Make bindings refcounted

Refcounting our bindings greatly simplifies our memory management
of the objects and ensures we safely clean them all up. In addition,
it allows us to remove the m_mePtr and weak reference handling from
QQmlAbstractBinding as we can safely handle this through the same
mechanism.

Change-Id: If23ebc8be276096146952b0008b62018f5d57faf
Reviewed-by: Simon Hausmann <simon.hausmann@theqtcompany.com>

1 files changed, 35 insertions, 43 deletions

diff --git a/src/qml/qml/qqmlabstractbinding.cpp b/src/qml/qml/qqmlabstractbinding.cpp
index 4a081ae0e8..0d281b7750 100644
--- a/src/qml/qml/qqmlabstractbinding.cpp
+++ b/src/qml/qml/qqmlabstractbinding.cpp
@@ -40,15 +40,17 @@
 QT_BEGIN_NAMESPACE
 
 QQmlAbstractBinding::QQmlAbstractBinding()
-    : m_nextBinding(0)
+    : m_nextBinding(0),
+      m_targetIndex(-1),
+      m_isAddedToObject(false)
 {
+    Q_ASSERT(!isAddedToObject());
 }
 
 QQmlAbstractBinding::~QQmlAbstractBinding()
 {
-    Q_ASSERT(isAddedToObject() == false);
-    Q_ASSERT(nextBinding() == 0);
-    Q_ASSERT(*m_mePtr == 0);
+    Q_ASSERT(!ref);
+    Q_ASSERT(!isAddedToObject());
 }
 
 /*!
@@ -92,12 +94,17 @@ void QQmlAbstractBinding::addToObject()
             proxy->addToObject();
         }
 
-        setNextBinding(proxy->m_bindings);
+        setNextBinding(proxy->m_bindings.data());
         proxy->m_bindings = this;
 
     } else {
         setNextBinding(data->bindings);
+        if (data->bindings) {
+            data->bindings->ref.deref();
+            Q_ASSERT(data->bindings->ref.refCount > 0);
+        }
         data->bindings = this;
+        ref.ref();
 
         data->setBindingBit(obj, coreIndex);
     }
@@ -113,10 +120,16 @@ void QQmlAbstractBinding::removeFromObject()
     if (!isAddedToObject())
         return;
 
+    setAddedToObject(false);
+
     QObject *obj = targetObject();
     QQmlData *data = QQmlData::get(obj, false);
     Q_ASSERT(data);
 
+    QQmlAbstractBinding::Ptr next;
+    next = nextBinding();
+    setNextBinding(0);
+
     int coreIndex;
     if (QQmlPropertyData::decodeValueTypePropertyIndex(targetPropertyIndex(), &coreIndex) != -1) {
 
@@ -131,39 +144,39 @@ void QQmlAbstractBinding::removeFromObject()
         QQmlValueTypeProxyBinding *vtproxybinding =
             static_cast<QQmlValueTypeProxyBinding *>(vtbinding);
 
-        QQmlAbstractBinding *binding = vtproxybinding->m_bindings;
+        QQmlAbstractBinding *binding = vtproxybinding->m_bindings.data();
         if (binding == this) {
-            vtproxybinding->m_bindings = nextBinding();
+            vtproxybinding->m_bindings = next;
         } else {
            while (binding->nextBinding() != this) {
               binding = binding->nextBinding();
               Q_ASSERT(binding);
            }
-           binding->setNextBinding(nextBinding());
+           binding->setNextBinding(next.data());
         }
 
         // Value type - we don't remove the proxy from the object.  It will sit their happily
         // doing nothing until it is removed by a write, a binding change or it is reused
         // to hold more sub-bindings.
+        return;
+    }
 
+    if (data->bindings == this) {
+        if (next.data())
+            next->ref.ref();
+        data->bindings = next.data();
+        if (!ref.deref())
+            delete this;
     } else {
-
-        if (data->bindings == this) {
-            data->bindings = nextBinding();
-        } else {
-            QQmlAbstractBinding *binding = data->bindings;
-            while (binding->nextBinding() != this) {
-                binding = binding->nextBinding();
-                Q_ASSERT(binding);
-            }
-            binding->setNextBinding(nextBinding());
+        QQmlAbstractBinding *binding = data->bindings;
+        while (binding->nextBinding() != this) {
+            binding = binding->nextBinding();
+            Q_ASSERT(binding);
         }
-
-        data->clearBindingBit(coreIndex);
+        binding->setNextBinding(next.data());
     }
 
-    setNextBinding(0);
-    setAddedToObject(false);
+    data->clearBindingBit(coreIndex);
 }
 
 void QQmlAbstractBinding::printBindingLoopError(QQmlProperty &prop)
@@ -171,27 +184,6 @@ void QQmlAbstractBinding::printBindingLoopError(QQmlProperty &prop)
     qmlInfo(prop.object()) << QString(QLatin1String("Binding loop detected for property \"%1\"")).arg(prop.name());
 }
 
-
-static void bindingDummyDeleter(QQmlAbstractBinding *)
-{
-}
-
-QQmlAbstractBinding::Pointer QQmlAbstractBinding::weakPointer()
-{
-    if (m_mePtr.value().isNull())
-        m_mePtr.value() = QSharedPointer<QQmlAbstractBinding>(this, bindingDummyDeleter);
-
-    return m_mePtr.value().toWeakRef();
-}
-
-void QQmlAbstractBinding::clear()
-{
-    if (!m_mePtr.isNull()) {
-        **m_mePtr = 0;
-        m_mePtr = 0;
-    }
-}
-
 QString QQmlAbstractBinding::expression() const
 {
     return QLatin1String("<Unknown>");