Polish the SimpleTreeModel example

- Fix/silence most clang-tidy/compiler warnings
  * unsigned/int comparison
  * Avoid repeating return / default parameter types
  * Make functions static/use static invocations
  * Use string literals everywhere
  * Use auto * for pointers
  * Streamline code, use ternary operators
  * Move constructor parameters
  * Observe rule of 5 by using Q_DISABLE_COPY_MOVE
- Add some bells && whistles, resize properly, expand all

Complements 25027444a9b53d61a6257dc5f5ce0ffdb3b06f98.

Pick-to: 6.6
Change-Id: I78f48d187981ecabf69a5d4d42715bad026fa9e6
Reviewed-by: Kai Köhne <kai.koehne@qt.io>

1 files changed, 7 insertions, 5 deletions

diff --git a/examples/widgets/itemviews/simpletreemodel/treemodel.h b/examples/widgets/itemviews/simpletreemodel/treemodel.h
index 0a771088ed..55c72bb3bd 100644
--- a/examples/widgets/itemviews/simpletreemodel/treemodel.h
+++ b/examples/widgets/itemviews/simpletreemodel/treemodel.h
@@ -16,21 +16,23 @@ class TreeModel : public QAbstractItemModel
     Q_OBJECT
 
 public:
+    Q_DISABLE_COPY_MOVE(TreeModel)
+
     explicit TreeModel(const QString &data, QObject *parent = nullptr);
-    ~TreeModel();
+    ~TreeModel() override;
 
     QVariant data(const QModelIndex &index, int role) const override;
     Qt::ItemFlags flags(const QModelIndex &index) const override;
     QVariant headerData(int section, Qt::Orientation orientation,
                         int role = Qt::DisplayRole) const override;
     QModelIndex index(int row, int column,
-                      const QModelIndex &parent = QModelIndex()) const override;
+                      const QModelIndex &parent = {}) 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;
+    int rowCount(const QModelIndex &parent = {}) const override;
+    int columnCount(const QModelIndex &parent = {}) const override;
 
 private:
-    void setupModelData(const QStringList &lines, TreeItem *parent);
+    static void setupModelData(const QStringList &lines, TreeItem *parent);
 
     std::unique_ptr<TreeItem> rootItem;
 };