Allow retrieval of sequences from QJSValue

As we can store sequence types in QJSValue, we should be able to
retrieve them, too.

Move the declaration of the QV4::Sequence struct into a header to make
it less of a hassle to identify sequences.

Change-Id: I3e45bfe193c669107f90cd6c502765c0c9f60fb0
Reviewed-by: Andrei Golubev <andrei.golubev@qt.io>
Reviewed-by: Sami Shalayel <sami.shalayel@qt.io>
Reviewed-by: Qt CI Bot <qt_ci_bot@qt-project.org>
Reviewed-by: Ulf Hermann <ulf.hermann@qt.io>

6 files changed, 481 insertions, 452 deletions

diff --git a/src/qml/jsruntime/qv4engine.cpp b/src/qml/jsruntime/qv4engine.cpp
index 6ace973124..81da5162a9 100644
--- a/src/qml/jsruntime/qv4engine.cpp
+++ b/src/qml/jsruntime/qv4engine.cpp
@@ -1568,8 +1568,8 @@ static QVariant toVariant(QV4::ExecutionEngine *e, const QV4::Value &value, QMet
             return v->toVariant();
         } else if (QV4::QmlListWrapper *l = object->as<QV4::QmlListWrapper>()) {
             return l->toVariant();
-        } else if (object->isListType()) {
-            return QV4::SequencePrototype::toVariant(object);
+        } else if (QV4::Sequence *s = object->as<QV4::Sequence>()) {
+            return QV4::SequencePrototype::toVariant(s);
         }
     }
 
@@ -2462,28 +2462,24 @@ bool ExecutionEngine::metaTypeFromJS(const Value &value, QMetaType metaType, voi
     ;
     }
 
-    {
-        if (metaType.flags() & QMetaType::IsEnumeration) {
-            *reinterpret_cast<int *>(data) = value.toInt32();
-            return true;
-        }
+    if (metaType.flags() & QMetaType::IsEnumeration) {
+        *reinterpret_cast<int *>(data) = value.toInt32();
+        return true;
+    }
 
-        if (metaType == QMetaType::fromType<QQmlListReference>()) {
-            if (const QV4::QmlListWrapper *wrapper = value.as<QV4::QmlListWrapper>()) {
-                *reinterpret_cast<QQmlListReference *>(data) = wrapper->toListReference();
-                return true;
-            }
+    if (metaType == QMetaType::fromType<QQmlListReference>()) {
+        if (const QV4::QmlListWrapper *wrapper = value.as<QV4::QmlListWrapper>()) {
+            *reinterpret_cast<QQmlListReference *>(data) = wrapper->toListReference();
+            return true;
         }
     }
 
-    {
-        if (const QQmlValueTypeWrapper *vtw = value.as<QQmlValueTypeWrapper>()) {
-            const QMetaType valueType = vtw->type();
-            if (valueType == metaType)
-                return vtw->toGadget(data);
-            if (QMetaType::canConvert(valueType, metaType))
-                return QMetaType::convert(valueType, vtw->d()->gadgetPtr(), metaType, data);
-        }
+    if (const QQmlValueTypeWrapper *vtw = value.as<QQmlValueTypeWrapper>()) {
+        const QMetaType valueType = vtw->type();
+        if (valueType == metaType)
+            return vtw->toGadget(data);
+        if (QMetaType::canConvert(valueType, metaType))
+            return QMetaType::convert(valueType, vtw->d()->gadgetPtr(), metaType, data);
     }
 
     // Try to use magic; for compatibility with qjsvalue_cast.
@@ -2547,6 +2543,15 @@ bool ExecutionEngine::metaTypeFromJS(const Value &value, QMetaType metaType, voi
         }
     }
 
+    if (const QV4::Sequence *sequence = value.as<Sequence>()) {
+        const QVariant result = QV4::SequencePrototype::toVariant(sequence);
+        if (result.metaType() == metaType) {
+            metaType.destruct(data);
+            metaType.construct(data, result.constData());
+            return true;
+        }
+    }
+
     return false;
 }
 
diff --git a/src/qml/jsruntime/qv4qobjectwrapper.cpp b/src/qml/jsruntime/qv4qobjectwrapper.cpp
index 3d5371b7e0..490cf1be2d 100644
--- a/src/qml/jsruntime/qv4qobjectwrapper.cpp
+++ b/src/qml/jsruntime/qv4qobjectwrapper.cpp
@@ -1543,8 +1543,8 @@ static int MatchScore(const Value &actual, QMetaType conversionMetaType)
             }
         }
 
-        if (auto sequenceMetaType = SequencePrototype::metaTypeForSequence(obj); sequenceMetaType.isValid()) {
-            if (sequenceMetaType == conversionMetaType)
+        if (const Sequence *sequence = obj->as<Sequence>()) {
+            if (SequencePrototype::metaTypeForSequence(sequence) == conversionMetaType)
                 return 1;
             else
                 return 10;
@@ -1888,10 +1888,9 @@ void CallArgument::initAsType(QMetaType metaType)
 template <class T, class M>
 bool CallArgument::fromContainerValue(const Value &value, M CallArgument::*member)
 {
-    const Object *object = value.as<Object>();
-    if (object && object->isListType()) {
+    if (const Sequence *sequence = value.as<Sequence>()) {
         if (T* ptr = static_cast<T *>(SequencePrototype::getRawContainerPtr(
-                                          object, QMetaType(type)))) {
+                    sequence, QMetaType(type)))) {
             (this->*member) = ptr;
             return true;
         }
diff --git a/src/qml/jsruntime/qv4sequenceobject.cpp b/src/qml/jsruntime/qv4sequenceobject.cpp
index c374a9f3cf..fa7bb9d3dd 100644
--- a/src/qml/jsruntime/qv4sequenceobject.cpp
+++ b/src/qml/jsruntime/qv4sequenceobject.cpp
@@ -55,7 +55,34 @@
 
 QT_BEGIN_NAMESPACE
 
-using namespace QV4;
+namespace QV4 {
+
+DEFINE_OBJECT_VTABLE(Sequence);
+
+static const QMetaSequence *metaSequence(const Heap::Sequence *p)
+{
+    return p->typePrivate->extraData.ld;
+}
+
+template<typename Compare>
+void sortSequence(Sequence *sequence, const Compare &compare)
+{
+    const auto *p = sequence->d();
+    const auto *m = metaSequence(p);
+
+    QSequentialIterable iterable(*m, p->typePrivate->listId, p->container);
+    if (iterable.canRandomAccessIterate()) {
+        std::sort(QSequentialIterable::RandomAccessIterator(iterable.mutableBegin()),
+                  QSequentialIterable::RandomAccessIterator(iterable.mutableEnd()),
+                  compare);
+    } else if (iterable.canReverseIterate()) {
+        std::sort(QSequentialIterable::BidirectionalIterator(iterable.mutableBegin()),
+                  QSequentialIterable::BidirectionalIterator(iterable.mutableEnd()),
+                  compare);
+    } else {
+        qWarning() << "Container has no suitable iterator for sorting";
+    }
+}
 
 // helper function to generate valid warnings if errors occur during sequence operations.
 static void generateWarning(QV4::ExecutionEngine *v4, const QString& description)
@@ -73,468 +100,413 @@ static void generateWarning(QV4::ExecutionEngine *v4, const QString& description
     QQmlEnginePrivate::warning(engine, retn);
 }
 
-namespace QV4 {
+struct SequenceOwnPropertyKeyIterator : ObjectOwnPropertyKeyIterator
+{
+    ~SequenceOwnPropertyKeyIterator() override = default;
+    PropertyKey next(const Object *o, Property *pd = nullptr, PropertyAttributes *attrs = nullptr) override
+    {
+        const Sequence *s = static_cast<const Sequence *>(o);
+
+        if (s->d()->isReference) {
+            if (!s->d()->object)
+                return ObjectOwnPropertyKeyIterator::next(o, pd, attrs);
+            s->loadReference();
+        }
 
-namespace Heap {
+        if (arrayIndex < quint32(s->size())) {
+            uint index = arrayIndex;
+            ++arrayIndex;
+            if (attrs)
+                *attrs = QV4::Attr_Data;
+            if (pd)
+                pd->value = s->engine()->fromVariant(s->at(index));
+            return PropertyKey::fromArrayIndex(index);
+        }
 
-struct QV4Sequence : Object {
-    void init(const QQmlType &qmlType, const void *container);
-    void init(QObject *object, int propertyIndex, const QQmlType &qmlType, bool readOnly);
-    void destroy() {
-        typePrivate->listId.destroy(container);
-        QQmlType::derefHandle(typePrivate);
-        object.destroy();
-        Object::destroy();
+        return ObjectOwnPropertyKeyIterator::next(o, pd, attrs);
     }
+};
+
+struct SequenceCompareFunctor
+{
+    SequenceCompareFunctor(QV4::ExecutionEngine *v4, const QV4::Value &compareFn)
+        : m_v4(v4), m_compareFn(&compareFn)
+    {}
 
-    mutable void *container;
-    const QQmlTypePrivate *typePrivate;
-    QV4QPointer<QObject> object;
-    int propertyIndex;
-    bool isReference : 1;
-    bool isReadOnly : 1;
+    bool operator()(const QVariant &lhs, const QVariant &rhs)
+    {
+        QV4::Scope scope(m_v4);
+        ScopedFunctionObject compare(scope, m_compareFn);
+        if (!compare)
+            return m_v4->throwTypeError();
+        Value *argv = scope.alloc(2);
+        argv[0] = m_v4->fromVariant(lhs);
+        argv[1] = m_v4->fromVariant(rhs);
+        QV4::ScopedValue result(scope, compare->call(m_v4->globalObject, argv, 2));
+        if (scope.hasException())
+            return false;
+        return result->toNumber() < 0;
+    }
+
+private:
+    QV4::ExecutionEngine *m_v4;
+    const QV4::Value *m_compareFn;
 };
 
-}
+struct SequenceDefaultCompareFunctor
+{
+    bool operator()(const QVariant &lhs, const QVariant &rhs)
+    {
+        return lhs.toString() < rhs.toString();
+    }
+};
 
-static const QMetaSequence *meta(const Heap::QV4Sequence *p)
+void Heap::Sequence::init(const QQmlType &qmlType, const void *container)
 {
-    return p->typePrivate->extraData.ld;
+    Object::init();
+
+    Q_ASSERT(qmlType.isSequentialContainer());
+    typePrivate = qmlType.priv();
+    QQmlType::refHandle(typePrivate);
+
+    this->container = typePrivate->listId.create(container);
+    propertyIndex = -1;
+    isReference = false;
+    isReadOnly = false;
+    object.init();
+
+    QV4::Scope scope(internalClass->engine);
+    QV4::Scoped<QV4::Sequence> o(scope, this);
+    o->setArrayType(Heap::ArrayData::Custom);
 }
 
-struct QV4Sequence : public QV4::Object
+void Heap::Sequence::init(
+        QObject *object, int propertyIndex, const QQmlType &qmlType, bool readOnly)
 {
-    V4_OBJECT2(QV4Sequence, QV4::Object)
-    Q_MANAGED_TYPE(V4Sequence)
-    V4_PROTOTYPE(sequencePrototype)
-    V4_NEEDS_DESTROY
-public:
+    Object::init();
 
-    static const QMetaSequence *metaSequence(const Heap::QV4Sequence *p)
-    {
-        return p->typePrivate->extraData.ld;
-    }
+    Q_ASSERT(qmlType.isSequentialContainer());
+    typePrivate = qmlType.priv();
+    QQmlType::refHandle(typePrivate);
+    container = QMetaType(typePrivate->listId).create();
+    this->propertyIndex = propertyIndex;
+    isReference = true;
+    this->isReadOnly = readOnly;
+    this->object.init(object);
+    QV4::Scope scope(internalClass->engine);
+    QV4::Scoped<QV4::Sequence> o(scope, this);
+    o->setArrayType(Heap::ArrayData::Custom);
+    o->loadReference();
+}
 
-    static const QMetaType valueMetaType(const Heap::QV4Sequence *p)
-    {
-        return p->typePrivate->typeId;
-    }
+void Heap::Sequence::destroy()
+{
+    typePrivate->listId.destroy(container);
+    QQmlType::derefHandle(typePrivate);
+    object.destroy();
+    Object::destroy();
+}
 
-    qsizetype size() const
-    {
-        const auto *p = d();
-        return metaSequence(p)->size(p->container);
-    }
+const QMetaType Sequence::valueMetaType(const Heap::Sequence *p)
+{
+    return p->typePrivate->typeId;
+}
 
-    QVariant at(int index) const
-    {
-        const auto *p = d();
-        const QMetaType v = valueMetaType(p);
-        QVariant result;
-        if (v == QMetaType::fromType<QVariant>()) {
-            metaSequence(p)->valueAtIndex(p->container, index, &result);
-        } else {
-            result = QVariant(v);
-            metaSequence(p)->valueAtIndex(p->container, index, result.data());
-        }
-        return result;
-    }
+qsizetype Sequence::size() const
+{
+    const auto *p = d();
+    return metaSequence(p)->size(p->container);
+}
 
-    void append(const QVariant &item)
-    {
-        const auto *p = d();
-        const auto *m = metaSequence(p);
-        const QMetaType v = valueMetaType(p);
-        if (item.metaType() == v) {
-            m->addValueAtEnd(p->container, item.constData());
-        } else if (v == QMetaType::fromType<QVariant>()) {
-            m->addValueAtEnd(p->container, &item);
-        } else {
-            QVariant converted = item;
-            if (!converted.convert(v))
-                converted = QVariant(v);
-            m->addValueAtEnd(p->container, converted.constData());
-        }
+QVariant Sequence::at(int index) const
+{
+    const auto *p = d();
+    const QMetaType v = valueMetaType(p);
+    QVariant result;
+    if (v == QMetaType::fromType<QVariant>()) {
+        metaSequence(p)->valueAtIndex(p->container, index, &result);
+    } else {
+        result = QVariant(v);
+        metaSequence(p)->valueAtIndex(p->container, index, result.data());
     }
+    return result;
+}
 
-    void replace(int index, const QVariant &item)
-    {
-        const auto *p = d();
-        const auto *m = metaSequence(p);
-        const QMetaType v = valueMetaType(p);
-        if (item.metaType() == v) {
-            m->setValueAtIndex(p->container, index, item.constData());
-        } else if (v == QMetaType::fromType<QVariant>()) {
-            m->setValueAtIndex(p->container, index, &item);
-        } else {
-            QVariant converted = item;
-            if (!converted.convert(v))
-                converted = QVariant(v);
-            m->setValueAtIndex(p->container, index, converted.constData());
-        }
+void Sequence::append(const QVariant &item)
+{
+    const auto *p = d();
+    const auto *m = metaSequence(p);
+    const QMetaType v = valueMetaType(p);
+    if (item.metaType() == v) {
+        m->addValueAtEnd(p->container, item.constData());
+    } else if (v == QMetaType::fromType<QVariant>()) {
+        m->addValueAtEnd(p->container, &item);
+    } else {
+        QVariant converted = item;
+        if (!converted.convert(v))
+            converted = QVariant(v);
+        m->addValueAtEnd(p->container, converted.constData());
     }
+}
 
-    template<typename Compare>
-    void sort(const Compare &compare)
-    {
-        const auto *p = d();
-        const auto *m = metaSequence(p);
-
-        QSequentialIterable iterable(*m, p->typePrivate->listId, p->container);
-        if (iterable.canRandomAccessIterate()) {
-            std::sort(QSequentialIterable::RandomAccessIterator(iterable.mutableBegin()),
-                      QSequentialIterable::RandomAccessIterator(iterable.mutableEnd()),
-                      compare);
-        } else if (iterable.canReverseIterate()) {
-            std::sort(QSequentialIterable::BidirectionalIterator(iterable.mutableBegin()),
-                      QSequentialIterable::BidirectionalIterator(iterable.mutableEnd()),
-                      compare);
-        } else {
-            qWarning() << "Container has no suitable iterator for sorting";
-        }
+void Sequence::replace(int index, const QVariant &item)
+{
+    const auto *p = d();
+    const auto *m = metaSequence(p);
+    const QMetaType v = valueMetaType(p);
+    if (item.metaType() == v) {
+        m->setValueAtIndex(p->container, index, item.constData());
+    } else if (v == QMetaType::fromType<QVariant>()) {
+        m->setValueAtIndex(p->container, index, &item);
+    } else {
+        QVariant converted = item;
+        if (!converted.convert(v))
+            converted = QVariant(v);
+        m->setValueAtIndex(p->container, index, converted.constData());
     }
+}
 
-    void removeLast(int num)
-    {
-        const auto *p = d();
-        const auto *m = metaSequence(p);
-
-        if (m->canEraseRangeAtIterator() && m->hasRandomAccessIterator() && num > 1) {
-            void *i = m->end(p->container);
-            m->advanceIterator(i, -num);
-            void *j = m->end(p->container);
-            m->eraseRangeAtIterator(p->container, i, j);
-            m->destroyIterator(i);
-            m->destroyIterator(j);
-        } else {
-            for (int i = 0; i < num; ++i)
-                m->removeValueAtEnd(p->container);
-        }
+void Sequence::removeLast(int num)
+{
+    const auto *p = d();
+    const auto *m = metaSequence(p);
+
+    if (m->canEraseRangeAtIterator() && m->hasRandomAccessIterator() && num > 1) {
+        void *i = m->end(p->container);
+        m->advanceIterator(i, -num);
+        void *j = m->end(p->container);
+        m->eraseRangeAtIterator(p->container, i, j);
+        m->destroyIterator(i);
+        m->destroyIterator(j);
+    } else {
+        for (int i = 0; i < num; ++i)
+            m->removeValueAtEnd(p->container);
     }
+}
 
-    QVariant toVariant()
-    {
-        const auto *p = d();
-        return QVariant(p->typePrivate->listId, p->container);
-    }
+QVariant Sequence::toVariant() const
+{
+    const auto *p = d();
+    return QVariant(p->typePrivate->listId, p->container);
+}
 
-    //  ### Qt 7 use qsizetype instead.
-    QV4::ReturnedValue containerGetIndexed(uint index, bool *hasProperty) const
-    {
-        /* Qt containers have int (rather than uint) allowable indexes. */
-        if (index > INT_MAX) {
-            generateWarning(engine(), QLatin1String("Index out of range during indexed get"));
+ReturnedValue Sequence::containerGetIndexed(uint index, bool *hasProperty) const
+{
+    /* Qt containers have int (rather than uint) allowable indexes. */
+    if (index > INT_MAX) {
+        generateWarning(engine(), QLatin1String("Index out of range during indexed get"));
+        if (hasProperty)
+            *hasProperty = false;
+        return Encode::undefined();
+    }
+    if (d()->isReference) {
+        if (!d()->object) {
             if (hasProperty)
                 *hasProperty = false;
             return Encode::undefined();
         }
-        if (d()->isReference) {
-            if (!d()->object) {
-                if (hasProperty)
-                    *hasProperty = false;
-                return Encode::undefined();
-            }
-            loadReference();
-        }
-        if (index < quint32(size())) {
-            if (hasProperty)
-                *hasProperty = true;
-            return engine()->fromVariant(at(index));
-        }
+        loadReference();
+    }
+    if (index < quint32(size())) {
         if (hasProperty)
-            *hasProperty = false;
-        return Encode::undefined();
+            *hasProperty = true;
+        return engine()->fromVariant(at(index));
     }
+    if (hasProperty)
+        *hasProperty = false;
+    return Encode::undefined();
+}
 
-    //  ### Qt 7 use qsizetype instead.
-    bool containerPutIndexed(uint index, const QV4::Value &value)
-    {
-        if (internalClass()->engine->hasException)
-            return false;
+bool Sequence::containerPutIndexed(uint index, const Value &value)
+{
+    if (internalClass()->engine->hasException)
+        return false;
 
-        /* Qt containers have int (rather than uint) allowable indexes. */
-        if (index > INT_MAX) {
-            generateWarning(engine(), QLatin1String("Index out of range during indexed set"));
-            return false;
-        }
+    /* Qt containers have int (rather than uint) allowable indexes. */
+    if (index > INT_MAX) {
+        generateWarning(engine(), QLatin1String("Index out of range during indexed set"));
+        return false;
+    }
 
-        if (d()->isReadOnly) {
-            engine()->throwTypeError(QLatin1String("Cannot insert into a readonly container"));
+    if (d()->isReadOnly) {
+        engine()->throwTypeError(QLatin1String("Cannot insert into a readonly container"));
+        return false;
+    }
+
+    if (d()->isReference) {
+        if (!d()->object)
             return false;
-        }
+        loadReference();
+    }
 
-        if (d()->isReference) {
-            if (!d()->object)
-                return false;
-            loadReference();
-        }
+    quint32 count = quint32(size());
+    const QMetaType valueType = valueMetaType(d());
+    const QVariant element = engine()->toVariant(value, valueType, false);
 
-        quint32 count = quint32(size());
-        const QMetaType valueType = valueMetaType(d());
-        const QVariant element = engine()->toVariant(value, valueType, false);
-
-        if (index == count) {
-            append(element);
-        } else if (index < count) {
-            replace(index, element);
-        } else {
-            /* according to ECMA262r3 we need to insert */
-            /* the value at the given index, increasing length to index+1. */
-            while (index > count++) {
-                append(valueType == QMetaType::fromType<QVariant>()
-                       ? QVariant()
-                       : QVariant(valueType));
-            }
-            append(element);
+    if (index == count) {
+        append(element);
+    } else if (index < count) {
+        replace(index, element);
+    } else {
+        /* according to ECMA262r3 we need to insert */
+        /* the value at the given index, increasing length to index+1. */
+        while (index > count++) {
+            append(valueType == QMetaType::fromType<QVariant>()
+                           ? QVariant()
+                           : QVariant(valueType));
         }
-
-        if (d()->isReference)
-            storeReference();
-        return true;
+        append(element);
     }
 
-    QV4::PropertyAttributes containerQueryIndexed(uint index) const
-    {
-        /* Qt containers have int (rather than uint) allowable indexes. */
-        if (index > INT_MAX) {
-            generateWarning(engine(), QLatin1String("Index out of range during indexed query"));
+    if (d()->isReference)
+        storeReference();
+    return true;
+}
+
+PropertyAttributes Sequence::containerQueryIndexed(uint index) const
+{
+    /* Qt containers have int (rather than uint) allowable indexes. */
+    if (index > INT_MAX) {
+        generateWarning(engine(), QLatin1String("Index out of range during indexed query"));
+        return QV4::Attr_Invalid;
+    }
+    if (d()->isReference) {
+        if (!d()->object)
             return QV4::Attr_Invalid;
-        }
-        if (d()->isReference) {
-            if (!d()->object)
-                return QV4::Attr_Invalid;
-            loadReference();
-        }
-        return (index < quint32(size())) ? QV4::Attr_Data : QV4::Attr_Invalid;
+        loadReference();
     }
+    return (index < quint32(size())) ? QV4::Attr_Data : QV4::Attr_Invalid;
+}
 
-    struct OwnPropertyKeyIterator : ObjectOwnPropertyKeyIterator
-    {
-        ~OwnPropertyKeyIterator() override = default;
-        PropertyKey next(const Object *o, Property *pd = nullptr, PropertyAttributes *attrs = nullptr) override
-        {
-            const QV4Sequence *s = static_cast<const QV4Sequence *>(o);
-
-            if (s->d()->isReference) {
-                if (!s->d()->object)
-                    return ObjectOwnPropertyKeyIterator::next(o, pd, attrs);
-                s->loadReference();
-            }
-
-            if (arrayIndex < quint32(s->size())) {
-                uint index = arrayIndex;
-                ++arrayIndex;
-                if (attrs)
-                    *attrs = QV4::Attr_Data;
-                if (pd)
-                    pd->value = s->engine()->fromVariant(s->at(index));
-                return PropertyKey::fromArrayIndex(index);
-            }
-
-            return ObjectOwnPropertyKeyIterator::next(o, pd, attrs);
-        }
-    };
-
-    static OwnPropertyKeyIterator *containerOwnPropertyKeys(const Object *m, Value *target)
-    {
-        *target = *m;
-        return new OwnPropertyKeyIterator;
-    }
+SequenceOwnPropertyKeyIterator *containerOwnPropertyKeys(const Object *m, Value *target)
+{
+    *target = *m;
+    return new SequenceOwnPropertyKeyIterator;
+}
 
-    bool containerDeleteIndexedProperty(uint index)
-    {
-        /* Qt containers have int (rather than uint) allowable indexes. */
-        if (index > INT_MAX)
-            return false;
-        if (d()->isReadOnly)
+bool Sequence::containerDeleteIndexedProperty(uint index)
+{
+    /* Qt containers have int (rather than uint) allowable indexes. */
+    if (index > INT_MAX)
+        return false;
+    if (d()->isReadOnly)
+        return false;
+    if (d()->isReference) {
+        if (!d()->object)
             return false;
-        if (d()->isReference) {
-            if (!d()->object)
-                return false;
-            loadReference();
-        }
+        loadReference();
+    }
 
-        if (index >= quint32(size()))
-            return false;
+    if (index >= quint32(size()))
+        return false;
 
-        /* according to ECMA262r3 it should be Undefined, */
-        /* but we cannot, so we insert a default-value instead. */
-        replace(index, QVariant());
+    /* according to ECMA262r3 it should be Undefined, */
+    /* but we cannot, so we insert a default-value instead. */
+    replace(index, QVariant());
 
-        if (d()->isReference)
-            storeReference();
+    if (d()->isReference)
+        storeReference();
 
-        return true;
-    }
+    return true;
+}
 
-    bool containerIsEqualTo(Managed *other)
-    {
-        if (!other)
-            return false;
-        QV4Sequence *otherSequence = other->as<QV4Sequence>();
-        if (!otherSequence)
-            return false;
-        if (d()->isReference && otherSequence->d()->isReference) {
-            return d()->object == otherSequence->d()->object && d()->propertyIndex == otherSequence->d()->propertyIndex;
-        } else if (!d()->isReference && !otherSequence->d()->isReference) {
-            return this == otherSequence;
-        }
+bool Sequence::containerIsEqualTo(Managed *other)
+{
+    if (!other)
+        return false;
+    Sequence *otherSequence = other->as<Sequence>();
+    if (!otherSequence)
         return false;
+    if (d()->isReference && otherSequence->d()->isReference) {
+        return d()->object == otherSequence->d()->object && d()->propertyIndex == otherSequence->d()->propertyIndex;
+    } else if (!d()->isReference && !otherSequence->d()->isReference) {
+        return this == otherSequence;
     }
+    return false;
+}
 
-    struct DefaultCompareFunctor
-    {
-        bool operator()(const QVariant &lhs, const QVariant &rhs)
-        {
-            return lhs.toString() < rhs.toString();
-        }
-    };
-
-    struct CompareFunctor
-    {
-        CompareFunctor(QV4::ExecutionEngine *v4, const QV4::Value &compareFn)
-            : m_v4(v4), m_compareFn(&compareFn)
-        {}
-
-        bool operator()(const QVariant &lhs, const QVariant &rhs)
-        {
-            QV4::Scope scope(m_v4);
-            ScopedFunctionObject compare(scope, m_compareFn);
-            if (!compare)
-                return m_v4->throwTypeError();
-            Value *argv = scope.alloc(2);
-            argv[0] = m_v4->fromVariant(lhs);
-            argv[1] = m_v4->fromVariant(rhs);
-            QV4::ScopedValue result(scope, compare->call(m_v4->globalObject, argv, 2));
-            if (scope.hasException())
-                return false;
-            return result->toNumber() < 0;
-        }
-
-    private:
-        QV4::ExecutionEngine *m_v4;
-        const QV4::Value *m_compareFn;
-    };
-
-    bool sort(const FunctionObject *f, const Value *, const Value *argv, int argc)
-    {
-        if (d()->isReadOnly)
+bool Sequence::sort(const FunctionObject *f, const Value *, const Value *argv, int argc)
+{
+    if (d()->isReadOnly)
+        return false;
+    if (d()->isReference) {
+        if (!d()->object)
             return false;
-        if (d()->isReference) {
-            if (!d()->object)
-                return false;
-            loadReference();
-        }
-
-        if (argc == 1 && argv[0].as<FunctionObject>())
-            sort(CompareFunctor(f->engine(), argv[0]));
-        else
-            sort(DefaultCompareFunctor());
-
-        if (d()->isReference)
-            storeReference();
-
-        return true;
+        loadReference();
     }
 
-    void* getRawContainerPtr() const
-    { return d()->container; }
+    if (argc == 1 && argv[0].as<FunctionObject>())
+        sortSequence(this, SequenceCompareFunctor(f->engine(), argv[0]));
+    else
+        sortSequence(this, SequenceDefaultCompareFunctor());
 
-    void loadReference() const
-    {
-        Q_ASSERT(d()->object);
-        Q_ASSERT(d()->isReference);
-        void *a[] = { d()->container, nullptr };
-        QMetaObject::metacall(d()->object, QMetaObject::ReadProperty, d()->propertyIndex, a);
-    }
+    if (d()->isReference)
+        storeReference();
 
-    void storeReference()
-    {
-        Q_ASSERT(d()->object);
-        Q_ASSERT(d()->isReference);
-        int status = -1;
-        QQmlPropertyData::WriteFlags flags = QQmlPropertyData::DontRemoveBinding;
-        void *a[] = { d()->container, nullptr, &status, &flags };
-        QMetaObject::metacall(d()->object, QMetaObject::WriteProperty, d()->propertyIndex, a);
-    }
-
-    static QV4::ReturnedValue virtualGet(const QV4::Managed *that, PropertyKey id, const Value *receiver, bool *hasProperty)
-    {
-        if (!id.isArrayIndex())
-            return Object::virtualGet(that, id, receiver, hasProperty);
-        return static_cast<const QV4Sequence *>(that)->containerGetIndexed(id.asArrayIndex(), hasProperty);
-    }
-    static bool virtualPut(Managed *that, PropertyKey id, const QV4::Value &value, Value *receiver)
-    {
-        if (id.isArrayIndex())
-            return static_cast<QV4Sequence *>(that)->containerPutIndexed(id.asArrayIndex(), value);
-        return Object::virtualPut(that, id, value, receiver);
-    }
-    static QV4::PropertyAttributes queryIndexed(const QV4::Managed *that, uint index)
-    { return static_cast<const QV4Sequence *>(that)->containerQueryIndexed(index); }
-    static bool virtualDeleteProperty(QV4::Managed *that, PropertyKey id)
-    {
-        if (id.isArrayIndex()) {
-            uint index = id.asArrayIndex();
-            return static_cast<QV4Sequence *>(that)->containerDeleteIndexedProperty(index);
-        }
-        return Object::virtualDeleteProperty(that, id);
-    }
-    static bool virtualIsEqualTo(Managed *that, Managed *other)
-    { return static_cast<QV4Sequence *>(that)->containerIsEqualTo(other); }
-    static QV4::OwnPropertyKeyIterator *virtualOwnPropertyKeys(const Object *m, Value *target)
-    { return static_cast<const QV4Sequence *>(m)->containerOwnPropertyKeys(m, target);}
-};
+    return true;
+}
 
+void *Sequence::getRawContainerPtr() const
+{ return d()->container; }
 
-void Heap::QV4Sequence::init(const QQmlType &qmlType, const void *container)
+void Sequence::loadReference() const
 {
-    Object::init();
-
-    Q_ASSERT(qmlType.isSequentialContainer());
-    typePrivate = qmlType.priv();
-    QQmlType::refHandle(typePrivate);
+    Q_ASSERT(d()->object);
+    Q_ASSERT(d()->isReference);
+    void *a[] = { d()->container, nullptr };
+    QMetaObject::metacall(d()->object, QMetaObject::ReadProperty, d()->propertyIndex, a);
+}
 
-    this->container = typePrivate->listId.create(container);
-    propertyIndex = -1;
-    isReference = false;
-    isReadOnly = false;
-    object.init();
+void Sequence::storeReference()
+{
+    Q_ASSERT(d()->object);
+    Q_ASSERT(d()->isReference);
+    int status = -1;
+    QQmlPropertyData::WriteFlags flags = QQmlPropertyData::DontRemoveBinding;
+    void *a[] = { d()->container, nullptr, &status, &flags };
+    QMetaObject::metacall(d()->object, QMetaObject::WriteProperty, d()->propertyIndex, a);
+}
 
-    QV4::Scope scope(internalClass->engine);
-    QV4::Scoped<QV4::QV4Sequence> o(scope, this);
-    o->setArrayType(Heap::ArrayData::Custom);
+ReturnedValue Sequence::virtualGet(const Managed *that, PropertyKey id, const Value *receiver, bool *hasProperty)
+{
+    if (!id.isArrayIndex())
+        return Object::virtualGet(that, id, receiver, hasProperty);
+    return static_cast<const Sequence *>(that)->containerGetIndexed(id.asArrayIndex(), hasProperty);
 }
 
-void Heap::QV4Sequence::init(QObject *object, int propertyIndex, const QQmlType &qmlType,
-                             bool readOnly)
+bool Sequence::virtualPut(Managed *that, PropertyKey id, const Value &value, Value *receiver)
 {
-    Object::init();
+    if (id.isArrayIndex())
+        return static_cast<Sequence *>(that)->containerPutIndexed(id.asArrayIndex(), value);
+    return Object::virtualPut(that, id, value, receiver);
+}
 
-    Q_ASSERT(qmlType.isSequentialContainer());
-    typePrivate = qmlType.priv();
-    QQmlType::refHandle(typePrivate);
-    container = QMetaType(typePrivate->listId).create();
-    this->propertyIndex = propertyIndex;
-    isReference = true;
-    this->isReadOnly = readOnly;
-    this->object.init(object);
-    QV4::Scope scope(internalClass->engine);
-    QV4::Scoped<QV4::QV4Sequence> o(scope, this);
-    o->setArrayType(Heap::ArrayData::Custom);
-    o->loadReference();
+PropertyAttributes Sequence::queryIndexed(const Managed *that, uint index)
+{ return static_cast<const Sequence *>(that)->containerQueryIndexed(index); }
+
+bool Sequence::virtualDeleteProperty(Managed *that, PropertyKey id)
+{
+    if (id.isArrayIndex()) {
+        uint index = id.asArrayIndex();
+        return static_cast<Sequence *>(that)->containerDeleteIndexedProperty(index);
+    }
+    return Object::virtualDeleteProperty(that, id);
 }
 
+bool Sequence::virtualIsEqualTo(Managed *that, Managed *other)
+{
+    return static_cast<Sequence *>(that)->containerIsEqualTo(other);
 }
 
-namespace QV4 {
-DEFINE_OBJECT_VTABLE(QV4Sequence);
+OwnPropertyKeyIterator *Sequence::virtualOwnPropertyKeys(const Object *m, Value *target)
+{
+    return containerOwnPropertyKeys(m, target);
 }
 
 static QV4::ReturnedValue method_get_length(const FunctionObject *b, const Value *thisObject, const Value *, int)
 {
     QV4::Scope scope(b);
-    QV4::Scoped<QV4Sequence> This(scope, thisObject->as<QV4Sequence>());
+    QV4::Scoped<Sequence> This(scope, thisObject->as<Sequence>());
     if (!This)
         THROW_TYPE_ERROR();
 
@@ -549,7 +521,7 @@ static QV4::ReturnedValue method_get_length(const FunctionObject *b, const Value
 static QV4::ReturnedValue method_set_length(const FunctionObject *f, const Value *thisObject, const Value *argv, int argc)
 {
     QV4::Scope scope(f);
-    QV4::Scoped<QV4Sequence> This(scope, thisObject->as<QV4Sequence>());
+    QV4::Scoped<Sequence> This(scope, thisObject->as<Sequence>());
     if (!This)
         THROW_TYPE_ERROR();
 
@@ -575,7 +547,7 @@ static QV4::ReturnedValue method_set_length(const FunctionObject *f, const Value
     if (newCount == count) {
         RETURN_UNDEFINED();
     } else if (newCount > count) {
-        const QMetaType valueMetaType = meta(This->d())->valueMetaType();
+        const QMetaType valueMetaType = metaSequence(This->d())->valueMetaType();
         /* according to ECMA262r3 we need to insert */
         /* undefined values increasing length to newLength. */
         /* We cannot, so we insert default-values instead. */
@@ -617,7 +589,7 @@ ReturnedValue SequencePrototype::method_sort(const FunctionObject *b, const Valu
     if (argc >= 2)
         return o.asReturnedValue();
 
-    if (auto *s = o->as<QV4Sequence>()) {
+    if (auto *s = o->as<Sequence>()) {
         if (!s->sort(b, thisObject, argv, argc))
             THROW_TYPE_ERROR();
     }
@@ -638,7 +610,7 @@ ReturnedValue SequencePrototype::newSequence(
     const QQmlType qmlType = QQmlMetaType::qmlListType(sequenceType);
     if (qmlType.isSequentialContainer()) {
         *succeeded = true;
-        QV4::ScopedObject obj(scope, engine->memoryManager->allocate<QV4Sequence>(
+        QV4::ScopedObject obj(scope, engine->memoryManager->allocate<Sequence>(
                                   object, propertyIndex, qmlType, readOnly));
         return obj.asReturnedValue();
     }
@@ -664,7 +636,7 @@ ReturnedValue SequencePrototype::fromData(ExecutionEngine *engine, QMetaType typ
     const QQmlType qmlType = QQmlMetaType::qmlListType(type);
     if (qmlType.isSequentialContainer()) {
         *succeeded = true;
-        QV4::ScopedObject obj(scope, engine->memoryManager->allocate<QV4Sequence>(qmlType, data));
+        QV4::ScopedObject obj(scope, engine->memoryManager->allocate<Sequence>(qmlType, data));
         return obj.asReturnedValue();
     }
 
@@ -672,10 +644,10 @@ ReturnedValue SequencePrototype::fromData(ExecutionEngine *engine, QMetaType typ
     return Encode::undefined();
 }
 
-QVariant SequencePrototype::toVariant(Object *object)
+QVariant SequencePrototype::toVariant(const Sequence *object)
 {
     Q_ASSERT(object->isListType());
-    return object->as<QV4Sequence>()->toVariant();
+    return object->toVariant();
 }
 
 QVariant SequencePrototype::toVariant(const QV4::Value &array, QMetaType typeHint, bool *succeeded)
@@ -721,22 +693,20 @@ QVariant SequencePrototype::toVariant(const QV4::Value &array, QMetaType typeHin
     return QVariant();
 }
 
-void *SequencePrototype::getRawContainerPtr(const Object *object, QMetaType typeHint)
+void *SequencePrototype::getRawContainerPtr(const Sequence *object, QMetaType typeHint)
 {
-    if (auto *s = object->as<QV4Sequence>()) {
-        if (s->d()->typePrivate->listId == typeHint)
-            return s->getRawContainerPtr();
-    }
+    if (object->d()->typePrivate->listId == typeHint)
+        return object->getRawContainerPtr();
     return nullptr;
 }
 
-QMetaType SequencePrototype::metaTypeForSequence(const QV4::Object *object)
+QMetaType SequencePrototype::metaTypeForSequence(const Sequence *object)
 {
-    if (auto *s = object->as<QV4Sequence>())
-        return s->d()->typePrivate->listId;
-    return QMetaType();
+    return object->d()->typePrivate->listId;
 }
 
+} // namespace QV4
+
 QT_END_NAMESPACE
 
 #include "moc_qv4sequenceobject_p.cpp"
diff --git a/src/qml/jsruntime/qv4sequenceobject_p.h b/src/qml/jsruntime/qv4sequenceobject_p.h
index ff09ec815c..65ccb32a26 100644
--- a/src/qml/jsruntime/qv4sequenceobject_p.h
+++ b/src/qml/jsruntime/qv4sequenceobject_p.h
@@ -69,6 +69,7 @@ QT_BEGIN_NAMESPACE
 
 namespace QV4 {
 
+struct Sequence;
 struct Q_QML_PRIVATE_EXPORT SequencePrototype : public QV4::Object
 {
     V4_PROTOTYPE(arrayPrototype)
@@ -81,10 +82,65 @@ struct Q_QML_PRIVATE_EXPORT SequencePrototype : public QV4::Object
     static ReturnedValue fromVariant(QV4::ExecutionEngine *engine, const QVariant &v, bool *succeeded);
     static ReturnedValue fromData(QV4::ExecutionEngine *engine, QMetaType type, const void *data, bool *succeeded);
 
-    static QMetaType metaTypeForSequence(const Object *object);
-    static QVariant toVariant(Object *object);
+    static QMetaType metaTypeForSequence(const Sequence *object);
+    static QVariant toVariant(const Sequence *object);
     static QVariant toVariant(const Value &array, QMetaType typeHint, bool *succeeded);
-    static void *getRawContainerPtr(const Object *object, QMetaType typeHint);
+    static void *getRawContainerPtr(const Sequence *object, QMetaType typeHint);
+};
+
+namespace Heap {
+
+struct Sequence : Object {
+    void init(const QQmlType &qmlType, const void *container);
+    void init(QObject *object, int propertyIndex, const QQmlType &qmlType, bool readOnly);
+    void destroy();
+
+    mutable void *container;
+    const QQmlTypePrivate *typePrivate;
+    QV4QPointer<QObject> object;
+    int propertyIndex;
+    bool isReference : 1;
+    bool isReadOnly : 1;
+};
+
+}
+
+struct Q_QML_PRIVATE_EXPORT Sequence : public QV4::Object
+{
+    V4_OBJECT2(Sequence, QV4::Object)
+    Q_MANAGED_TYPE(V4Sequence)
+    V4_PROTOTYPE(sequencePrototype)
+    V4_NEEDS_DESTROY
+public:
+    static const QMetaType valueMetaType(const Heap::Sequence *p);
+    static QV4::ReturnedValue virtualGet(
+            const QV4::Managed *that, PropertyKey id, const Value *receiver, bool *hasProperty);
+    static bool virtualPut(Managed *that, PropertyKey id, const QV4::Value &value, Value *receiver);
+    static QV4::PropertyAttributes queryIndexed(const QV4::Managed *that, uint index);
+    static bool virtualDeleteProperty(QV4::Managed *that, PropertyKey id);
+    static bool virtualIsEqualTo(Managed *that, Managed *other);
+    static QV4::OwnPropertyKeyIterator *virtualOwnPropertyKeys(const Object *m, Value *target);
+
+    qsizetype size() const;
+    QVariant at(int index) const;
+    void append(const QVariant &item);
+    void replace(int index, const QVariant &item);
+    void removeLast(int num);
+    QVariant toVariant() const;
+
+    //  ### Qt 7 use qsizetype instead.
+    QV4::ReturnedValue containerGetIndexed(uint index, bool *hasProperty) const;
+
+    //  ### Qt 7 use qsizetype instead.
+    bool containerPutIndexed(uint index, const QV4::Value &value);
+
+    QV4::PropertyAttributes containerQueryIndexed(uint index) const;
+    bool containerDeleteIndexedProperty(uint index);
+    bool containerIsEqualTo(Managed *other);
+    bool sort(const FunctionObject *f, const Value *, const Value *argv, int argc);
+    void *getRawContainerPtr() const;
+    void loadReference() const;
+    void storeReference();
 };
 
 }
diff --git a/src/qml/qml/qqmlvmemetaobject.cpp b/src/qml/qml/qqmlvmemetaobject.cpp
index cd847903e4..919bbeb572 100644
--- a/src/qml/qml/qqmlvmemetaobject.cpp
+++ b/src/qml/qml/qqmlvmemetaobject.cpp
@@ -753,7 +753,7 @@ int QQmlVMEMetaObject::metaCall(QObject *o, QMetaObject::Call c, int _id, void *
                         } else if (QV4::MemberData *md = propertyAndMethodStorageAsMemberData()) {
                             // Value type list
                             QV4::Scope scope(engine);
-                            QV4::ScopedObject sequence(scope, *(md->data() + id));
+                            QV4::Scoped<QV4::Sequence> sequence(scope, *(md->data() + id));
                             const void *data = sequence
                                     ? QV4::SequencePrototype::getRawContainerPtr(sequence, propType)
                                     : nullptr;
@@ -849,7 +849,7 @@ int QQmlVMEMetaObject::metaCall(QObject *o, QMetaObject::Call c, int _id, void *
                         } else if (QV4::MemberData *md = propertyAndMethodStorageAsMemberData()) {
                             // Value type list
                             QV4::Scope scope(engine);
-                            QV4::ScopedObject sequence(scope, *(md->data() + id));
+                            QV4::Scoped<QV4::Sequence> sequence(scope, *(md->data() + id));
                             void *data = sequence
                                     ? QV4::SequencePrototype::getRawContainerPtr(sequence, propType)
                                     : nullptr;
diff --git a/src/qmlworkerscript/qv4serialize.cpp b/src/qmlworkerscript/qv4serialize.cpp
index b9b4d6aa08..b7ad2a6313 100644
--- a/src/qmlworkerscript/qv4serialize.cpp
+++ b/src/qmlworkerscript/qv4serialize.cpp
@@ -240,28 +240,27 @@ void Serialize::serialize(QByteArray &data, const QV4::Value &v, ExecutionEngine
         }
         // No other QObject's are allowed to be sent
         push(data, valueheader(WorkerUndefined));
-    } else if (const Object *o = v.as<Object>()) {
-        if (o->isListType()) {
-            // valid sequence.  we generate a length (sequence length + 1 for the sequence type)
-            uint seqLength = ScopedValue(scope, o->get(engine->id_length()))->toUInt32();
-            uint length = seqLength + 1;
-            if (length > 0xFFFFFF) {
-                push(data, valueheader(WorkerUndefined));
-                return;
-            }
-            reserve(data, sizeof(quint32) + length * sizeof(quint32));
-            push(data, valueheader(WorkerSequence, length));
+    } else if (const Sequence *s = v.as<Sequence>()) {
+        // valid sequence.  we generate a length (sequence length + 1 for the sequence type)
+        uint seqLength = ScopedValue(scope, s->get(engine->id_length()))->toUInt32();
+        uint length = seqLength + 1;
+        if (length > 0xFFFFFF) {
+            push(data, valueheader(WorkerUndefined));
+            return;
+        }
+        reserve(data, sizeof(quint32) + length * sizeof(quint32));
+        push(data, valueheader(WorkerSequence, length));
 
-            // sequence type
-            serialize(data, QV4::Value::fromInt32(
-                          QV4::SequencePrototype::metaTypeForSequence(o).id()), engine);
+        // sequence type
+        serialize(data, QV4::Value::fromInt32(
+                                QV4::SequencePrototype::metaTypeForSequence(s).id()), engine);
 
-            ScopedValue val(scope);
-            for (uint ii = 0; ii < seqLength; ++ii)
-                serialize(data, (val = o->get(ii)), engine); // sequence elements
+        ScopedValue val(scope);
+        for (uint ii = 0; ii < seqLength; ++ii)
+            serialize(data, (val = s->get(ii)), engine); // sequence elements
 
-            return;
-        }
+        return;
+    } else if (const Object *o = v.as<Object>()) {
         const QVariant variant = engine->toVariant(v, QMetaType::fromType<QUrl>(), false);
         if (variant.userType() == QMetaType::QUrl) {
             serializeString(data, variant.value<QUrl>().toString(), WorkerUrl);