#include <QCoreApplication>
#include <QtWidgets/QtWidgets>

struct Small {
    int a;
    friend QDataStream& operator<<(QDataStream& out,const Small& s) {
        out << s.a;
        return out;
    }
    friend QDataStream& operator>>(QDataStream& in,Small& s){
        in >> s.a;
        return in;
    }
    bool operator==(const Small& other) const {
        return a == other.a;
    }

};
struct Medium {
    int a;
    double b;
    Small s;
    friend QDataStream& operator<<(QDataStream& out,const Medium& s) {
        out << s.a << s.b << s.s;
        return out;
    }
    friend QDataStream& operator>>(QDataStream& in,Medium& s){
        in >> s.a >> s.b >> s.s;
        return in;
    }
    bool operator==(const Medium& other) const {
        return a == other.a && b == other.b && s == other.s;
    }

};
struct Large {
    int k;
    Medium m;
    friend QDataStream& operator<<(QDataStream& out,const Large& s) {
        out << s.k << s.m;
        return out;
    }
    friend QDataStream& operator>>(QDataStream& in,Large& s){
        in >> s.k >> s.m;
        return in;
    }
    bool operator==(const Large& other) const {
        return k == other.k && m == other.m;
    }


};
struct Aggregate {
    Large l;
    Medium m;
    QVector<Small> s;
    friend QDataStream& operator<<(QDataStream& out,const Aggregate& s) {
        out << s.l << s.m << s.s;
        return out;
    }
    friend QDataStream& operator>>(QDataStream& in,Aggregate& s){
        in >> s.l >> s.m >> s.s;
        return in;
    }
    bool operator==(const Aggregate& other) const {
        return l == other.l && m == other.m && s == other.s;
    }

};

int main(int argc, char *argv[])
{
    QCoreApplication a(argc, argv);
    QFile file("test.txt");
    Aggregate ag{{5,{1,2.5f,{6}}},{2,3.5f,{25}},{{1},{2},{3}}};
    if (file.open(QIODevice::WriteOnly)) {
        QDataStream s(&file);
        s << ag;
    }
    file.close();
    QFile file_in("test.txt");
    if (file_in.open(QIODevice::ReadOnly)) {
        Aggregate g;
        QDataStream in(&file_in);
        in >> g;
        qDebug() << (g == ag);
    }
    QDataStream s;
    return a.exec();
}