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, 33 insertions, 26 deletions

diff --git a/src/qml/qml/qqmlproperty.cpp b/src/qml/qml/qqmlproperty.cpp
index 8521de6ab3..3824a7fb6d 100644
--- a/src/qml/qml/qqmlproperty.cpp
+++ b/src/qml/qml/qqmlproperty.cpp
@@ -163,7 +163,6 @@ QQmlProperty::QQmlProperty(QObject *obj, QQmlContext *ctxt)
 QQmlProperty::QQmlProperty(QObject *obj, QQmlEngine *engine)
   : d(new QQmlPropertyPrivate)
 {
-    d->context = nullptr;
     d->engine = engine;
     d->initDefault(obj);
 }
@@ -205,7 +204,11 @@ QQmlProperty::QQmlProperty(QObject *obj, const QString &name, QQmlContext *ctxt)
     d->context = ctxt?QQmlContextData::get(ctxt):nullptr;
     d->engine = ctxt?ctxt->engine():nullptr;
     d->initProperty(obj, name);
-    if (!isValid()) { d->object = nullptr; d->context = nullptr; d->engine = nullptr; }
+    if (!isValid()) {
+        d->object = nullptr;
+        d->context = nullptr;
+        d->engine = nullptr;
+    }
 }
 
 /*!
@@ -216,19 +219,23 @@ QQmlProperty::QQmlProperty(QObject *obj, const QString &name, QQmlContext *ctxt)
 QQmlProperty::QQmlProperty(QObject *obj, const QString &name, QQmlEngine *engine)
 : d(new QQmlPropertyPrivate)
 {
-    d->context = nullptr;
     d->engine = engine;
     d->initProperty(obj, name);
-    if (!isValid()) { d->object = nullptr; d->context = nullptr; d->engine = nullptr; }
+    if (!isValid()) {
+        d->object = nullptr;
+        d->context = nullptr;
+        d->engine = nullptr;
+    }
 }
 
-QQmlProperty QQmlPropertyPrivate::create(QObject *target, const QString &propertyName, QQmlContextData *context)
+QQmlProperty QQmlPropertyPrivate::create(QObject *target, const QString &propertyName,
+                                         const QQmlRefPointer<QQmlContextData> &context)
 {
     QQmlProperty result;
     auto d = new QQmlPropertyPrivate;
     result.d = d;
     d->context = context;
-    d->engine = context ? context->engine : nullptr;
+    d->engine = context ? context->engine() : nullptr;
     d->initProperty(target, propertyName);
     if (!result.isValid()) {
         d->object = nullptr;
@@ -238,23 +245,21 @@ QQmlProperty QQmlPropertyPrivate::create(QObject *target, const QString &propert
     return result;
 }
 
-QQmlPropertyPrivate::QQmlPropertyPrivate()
-: context(nullptr), engine(nullptr), object(nullptr), isNameCached(false)
+QQmlRefPointer<QQmlContextData> QQmlPropertyPrivate::effectiveContext() const
 {
-}
-
-QQmlContextData *QQmlPropertyPrivate::effectiveContext() const
-{
-    if (context) return context;
-    else if (engine) return QQmlContextData::get(engine->rootContext());
-    else return nullptr;
+    if (context)
+        return context;
+    else if (engine)
+        return QQmlContextData::get(engine->rootContext());
+    else
+        return nullptr;
 }
 
 void QQmlPropertyPrivate::initProperty(QObject *obj, const QString &name)
 {
     if (!obj) return;
 
-    QQmlRefPointer<QQmlTypeNameCache> typeNameCache = context?context->imports:nullptr;
+    QQmlRefPointer<QQmlTypeNameCache> typeNameCache = context ? context->imports() : nullptr;
 
     QObject *currentObject = obj;
     QVector<QStringRef> path;
@@ -974,7 +979,7 @@ void QQmlPropertyPrivate::takeSignalExpression(const QQmlProperty &that,
     if (expr) {
         int signalIndex = QQmlPropertyPrivate::get(that)->signalIndex();
         QQmlBoundSignal *signal = new QQmlBoundSignal(that.d->object, signalIndex, that.d->object,
-                                                      expr->context()->engine);
+                                                      expr->engine());
         signal->takeExpression(expr);
     }
 }
@@ -1097,7 +1102,8 @@ QVariant QQmlPropertyPrivate::readValueProperty()
 }
 
 // helper function to allow assignment / binding to QList<QUrl> properties.
-QVariant QQmlPropertyPrivate::resolvedUrlSequence(const QVariant &value, QQmlContextData *context)
+QVariant QQmlPropertyPrivate::resolvedUrlSequence(
+        const QVariant &value, const QQmlRefPointer<QQmlContextData> &context)
 {
     QList<QUrl> urls;
     if (value.userType() == qMetaTypeId<QUrl>()) {
@@ -1186,7 +1192,8 @@ QQmlPropertyPrivate::writeValueProperty(QObject *object,
                                         const QQmlPropertyData &core,
                                         const QQmlPropertyData &valueTypeData,
                                         const QVariant &value,
-                                        QQmlContextData *context,QQmlPropertyData::WriteFlags flags)
+                                        const QQmlRefPointer<QQmlContextData> &context,
+                                        QQmlPropertyData::WriteFlags flags)
 {
     // Remove any existing bindings on this property
     if (!(flags & QQmlPropertyData::DontRemoveBinding) && object)
@@ -1201,7 +1208,7 @@ QQmlPropertyPrivate::writeValueProperty(QObject *object,
         };
 
         QQmlGadgetPtrWrapper *wrapper = context
-                ? QQmlGadgetPtrWrapper::instance(context->engine, core.propType())
+                ? QQmlGadgetPtrWrapper::instance(context->engine(), core.propType())
                 : nullptr;
         if (wrapper) {
             doWrite(wrapper);
@@ -1217,10 +1224,9 @@ QQmlPropertyPrivate::writeValueProperty(QObject *object,
     return rv;
 }
 
-bool QQmlPropertyPrivate::write(QObject *object,
-                                        const QQmlPropertyData &property,
-                                        const QVariant &value, QQmlContextData *context,
-                                        QQmlPropertyData::WriteFlags flags)
+bool QQmlPropertyPrivate::write(
+        QObject *object, const QQmlPropertyData &property, const QVariant &value,
+        const QQmlRefPointer<QQmlContextData> &context, QQmlPropertyData::WriteFlags flags)
 {
     const int propertyType = property.propType();
     const int variantType = value.userType();
@@ -1647,14 +1653,15 @@ QQmlPropertyIndex QQmlPropertyPrivate::propertyIndex(const QQmlProperty &that)
 
 QQmlProperty
 QQmlPropertyPrivate::restore(QObject *object, const QQmlPropertyData &data,
-                             const QQmlPropertyData *valueTypeData, QQmlContextData *ctxt)
+                             const QQmlPropertyData *valueTypeData,
+                             const QQmlRefPointer<QQmlContextData> &ctxt)
 {
     QQmlProperty prop;
 
     prop.d = new QQmlPropertyPrivate;
     prop.d->object = object;
     prop.d->context = ctxt;
-    prop.d->engine = ctxt ? ctxt->engine : nullptr;
+    prop.d->engine = ctxt ? ctxt->engine() : nullptr;
 
     prop.d->core = data;
     if (valueTypeData)