如何创建基于QVariant的泛型模型？

#include <QAbstractItemModel>
#include <QVariant>
#include <QList>

class GenericItem
{
public:
    GenericItem(const QVariant& data, GenericItem* parent = nullptr);
    ~GenericItem();

    void appendChild(GenericItem* child);
    GenericItem* child(int row);
    int childCount() const;
    int columnCount() const;
    QVariant data(int column) const;
    int row() const;
    GenericItem* parent();

private:
    QList<GenericItem*> m_children;
    QVariant m_itemData;
    GenericItem* m_parent;
};

GenericItem::GenericItem(const QVariant& data, GenericItem* parent)
    : m_itemData(data), m_parent(parent)
{
}

GenericItem::~GenericItem()
{
    qDeleteAll(m_children);
}

void GenericItem::appendChild(GenericItem* child)
{
    m_children.append(child);
}

GenericItem* GenericItem::child(int row)
{
    return m_children.value(row);
}

int GenericItem::childCount() const
{
    return m_children.count();
}

int GenericItem::columnCount() const
{
    return 1; // 只有一列数据
}

QVariant GenericItem::data(int column) const
{
    if (column == 0)
        return m_itemData;

    return QVariant();
}

int GenericItem::row() const
{
    if (m_parent)
        return m_parent->m_children.indexOf(const_cast<GenericItem*>(this));

    return 0;
}

GenericItem* GenericItem::parent()
{
    return m_parent;
}

class GenericModel : public QAbstractItemModel
{
public:
    GenericModel(QObject* parent = nullptr);
    ~GenericModel();

    QModelIndex index(int row, int column, const QModelIndex& parent = QModelIndex()) const override;
    QModelIndex parent(const QModelIndex& index) const override;
    int rowCount(const QModelIndex& parent = QModelIndex()) const override;
    int columnCount(const QModelIndex& parent = QModelIndex()) const override;
    QVariant data(const QModelIndex& index, int role = Qt::DisplayRole) const override;

private:
    GenericItem* m_rootItem;
};

GenericModel::GenericModel(QObject* parent)
    : QAbstractItemModel(parent), m_rootItem(nullptr)
{
}

GenericModel::~GenericModel()
{
    delete m_rootItem;
}

QModelIndex GenericModel::index(int row, int column, const QModelIndex& parent) const
{
    if (!hasIndex(row, column, parent))
        return QModelIndex();

    GenericItem* parentItem;

    if (!parent.isValid())
        parentItem = m_rootItem;
    else
        parentItem = static_cast<GenericItem*>(parent.internalPointer());

    GenericItem* childItem = parentItem->child(row);
    if (childItem)
        return createIndex(row, column, childItem);
    else
        return QModelIndex();
}

QModelIndex GenericModel::parent(const QModelIndex& index) const
{
    if (!index.isValid())
        return QModelIndex();

    GenericItem* childItem = static_cast<GenericItem*>(index.internalPointer());
    GenericItem* parentItem = childItem->parent();

    if (parentItem == m_rootItem)
        return QModelIndex();

    return createIndex(parentItem->row(), 0, parentItem);
}

int GenericModel::rowCount(const QModelIndex& parent) const
{
    if (parent.column() > 0)
        return 0;

    GenericItem* parentItem;
    if (!parent.isValid())
        parentItem = m_rootItem;
    else
        parentItem = static_cast<GenericItem*>(parent.internalPointer());

    return parentItem->childCount();
}

int GenericModel::columnCount(const QModelIndex& parent) const
{
    if (parent.isValid())
        return static_cast<GenericItem*>(parent.internalPointer())->columnCount();
    else
        return 1; // 只有一列数据
}

QVariant GenericModel::data(const QModelIndex& index, int role) const
{
    if (!index.isValid())
        return QVariant();

    if (role != Qt::DisplayRole)
        return QVariant();

    GenericItem* item = static_cast<GenericItem*>(index.internalPointer());

    return item->data(index.column());
}

GenericModel* model = new GenericModel(this);
GenericItem* rootItem = new GenericItem("Root Item");
model->setRootItem(rootItem);

GenericItem* childItem1 = new GenericItem("Child Item 1", rootItem);
rootItem->appendChild(childItem1);

GenericItem* childItem2 = new GenericItem("Child Item 2", rootItem);
rootItem->appendChild(childItem2);