TreeView с фильтром

#include <QtWidgets>
 
QStandardItemModel* createModel();
 
int main(int argc, char *argv[])
{
    QApplication app(argc, argv);
    auto edit = new QLineEdit();
    auto view = new QTreeView();
    auto layout = new QVBoxLayout();
    layout->addWidget(edit);
    layout->addWidget(view);
    auto proxy = new QSortFilterProxyModel();
    proxy->setSourceModel(createModel());
    proxy->setFilterCaseSensitivity(Qt::CaseInsensitive);
    QObject::connect(edit, &QLineEdit::textChanged,
      [&] (QString text) { proxy->setFilterWildcard("*" + text); });
    view->setModel(proxy);
    view->setEditTriggers(QAbstractItemView::NoEditTriggers);
    view->header()->hide();
    view->expandAll();
    QWidget widget;
    widget.setLayout(layout);
    widget.resize(400, 400);
    widget.show();
    return app.exec();
}
 
QStandardItemModel* createModel()
{
    auto model = new QStandardItemModel();
    auto root = model->invisibleRootItem();
    auto append = [&] (QStandardItem *parent, QStandardItem *item) {
        parent->appendRow(item); return item;
    };
    auto world   = append(root, new QStandardItem("World"));
    auto europe  = append(world, new QStandardItem("Europe"));
    auto asia    = append(world, new QStandardItem("Asia"));
    auto america = append(world, new QStandardItem("America"));
    append(europe,  new QStandardItem("Germany"));
    append(europe,  new QStandardItem("France"));
    append(europe,  new QStandardItem("Great Britain"));
    append(asia,    new QStandardItem("Japan"));
    append(asia,    new QStandardItem("Korea"));
    append(asia,    new QStandardItem("China"));
    append(america, new QStandardItem("Unated States"));
    append(america, new QStandardItem("Brazil"));
    append(america, new QStandardItem("Mexico"));
    return model;
}

bool QSortFilterProxyModel::filterAcceptsRow(int source_row, const QModelIndex & source_parent) const