Modernize EditableTreeModel

- Use unique_ptr instead of manual memory management
- Improve consistenty in variable name with the simpletreemodel
  childrenNumber -> row, m_ prefix for member variables

Change-Id: Iface30c2224c2b1db7c623a9e6fcbb449c556f3e
Reviewed-by: Volker Hilsheimer <volker.hilsheimer@qt.io>
(cherry picked from commit 604b2feca751c5eb43b20e180c175acc2a87099e)
Reviewed-by: <carl@carlschwan.eu>
Reviewed-by: Kai Köhne <kai.koehne@qt.io>

examples/widgets/doc/src/editabletreemodel.qdoc

@@ -230,32 +230,30 @@
     internal \c childItems member using the \c insertChildren() function
     described later.
 
-    The destructor ensures that each child added to the item is deleted
+    The children are stored in std::unique_ptr to ensures that each child
-    when the item itself is deleted:
+    added to the item is deleted when the item itself is deleted.
-
-    \snippet itemviews/editabletreemodel/treeitem.cpp 1
 
     \target TreeItem::parent
     Since each item stores a pointer to its parent, the \c parent() function
     is trivial:
 
-    \snippet itemviews/editabletreemodel/treeitem.cpp 9
+    \snippet itemviews/editabletreemodel/treeitem.cpp 8
 
     \target TreeItem::child
     Three functions provide information about the children of an item.
     \c child() returns a specific child from the internal list of children:
 
-    \snippet itemviews/editabletreemodel/treeitem.cpp 2
+    \snippet itemviews/editabletreemodel/treeitem.cpp 1
 
     The \c childCount() function returns the total number of children:
 
-    \snippet itemviews/editabletreemodel/treeitem.cpp 3
+    \snippet itemviews/editabletreemodel/treeitem.cpp 2
 
     The \c childNumber() function is used to determine the index of the child
     in its parent's list of children. It accesses the parent's \c childItems
     member directly to obtain this information:
 
-    \snippet itemviews/editabletreemodel/treeitem.cpp 4
+    \snippet itemviews/editabletreemodel/treeitem.cpp 3
 
     The root item has no parent item; for this item, we return zero to be
     consistent with the other items.
@@ -263,20 +261,20 @@
     The \c columnCount() function simply returns the number of elements in
     the internal \c itemData list of QVariant objects:
 
-    \snippet itemviews/editabletreemodel/treeitem.cpp 5
+    \snippet itemviews/editabletreemodel/treeitem.cpp 4
 
     \target TreeItem::data
     Data is retrieved using the \c data() function, which accesses the
     appropriate element in the \c itemData list:
 
-    \snippet itemviews/editabletreemodel/treeitem.cpp 6
+    \snippet itemviews/editabletreemodel/treeitem.cpp 5
 
     \target TreeItem::setData
     Data is set using the \c setData() function, which only stores values
     in the \c itemData list for valid list indexes, corresponding to column
     values in the model:
 
-    \snippet itemviews/editabletreemodel/treeitem.cpp 11
+    \snippet itemviews/editabletreemodel/treeitem.cpp 10
 
     To make implementation of the model easier, we return true to indicate
     that the data was set successfully.
@@ -286,20 +284,20 @@
     in the model leads to the insertion of new child items in the corresponding
     item, handled by the \c insertChildren() function:
 
-    \snippet itemviews/editabletreemodel/treeitem.cpp 7
+    \snippet itemviews/editabletreemodel/treeitem.cpp 6
 
     This ensures that new items are created with the required number of columns
     and inserted at a valid position in the internal \c childItems list.
     Items are removed with the \c removeChildren() function:
 
-    \snippet itemviews/editabletreemodel/treeitem.cpp 10
+    \snippet itemviews/editabletreemodel/treeitem.cpp 9
 
     As discussed above, the functions for inserting and removing columns are
     used differently to those for inserting and removing child items because
     they are expected to be called on every item in the tree. We do this by
     recursively calling this function on each child of the item:
 
-    \snippet itemviews/editabletreemodel/treeitem.cpp 8
+    \snippet itemviews/editabletreemodel/treeitem.cpp 7
 
     \section1 TreeModel Class Definition
 
@@ -335,11 +333,12 @@
     use with the model. Other models may be initialized with a ready-made
     data structure, or use an API from a library that maintains its own data.
 
-    The destructor only has to delete the root item, which will cause all child
-    items to be recursively deleted.
-
     \snippet itemviews/editabletreemodel/treemodel.cpp 1
 
+    The destructor only has to delete the root item, which will cause all child
+    items to be recursively deleted. This is done automatically by the default
+    destructor since the root item is stored inside an unique_ptr.
+
     \target TreeModel::getItem
     Since the model's interface to the other model/view components is based
     on model indexes, and since the internal data structure is item-based,

examples/widgets/itemviews/editabletreemodel/treeitem.cpp

@@ -10,76 +10,77 @@
 #include "treeitem.h"
 
 //! [0]
-TreeItem::TreeItem(const QList<QVariant> &data, TreeItem *parent)
+TreeItem::TreeItem(const QVariantList &data, TreeItem *parent)
-    : itemData(data), parentItem(parent)
+    : itemData(data), m_parentItem(parent)
 {}
 //! [0]
 
 //! [1]
-TreeItem::~TreeItem()
+TreeItem *TreeItem::child(int number)
 {
-    qDeleteAll(childItems);
+    if (number < 0 || number >= m_childItems.size())
+        return nullptr;
+    return m_childItems.at(number).get();
 }
 //! [1]
 
 //! [2]
-TreeItem *TreeItem::child(int number)
+int TreeItem::childCount() const
 {
-    if (number < 0 || number >= childItems.size())
+    return m_childItems.size();
-        return nullptr;
-    return childItems.at(number);
 }
 //! [2]
 
 //! [3]
-int TreeItem::childCount() const
+int TreeItem::row() const
 {
-    return childItems.count();
+    if (!m_parentItem)
+        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);
+    });
+
+    if (it != m_parentItem->m_childItems.cend())
+        return std::distance(m_parentItem->m_childItems.cbegin(), it);
+    Q_ASSERT(false); // should not happen
+    return -1;
 }
 //! [3]
 
 //! [4]
-int TreeItem::childNumber() const
-{
-    if (parentItem)
-        return parentItem->childItems.indexOf(const_cast<TreeItem*>(this));
-    return 0;
-}
-//! [4]
-
-//! [5]
 int TreeItem::columnCount() const
 {
     return itemData.count();
 }
-//! [5]
+//! [4]
 
-//! [6]
+//! [5]
 QVariant TreeItem::data(int column) const
 {
     if (column < 0 || column >= itemData.size())
         return QVariant();
     return itemData.at(column);
 }
-//! [6]
+//! [5]
 
-//! [7]
+//! [6]
 bool TreeItem::insertChildren(int position, int count, int columns)
 {
-    if (position < 0 || position > childItems.size())
+    if (position < 0 || position > m_childItems.size())
         return false;
 
     for (int row = 0; row < count; ++row) {
-        QList<QVariant> data(columns);
+        QVariantList data(columns);
-        TreeItem *item = new TreeItem(data, this);
+        m_childItems.insert(m_childItems.cbegin() + position,
-        childItems.insert(position, item);
+                std::make_unique<TreeItem>(data, this));
     }
 
     return true;
 }
-//! [7]
+//! [6]
 
-//! [8]
+//! [7]
 bool TreeItem::insertColumns(int position, int columns)
 {
     if (position < 0 || position > itemData.size())
@@ -88,32 +89,32 @@ bool TreeItem::insertColumns(int position, int columns)
     for (int column = 0; column < columns; ++column)
         itemData.insert(position, QVariant());
 
-    for (TreeItem *child : std::as_const(childItems))
+    for (auto &child : std::as_const(m_childItems))
         child->insertColumns(position, columns);
 
     return true;
 }
+//! [7]
+
+//! [8]
+TreeItem *TreeItem::parent()
+{
+    return m_parentItem;
+}
 //! [8]
 
 //! [9]
-TreeItem *TreeItem::parent()
-{
-    return parentItem;
-}
-//! [9]
-
-//! [10]
 bool TreeItem::removeChildren(int position, int count)
 {
-    if (position < 0 || position + count > childItems.size())
+    if (position < 0 || position + count > m_childItems.size())
         return false;
 
     for (int row = 0; row < count; ++row)
-        delete childItems.takeAt(position);
+        m_childItems.erase(m_childItems.cbegin() + position);
 
     return true;
 }
-//! [10]
+//! [9]
 
 bool TreeItem::removeColumns(int position, int columns)
 {
@@ -123,13 +124,13 @@ bool TreeItem::removeColumns(int position, int columns)
     for (int column = 0; column < columns; ++column)
         itemData.remove(position);
 
-    for (TreeItem *child : std::as_const(childItems))
+    for (auto &child : std::as_const(m_childItems))
         child->removeColumns(position, columns);
 
     return true;
 }
 
-//! [11]
+//! [10]
 bool TreeItem::setData(int column, const QVariant &value)
 {
     if (column < 0 || column >= itemData.size())
@@ -138,4 +139,4 @@ bool TreeItem::setData(int column, const QVariant &value)
     itemData[column] = value;
     return true;
 }
-//! [11]
+//! [10]

examples/widgets/itemviews/editabletreemodel/treeitem.h

@@ -11,8 +11,7 @@
 class TreeItem
 {
 public:
-    explicit TreeItem(const QList<QVariant> &data, TreeItem *parent = nullptr);
+    explicit TreeItem(const QVariantList &data, TreeItem *parent = nullptr);
-    ~TreeItem();
 
     TreeItem *child(int number);
     int childCount() const;
@@ -23,13 +22,13 @@ public:
     TreeItem *parent();
     bool removeChildren(int position, int count);
     bool removeColumns(int position, int columns);
-    int childNumber() const;
+    int row() const;
     bool setData(int column, const QVariant &value);
 
 private:
-    QList<TreeItem *> childItems;
+    std::vector<std::unique_ptr<TreeItem>> m_childItems;
-    QList<QVariant> itemData;
+    QVariantList itemData;
-    TreeItem *parentItem;
+    TreeItem *m_parentItem;
 };
 //! [0]
 

examples/widgets/itemviews/editabletreemodel/treemodel.cpp

@@ -6,24 +6,23 @@
 
 #include <QtWidgets>
 
+using namespace Qt::StringLiterals;
+
 //! [0]
 TreeModel::TreeModel(const QStringList &headers, const QString &data, QObject *parent)
     : QAbstractItemModel(parent)
 {
-    QList<QVariant> rootData;
+    QVariantList rootData;
     for (const QString &header : headers)
         rootData << header;
 
-    rootItem = new TreeItem(rootData);
+    rootItem = std::make_unique<TreeItem>(rootData);
-    setupModelData(data.split('\n'), rootItem);
+    setupModelData(data.split('\n'_L1));
 }
 //! [0]
 
 //! [1]
-TreeModel::~TreeModel()
+TreeModel::~TreeModel() = default;
-{
-    delete rootItem;
-}
 //! [1]
 
 //! [2]
@@ -65,7 +64,7 @@ TreeItem *TreeModel::getItem(const QModelIndex &index) const
         if (item)
             return item;
     }
-    return rootItem;
+    return rootItem.get();
 }
 //! [4]
 
@@ -130,10 +129,10 @@ QModelIndex TreeModel::parent(const QModelIndex &index) const
     TreeItem *childItem = getItem(index);
     TreeItem *parentItem = childItem ? childItem->parent() : nullptr;
 
-    if (parentItem == rootItem || !parentItem)
+    if (parentItem == rootItem.get() || !parentItem)
         return QModelIndex();
 
-    return createIndex(parentItem->childNumber(), 0, parentItem);
+    return createIndex(parentItem->row(), 0, parentItem);
 }
 //! [7]
 
@@ -202,11 +201,11 @@ bool TreeModel::setHeaderData(int section, Qt::Orientation orientation,
     return result;
 }
 
-void TreeModel::setupModelData(const QStringList &lines, TreeItem *parent)
+void TreeModel::setupModelData(const QStringList &lines)
 {
     QList<TreeItem *> parents;
     QList<int> indentations;
-    parents << parent;
+    parents << rootItem.get();
     indentations << 0;
 
     int number = 0;
@@ -214,7 +213,7 @@ void TreeModel::setupModelData(const QStringList &lines, TreeItem *parent)
     while (number < lines.count()) {
         int position = 0;
         while (position < lines[number].length()) {
-            if (lines[number].at(position) != ' ')
+            if (lines[number].at(position) != ' '_L1)
                 break;
             ++position;
         }
@@ -224,8 +223,8 @@ void TreeModel::setupModelData(const QStringList &lines, TreeItem *parent)
         if (!lineData.isEmpty()) {
             // Read the column data from the rest of the line.
             const QStringList columnStrings =
-                lineData.split(QLatin1Char('\t'), Qt::SkipEmptyParts);
+                lineData.split('\t'_L1, Qt::SkipEmptyParts);
-            QList<QVariant> columnData;
+            QVariantList columnData;
             columnData.reserve(columnStrings.size());
             for (const QString &columnString : columnStrings)
                 columnData << columnString;

examples/widgets/itemviews/editabletreemodel/treemodel.h

@@ -50,10 +50,10 @@ public:
                     const QModelIndex &parent = QModelIndex()) override;
 
 private:
-    void setupModelData(const QStringList &lines, TreeItem *parent);
+    void setupModelData(const QStringList &lines);
     TreeItem *getItem(const QModelIndex &index) const;
 
-    TreeItem *rootItem;
+    std::unique_ptr<TreeItem> rootItem;
 };
 //! [2]