is internally QHash as well. Note that the above does not support removal without modification.