Integrate QML's object ownership with the JS collector

QML now behaves in a way similar to QtScript when it comes to QObject
ownership.

QT-2803

14 files changed, 230 insertions, 23 deletions

diff --git a/src/corelib/kernel/qobject.cpp b/src/corelib/kernel/qobject.cpp
index 389e6e7..68f34ca 100644
--- a/src/corelib/kernel/qobject.cpp
+++ b/src/corelib/kernel/qobject.cpp
@@ -2033,6 +2033,8 @@ void QObjectPrivate::setParent_helper(QObject *o)
             }
         }
     }
+    if (!wasDeleted && declarativeData)
+        declarativeData->parentChanged(q, o);
 }
 
 /*!
diff --git a/src/corelib/kernel/qobject_p.h b/src/corelib/kernel/qobject_p.h
index cc5bf97..20e3da1 100644
--- a/src/corelib/kernel/qobject_p.h
+++ b/src/corelib/kernel/qobject_p.h
@@ -90,6 +90,7 @@ class Q_CORE_EXPORT QDeclarativeData
 public:
     virtual ~QDeclarativeData();
     virtual void destroyed(QObject *) = 0;
+    virtual void parentChanged(QObject *, QObject *) = 0;
 };
 
 class Q_CORE_EXPORT QObjectPrivate : public QObjectData
diff --git a/src/declarative/qml/qdeclarativecomponent.cpp b/src/declarative/qml/qdeclarativecomponent.cpp
index d6bb216..d3608c4 100644
--- a/src/declarative/qml/qdeclarativecomponent.cpp
+++ b/src/declarative/qml/qdeclarativecomponent.cpp
@@ -512,7 +512,6 @@ QDeclarativeComponent::QDeclarativeComponent(QDeclarativeComponentPrivate &dd, Q
 {
 }
 
-
 /*!
     \internal
     A version of create which returns a scriptObject, for use in script
@@ -526,7 +525,9 @@ QScriptValue QDeclarativeComponent::createObject()
         return QScriptValue();
     }
     QObject* ret = create(ctxt);
-    return QDeclarativeEnginePrivate::qmlScriptObject(ret, d->engine);
+    QDeclarativeEnginePrivate *priv = QDeclarativeEnginePrivate::get(d->engine);
+    QDeclarativeDeclarativeData::get(ret, true)->setImplicitDestructible();
+    return priv->objectClass->newQObject(ret, QMetaType::QObjectStar);
 }
 
 /*!
@@ -541,7 +542,12 @@ QObject *QDeclarativeComponent::create(QDeclarativeContext *context)
 {
     Q_D(QDeclarativeComponent);
 
-    return d->create(context, QBitField());
+    if (!context)
+        context = d->engine->rootContext();
+
+    QObject *rv = beginCreate(context);
+    completeCreate();
+    return rv;
 }
 
 QObject *QDeclarativeComponentPrivate::create(QDeclarativeContext *context, 
@@ -586,7 +592,13 @@ QObject *QDeclarativeComponentPrivate::create(QDeclarativeContext *context,
 QObject *QDeclarativeComponent::beginCreate(QDeclarativeContext *context)
 {
     Q_D(QDeclarativeComponent);
-    return d->beginCreate(context, QBitField());
+    QObject *rv = d->beginCreate(context, QBitField());
+    if (rv) {
+        QDeclarativeDeclarativeData *ddata = QDeclarativeDeclarativeData::get(rv);
+        Q_ASSERT(ddata);
+        ddata->indestructible = true;
+    }
+    return rv;
 }
 
 QObject *
diff --git a/src/declarative/qml/qdeclarativedeclarativedata_p.h b/src/declarative/qml/qdeclarativedeclarativedata_p.h
index ae40130..ffce9c9 100644
--- a/src/declarative/qml/qdeclarativedeclarativedata_p.h
+++ b/src/declarative/qml/qdeclarativedeclarativedata_p.h
@@ -67,12 +67,21 @@ class Q_AUTOTEST_EXPORT QDeclarativeDeclarativeData : public QDeclarativeData
 {
 public:
     QDeclarativeDeclarativeData(QDeclarativeContext *ctxt = 0)
-        : context(ctxt), bindings(0), nextContextObject(0), prevContextObject(0),
-          bindingBitsSize(0), bindingBits(0), outerContext(0), lineNumber(0), 
-          columnNumber(0), deferredComponent(0), deferredIdx(0), attachedProperties(0), 
-          propertyCache(0), guards(0) {}
+        : indestructible(true), explicitIndestructibleSet(false), context(ctxt), 
+          bindings(0), nextContextObject(0), prevContextObject(0), bindingBitsSize(0), bindingBits(0), 
+          outerContext(0), lineNumber(0), columnNumber(0), deferredComponent(0), deferredIdx(0), 
+          attachedProperties(0), propertyCache(0), guards(0) {}
 
     virtual void destroyed(QObject *);
+    virtual void parentChanged(QObject *, QObject *);
+
+    void setImplicitDestructible() {
+        if (!explicitIndestructibleSet) indestructible = false;
+    }
+
+    quint32 indestructible:1;
+    quint32 explicitIndestructibleSet:1;
+    quint32 dummy:29;
 
     QDeclarativeContext *context;
     QDeclarativeAbstractBinding *bindings;
diff --git a/src/declarative/qml/qdeclarativeengine.cpp b/src/declarative/qml/qdeclarativeengine.cpp
index 41d55d7..791df9f 100644
--- a/src/declarative/qml/qdeclarativeengine.cpp
+++ b/src/declarative/qml/qdeclarativeengine.cpp
@@ -668,6 +668,59 @@ void QDeclarativeEngine::setContextForObject(QObject *object, QDeclarativeContex
     context->d_func()->contextObjects = data;
 }
 
+/*!
+\enum QDeclarativeEngine::ObjectOwnership
+
+Ownership controls whether or not QML automatically destroys the QObject when the object 
+is garbage collected by the JavaScript engine.  The two ownership options are:
+
+\o CppOwnership The object is owned by C++ code, and will never be deleted by QML.  The
+JavaScript destroy() method cannot be used on objects with CppOwnership.  This option
+is similar to QScriptEngine::QtOwnership.
+
+\o JavaScriptOwnership The object is owned by JavaScript.  When the object is returned to QML 
+as the return value of a method call or property access, QML will delete the object if there
+are no remaining JavaScript references to it and it has no QObject::parent().  This option
+is similar to QScriptEngine::ScriptOwnership.
+
+Generally an application doesn't need to set an object's ownership explicitly.  QML uses
+a heuristic to set the default object ownership.  By default, an object that is created by
+QML has JavaScriptOwnership.  The exception to this are the root objects created by calling
+QDeclarativeCompnent::create() or QDeclarativeComponent::beginCreate() which have 
+CppOwnership by default.  The ownership of these root-level objects is considered to have
+been transfered to the C++ caller.
+
+Objects not-created by QML have CppOwnership by default.  The exception to this is objects
+returned from a C++ method call.  The ownership of these objects is passed to JavaScript.
+
+Calling setObjectOwnership() overrides the default ownership heuristic used by QML.
+*/
+
+/*!
+Sets the \a ownership of \a object.
+*/
+void QDeclarativeEngine::setObjectOwnership(QObject *object, ObjectOwnership ownership)
+{
+    QDeclarativeDeclarativeData *ddata = QDeclarativeDeclarativeData::get(object, true);
+    if (!ddata)
+        return;
+
+    ddata->indestructible = (ownership == CppOwnership)?true:false;
+    ddata->explicitIndestructibleSet = true;
+}
+
+/*!
+Returns the ownership of \a object.
+*/
+QDeclarativeEngine::ObjectOwnership QDeclarativeEngine::objectOwnership(QObject *object)
+{
+    QDeclarativeDeclarativeData *ddata = QDeclarativeDeclarativeData::get(object, false);
+    if (!ddata) 
+        return CppOwnership;
+    else
+        return ddata->indestructible?CppOwnership:JavaScriptOwnership;
+}
+
 void qmlExecuteDeferred(QObject *object)
 {
     QDeclarativeDeclarativeData *data = QDeclarativeDeclarativeData::get(object);
@@ -778,6 +831,11 @@ void QDeclarativeDeclarativeData::destroyed(QObject *object)
     delete this;
 }
 
+void QDeclarativeDeclarativeData::parentChanged(QObject *, QObject *parent)
+{
+    if (!parent && scriptValue.isValid()) scriptValue = QScriptValue();
+}
+
 bool QDeclarativeDeclarativeData::hasBindingBit(int bit) const
 {
     if (bindingBitsSize > bit) 
@@ -858,6 +916,7 @@ QScriptValue QDeclarativeEnginePrivate::createComponent(QScriptContext *ctxt,
         QUrl url = QUrl(context->resolvedUrl(QUrl(arg)));
         QDeclarativeComponent *c = new QDeclarativeComponent(activeEngine, url, activeEngine);
         c->setCreationContext(context);
+        QDeclarativeDeclarativeData::get(c, true)->setImplicitDestructible();
         return activeEnginePriv->objectClass->newQObject(c, qMetaTypeId<QDeclarativeComponent*>());
     }
 }
@@ -928,7 +987,8 @@ QScriptValue QDeclarativeEnginePrivate::createQmlObject(QScriptContext *ctxt, QS
     if(gobj && gparent)
         gobj->setParentItem(gparent);
 
-    return qmlScriptObject(obj, activeEngine);
+    QDeclarativeDeclarativeData::get(obj, true)->setImplicitDestructible();
+    return activeEnginePriv->objectClass->newQObject(obj, QMetaType::QObjectStar);
 }
 
 QScriptValue QDeclarativeEnginePrivate::vector(QScriptContext *ctxt, QScriptEngine *engine)
diff --git a/src/declarative/qml/qdeclarativeengine.h b/src/declarative/qml/qdeclarativeengine.h
index fd66358..19e81b6 100644
--- a/src/declarative/qml/qdeclarativeengine.h
+++ b/src/declarative/qml/qdeclarativeengine.h
@@ -98,6 +98,10 @@ public:
     static QDeclarativeContext *contextForObject(const QObject *);
     static void setContextForObject(QObject *, QDeclarativeContext *);
 
+    enum ObjectOwnership { CppOwnership, JavaScriptOwnership };
+    static void setObjectOwnership(QObject *, ObjectOwnership);
+    static ObjectOwnership objectOwnership(QObject *);
+
 Q_SIGNALS:
     void quit ();
 
diff --git a/src/declarative/qml/qdeclarativeobjectscriptclass.cpp b/src/declarative/qml/qdeclarativeobjectscriptclass.cpp
index e6f6e5f..3ca03b4 100644
--- a/src/declarative/qml/qdeclarativeobjectscriptclass.cpp
+++ b/src/declarative/qml/qdeclarativeobjectscriptclass.cpp
@@ -59,6 +59,15 @@ QT_BEGIN_NAMESPACE
 
 struct ObjectData : public QScriptDeclarativeClass::Object {
     ObjectData(QObject *o, int t) : object(o), type(t) {}
+
+    virtual ~ObjectData() {
+        if (object && !object->parent()) {
+            QDeclarativeDeclarativeData *ddata = QDeclarativeDeclarativeData::get(object, false);
+            if (ddata && !ddata->indestructible)
+                object->deleteLater();
+        }
+    }
+
     QDeclarativeGuard<QObject> object;
     int type;
 };
@@ -87,7 +96,7 @@ QDeclarativeObjectScriptClass::~QDeclarativeObjectScriptClass()
 {
 }
 
-QScriptValue QDeclarativeObjectScriptClass::newQObject(QObject *object, int type) 
+QScriptValue QDeclarativeObjectScriptClass::newQObject(QObject *object, int type)
 {
     QScriptEngine *scriptEngine = QDeclarativeEnginePrivate::getScriptEngine(engine);
 
@@ -96,7 +105,11 @@ QScriptValue QDeclarativeObjectScriptClass::newQObject(QObject *object, int type
 
     QDeclarativeDeclarativeData *ddata = QDeclarativeDeclarativeData::get(object, true);
 
-    if (!ddata->scriptValue.isValid()) {
+    if (!ddata) {
+       return scriptEngine->undefinedValue();
+    } else if (!ddata->indestructible && !object->parent()) {
+        return newObject(scriptEngine, this, new ObjectData(object, type));
+    } else if (!ddata->scriptValue.isValid()) {
         ddata->scriptValue = newObject(scriptEngine, this, new ObjectData(object, type));
         return ddata->scriptValue;
     } else if (ddata->scriptValue.engine() == QDeclarativeEnginePrivate::getScriptEngine(engine)) {
@@ -392,17 +405,30 @@ QScriptValue QDeclarativeObjectScriptClass::tostring(QScriptContext *context, QS
 
 QScriptValue QDeclarativeObjectScriptClass::destroy(QScriptContext *context, QScriptEngine *engine)
 {
-    QObject* obj = context->thisObject().toQObject();
-    if(obj){
-        int delay = 0;
-        if(context->argumentCount() > 0)
-            delay = context->argument(0).toInt32();
-        if (delay > 0)
-            QTimer::singleShot(delay, obj, SLOT(deleteLater()));
-        else
-            obj->deleteLater();
-    }
-    return engine->nullValue();
+    QDeclarativeEnginePrivate *p = QDeclarativeEnginePrivate::get(engine);
+    QScriptValue that = context->thisObject();
+
+    if (scriptClass(that) != p->objectClass)
+        return engine->undefinedValue();
+
+    ObjectData *data = (ObjectData *)p->objectClass->object(that);
+    if (!data->object)
+        return engine->undefinedValue();
+
+    QDeclarativeDeclarativeData *ddata = QDeclarativeDeclarativeData::get(data->object, false);
+    if (!ddata || ddata->indestructible) 
+        return engine->currentContext()->throwError(QLatin1String("Invalid attempt  to destroy() an indestructible object"));
+
+    QObject *obj = data->object;
+    int delay = 0;
+    if (context->argumentCount() > 0)
+        delay = context->argument(0).toInt32();
+    if (delay > 0)
+        QTimer::singleShot(delay, obj, SLOT(deleteLater()));
+    else
+        obj->deleteLater();
+
+    return engine->undefinedValue();
 }
 
 QStringList QDeclarativeObjectScriptClass::propertyNames(Object *object)
@@ -428,6 +454,14 @@ QStringList QDeclarativeObjectScriptClass::propertyNames(Object *object)
     return cache->propertyNames();
 }
 
+bool QDeclarativeObjectScriptClass::compare(Object *o1, Object *o2)
+{
+    ObjectData *d1 = (ObjectData *)o1;
+    ObjectData *d2 = (ObjectData *)o2;
+
+    return d1 == d2 || d1->object == d2->object;
+}
+
 #if (QT_VERSION > QT_VERSION_CHECK(4, 6, 2)) || defined(QT_HAVE_QSCRIPTDECLARATIVECLASS_VALUE)
 
 struct MethodData : public QScriptDeclarativeClass::Object {
@@ -685,7 +719,10 @@ QScriptDeclarativeClass::Value MetaCallArgument::toValue(QDeclarativeEngine *e)
     } else if (type == QMetaType::QString) {
         return QScriptDeclarativeClass::Value(engine, *((QString *)data));
     } else if (type == QMetaType::QObjectStar) {
-        return QScriptDeclarativeClass::Value(engine, QDeclarativeEnginePrivate::get(e)->objectClass->newQObject(*((QObject **)data)));
+        QObject *object = *((QObject **)data);
+        QDeclarativeDeclarativeData::get(object, true)->setImplicitDestructible();
+        QDeclarativeEnginePrivate *priv = QDeclarativeEnginePrivate::get(e);
+        return QScriptDeclarativeClass::Value(engine, priv->objectClass->newQObject(object));
     } else if (type == -1 || type == qMetaTypeId<QVariant>()) {
         return QScriptDeclarativeClass::Value(engine, QDeclarativeEnginePrivate::get(e)->scriptValueFromVariant(*((QVariant *)data)));
     } else {
diff --git a/src/declarative/qml/qdeclarativeobjectscriptclass_p.h b/src/declarative/qml/qdeclarativeobjectscriptclass_p.h
index 04e760f..1f7d1c9 100644
--- a/src/declarative/qml/qdeclarativeobjectscriptclass_p.h
+++ b/src/declarative/qml/qdeclarativeobjectscriptclass_p.h
@@ -57,6 +57,7 @@
 #include "qdeclarativetypenamecache_p.h"
 
 #include <private/qdeclarativescriptclass_p.h>
+#include <QtScript/qscriptengine.h>
 
 QT_BEGIN_NAMESPACE
 
@@ -99,6 +100,7 @@ public:
     ~QDeclarativeObjectScriptClass();
 
     QScriptValue newQObject(QObject *, int type = QMetaType::QObjectStar);
+
     QObject *toQObject(const QScriptValue &) const;
     int objectType(const QScriptValue &) const;
 
@@ -118,6 +120,7 @@ public:
     void setProperty(QObject *, const Identifier &name, const QScriptValue &,
                      QDeclarativeContext *evalContext = 0);
     virtual QStringList propertyNames(Object *);
+    virtual bool compare(Object *, Object *);
 
 protected:
     virtual QScriptClass::QueryFlags queryProperty(Object *, const Identifier &, 
diff --git a/src/declarative/qml/qdeclarativevme.cpp b/src/declarative/qml/qdeclarativevme.cpp
index 6a08674..d916900 100644
--- a/src/declarative/qml/qdeclarativevme.cpp
+++ b/src/declarative/qml/qdeclarativevme.cpp
@@ -197,6 +197,7 @@ QObject *QDeclarativeVME::run(QDeclarativeVMEStack<QObject *> &stack, QDeclarati
 
                 QDeclarativeDeclarativeData *ddata = QDeclarativeDeclarativeData::get(o);
                 Q_ASSERT(ddata);
+                ddata->setImplicitDestructible();
                 ddata->outerContext = ctxt;
                 ddata->lineNumber = instr.line;
                 ddata->columnNumber = instr.create.column;
@@ -247,6 +248,7 @@ QObject *QDeclarativeVME::run(QDeclarativeVMEStack<QObject *> &stack, QDeclarati
                 QDeclarativeEngine::setContextForObject(qcomp, ctxt);
                 QDeclarativeDeclarativeData *ddata = QDeclarativeDeclarativeData::get(qcomp);
                 Q_ASSERT(ddata);
+                ddata->setImplicitDestructible();
                 ddata->outerContext = ctxt;
                 ddata->lineNumber = instr.line;
                 ddata->columnNumber = instr.create.column;
diff --git a/src/script/bridge/qscriptdeclarativeclass.cpp b/src/script/bridge/qscriptdeclarativeclass.cpp
index 1d11ede..46c68ed 100644
--- a/src/script/bridge/qscriptdeclarativeclass.cpp
+++ b/src/script/bridge/qscriptdeclarativeclass.cpp
@@ -493,6 +493,11 @@ QScriptDeclarativeClass::Value QScriptDeclarativeClass::call(Object *object,
     return Value();
 }
 
+bool QScriptDeclarativeClass::compare(Object *o, Object *o2)
+{
+    return o == o2;
+}
+
 QStringList QScriptDeclarativeClass::propertyNames(Object *object)
 {
     Q_UNUSED(object);
diff --git a/src/script/bridge/qscriptdeclarativeclass_p.h b/src/script/bridge/qscriptdeclarativeclass_p.h
index a0fd6d5..7037e22 100644
--- a/src/script/bridge/qscriptdeclarativeclass_p.h
+++ b/src/script/bridge/qscriptdeclarativeclass_p.h
@@ -129,6 +129,7 @@ public:
     virtual void setProperty(Object *, const Identifier &name, const QScriptValue &);
     virtual QScriptValue::PropertyFlags propertyFlags(Object *, const Identifier &);
     virtual Value call(Object *, QScriptContext *);
+    virtual bool compare(Object *, Object *);
 
     virtual QStringList propertyNames(Object *);
 
diff --git a/src/script/bridge/qscriptdeclarativeobject.cpp b/src/script/bridge/qscriptdeclarativeobject.cpp
index c6ab6a7..70bb1bb 100644
--- a/src/script/bridge/qscriptdeclarativeobject.cpp
+++ b/src/script/bridge/qscriptdeclarativeobject.cpp
@@ -198,6 +198,23 @@ bool DeclarativeObjectDelegate::hasInstance(QScriptObject* object, JSC::ExecStat
     return QScriptObjectDelegate::hasInstance(object, exec, value, proto);
 }
 
+bool DeclarativeObjectDelegate::compareToObject(QScriptObject *o, JSC::ExecState *exec, JSC::JSObject *o2)
+{
+    if (!o2->inherits(&QScriptObject::info))
+        return false;
+    
+    QScriptObject *scriptObject = static_cast<QScriptObject*>(o2);
+    QScriptObjectDelegate *delegate = scriptObject->delegate();
+    if (!delegate || (delegate->type() != QScriptObjectDelegate::DeclarativeClassObject))
+        return false;
+
+    DeclarativeObjectDelegate *other = static_cast<DeclarativeObjectDelegate*>(delegate);
+    if (m_class != other->m_class)
+        return false;
+    else
+        return m_class->compare(m_object, other->m_object);
+}
+
 } // namespace QScript
 
 QT_END_NAMESPACE
diff --git a/src/script/bridge/qscriptdeclarativeobject_p.h b/src/script/bridge/qscriptdeclarativeobject_p.h
index ec8a43e..878af24 100644
--- a/src/script/bridge/qscriptdeclarativeobject_p.h
+++ b/src/script/bridge/qscriptdeclarativeobject_p.h
@@ -99,6 +99,8 @@ public:
     virtual bool hasInstance(QScriptObject*, JSC::ExecState*,
                              JSC::JSValue value, JSC::JSValue proto);
 
+    bool compareToObject(QScriptObject *, JSC::ExecState *, JSC::JSObject *);
+
 private:
     QScriptDeclarativeClass *m_class;
     QScriptDeclarativeClass::Object *m_object;
diff --git a/tests/auto/declarative/qdeclarativeecmascript/tst_qdeclarativeecmascript.cpp b/tests/auto/declarative/qdeclarativeecmascript/tst_qdeclarativeecmascript.cpp
index 4838288..d134750 100644
--- a/tests/auto/declarative/qdeclarativeecmascript/tst_qdeclarativeecmascript.cpp
+++ b/tests/auto/declarative/qdeclarativeecmascript/tst_qdeclarativeecmascript.cpp
@@ -126,6 +126,7 @@ private slots:
     void attachedPropertyScope();
     void scriptConnect();
     void scriptDisconnect();
+    void ownership();
 
     void bug1();
 
@@ -889,6 +890,7 @@ void tst_qdeclarativeecmascript::dynamicDestruction()
     }
     QVERIFY(!createdQmlObject);
 
+    QDeclarativeEngine::setObjectOwnership(object, QDeclarativeEngine::QMLOwnership);
     QMetaObject::invokeMethod(object, "killMe");
     QVERIFY(object);
     QTest::qWait(0);
@@ -1890,7 +1892,57 @@ void tst_qdeclarativeecmascript::scriptDisconnect()
 
         delete object;
     }
+}
+
+class OwnershipObject : public QObject
+{
+    Q_OBJECT
+public:
+    OwnershipObject() { object = new QObject; }
+
+    QPointer<QObject> object;
+
+public slots:
+    QObject *getObject() { return object; }
+};
+
+void tst_qdeclarativeecmascript::ownership()
+{
+    OwnershipObject own;
+    QDeclarativeContext *context = new QDeclarativeContext(engine.rootContext());
+    context->addDefaultObject(&own);
+
+    {
+        QDeclarativeComponent component(&engine, TEST_FILE("ownership.qml"));
+
+        QVERIFY(own.object != 0);
+
+        QObject *object = component.create(context);
+        QDeclarativeEnginePrivate::getScriptEngine(&engine)->collectGarbage();
 
+        QCoreApplication::processEvents(QEventLoop::DeferredDeletion);
+
+        QVERIFY(own.object == 0);
+
+        delete object;
+    }
+
+    own.object = new QObject(&own);
+
+    {
+        QDeclarativeComponent component(&engine, TEST_FILE("ownership.qml"));
+
+        QVERIFY(own.object != 0);
+
+        QObject *object = component.create(context);
+        QDeclarativeEnginePrivate::getScriptEngine(&engine)->collectGarbage();
+
+        QCoreApplication::processEvents(QEventLoop::DeferredDeletion);
+
+        QVERIFY(own.object != 0);
+
+        delete object;
+    }
 }
 
 QTEST_MAIN(tst_qdeclarativeecmascript)