Don't destroy ListModel child list nodes.

These are owned by the root and must not be destroyed by child lists.

Task-number: QTBUG-12771
Reviewed-by: Bea Lam

2 files changed, 28 insertions, 11 deletions

diff --git a/src/declarative/util/qdeclarativelistmodel.cpp b/src/declarative/util/qdeclarativelistmodel.cpp
index 3ede335..b0d47a9 100644
--- a/src/declarative/util/qdeclarativelistmodel.cpp
+++ b/src/declarative/util/qdeclarativelistmodel.cpp
@@ -108,9 +108,9 @@ QDeclarativeListModelParser::ListInstruction *QDeclarativeListModelParser::ListM
     
     \snippet doc/src/snippets/declarative/listmodel-modify.qml delegate
 
-    When creating content dynamically, note that the set of available properties cannot be changed
-    except by first clearing the model. Whatever properties are first added to the model are then the
-    only permitted properties in the model until it is cleared.
+    Note that when creating content dynamically the set of available properties cannot be changed
+    once set. Whatever properties are first added to the model are the
+    only permitted properties in the model.
 
 
     \section2 Using threaded list models with WorkerScript
@@ -283,8 +283,7 @@ int QDeclarativeListModel::count() const
 /*!
     \qmlmethod ListModel::clear()
 
-    Deletes all content from the model. The properties are cleared such that
-    different properties may be set on subsequent additions.
+    Deletes all content from the model.
 
     \sa append() remove()
 */
@@ -945,13 +944,14 @@ bool FlatListModel::addValue(const QScriptValue &value, QHash<int, QVariant> *ro
 }
 
 NestedListModel::NestedListModel(QDeclarativeListModel *base)
-    : _root(0), m_listModel(base), _rolesOk(false)
+    : _root(0), m_ownsRoot(false), m_listModel(base), _rolesOk(false)
 {
 }
 
 NestedListModel::~NestedListModel()
 {
-    delete _root;
+    if (m_ownsRoot)
+        delete _root;
 }
 
 QVariant NestedListModel::valueForNode(ModelNode *node, bool *hasNested) const
@@ -1051,8 +1051,8 @@ void NestedListModel::clear()
     _rolesOk = false;
     roleStrings.clear();
 
-    delete _root;
-    _root = 0;
+    if (_root)
+        _root->clear();
 }
 
 void NestedListModel::remove(int index)
@@ -1067,8 +1067,10 @@ void NestedListModel::remove(int index)
 
 bool NestedListModel::insert(int index, const QScriptValue& valuemap)
 {
-    if (!_root)
+    if (!_root) {
         _root = new ModelNode;
+        m_ownsRoot = true;
+    }
 
     ModelNode *mn = new ModelNode;
     mn->setObjectValue(valuemap);
@@ -1099,8 +1101,10 @@ void NestedListModel::move(int from, int to, int n)
 
 bool NestedListModel::append(const QScriptValue& valuemap)
 {
-    if (!_root)
+    if (!_root) {
         _root = new ModelNode;
+        m_ownsRoot = true;
+    }
     ModelNode *mn = new ModelNode;
     mn->setObjectValue(valuemap);
     _root->values << qVariantFromValue(mn);
diff --git a/src/declarative/util/qdeclarativelistmodel_p_p.h b/src/declarative/util/qdeclarativelistmodel_p_p.h
index 532eefa..c41f016 100644
--- a/src/declarative/util/qdeclarativelistmodel_p_p.h
+++ b/src/declarative/util/qdeclarativelistmodel_p_p.h
@@ -130,6 +130,7 @@ public:
     void checkRoles() const;
 
     ModelNode *_root;
+    bool m_ownsRoot;
     QDeclarativeListModel *m_listModel;
 
 private:
@@ -157,6 +158,18 @@ struct ModelNode
     QList<QVariant> values;
     QHash<QString, ModelNode *> properties;
 
+    void clear() {
+        ModelNode *node;
+        for (int ii = 0; ii < values.count(); ++ii) {
+            node = qvariant_cast<ModelNode *>(values.at(ii));
+            if (node) { delete node; node = 0; }
+        }
+        values.clear();
+
+        qDeleteAll(properties.values());
+        properties.clear();
+    }
+
     QDeclarativeListModel *model(const NestedListModel *model) {
         if (!modelCache) { 
             modelCache = new QDeclarativeListModel;