Polish the EditableTreeModel example

- Fix/silence most clang-tidy/compiler warnings
  * unsigned/int comparison
  * Avoid repeating return / default parameter types
  * 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

Change-Id: I1721458ff66dcba123ff3a2cf50e7d15387a4e8b
Reviewed-by: Kai Köhne <kai.koehne@qt.io>

6 files changed, 41 insertions, 44 deletions

diff --git a/examples/widgets/itemviews/editabletreemodel/main.cpp b/examples/widgets/itemviews/editabletreemodel/main.cpp
index 40a8fa104c..7ed4cf1dc4 100644
--- a/examples/widgets/itemviews/editabletreemodel/main.cpp
+++ b/examples/widgets/itemviews/editabletreemodel/main.cpp
@@ -4,11 +4,14 @@
 #include "mainwindow.h"
 
 #include <QApplication>
+#include <QScreen>
 
 int main(int argc, char *argv[])
 {
     QApplication app(argc, argv);
     MainWindow window;
+    const auto screenSize = window.screen()->availableSize();
+    window.resize({screenSize.width() / 2, screenSize.height() * 2 / 3});
     window.show();
-    return app.exec();
+    return QCoreApplication::exec();
 }
diff --git a/examples/widgets/itemviews/editabletreemodel/mainwindow.cpp b/examples/widgets/itemviews/editabletreemodel/mainwindow.cpp
index fa7b31746a..cf88932cdb 100644
--- a/examples/widgets/itemviews/editabletreemodel/mainwindow.cpp
+++ b/examples/widgets/itemviews/editabletreemodel/mainwindow.cpp
@@ -6,6 +6,8 @@
 
 #include <QFile>
 
+using namespace Qt::StringLiterals;
+
 MainWindow::MainWindow(QWidget *parent)
     : QMainWindow(parent)
 {
@@ -13,14 +15,15 @@ MainWindow::MainWindow(QWidget *parent)
 
     const QStringList headers({tr("Title"), tr("Description")});
 
-    QFile file(":/default.txt");
-    file.open(QIODevice::ReadOnly);
-    TreeModel *model = new TreeModel(headers, file.readAll(), this);
+    QFile file(":/default.txt"_L1);
+    file.open(QIODevice::ReadOnly | QIODevice::Text);
+    auto *model = new TreeModel(headers, QString::fromUtf8(file.readAll()), this);
     file.close();
 
     view->setModel(model);
     for (int column = 0; column < model->columnCount(); ++column)
         view->resizeColumnToContents(column);
+    view->expandAll();
 
     connect(exitAction, &QAction::triggered, qApp, &QCoreApplication::quit);
 
diff --git a/examples/widgets/itemviews/editabletreemodel/treeitem.cpp b/examples/widgets/itemviews/editabletreemodel/treeitem.cpp
index 27cf2ea2b1..42d911823d 100644
--- a/examples/widgets/itemviews/editabletreemodel/treeitem.cpp
+++ b/examples/widgets/itemviews/editabletreemodel/treeitem.cpp
@@ -10,24 +10,23 @@
 #include "treeitem.h"
 
 //! [0]
-TreeItem::TreeItem(const QVariantList &data, TreeItem *parent)
-    : itemData(data), m_parentItem(parent)
+TreeItem::TreeItem(QVariantList data, TreeItem *parent)
+    : itemData(std::move(data)), m_parentItem(parent)
 {}
 //! [0]
 
 //! [1]
 TreeItem *TreeItem::child(int number)
 {
-    if (number < 0 || number >= qsizetype(m_childItems.size()))
-        return nullptr;
-    return m_childItems.at(number).get();
+    return (number >= 0 && number < childCount())
+        ? m_childItems.at(number).get() : nullptr;
 }
 //! [1]
 
 //! [2]
 int TreeItem::childCount() const
 {
-    return m_childItems.size();
+    return int(m_childItems.size());
 }
 //! [2]
 
@@ -38,7 +37,7 @@ int TreeItem::row() const
         return 0;
     const auto it = std::find_if(m_parentItem->m_childItems.cbegin(), m_parentItem->m_childItems.cend(),
                                  [this](const std::unique_ptr<TreeItem> &treeItem) {
-        return treeItem.get() == const_cast<TreeItem *>(this);
+        return treeItem.get() == this;
     });
 
     if (it != m_parentItem->m_childItems.cend())
@@ -51,16 +50,14 @@ int TreeItem::row() const
 //! [4]
 int TreeItem::columnCount() const
 {
-    return itemData.count();
+    return int(itemData.count());
 }
 //! [4]
 
 //! [5]
 QVariant TreeItem::data(int column) const
 {
-    if (column < 0 || column >= itemData.size())
-        return QVariant();
-    return itemData.at(column);
+    return itemData.value(column);
 }
 //! [5]
 
diff --git a/examples/widgets/itemviews/editabletreemodel/treeitem.h b/examples/widgets/itemviews/editabletreemodel/treeitem.h
index d30047dd2a..8910312ade 100644
--- a/examples/widgets/itemviews/editabletreemodel/treeitem.h
+++ b/examples/widgets/itemviews/editabletreemodel/treeitem.h
@@ -11,7 +11,7 @@
 class TreeItem
 {
 public:
-    explicit TreeItem(const QVariantList &data, TreeItem *parent = nullptr);
+    explicit TreeItem(QVariantList data, TreeItem *parent = nullptr);
 
     TreeItem *child(int number);
     int childCount() const;
diff --git a/examples/widgets/itemviews/editabletreemodel/treemodel.cpp b/examples/widgets/itemviews/editabletreemodel/treemodel.cpp
index 79be938d88..6511b06780 100644
--- a/examples/widgets/itemviews/editabletreemodel/treemodel.cpp
+++ b/examples/widgets/itemviews/editabletreemodel/treemodel.cpp
@@ -4,8 +4,6 @@
 #include "treemodel.h"
 #include "treeitem.h"
 
-#include <QtWidgets>
-
 using namespace Qt::StringLiterals;
 
 //! [0]
@@ -36,10 +34,10 @@ int TreeModel::columnCount(const QModelIndex &parent) const
 QVariant TreeModel::data(const QModelIndex &index, int role) const
 {
     if (!index.isValid())
-        return QVariant();
+        return {};
 
     if (role != Qt::DisplayRole && role != Qt::EditRole)
-        return QVariant();
+        return {};
 
     TreeItem *item = getItem(index);
 
@@ -60,8 +58,7 @@ Qt::ItemFlags TreeModel::flags(const QModelIndex &index) const
 TreeItem *TreeModel::getItem(const QModelIndex &index) const
 {
     if (index.isValid()) {
-        TreeItem *item = static_cast<TreeItem*>(index.internalPointer());
-        if (item)
+        if (auto *item = static_cast<TreeItem*>(index.internalPointer()))
             return item;
     }
     return rootItem.get();
@@ -71,28 +68,25 @@ TreeItem *TreeModel::getItem(const QModelIndex &index) const
 QVariant TreeModel::headerData(int section, Qt::Orientation orientation,
                                int role) const
 {
-    if (orientation == Qt::Horizontal && role == Qt::DisplayRole)
-        return rootItem->data(section);
-
-    return QVariant();
+    return (orientation == Qt::Horizontal && role == Qt::DisplayRole)
+        ? rootItem->data(section) : QVariant{};
 }
 
 //! [5]
 QModelIndex TreeModel::index(int row, int column, const QModelIndex &parent) const
 {
     if (parent.isValid() && parent.column() != 0)
-        return QModelIndex();
+        return {};
 //! [5]
 
 //! [6]
     TreeItem *parentItem = getItem(parent);
     if (!parentItem)
-        return QModelIndex();
+        return {};
 
-    TreeItem *childItem = parentItem->child(row);
-    if (childItem)
+    if (auto *childItem = parentItem->child(row))
         return createIndex(row, column, childItem);
-    return QModelIndex();
+    return {};
 }
 //! [6]
 
@@ -124,15 +118,13 @@ bool TreeModel::insertRows(int position, int rows, const QModelIndex &parent)
 QModelIndex TreeModel::parent(const QModelIndex &index) const
 {
     if (!index.isValid())
-        return QModelIndex();
+        return {};
 
     TreeItem *childItem = getItem(index);
     TreeItem *parentItem = childItem ? childItem->parent() : nullptr;
 
-    if (parentItem == rootItem.get() || !parentItem)
-        return QModelIndex();
-
-    return createIndex(parentItem->row(), 0, parentItem);
+    return (parentItem != rootItem.get() && parentItem != nullptr)
+        ? createIndex(parentItem->row(), 0, parentItem) : QModelIndex{};
 }
 //! [7]
 
diff --git a/examples/widgets/itemviews/editabletreemodel/treemodel.h b/examples/widgets/itemviews/editabletreemodel/treemodel.h
index 42b6a96357..4f781c8144 100644
--- a/examples/widgets/itemviews/editabletreemodel/treemodel.h
+++ b/examples/widgets/itemviews/editabletreemodel/treemodel.h
@@ -16,9 +16,11 @@ class TreeModel : public QAbstractItemModel
     Q_OBJECT
 
 public:
+    Q_DISABLE_COPY_MOVE(TreeModel)
+
     TreeModel(const QStringList &headers, const QString &data,
               QObject *parent = nullptr);
-    ~TreeModel();
+    ~TreeModel() override;
 //! [0] //! [1]
 
     QVariant data(const QModelIndex &index, int role) const override;
@@ -26,11 +28,11 @@ public:
                         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;
 //! [1]
 
 //! [2]
@@ -41,13 +43,13 @@ public:
                        const QVariant &value, int role = Qt::EditRole) override;
 
     bool insertColumns(int position, int columns,
-                       const QModelIndex &parent = QModelIndex()) override;
+                       const QModelIndex &parent = {}) override;
     bool removeColumns(int position, int columns,
-                       const QModelIndex &parent = QModelIndex()) override;
+                       const QModelIndex &parent = {}) override;
     bool insertRows(int position, int rows,
-                    const QModelIndex &parent = QModelIndex()) override;
+                    const QModelIndex &parent = {}) override;
     bool removeRows(int position, int rows,
-                    const QModelIndex &parent = QModelIndex()) override;
+                    const QModelIndex &parent = {}) override;
 
 private:
     void setupModelData(const QList<QStringView> &lines);