Encapsulate QQmlContextData

This class is not a private detail of QQmlContext. And it is incredibly
hard to see who owns what in there. Let's add some civilization ...

We enforce refcounting for QQmlContextData across the code base, with
two exceptions:

1. QQmlContextPrivate may or may not own its QQmlContextData.
2. We may request a QQmlContextData owned by its parent QQmlContextData.

For these two cases we keep flags in QQmlContextData and when the
respective field (m_parent or m_publicContext) is reset, we release()
once.

Furthermore, QQmlContextData and QQmlGuardedContextData are moved to
their own files, in order to de-spaghettify qqmlcontext_p.h and
qqmlcontext.cpp.

When the QQmlEngine is deleted, any QQmlComponents drop their object
creators now, in order to release any context data held by those.
Before, the context data would be deleted, but the object creators would
retain the dangling pointer.

[ChangeLog][QML][Important Behavior Changes] QQmlContext::baseUrl() does
what the documentation says now: It prefers explicitly set baseUrls over
compilation unit URLs. Only if no baseUrl is set, the CU's URL is
returned. It used to prefer the CU's URL.

Change-Id: Ieeb5dcb07b45d891526191321386d5443b8f5738
Reviewed-by: Fabian Kosmale <fabian.kosmale@qt.io>

1 files changed, 11 insertions, 34 deletions

diff --git a/src/qml/qml/qqmldata_p.h b/src/qml/qml/qqmldata_p.h
index ee31cb38d9..1c238767d8 100644
--- a/src/qml/qml/qqmldata_p.h
+++ b/src/qml/qml/qqmldata_p.h
@@ -82,34 +82,6 @@ struct Binding;
 }
 }
 
-// This is declared here because QQmlData below needs it and this file
-// in turn is included from qqmlcontext_p.h.
-class QQmlContextData;
-class Q_QML_PRIVATE_EXPORT QQmlContextDataRef
-{
-public:
-    inline QQmlContextDataRef();
-    inline QQmlContextDataRef(QQmlContextData *);
-    inline QQmlContextDataRef(const QQmlContextDataRef &);
-    inline ~QQmlContextDataRef();
-
-    inline QQmlContextData *contextData() const;
-    inline void setContextData(QQmlContextData *);
-
-    inline bool isNull() const { return !m_contextData; }
-
-    inline operator QQmlContextData*() const { return m_contextData; }
-    inline QQmlContextData* operator->() const { return m_contextData; }
-    inline QQmlContextDataRef &operator=(QQmlContextData *d);
-    inline QQmlContextDataRef &operator=(const QQmlContextDataRef &other);
-
-private:
-
-    inline void clear();
-
-    QQmlContextData *m_contextData;
-};
-
 // This class is structured in such a way, that simply zero'ing it is the
 // default state for elemental object allocations.  This is crucial in the
 // workings of the QQmlInstruction::CreateSimpleObject instruction.
@@ -195,11 +167,11 @@ public:
     bool signalHasEndpoint(int index) const;
     void disconnectNotifiers();
 
-    // The context that created the C++ object
+    // The context that created the C++ object; not refcounted to prevent cycles
     QQmlContextData *context = nullptr;
-    // The outermost context in which this object lives
+    // The outermost context in which this object lives; not refcounted to prevent cycles
     QQmlContextData *outerContext = nullptr;
-    QQmlContextDataRef ownContext;
+    QQmlRefPointer<QQmlContextData> ownContext;
 
     QQmlAbstractBinding *bindings;
     QQmlBoundSignal *signalHandlers;
@@ -226,14 +198,19 @@ public:
         ~DeferredData();
         unsigned int deferredIdx;
         QMultiHash<int, const QV4::CompiledData::Binding *> bindings;
-        QQmlRefPointer<QV4::ExecutableCompilationUnit> compilationUnit;//Not always the same as the other compilation unit
-        QQmlContextData *context;//Could be either context or outerContext
+
+        // Not always the same as the other compilation unit
+        QQmlRefPointer<QV4::ExecutableCompilationUnit> compilationUnit;
+
+        // Could be either context or outerContext
+        QQmlRefPointer<QQmlContextData> context;
         Q_DISABLE_COPY(DeferredData);
     };
     QQmlRefPointer<QV4::ExecutableCompilationUnit> compilationUnit;
     QVector<DeferredData *> deferredData;
 
-    void deferData(int objectIndex, const QQmlRefPointer<QV4::ExecutableCompilationUnit> &, QQmlContextData *);
+    void deferData(int objectIndex, const QQmlRefPointer<QV4::ExecutableCompilationUnit> &,
+                   const QQmlRefPointer<QQmlContextData> &);
     void releaseDeferredData();
 
     QV4::WeakValue jsWrapper;