Cleanup SimpleDomModel example

Cleanup the SimpleDomModel example:
 - include own headers first
 - use nullptr
 - use const where possible
 - init members in initialization list

Change-Id: If7029a774793927b9a3a9115ea4a7053402a86a1
Reviewed-by: Sze Howe Koh <szehowe.koh@gmail.com>
Reviewed-by: Luca Beldi <v.ronin@yahoo.it>

examples/widgets/itemviews/simpledommodel/domitem.cpp

@@ -53,23 +53,20 @@
 #include <QtXml>
 
 //! [0]
-DomItem::DomItem(QDomNode &node, int row, DomItem *parent)
-{
-    domNode = node;
+DomItem::DomItem(const QDomNode &node, int row, DomItem *parent)
+    : domNode(node),
 //! [0]
-    // Record the item's location within its parent.
+      // Record the item's location within its parent.
 //! [1]
-    rowNumber = row;
-    parentItem = parent;
-}
+      parentItem(parent),
+      rowNumber(row)
+{}
 //! [1]
 
 //! [2]
 DomItem::~DomItem()
 {
-    QHash<int,DomItem*>::iterator it;
-    for (it = childItems.begin(); it != childItems.end(); ++it)
-        delete it.value();
+    qDeleteAll(childItems);
 }
 //! [2]
 
@@ -90,21 +87,22 @@ DomItem *DomItem::parent()
 //! [5]
 DomItem *DomItem::child(int i)
 {
-    if (childItems.contains(i))
-        return childItems[i];
+    DomItem *childItem = childItems.value(i);
+    if (childItem)
+        return childItem;
 
+    // if child does not yet exist, create it
     if (i >= 0 && i < domNode.childNodes().count()) {
         QDomNode childNode = domNode.childNodes().item(i);
-        DomItem *childItem = new DomItem(childNode, i, this);
+        childItem = new DomItem(childNode, i, this);
         childItems[i] = childItem;
-        return childItem;
     }
-    return 0;
+    return childItem;
 }
 //! [5]
 
 //! [6]
-int DomItem::row()
+int DomItem::row() const
 {
     return rowNumber;
 }

examples/widgets/itemviews/simpledommodel/domitem.h

@@ -58,16 +58,16 @@
 class DomItem
 {
 public:
-    DomItem(QDomNode &node, int row, DomItem *parent = 0);
+    DomItem(const QDomNode &node, int row, DomItem *parent = nullptr);
     ~DomItem();
     DomItem *child(int i);
     DomItem *parent();
     QDomNode node() const;
-    int row();
+    int row() const;
 
 private:
     QDomNode domNode;
-    QHash<int,DomItem*> childItems;
+    QHash<int, DomItem *> childItems;
     DomItem *parentItem;
     int rowNumber;
 };

examples/widgets/itemviews/simpledommodel/dommodel.cpp

@@ -48,16 +48,17 @@
 **
 ****************************************************************************/
 
-#include "domitem.h"
 #include "dommodel.h"
+#include "domitem.h"
 
 #include <QtXml>
 
 //! [0]
-DomModel::DomModel(QDomDocument document, QObject *parent)
-    : QAbstractItemModel(parent), domDocument(document)
+DomModel::DomModel(const QDomDocument &document, QObject *parent)
+    : QAbstractItemModel(parent),
+      domDocument(document),
+      rootItem(new DomItem(domDocument, 0))
 {
-    rootItem = new DomItem(domDocument, 0);
 }
 //! [0]
 
@@ -69,8 +70,9 @@ DomModel::~DomModel()
 //! [1]
 
 //! [2]
-int DomModel::columnCount(const QModelIndex &/*parent*/) const
+int DomModel::columnCount(const QModelIndex &parent) const
 {
+    Q_UNUSED(parent);
     return 3;
 }
 //! [2]
@@ -84,28 +86,31 @@ QVariant DomModel::data(const QModelIndex &index, int role) const
     if (role != Qt::DisplayRole)
         return QVariant();
 
-    DomItem *item = static_cast<DomItem*>(index.internalPointer());
+    const DomItem *item = static_cast<DomItem*>(index.internalPointer());
 
-    QDomNode node = item->node();
+    const QDomNode node = item->node();
 //! [3] //! [4]
-    QStringList attributes;
-    QDomNamedNodeMap attributeMap = node.attributes();
 
     switch (index.column()) {
         case 0:
             return node.nodeName();
         case 1:
+        {
+            const QDomNamedNodeMap attributeMap = node.attributes();
+            QStringList attributes;
             for (int i = 0; i < attributeMap.count(); ++i) {
                 QDomNode attribute = attributeMap.item(i);
                 attributes << attribute.nodeName() + "=\""
-                              +attribute.nodeValue() + '"';
+                              + attribute.nodeValue() + '"';
             }
             return attributes.join(' ');
+        }
         case 2:
-            return node.nodeValue().split("\n").join(' ');
+            return node.nodeValue().split('\n').join(' ');
         default:
-            return QVariant();
+            break;
     }
+    return QVariant();
 }
 //! [4]
 
@@ -113,7 +118,7 @@ QVariant DomModel::data(const QModelIndex &index, int role) const
 Qt::ItemFlags DomModel::flags(const QModelIndex &index) const
 {
     if (!index.isValid())
-        return 0;
+        return Qt::NoItemFlags;
 
     return QAbstractItemModel::flags(index);
 }
@@ -132,17 +137,15 @@ QVariant DomModel::headerData(int section, Qt::Orientation orientation,
             case 2:
                 return tr("Value");
             default:
-                return QVariant();
+                break;
         }
     }
-
     return QVariant();
 }
 //! [6]
 
 //! [7]
-QModelIndex DomModel::index(int row, int column, const QModelIndex &parent)
-            const
+QModelIndex DomModel::index(int row, int column, const QModelIndex &parent) const
 {
     if (!hasIndex(row, column, parent))
         return QModelIndex();
@@ -159,8 +162,7 @@ QModelIndex DomModel::index(int row, int column, const QModelIndex &parent)
     DomItem *childItem = parentItem->child(row);
     if (childItem)
         return createIndex(row, column, childItem);
-    else
-        return QModelIndex();
+    return QModelIndex();
 }
 //! [8]
 

examples/widgets/itemviews/simpledommodel/dommodel.h

@@ -63,7 +63,7 @@ class DomModel : public QAbstractItemModel
     Q_OBJECT
 
 public:
-    explicit DomModel(QDomDocument document, QObject *parent = 0);
+    explicit DomModel(const QDomDocument &document, QObject *parent = nullptr);
     ~DomModel();
 
     QVariant data(const QModelIndex &index, int role) const override;

examples/widgets/itemviews/simpledommodel/mainwindow.cpp

@@ -48,22 +48,23 @@
 **
 ****************************************************************************/
 
-#include "dommodel.h"
 #include "mainwindow.h"
+#include "dommodel.h"
 
 #include <QDomDocument>
 #include <QTreeView>
 #include <QMenuBar>
 #include <QFileDialog>
 
-MainWindow::MainWindow() : QMainWindow(), model(0)
+MainWindow::MainWindow(QWidget *parent)
+    : QMainWindow(parent),
+      model(new DomModel(QDomDocument(), this)),
+      view(new QTreeView(this))
 {
     fileMenu = menuBar()->addMenu(tr("&File"));
     fileMenu->addAction(tr("&Open..."), this, &MainWindow::openFile, QKeySequence::Open);
     fileMenu->addAction(tr("E&xit"), this, &QWidget::close, QKeySequence::Quit);
 
-    model = new DomModel(QDomDocument(), this);
-    view = new QTreeView(this);
     view->setModel(model);
 
     setCentralWidget(view);

examples/widgets/itemviews/simpledommodel/mainwindow.h

@@ -65,7 +65,7 @@ class MainWindow : public QMainWindow
     Q_OBJECT
 
 public:
-    MainWindow();
+    MainWindow(QWidget *parent = nullptr);
 
 public slots:
     void openFile();