How simpletreeview example works?

Dear All,

I am trying to learn how the example SimpleTreeView works.
I can hardly understand one, maybe the key part of the implementation.

void TreeModel::setupModelData(const QStringList &lines, TreeItem *parent)
{
QList<TreeItem*> parents;
...

// Append a new item to the current parent's list of children.
parents.last()->appendChild(new TreeItem(columnData, parents.last()));

...
}

Could you kindly explain me how it works?

parents is declared in TreeModel::setupModelData
and as far as I understand, it's scope is in this method.
So when exited from setupModelData the list is destroyed.

How then can the model access all the items?

I presume that all is hiden in QModelIndex mechanism.
But unfortunately I cannot understand it's profundity even though I have read the docs.
I would higly appreciate all your comments.

Thank you very much.