Serialization using QDataStream and std::vector

gistfile1.txt

#include <QDataStream>
#include <QIODevice>
#include <vector>

struct StdVectorDevice : public QIODevice
{
    std::vector<char> _data;

public:
    StdVectorDevice ();
    StdVectorDevice (std::size_t reserveSize);

public:
    std::vector<char> move ()
    {
        return std::move(_data);
    }

protected:
    qint64 readData (char * data, qint64 len) override;
    qint64 writeData (char const * data, qint64 len) override;
};

// Минимальные требования к сериализатору:
//
// Serializer & Serializer::operator << (T i), где T скалярный тип данных.
// Serializer & Serializer::writeBytes (char const * s, std::size_t len)
//
class Serializer: public QDataStream
{
    StdVectorDevice _dev;

public:
    Serializer (): QDataStream(& _dev)
    {}

    Serializer (std::size_t reserveSize)
        : QDataStream(& _dev)
        , _dev(reserveSize)
    {}

public:
    std::vector<char> move ()
    {
        return _dev.move();
    }
};

class Deserializer: public QDataStream
{
public:
    Deserializer(std::vector<char> && data): QDataStream()
    {}
};

StdVectorDevice::StdVectorDevice ()
    : QIODevice()
{}

StdVectorDevice::StdVectorDevice (std::size_t reserveSize)
    : QIODevice()
    , _data(reserveSize)
{}

qint64 StdVectorDevice::readData (char * data, qint64 len)
{
//         if ((len = qMin(len, static_cast<qint64>(m_vector.size()) - m_ioIndex))
//             <= 0) {
//             return qint64(0);
//         }
//         std::copy(m_vector.cbegin() + m_ioIndex, m_vector.cbegin() + len, data);
//         m_ioIndex += static_cast<int>(len);
//         return len;

    return qint64{0};
}

qint64 StdVectorDevice::writeData (char const * data, qint64 len)
{
    if (len == 0)
        return qint64{0};

    auto offset = _data.size();
    _data.resize(offset + len);

    std::copy(data, data + len, _data.begin() + offset);

    return len;
}