qv4qobjectwrapper.cpp

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// Copyright (C) 2016 The Qt Company Ltd.
// SPDX-License-Identifier: LicenseRef-Qt-Commercial OR LGPL-3.0-only OR GPL-2.0-only OR GPL-3.0-only
// Qt-Security score:significant
 
#include "qv4qobjectwrapper_p.h"
 
#include <private/qjsvalue_p.h>
#include <private/qjsmanagedvalue_p.h>
 
#include <private/qqmlbinding_p.h>
#include <private/qqmlbuiltinfunctions_p.h>
#include <private/qqmlengine_p.h>
#include <private/qqmlobjectorgadget_p.h>
#include <private/qqmlpropertybinding_p.h>
#include <private/qqmlscriptstring_p.h>
#include <private/qqmlsignalnames_p.h>
#include <private/qqmltypewrapper_p.h>
#include <private/qqmlvaluetypewrapper_p.h>
#include <private/qqmlvmemetaobject_p.h>
 
#include <private/qv4arraybuffer_p.h>
#include <private/qv4arrayobject_p.h>
#include <private/qv4compileddata_p.h>
#include <private/qv4dateobject_p.h>
#include <private/qv4functionobject_p.h>
#include <private/qv4identifiertable_p.h>
#include <private/qv4jscall_p.h>
#include <private/qv4jsonobject_p.h>
#include <private/qv4lookup_p.h>
#include <private/qv4mm_p.h>
#include <private/qv4regexpobject_p.h>
#include <private/qv4runtime_p.h>
#include <private/qv4scopedvalue_p.h>
#include <private/qv4sequenceobject_p.h>
#include <private/qv4variantobject_p.h>
 
#include <QtCore/qjsonarray.h>
#include <QtCore/qjsonobject.h>
#include <QtCore/qjsonvalue.h>
#include <QtCore/qloggingcategory.h>
#include <QtCore/qmetaobject.h>
#include <QtCore/qqueue.h>
#include <QtCore/qtimer.h>
#include <QtCore/qtypes.h>
#include <QtCore/qvarlengtharray.h>
 
#include <vector>
 
#if QT_CONFIG(qml_itemmodel)
#include <QtCore/qabstractitemmodel.h>
#endif
 
extern "C" {
 
Q_QML_EXPORT bool qt_v4NativeCallHookEnabled = false;
 
/*! \internal
    Called right before a QML-to-C++ method call is dispatched, but only
    when qt_v4NativeCallHookEnabled is set. An attached debugger can set
    a breakpoint here. \a receiverMeta is the meta object of the call
    receiver.
*/
Q_QML_EXPORT Q_DECL_COLD_FUNCTION void qt_v4AboutToCallNativeMethodHook(const QMetaObject *receiverMeta)
{
    Q_UNUSED(receiverMeta);
}
 
} // extern "C"
 
QT_BEGIN_NAMESPACE
 
Q_LOGGING_CATEGORY(lcBuiltinsBindingRemoval, "qt.qml.binding.removal", QtWarningMsg)
Q_STATIC_LOGGING_CATEGORY(lcObjectConnect, "qt.qml.object.connect", QtWarningMsg)
Q_STATIC_LOGGING_CATEGORY(lcOverloadResolution, "qt.qml.overloadresolution", QtWarningMsg)
Q_STATIC_LOGGING_CATEGORY(lcMethodBehavior, "qt.qml.method.behavior")
Q_STATIC_LOGGING_CATEGORY(lcSignalHandler, "qt.qml.signalhandler")
 
// The code in this file does not violate strict aliasing, but GCC thinks it does
// so turn off the warnings for us to have a clean build
QT_WARNING_DISABLE_GCC("-Wstrict-aliasing")
 
using namespace Qt::StringLiterals;
 
namespace QV4 {
 
std::pair<QObject *, int> QObjectMethod::extractQtMethod(const FunctionObject *function)
{
    ExecutionEngine *v4 = function->engine();
    if (v4) {
        Scope scope(v4);
        Scoped<QObjectMethod> method(scope, function->as<QObjectMethod>());
        if (method)
            return std::make_pair(method->object(), method->methodIndex());
    }
 
    return std::make_pair((QObject *)nullptr, -1);
}
 
static std::pair<QObject *, int> extractQtSignal(const Value &value)
{
    if (value.isObject()) {
        ExecutionEngine *v4 = value.as<Object>()->engine();
        Scope scope(v4);
        ScopedFunctionObject function(scope, value);
        if (function)
            return QObjectMethod::extractQtMethod(function);
 
        Scoped<QmlSignalHandler> handler(scope, value);
        if (handler)
            return std::make_pair(handler->object(), handler->signalIndex());
    }
 
    return std::make_pair((QObject *)nullptr, -1);
}
 
static Heap::ReferenceObject::Flags referenceFlags(
        ExecutionEngine *v4,
        const QQmlPropertyData &property)
{
    Heap::ReferenceObject::Flags flags = Heap::ReferenceObject::NoFlag;
    if (CppStackFrame *stackFrame = v4->currentStackFrame) {
        if (stackFrame->v4Function->executableCompilationUnit()->valueTypesAreCopied())
            flags |= Heap::ReferenceObject::EnforcesLocation;
    }
 
    if (property.isWritable())
        flags |= Heap::ReferenceObject::CanWriteBack;
 
    return flags;
}
 
static ReturnedValue loadProperty(
        ExecutionEngine *v4, Heap::Object *wrapper,
        QObject *object, const QQmlPropertyData &property)
{
    Q_ASSERT(!property.isFunction());
    Scope scope(v4);
 
    const QMetaType propMetaType = property.propType();
    if (property.isQObject()) {
        QObject *rv = nullptr;
        property.readProperty(object, &rv);
        if (propMetaType.flags().testFlag(QMetaType::IsConst))
            return QObjectWrapper::wrapConst(v4, rv);
        else
            return QObjectWrapper::wrap(v4, rv);
    }
 
    if (property.isQList() && propMetaType.flags().testFlag(QMetaType::IsQmlList))
        return QmlListWrapper::create(v4, object, property.coreIndex(), propMetaType);
 
    const auto encodeSimple = [&](auto v) {
        property.readProperty(object, &v);
        return Encode(v);
    };
 
    const auto encodeInt = [&](auto v) {
        property.readProperty(object, &v);
        return Encode(int(v));
    };
 
    const auto encodeDouble = [&](auto v) {
        property.readProperty(object, &v);
        return Encode(double(v));
    };
 
    const auto encodeDate = [&](auto v) {
        property.readProperty(object, &v);
        return Encode(v4->newDateObject(
                v, wrapper, property.coreIndex(), referenceFlags(scope.engine, property)));
    };
 
    const auto encodeString = [&](auto v) {
        property.readProperty(object, &v);
        return v4->newString(v)->asReturnedValue();
    };
 
    const auto encodeSequence = [&](QMetaSequence metaSequence) {
        // Pass nullptr as data. It's lazy-loaded.
        return QV4::SequencePrototype::newSequence(
                v4, propMetaType, metaSequence, nullptr,
                wrapper, property.coreIndex(), referenceFlags(scope.engine, property));
    };
 
 
    switch (property.isEnum() ? propMetaType.underlyingType().id() : propMetaType.id()) {
    case QMetaType::UnknownType:
    case QMetaType::Void:
        return Encode::undefined();
    case QMetaType::Nullptr:
    case QMetaType::VoidStar:
        return Encode::null();
    case QMetaType::Int:
        return encodeSimple(int());
    case QMetaType::Bool:
        return encodeSimple(bool());
    case QMetaType::QString:
        return encodeString(QString());
    case QMetaType::QByteArray: {
        QByteArray v;
        property.readProperty(object, &v);
        return v4->newArrayBuffer(v)->asReturnedValue();
    }
    case QMetaType::QChar:
        return encodeString(QChar());
    case QMetaType::Char16:
        return encodeString(char16_t());
    case QMetaType::UInt:
        return encodeSimple(uint());
    case QMetaType::Float:
        return encodeSimple(float());
    case QMetaType::Double:
        return encodeSimple(double());
    case QMetaType::Short:
        return encodeInt(short());
    case QMetaType::UShort:
        return encodeInt(ushort());
    case QMetaType::Char:
        return encodeInt(char());
    case QMetaType::UChar:
        return encodeInt(uchar());
    case QMetaType::SChar:
        return encodeInt(qint8());
    case QMetaType::Long:
        return encodeDouble(long());
    case QMetaType::ULong:
        return encodeDouble(ulong());
    case QMetaType::LongLong:
        return encodeDouble(qlonglong());
    case QMetaType::ULongLong:
        return encodeDouble(qulonglong());
    case QMetaType::QDateTime:
        return encodeDate(QDateTime());
    case QMetaType::QDate:
        return encodeDate(QDate());
    case QMetaType::QTime:
        return encodeDate(QTime());
#if QT_CONFIG(regularexpression)
    case QMetaType::QRegularExpression: {
        QRegularExpression v;
        property.readProperty(object, &v);
        return Encode(v4->newRegExpObject(v));
    }
#endif
    case QMetaType::QVariantMap: {
        QVariantMap v;
        property.readProperty(object, &v);
        return scope.engine->fromData(
                propMetaType, &v, wrapper, property.coreIndex(), referenceFlags(v4, property));
    }
    case QMetaType::QVariantHash: {
        QVariantHash v;
        property.readProperty(object, &v);
        return scope.engine->fromData(
                propMetaType, &v, wrapper, property.coreIndex(), referenceFlags(v4, property));
    }
    case QMetaType::QJsonValue: {
        QJsonValue v;
        property.readProperty(object, &v);
        return QV4::JsonObject::fromJsonValue(v4, v);
    }
    case QMetaType::QJsonObject: {
        QJsonObject v;
        property.readProperty(object, &v);
        return QV4::JsonObject::fromJsonObject(v4, v);
    }
    case QMetaType::QJsonArray:
        return encodeSequence(QMetaSequence::fromContainer<QJsonArray>());
    case QMetaType::QStringList:
        return encodeSequence(QMetaSequence::fromContainer<QStringList>());
    case QMetaType::QVariantList:
        return encodeSequence(QMetaSequence::fromContainer<QVariantList>());
    case QMetaType::QUrl: {
        // ### Qt7: We really want this to be a JS URL object, but that would break things.
        QUrl v;
        property.readProperty(object, &v);
        return Encode(v4->newVariantObject(propMetaType, &v));
    }
    case QMetaType::QPixmap:
    case QMetaType::QImage: {
        // Scarce value types
        QVariant v(propMetaType);
        property.readProperty(object, v.data());
        return Encode(v4->newVariantObject(propMetaType, v.constData()));
    }
    default:
        break;
    }
 
    if (propMetaType == QMetaType::fromType<QJSValue>()) {
        QJSValue v;
        property.readProperty(object, &v);
        return QJSValuePrivate::convertToReturnedValue(v4, v);
    }
 
    if (property.isQVariant()) {
        // We have to read the property even if it's a lazy-loaded reference object.
        // Without reading it, we wouldn't know its inner type.
        QVariant v;
        property.readProperty(object, &v);
        return scope.engine->fromVariant(
                    v, wrapper, property.coreIndex(),
                    referenceFlags(scope.engine, property) | Heap::ReferenceObject::IsVariant);
    }
 
    if (!propMetaType.isValid()) {
        QMetaProperty p = object->metaObject()->property(property.coreIndex());
        qWarning("QMetaProperty::read: Unable to handle unregistered datatype '%s' for property "
                 "'%s::%s'", p.typeName(), object->metaObject()->className(), p.name());
        return Encode::undefined();
    }
 
    // TODO: For historical reasons we don't enforce locations for reference objects here.
    //       Once we do, we can eager load and use the fromVariant() below.
    //       Then the extra checks for value types and sequences can be dropped.
 
    if (QQmlMetaType::isValueType(propMetaType)) {
        if (const QMetaObject *valueTypeMetaObject
                = QQmlMetaType::metaObjectForValueType(propMetaType)) {
            // Lazy loaded value type reference. Pass nullptr as data.
            return QQmlValueTypeWrapper::create(
                        v4, nullptr, valueTypeMetaObject, propMetaType, wrapper,
                        property.coreIndex(), referenceFlags(scope.engine, property));
        }
    }
 
    // See if it's a sequence type.
    const QQmlType qmlType = QQmlMetaType::qmlListType(propMetaType);
    if (qmlType.isSequentialContainer())
        return encodeSequence(qmlType.listMetaSequence());
 
    QVariant v(propMetaType);
    property.readProperty(object, v.data());
    return scope.engine->fromVariant(
                v, wrapper, property.coreIndex(), referenceFlags(scope.engine, property));
}
 
void QObjectWrapper::initializeBindings(ExecutionEngine *engine)
{
    engine->functionPrototype()->defineDefaultProperty(QStringLiteral("connect"), method_connect);
    engine->functionPrototype()->defineDefaultProperty(QStringLiteral("disconnect"), method_disconnect);
}
 
const QQmlPropertyData *QObjectWrapper::findProperty(
        const QQmlRefPointer<QQmlContextData> &qmlContext, String *name,
        Flags flags, QQmlPropertyData *local) const
{
    return findProperty(d()->object(), qmlContext, name, flags, local);
}
 
const QQmlPropertyData *QObjectWrapper::findProperty(
        QObject *o, const QQmlRefPointer<QQmlContextData> &qmlContext,
        String *name, Flags flags, QQmlPropertyData *local)
{
    Q_UNUSED(flags);
 
    QQmlData *ddata = QQmlData::get(o, false);
    const QQmlPropertyData *result = nullptr;
    if (ddata && ddata->propertyCache)
        result = ddata->propertyCache->property(name, o, qmlContext);
    else
        result = QQmlPropertyCache::property(o, name, qmlContext, local);
    return result;
}
 
ReturnedValue QObjectWrapper::getProperty(
        ExecutionEngine *engine, Heap::Object *wrapper, QObject *object,
        const QQmlPropertyData *property, Flags flags)
{
    QQmlData::flushPendingBinding(object, property->coreIndex());
 
    if (property->isFunction() && !property->isVarProperty()) {
        if (property->isVMEFunction()) {
            QQmlVMEMetaObject *vmemo = QQmlVMEMetaObject::get(object);
            Q_ASSERT(vmemo);
            return vmemo->vmeMethod(property->coreIndex());
        } else if (property->isV4Function()) {
            return QObjectMethod::create(
                        engine, (flags & AttachMethods) ? wrapper : nullptr, property->coreIndex());
        } else if (property->isSignalHandler()) {
            QmlSignalHandler::initProto(engine);
            return engine->memoryManager->allocate<QmlSignalHandler>(
                        object, property->coreIndex())->asReturnedValue();
        } else {
            return QObjectMethod::create(
                        engine, (flags & AttachMethods) ? wrapper : nullptr, property->coreIndex());
        }
    }
 
    QQmlEnginePrivate *ep = engine->qmlEngine() ? QQmlEnginePrivate::get(engine->qmlEngine()) : nullptr;
 
    if (ep && ep->propertyCapture && !property->isConstant()) {
        if (!property->notifiesViaBindable()
                || ep->propertyCapture->expression->mustCaptureBindableProperty()) {
            ep->propertyCapture->captureProperty(
                    object, property->coreIndex(), property->notifyIndex());
        }
    }
 
    if (property->isVarProperty()) {
        QQmlVMEMetaObject *vmemo = QQmlVMEMetaObject::get(object);
        Q_ASSERT(vmemo);
        return vmemo->vmeProperty(property->coreIndex());
    } else {
        return loadProperty(engine, wrapper, object, *property);
    }
}
 
static OptionalReturnedValue getDestroyOrToStringMethod(
        ExecutionEngine *v4, String *name, Heap::Object *qobj, bool *hasProperty = nullptr)
{
    int index = 0;
    if (name->equals(v4->id_destroy()))
        index = QObjectMethod::DestroyMethod;
    else if (name->equals(v4->id_toString()))
        index = QObjectMethod::ToStringMethod;
    else
        return OptionalReturnedValue();
 
    if (hasProperty)
        *hasProperty = true;
    return OptionalReturnedValue(QObjectMethod::create(v4, qobj, index));
}
 
static OptionalReturnedValue getPropertyFromImports(
        ExecutionEngine *v4, String *name, const QQmlRefPointer<QQmlContextData> &qmlContext,
        QObject *qobj, bool *hasProperty = nullptr)
{
    if (!qmlContext || !qmlContext->imports())
        return OptionalReturnedValue();
 
    if (hasProperty)
        *hasProperty = true;
 
    if (QQmlTypeLoader *typeLoader = v4->typeLoader()) {
        QQmlTypeNameCache::Result r = qmlContext->imports()->query(name, typeLoader);
 
        if (!r.isValid())
            return OptionalReturnedValue();
 
        if (r.scriptIndex != -1) {
            return OptionalReturnedValue(Encode::undefined());
        } else if (r.type.isValid()) {
            return OptionalReturnedValue(
                    QQmlTypeWrapper::create(v4, qobj,r.type, Heap::QQmlTypeWrapper::ExcludeEnums));
        } else if (r.importNamespace) {
            return OptionalReturnedValue(QQmlTypeWrapper::create(
                    v4, qobj, qmlContext->imports(), r.importNamespace,
                    Heap::QQmlTypeWrapper::ExcludeEnums));
        }
        Q_UNREACHABLE_RETURN(OptionalReturnedValue());
    } else {
        return OptionalReturnedValue();
    }
}
 
ReturnedValue QObjectWrapper::getQmlProperty(
        const QQmlRefPointer<QQmlContextData> &qmlContext, String *name,
        QObjectWrapper::Flags flags, bool *hasProperty) const
{
    // Keep this code in sync with ::virtualResolveLookupGetter
 
    if (QQmlData::wasDeleted(d()->object())) {
        if (hasProperty)
            *hasProperty = false;
        return Encode::undefined();
    }
 
    ExecutionEngine *v4 = engine();
 
    if (auto methodValue = getDestroyOrToStringMethod(v4, name, d(), hasProperty))
        return *methodValue;
 
    QQmlPropertyData local;
    const QQmlPropertyData *result = findProperty(qmlContext, name, flags, &local);
 
    if (!result) {
        // Check for attached properties
        if ((flags & IncludeImports) && name->startsWithUpper()) {
            if (auto importProperty = getPropertyFromImports(
                        v4, name, qmlContext, d()->object(), hasProperty))
                return *importProperty;
        }
        return Object::virtualGet(this, name->propertyKey(), this, hasProperty);
    }
 
    QQmlData *ddata = QQmlData::get(d()->object(), false);
 
    if ((flags & CheckRevision) && result->hasRevision()) {
        if (ddata && ddata->propertyCache && !ddata->propertyCache->isAllowedInRevision(result)) {
            if (hasProperty)
                *hasProperty = false;
            return Encode::undefined();
        }
    }
 
    if (hasProperty)
        *hasProperty = true;
 
    return getProperty(v4, d(), d()->object(), result, flags);
}
 
ReturnedValue QObjectWrapper::getQmlProperty(
        ExecutionEngine *engine, const QQmlRefPointer<QQmlContextData> &qmlContext,
        Heap::Object *wrapper, QObject *object, String *name, QObjectWrapper::Flags flags,
        bool *hasProperty, const QQmlPropertyData **property)
{
    if (QQmlData::wasDeleted(object)) {
        if (hasProperty)
            *hasProperty = false;
        return Encode::null();
    }
 
    if (auto methodValue = getDestroyOrToStringMethod(engine, name, wrapper, hasProperty))
        return *methodValue;
 
    QQmlData *ddata = QQmlData::get(object, false);
    QQmlPropertyData local;
    const QQmlPropertyData *result = findProperty(object, qmlContext, name, flags, &local);
 
    if (result) {
        if ((flags & QObjectWrapper::CheckRevision) && result->hasRevision()) {
            if (ddata && ddata->propertyCache
                    && !ddata->propertyCache->isAllowedInRevision(result)) {
                if (hasProperty)
                    *hasProperty = false;
                return Encode::undefined();
            }
        }
 
        if (hasProperty)
            *hasProperty = true;
 
        if (property && result != &local)
            *property = result;
 
        return getProperty(engine, wrapper, object, result, flags);
    } else {
        // Check if this object is already wrapped.
        if (!ddata || (ddata->jsWrapper.isUndefined() &&
                        (ddata->jsEngineId == 0 || // Nobody owns the QObject
                          !ddata->hasTaintedV4Object))) { // Someone else has used the QObject, but it isn't tainted
 
            // Not wrapped. Last chance: try query QObjectWrapper's prototype.
            // If it can't handle this, then there is no point
            // to wrap the QObject just to look at an empty set of JS props.
            Object *proto = QObjectWrapper::defaultPrototype(engine);
            return proto->get(name, hasProperty);
        }
    }
 
    // If we get here, we must already be wrapped (which implies a ddata).
    // There's no point wrapping again, as there wouldn't be any new props.
    Q_ASSERT(ddata);
 
    Scope scope(engine);
    Scoped<QObjectWrapper> rewrapped(scope, wrap(engine, object));
    if (!rewrapped) {
        if (hasProperty)
            *hasProperty = false;
        return Encode::null();
    }
    return rewrapped->getQmlProperty(qmlContext, name, flags, hasProperty);
}
 
 
bool QObjectWrapper::setQmlProperty(
        ExecutionEngine *engine, const QQmlRefPointer<QQmlContextData> &qmlContext, QObject *object,
        String *name, QObjectWrapper::Flags flags, const Value &value)
{
    if (QQmlData::wasDeleted(object))
        return false;
 
    QQmlPropertyData local;
    const QQmlPropertyData *result = QQmlPropertyCache::property(object, name, qmlContext, &local);
    if (!result)
        return false;
 
    if ((flags & QObjectWrapper::CheckRevision) && result->hasRevision()) {
        QQmlData *ddata = QQmlData::get(object);
        if (ddata && ddata->propertyCache && !ddata->propertyCache->isAllowedInRevision(result))
            return false;
    }
 
    setProperty(engine, object, result, value);
    return true;
}
 
/*!
    \internal
    If an QObjectWrapper is created via wrap, then it needs to be stored somewhere.
    Otherwise, the garbage collector will immediately collect it if it is already
    past the "mark QObjectWrapper's" phase (note that QObjectWrapper are marked
    by iterating over a list of all QObjectWrapper, and then checking if the
    wrapper fulfills some conditions).
    However, sometimes we don't really want to keep a reference to the wrapper,
    but just want to make sure that it exists (and we know that the wrapper
    already fulfills the conditions to be kept alive). Then ensureWrapper
    can be used, which creates the wrapper and ensures that it is also
    marked.
 */
void QObjectWrapper::ensureWrapper(ExecutionEngine *engine, QObject *object)
{
    QV4::Scope scope(engine);
    QV4::Scoped<QV4::QObjectWrapper> wrapper {scope, QV4::QObjectWrapper::wrap(engine, object)};
    QV4::WriteBarrier::markCustom(engine, [&wrapper](QV4::MarkStack *ms) {
        wrapper->mark(ms);
    });
}
 
void QObjectWrapper::setProperty(
        ExecutionEngine *engine, QObject *object,
        const QQmlPropertyData *property, const Value &value)
{
    if (!property->isWritable() && !property->isQList()) {
        QString error = QLatin1String("Cannot assign to read-only property \"") +
                        property->name(object) + QLatin1Char('\"');
        engine->throwTypeError(error);
        return;
    }
 
    Scope scope(engine);
    if (ScopedFunctionObject f(scope, value); f) {
        if (f->as<QQmlTypeWrapper>()) {
            // Ignore. It's probably a singleton or an attached type.
        } else if (!f->isBinding()) {
            const bool isAliasToAllowed = [&]() {
                if (property->isAlias()) {
                    const QQmlPropertyIndex originalIndex(property->coreIndex(), -1);
                    auto [targetObject, targetIndex] = QQmlPropertyPrivate::findAliasTarget(object, originalIndex);
                    Q_ASSERT(targetObject);
                    const QQmlPropertyCache *targetCache
                            = QQmlData::get(targetObject)->propertyCache.data();
                    Q_ASSERT(targetCache);
                    const QQmlPropertyData *targetProperty
                            = targetCache->property(targetIndex.coreIndex());
                    object = targetObject;
                    property = targetProperty;
                    return targetProperty->isVarProperty() || targetProperty->propType() == QMetaType::fromType<QJSValue>();
                } else {
                    return false;
                }
            }();
            if (!isAliasToAllowed && !property->isVarProperty()
                    && property->propType() != QMetaType::fromType<QJSValue>()) {
                // assigning a JS function to a non var or QJSValue property or is not allowed.
                QString error = QLatin1String("Cannot assign JavaScript function to ");
                if (!QMetaType(property->propType()).name())
                    error += QLatin1String("[unknown property type]");
                else
                    error += QLatin1String(QMetaType(property->propType()).name());
                scope.engine->throwError(error);
                return;
            }
        } else {
 
            QQmlRefPointer<QQmlContextData> callingQmlContext = scope.engine->callingQmlContext();
            Scoped<QQmlBindingFunction> bindingFunction(scope, (const Value &)f);
            Scoped<JavaScriptFunctionObject> f(scope, bindingFunction->bindingFunction());
            ScopedContext ctx(scope, f->scope());
 
            // binding assignment.
            if (property->acceptsQBinding()) {
                const QQmlPropertyIndex idx(property->coreIndex(), /*not a value type*/-1);
                auto [targetObject, targetIndex] = QQmlPropertyPrivate::findAliasTarget(object, idx);
                QUntypedPropertyBinding binding;
                if (f->isBoundFunction()) {
                    auto boundFunction = static_cast<BoundFunction *>(f.getPointer());
                    binding = QQmlPropertyBinding::createFromBoundFunction(property, boundFunction, object, callingQmlContext,
                                                                           ctx, targetObject, targetIndex);
                } else {
                    binding = QQmlPropertyBinding::create(property, f->function(), object, callingQmlContext,
                                                           ctx, targetObject, targetIndex);
 
                }
                QUntypedBindable bindable;
                void *argv = {&bindable};
                // indirect metacall in case interceptors are installed
                targetObject->metaObject()->metacall(targetObject, QMetaObject::BindableProperty, targetIndex.coreIndex(), &argv);
                bool ok = bindable.setBinding(binding);
                if (!ok) {
                    auto error = QStringLiteral("Failed to set binding on %1::%2.").
                                                arg(QString::fromUtf8(object->metaObject()->className()), property->name(object));
                    scope.engine->throwError(error);
                }
            } else {
                QQmlBinding *newBinding = QQmlBinding::create(property, f->function(), object, callingQmlContext, ctx);
                newBinding->setSourceLocation(bindingFunction->currentLocation());
                if (f->isBoundFunction())
                newBinding->setBoundFunction(static_cast<BoundFunction *>(f.getPointer()));
                newBinding->setTarget(object, *property, nullptr);
                QQmlPropertyPrivate::setBinding(newBinding);
            }
            return;
        }
    }
 
    if (Q_UNLIKELY(lcBuiltinsBindingRemoval().isInfoEnabled())) {
        if (auto binding = QQmlPropertyPrivate::binding(
                    object, QQmlPropertyIndex(property->coreIndex()));
                binding && !binding->isSticky()) {
            const auto stackFrame = engine->currentStackFrame;
            switch (binding->kind()) {
            case QQmlAbstractBinding::QmlBinding: {
                const auto qmlBinding = static_cast<const QQmlBinding*>(binding);
                qCInfo(lcBuiltinsBindingRemoval,
                       "Overwriting binding on %s::%s at %s:%d that was initially bound at %s",
                       object->metaObject()->className(), qPrintable(property->name(object)),
                       qPrintable(stackFrame->source()), stackFrame->lineNumber(),
                       qPrintable(qmlBinding->expressionIdentifier()));
                break;
            }
            case QQmlAbstractBinding::ValueTypeProxy:
            case QQmlAbstractBinding::PropertyToPropertyBinding: {
                qCInfo(lcBuiltinsBindingRemoval,
                       "Overwriting binding on %s::%s at %s:%d",
                       object->metaObject()->className(), qPrintable(property->name(object)),
                       qPrintable(stackFrame->source()), stackFrame->lineNumber());
                break;
            }
            }
        }
    }
    QQmlPropertyPrivate::removeBinding(
            object, QQmlPropertyIndex(property->coreIndex()), QQmlPropertyPrivate::None);
 
    if (property->isVarProperty()) {
        // allow assignment of "special" values (null, undefined, function) to var properties
        QQmlVMEMetaObject *vmemo = QQmlVMEMetaObject::get(object);
        Q_ASSERT(vmemo);
        vmemo->setVMEProperty(property->coreIndex(), value);
        return;
    }
 
#define PROPERTY_STORE(cpptype, value)
    cpptype o = value;
    int status = -1;
    int flags = 0;
    void *argv[] = { &o, 0, &status, &flags };
    QMetaObject::metacall(object, QMetaObject::WriteProperty, property->coreIndex(), argv);
 
    const QMetaType propType = property->propType();
    // functions are already handled, except for the QJSValue case
    Q_ASSERT(!value.as<FunctionObject>()
             || value.as<QV4::QQmlTypeWrapper>()
             || propType == QMetaType::fromType<QJSValue>());
 
    if (value.isNull() && property->isQObject()) {
        PROPERTY_STORE(QObject*, nullptr);
    } else if (value.isUndefined() && property->isResettable()) {
        void *a[] = { nullptr };
        QMetaObject::metacall(object, QMetaObject::ResetProperty, property->coreIndex(), a);
    } else if (value.isUndefined() && propType == QMetaType::fromType<QVariant>()) {
        PROPERTY_STORE(QVariant, QVariant());
    } else if (value.isUndefined() && propType == QMetaType::fromType<QJsonValue>()) {
        PROPERTY_STORE(QJsonValue, QJsonValue(QJsonValue::Undefined));
    } else if (propType == QMetaType::fromType<QJSValue>()) {
        PROPERTY_STORE(QJSValue, QJSValuePrivate::fromReturnedValue(value.asReturnedValue()));
    } else if (value.isUndefined() && propType != QMetaType::fromType<QQmlScriptString>()) {
        QString error = QLatin1String("Cannot assign [undefined] to ");
        if (!propType.name())
            error += QLatin1String("[unknown property type]");
        else
            error += QLatin1String(propType.name());
        scope.engine->throwError(error);
        return;
    } else if (propType == QMetaType::fromType<int>() && value.isNumber()) {
        PROPERTY_STORE(int, value.toInt32());
    } else if (propType == QMetaType::fromType<qreal>() && value.isNumber()) {
        PROPERTY_STORE(qreal, qreal(value.asDouble()));
    } else if (propType == QMetaType::fromType<float>() && value.isNumber()) {
        PROPERTY_STORE(float, float(value.asDouble()));
    } else if (propType == QMetaType::fromType<double>() && value.isNumber()) {
        PROPERTY_STORE(double, double(value.asDouble()));
    } else if (propType == QMetaType::fromType<QString>() && value.isString()) {
        PROPERTY_STORE(QString, value.toQStringNoThrow());
    } else if (property->isVarProperty()) {
        QQmlVMEMetaObject *vmemo = QQmlVMEMetaObject::get(object);
        Q_ASSERT(vmemo);
        vmemo->setVMEProperty(property->coreIndex(), value);
    } else if (propType == QMetaType::fromType<QQmlScriptString>()
               && (value.isUndefined() || value.isPrimitive())) {
        QQmlScriptString ss(value.toQStringNoThrow(), nullptr /* context */, object);
        if (value.isNumber()) {
            ss.d->numberValue = value.toNumber();
            ss.d->isNumberLiteral = true;
        } else if (value.isString()) {
            ss.d->script = CompiledData::Binding::escapedString(ss.d->script);
            ss.d->isStringLiteral = true;
        }
        PROPERTY_STORE(QQmlScriptString, ss);
    } else {
        QVariant v;
        if (property->isQList() && propType.flags().testFlag(QMetaType::IsQmlList))
            v = ExecutionEngine::toVariant(value, QMetaType::fromType<QList<QObject *> >());
        else
            v = ExecutionEngine::toVariant(value, propType);
 
        QQmlRefPointer<QQmlContextData> callingQmlContext = scope.engine->callingQmlContext();
        if (!QQmlPropertyPrivate::write(object, *property, v, callingQmlContext)) {
            const char *valueType = (v.userType() == QMetaType::UnknownType)
                    ? "an unknown type"
                    : QMetaType(v.userType()).name();
 
            const char *targetTypeName = propType.name();
            if (!targetTypeName)
                targetTypeName = "an unregistered type";
 
            QString error = QLatin1String("Cannot assign ") +
                            QLatin1String(valueType) +
                            QLatin1String(" to ") +
                            QLatin1String(targetTypeName);
            scope.engine->throwError(error);
            return;
        }
    }
}
 
ReturnedValue QObjectWrapper::wrap_slowPath(ExecutionEngine *engine, QObject *object)
{
    Q_ASSERT(!QQmlData::wasDeleted(object));
 
    QQmlData *ddata = QQmlData::get(object, true);
    if (!ddata)
        return Encode::undefined();
 
    Scope scope(engine);
 
    if (ddata->jsWrapper.isUndefined() &&
               (ddata->jsEngineId == engine->m_engineId || // We own the QObject
                ddata->jsEngineId == 0 ||    // No one owns the QObject
                !ddata->hasTaintedV4Object)) { // Someone else has used the QObject, but it isn't tainted
 
        ScopedValue rv(scope, create(engine, object));
        ddata->jsWrapper.set(scope.engine, rv);
        ddata->jsEngineId = engine->m_engineId;
        return rv->asReturnedValue();
 
    } else {
        // If this object is tainted, we have to check to see if it is in our
        // tainted object list
        ScopedObject alternateWrapper(scope, (Object *)nullptr);
        if (engine->m_multiplyWrappedQObjects && ddata->hasTaintedV4Object)
            alternateWrapper = engine->m_multiplyWrappedQObjects->value(object);
 
        // If our tainted handle doesn't exist or has been collected, and there isn't
        // a handle in the ddata, we can assume ownership of the ddata->jsWrapper
        if (ddata->jsWrapper.isUndefined() && !alternateWrapper) {
            ScopedValue result(scope, create(engine, object));
            ddata->jsWrapper.set(scope.engine, result);
            ddata->jsEngineId = engine->m_engineId;
            return result->asReturnedValue();
        }
 
        if (!alternateWrapper) {
            alternateWrapper = create(engine, object);
            if (!engine->m_multiplyWrappedQObjects)
                engine->m_multiplyWrappedQObjects = new MultiplyWrappedQObjectMap;
            engine->m_multiplyWrappedQObjects->insert(object, alternateWrapper->d());
            ddata->hasTaintedV4Object = true;
        }
 
        return alternateWrapper.asReturnedValue();
    }
}
 
ReturnedValue QObjectWrapper::wrapConst_slowPath(ExecutionEngine *engine, QObject *object)
{
    const QObject *constObject = object;
 
    QQmlData *ddata = QQmlData::get(object, true);
 
    Scope scope(engine);
    ScopedObject constWrapper(scope);
    if (engine->m_multiplyWrappedQObjects && ddata->hasConstWrapper)
        constWrapper = engine->m_multiplyWrappedQObjects->value(constObject);
 
    if (!constWrapper) {
        constWrapper = create(engine, object);
        constWrapper->setInternalClass(constWrapper->internalClass()->cryopreserved());
        if (!engine->m_multiplyWrappedQObjects)
            engine->m_multiplyWrappedQObjects = new MultiplyWrappedQObjectMap;
        engine->m_multiplyWrappedQObjects->insert(constObject, constWrapper->d());
        ddata->hasConstWrapper = true;
    }
 
    return constWrapper.asReturnedValue();
}
 
void QObjectWrapper::markWrapper(QObject *object, MarkStack *markStack)
{
    if (QQmlData::wasDeleted(object))
        return;
 
    QQmlData *ddata = QQmlData::get(object);
    if (!ddata)
        return;
 
    const ExecutionEngine *engine = markStack->engine();
    if (ddata->jsEngineId == engine->m_engineId)
        ddata->jsWrapper.markOnce(markStack);
    else if (engine->m_multiplyWrappedQObjects && ddata->hasTaintedV4Object)
        engine->m_multiplyWrappedQObjects->mark(object, markStack);
    if (ddata->hasConstWrapper && engine->m_multiplyWrappedQObjects)
        engine->m_multiplyWrappedQObjects->mark(static_cast<const QObject *>(object), markStack);
}
 
void QObjectWrapper::setProperty(ExecutionEngine *engine, int propertyIndex, const Value &value)
{
    setProperty(engine, d()->object(), propertyIndex, value);
}
 
void QObjectWrapper::setProperty(ExecutionEngine *engine, QObject *object, int propertyIndex, const Value &value)
{
    Q_ASSERT(propertyIndex < 0xffff);
    Q_ASSERT(propertyIndex >= 0);
 
    if (QQmlData::wasDeleted(object))
        return;
    QQmlData *ddata = QQmlData::get(object, /*create*/false);
    if (!ddata)
        return;
 
    Q_ASSERT(ddata->propertyCache);
    const QQmlPropertyData *property = ddata->propertyCache->property(propertyIndex);
    Q_ASSERT(property); // We resolved this property earlier, so it better exist!
    return setProperty(engine, object, property, value);
}
 
bool QObjectWrapper::virtualIsEqualTo(Managed *a, Managed *b)
{
    Q_ASSERT(a->as<QObjectWrapper>());
    const QObjectWrapper *aobjectWrapper = static_cast<QObjectWrapper *>(a);
    if (const QQmlTypeWrapper *qmlTypeWrapper = b->as<QQmlTypeWrapper>())
        return qmlTypeWrapper->object() == aobjectWrapper->object();
 
    // We can have a const and a non-const wrapper for the same object.
    const QObjectWrapper *bobjectWrapper = b->as<QObjectWrapper>();
    return bobjectWrapper && aobjectWrapper->object() == bobjectWrapper->object();
}
 
ReturnedValue QObjectWrapper::create(ExecutionEngine *engine, QObject *object)
{
    if (QQmlPropertyCache::ConstPtr cache = QQmlData::ensurePropertyCache(object)) {
        ReturnedValue result = Encode::null();
        void *args[] = { &result, &engine };
        if (cache->callJSFactoryMethod(object, args))
            return result;
    }
    return (engine->memoryManager->allocate<QObjectWrapper>(object))->asReturnedValue();
}
 
ReturnedValue QObjectWrapper::virtualGet(const Managed *m, PropertyKey id, const Value *receiver, bool *hasProperty)
{
    if (!id.isString())
        return Object::virtualGet(m, id, receiver, hasProperty);
 
    const QObjectWrapper *that = static_cast<const QObjectWrapper*>(m);
    Scope scope(that);
    ScopedString n(scope, id.asStringOrSymbol());
    QQmlRefPointer<QQmlContextData> qmlContext = that->engine()->callingQmlContext();
    return that->getQmlProperty(qmlContext, n, IncludeImports | AttachMethods, hasProperty);
}
 
bool QObjectWrapper::virtualPut(Managed *m, PropertyKey id, const Value &value, Value *receiver)
{
    if (!id.isString())
        return Object::virtualPut(m, id, value, receiver);
 
    Scope scope(m);
    QObjectWrapper *that = static_cast<QObjectWrapper*>(m);
    ScopedString name(scope, id.asStringOrSymbol());
 
    if (that->internalClass()->isFrozen()) {
        QString error = QLatin1String("Cannot assign to property \"") +
                        name->toQString() + QLatin1String("\" of read-only object");
        scope.engine->throwError(error);
        return false;
    }
 
    if (scope.hasException() || QQmlData::wasDeleted(that->d()->object()))
        return false;
 
    QQmlRefPointer<QQmlContextData> qmlContext = scope.engine->callingQmlContext();
    if (!setQmlProperty(scope.engine, qmlContext, that->d()->object(), name, NoFlag, value)) {
        QQmlData *ddata = QQmlData::get(that->d()->object());
        // Types created by QML are not extensible at run-time, but for other QObjects we can store them
        // as regular JavaScript properties, like on JavaScript objects.
        if (ddata && ddata->context) {
            QString error = QLatin1String("Cannot assign to non-existent property \"") +
                            name->toQString() + QLatin1Char('\"');
            scope.engine->throwError(error);
            return false;
        } else {
            return Object::virtualPut(m, id, value, receiver);
        }
    }
 
    return true;
}
 
PropertyAttributes QObjectWrapper::virtualGetOwnProperty(const Managed *m, PropertyKey id, Property *p)
{
    if (id.isString()) {
        const QObjectWrapper *that = static_cast<const QObjectWrapper*>(m);
        const QObject *thatObject = that->d()->object();
        if (!QQmlData::wasDeleted(thatObject)) {
            Scope scope(m);
            ScopedString n(scope, id.asStringOrSymbol());
            QQmlRefPointer<QQmlContextData> qmlContext = scope.engine->callingQmlContext();
            QQmlPropertyData local;
            if (that->findProperty(qmlContext, n, NoFlag, &local)
                    || n->equals(scope.engine->id_destroy()) || n->equals(scope.engine->id_toString())) {
                if (p) {
                    // ### probably not the fastest implementation
                    bool hasProperty;
                    p->value = that->getQmlProperty(
                                qmlContext, n, IncludeImports | AttachMethods, &hasProperty);
                }
                return Attr_Data;
            }
        }
    }
 
    return Object::virtualGetOwnProperty(m, id, p);
}
 
struct QObjectWrapperOwnPropertyKeyIterator : ObjectOwnPropertyKeyIterator
{
    int propertyIndex = 0;
    ~QObjectWrapperOwnPropertyKeyIterator() override = default;
    PropertyKey next(const Object *o, Property *pd = nullptr, PropertyAttributes *attrs = nullptr) override;
 
private:
    QSet<QByteArray> m_alreadySeen;
};
 
PropertyKey QObjectWrapperOwnPropertyKeyIterator::next(const Object *o, Property *pd, PropertyAttributes *attrs)
{
    // Used to block access to QObject::destroyed() and QObject::deleteLater() from QML
    static const int destroyedIdx1 = QObject::staticMetaObject.indexOfSignal("destroyed(QObject*)");
    static const int destroyedIdx2 = QObject::staticMetaObject.indexOfSignal("destroyed()");
    static const int deleteLaterIdx = QObject::staticMetaObject.indexOfSlot("deleteLater()");
 
    const QObjectWrapper *that = static_cast<const QObjectWrapper*>(o);
 
    QObject *thatObject = that->d()->object();
    if (thatObject && !QQmlData::wasDeleted(thatObject)) {
        const QMetaObject *mo = thatObject->metaObject();
        // These indices don't apply to gadgets, so don't block them.
        const bool preventDestruction = mo->superClass() || mo == &QObject::staticMetaObject;
        const int propertyCount = mo->propertyCount();
        if (propertyIndex < propertyCount) {
            ExecutionEngine *thatEngine = that->engine();
            Scope scope(thatEngine);
            const QMetaProperty property = mo->property(propertyIndex);
            ScopedString propName(scope, thatEngine->newString(QString::fromUtf8(property.name())));
            ++propertyIndex;
            if (attrs)
                *attrs= Attr_Data;
            if (pd) {
                QQmlPropertyData local;
                local.load(property);
                pd->value = that->getProperty(
                            thatEngine, that->d(), thatObject, &local,
                            QObjectWrapper::AttachMethods);
            }
            return propName->toPropertyKey();
        }
        const int methodCount = mo->methodCount();
        while (propertyIndex < propertyCount + methodCount) {
            Q_ASSERT(propertyIndex >= propertyCount);
            int index = propertyIndex - propertyCount;
            const QMetaMethod method = mo->method(index);
            ++propertyIndex;
            if (method.access() == QMetaMethod::Private || (preventDestruction && (index == deleteLaterIdx || index == destroyedIdx1 || index == destroyedIdx2)))
                continue;
            // filter out duplicates due to overloads:
            if (m_alreadySeen.contains(method.name()))
                continue;
            else
                m_alreadySeen.insert(method.name());
            ExecutionEngine *thatEngine = that->engine();
            Scope scope(thatEngine);
            ScopedString methodName(scope, thatEngine->newString(QString::fromUtf8(method.name())));
            if (attrs)
                *attrs = Attr_Data;
            if (pd) {
                QQmlPropertyData local;
                local.load(method);
                pd->value = that->getProperty(
                            thatEngine, that->d(), thatObject, &local,
                            QObjectWrapper::AttachMethods);
            }
            return methodName->toPropertyKey();
        }
    }
 
    return ObjectOwnPropertyKeyIterator::next(o, pd, attrs);
}
 
OwnPropertyKeyIterator *QObjectWrapper::virtualOwnPropertyKeys(const Object *m, Value *target)
{
    *target = *m;
    return new QObjectWrapperOwnPropertyKeyIterator;
}
 
ReturnedValue QObjectWrapper::virtualResolveLookupGetter(const Object *object, ExecutionEngine *engine, Lookup *lookup)
{
    // Keep this code in sync with ::getQmlProperty
    PropertyKey id = engine->identifierTable->asPropertyKey(engine->currentStackFrame->v4Function->compilationUnit->
                                                            runtimeStrings[lookup->nameIndex]);
    if (!id.isString())
        return Object::virtualResolveLookupGetter(object, engine, lookup);
    Scope scope(engine);
 
    const QObjectWrapper *This = static_cast<const QObjectWrapper *>(object);
    ScopedString name(scope, id.asStringOrSymbol());
    QQmlRefPointer<QQmlContextData> qmlContext = engine->callingQmlContext();
 
    QObject * const qobj = This->d()->object();
 
    if (QQmlData::wasDeleted(qobj))
        return Encode::undefined();
 
    QQmlData *ddata = QQmlData::get(qobj, false);
    if (auto methodValue = getDestroyOrToStringMethod(engine, name, This->d())) {
        Scoped<QObjectMethod> method(scope, *methodValue);
        if (!ddata)
            ddata = QQmlData::get(qobj, true);
        const QQmlPropertyCache::ConstPtr propertyCache = (ddata && ddata->propertyCache)
                ? ddata->propertyCache
                : QQmlMetaType::propertyCacheForType(QMetaType::fromType<QObject *>());
        setupQObjectMethodLookup(lookup, propertyCache, nullptr, This, method->d());
        lookup->call = Lookup::Call::GetterQObjectMethod;
        return method.asReturnedValue();
    }
 
    if (!ddata || !ddata->propertyCache) {
        QQmlPropertyData local;
        const QQmlPropertyData *property = QQmlPropertyCache::property(
                qobj, name, engine->callingQmlContext(), &local);
        if (!property)
            return Encode::undefined();
        QV4::ScopedValue result(scope, getProperty(
                engine, This->d(), qobj, property, lookup->forCall ? NoFlag : AttachMethods));
        if (QObjectMethod *method = result->as<QObjectMethod>()) {
            lookup->qobjectMethodLookup.ic.set(engine, object->internalClass());
            lookup->qobjectMethodLookup.method.set(engine, method->d());
            lookup->call = Lookup::Call::GetterQObjectMethodFallback;
        } else {
            lookup->qobjectFallbackLookup.metaObject = quintptr(qobj->metaObject()) + 1;
            lookup->qobjectFallbackLookup.metaType = quintptr(property->propType().iface()) + 1;
            lookup->qobjectFallbackLookup.coreIndex = property->coreIndex();
            lookup->qobjectFallbackLookup.notifyIndex = property->notifyIndex();
            lookup->qobjectFallbackLookup.isConstantOrResettable = property->isConstant() ? 1 : 0;
            lookup->call = Lookup::Call::GetterQObjectPropertyFallback;
        }
        return result->asReturnedValue();
    }
    const QQmlPropertyData *property = ddata->propertyCache->property(name.getPointer(), qobj, qmlContext);
 
    if (!property) {
        // Check for attached properties
        if (name->startsWithUpper()) {
            if (auto importProperty = getPropertyFromImports(engine, name, qmlContext, qobj))
                return *importProperty;
        }
        return Object::virtualResolveLookupGetter(object, engine, lookup);
    }
 
    if (property->isFunction()
            && !property->isVarProperty()
            && !property->isVMEFunction() // Handled by QObjectLookup
            && !property->isSignalHandler()) { // TODO: Optimize SignalHandler, too
        QV4::Heap::QObjectMethod *method = nullptr;
        setupQObjectMethodLookup(lookup, ddata->propertyCache, property, This, method);
        lookup->call = Lookup::Call::GetterQObjectMethod;
        return lookup->getter(engine, *object);
    }
 
    setupQObjectLookup(lookup, ddata, property, This);
 
    lookup->call = Lookup::Call::GetterQObjectProperty;
    return lookup->getter(engine, *object);
}
 
bool QObjectWrapper::virtualResolveLookupSetter(Object *object, ExecutionEngine *engine, Lookup *lookup,
                                                const Value &value)
{
    return Object::virtualResolveLookupSetter(object, engine, lookup, value);
}
 
int QObjectWrapper::virtualMetacall(Object *object, QMetaObject::Call call, int index, void **a)
{
    QObjectWrapper *wrapper = object->as<QObjectWrapper>();
    Q_ASSERT(wrapper);
 
    if (QObject *qObject = wrapper->object())
        return QMetaObject::metacall(qObject, call, index, a);
 
    return 0;
}
 
QString QObjectWrapper::objectToString(
        ExecutionEngine *engine, const QMetaObject *metaObject, QObject *object)
{
    if (!metaObject)
        return QLatin1String("null");
 
    if (!object)
        return QString::fromUtf8(metaObject->className()) + QLatin1String("(0x0)");
 
    const int id = metaObject->indexOfMethod("toString()");
    if (id >= 0) {
        const QMetaMethod method = metaObject->method(id);
        const QMetaType returnType = method.returnMetaType();
        QVariant result(returnType);
        method.invoke(object, QGenericReturnArgument(returnType.name(), result.data()));
        if (result.metaType() == QMetaType::fromType<QString>())
            return result.toString();
        QV4::Scope scope(engine);
        QV4::ScopedValue value(scope, engine->fromVariant(result));
        return value->toQString();
    }
 
    QString result;
    result += QString::fromUtf8(metaObject->className()) +
            QLatin1String("(0x") + QString::number(quintptr(object), 16);
    QString objectName = object->objectName();
    if (!objectName.isEmpty())
        result += QLatin1String(", \"") + objectName + QLatin1Char('\"');
    result += QLatin1Char(')');
    return result;
}
 
struct QObjectSlotDispatcher : public QtPrivate::QSlotObjectBase
{
    PersistentValue function;
    PersistentValue thisObject;
    QMetaMethod signal;
    qsizetype maxNumArguments;
 
    QObjectSlotDispatcher()
        : QtPrivate::QSlotObjectBase(&impl)
    {}
 
    static void impl(int which, QSlotObjectBase *this_, QObject *receiver, void **metaArgs, bool *ret)
    {
        switch (which) {
        case Destroy: {
            delete static_cast<QObjectSlotDispatcher*>(this_);
        }
        break;
        case Call: {
            if (QQmlData::wasDeleted(receiver))
                break;
 
            QObjectSlotDispatcher *This = static_cast<QObjectSlotDispatcher*>(this_);
            ExecutionEngine *v4 = This->function.engine();
            // Might be that we're still connected to a signal that's emitted long
            // after the engine died. We don't track connections in a global list, so
            // we need this safeguard.
            if (!v4)
                break;
 
            QQmlMetaObject::ArgTypeStorage<9> storage;
            QQmlMetaObject::methodParameterTypes(This->signal, &storage, nullptr);
 
            const qsizetype argCount = std::min(storage.size(), This->maxNumArguments);
 
            Scope scope(v4);
            ScopedFunctionObject f(scope, This->function.value());
 
            JSCallArguments jsCallData(scope, argCount);
            *jsCallData.thisObject = This->thisObject.isUndefined()
                    ? v4->globalObject->asReturnedValue()
                    : This->thisObject.value();
            for (qsizetype ii = 0; ii < argCount; ++ii) {
                QMetaType type = storage[ii];
                if (type == QMetaType::fromType<QVariant>()) {
                    jsCallData.args[ii] = v4->fromVariant(*((QVariant *)metaArgs[ii + 1]));
                } else {
                    jsCallData.args[ii] = v4->fromVariant(QVariant(type, metaArgs[ii + 1]));
                }
            }
 
            f->call(jsCallData);
            if (scope.hasException()) {
                QQmlError error = v4->catchExceptionAsQmlError();
                if (error.description().isEmpty()) {
                    ScopedString name(scope, f->name());
                    error.setDescription(QStringLiteral("Unknown exception occurred during evaluation of connected function: %1").arg(name->toQString()));
                }
                if (QQmlEngine *qmlEngine = v4->qmlEngine()) {
                    QQmlEnginePrivate::get(qmlEngine)->warning(error);
                } else {
                    QMessageLogger(error.url().toString().toLatin1().constData(),
                                   error.line(), nullptr).warning().noquote()
                            << error.toString();
                }
            }
        }
        break;
        case Compare: {
            QObjectSlotDispatcher *connection = static_cast<QObjectSlotDispatcher*>(this_);
            if (connection->function.isUndefined()) {
                *ret = false;
                return;
            }
 
            // This is tricky. Normally the metaArgs[0] pointer is a pointer to the _function_
            // for the new-style QObject::connect. Here we use the engine pointer as sentinel
            // to distinguish those type of QSlotObjectBase connections from our QML connections.
            ExecutionEngine *v4 = reinterpret_cast<ExecutionEngine*>(metaArgs[0]);
            if (v4 != connection->function.engine()) {
                *ret = false;
                return;
            }
 
            Scope scope(v4);
            ScopedValue function(scope, *reinterpret_cast<Value*>(metaArgs[1]));
            ScopedValue thisObject(scope, *reinterpret_cast<Value*>(metaArgs[2]));
            QObject *receiverToDisconnect = reinterpret_cast<QObject*>(metaArgs[3]);
            int slotIndexToDisconnect = *reinterpret_cast<int*>(metaArgs[4]);
 
            if (slotIndexToDisconnect != -1) {
                // This is a QObject function wrapper
                if (connection->thisObject.isUndefined() == thisObject->isUndefined() &&
                        (connection->thisObject.isUndefined() || RuntimeHelpers::strictEqual(*connection->thisObject.valueRef(), thisObject))) {
 
                    ScopedFunctionObject f(scope, connection->function.value());
                    std::pair<QObject *, int> connectedFunctionData = QObjectMethod::extractQtMethod(f);
                    if (connectedFunctionData.first == receiverToDisconnect &&
                        connectedFunctionData.second == slotIndexToDisconnect) {
                        *ret = true;
                        return;
                    }
                }
            } else {
                // This is a normal JS function
                if (RuntimeHelpers::strictEqual(*connection->function.valueRef(), function) &&
                        connection->thisObject.isUndefined() == thisObject->isUndefined() &&
                        (connection->thisObject.isUndefined() || RuntimeHelpers::strictEqual(*connection->thisObject.valueRef(), thisObject))) {
                    *ret = true;
                    return;
                }
            }
 
            *ret = false;
        }
        break;
        case NumOperations:
        break;
        }
    };
};
 
ReturnedValue QObjectWrapper::method_connect(const FunctionObject *b, const Value *thisObject, const Value *argv, int argc)
{
    Scope scope(b);
 
    if (argc == 0)
        THROW_GENERIC_ERROR("Function.prototype.connect: no arguments given");
 
    std::pair<QObject *, int> signalInfo = extractQtSignal(*thisObject);
    QObject *signalObject = signalInfo.first;
    int signalIndex = signalInfo.second; // in method range, not signal range!
 
    if (signalIndex < 0)
        THROW_GENERIC_ERROR("Function.prototype.connect: this object is not a signal");
 
    if (!signalObject)
        THROW_GENERIC_ERROR("Function.prototype.connect: cannot connect to deleted QObject");
 
    auto signalMetaMethod = signalObject->metaObject()->method(signalIndex);
    if (signalMetaMethod.methodType() != QMetaMethod::Signal)
        THROW_GENERIC_ERROR("Function.prototype.connect: this object is not a signal");
 
    ScopedFunctionObject f(scope);
    ScopedValue object (scope, Encode::undefined());
 
    if (argc == 1) {
        f = argv[0];
    } else if (argc >= 2) {
        object = argv[0];
        f = argv[1];
    }
 
    if (!f)
        THROW_GENERIC_ERROR("Function.prototype.connect: target is not a function");
 
    if (!object->isUndefined() && !object->isObject())
        THROW_GENERIC_ERROR("Function.prototype.connect: target this is not an object");
 
    QObjectSlotDispatcher *slot = new QObjectSlotDispatcher;
    slot->signal = signalMetaMethod;
 
    slot->thisObject.set(scope.engine, object);
    slot->function.set(scope.engine, f);
 
    if (QQmlData *ddata = QQmlData::get(signalObject)) {
        if (const QQmlPropertyCache *propertyCache = ddata->propertyCache.data()) {
            QQmlPropertyPrivate::flushSignal(signalObject, propertyCache->methodIndexToSignalIndex(signalIndex));
        }
    }
 
    std::pair<QObject *, int> functionData = QObjectMethod::extractQtMethod(f); // align with disconnect
    QObject *receiver = nullptr;
 
    if (functionData.first)
        receiver = functionData.first;
    else if (auto qobjectWrapper = object->as<QV4::QObjectWrapper>())
        receiver = qobjectWrapper->object();
    else if (auto typeWrapper = object->as<QV4::QQmlTypeWrapper>())
        receiver = typeWrapper->object();
 
    if (receiver) {
        if (functionData.second == -1) {
            slot->maxNumArguments = std::numeric_limits<qsizetype>::max();
        } else {
            // This means we are connecting to QObjectMethod which complains about extra arguments.
            Heap::QObjectMethod *d = static_cast<Heap::QObjectMethod *>(f->d());
            d->ensureMethodsCache(receiver->metaObject());
            slot->maxNumArguments = std::accumulate(d->methods, d->methods + d->methodCount, 0,
                                                    [](int a, const QQmlPropertyData &b) {
                return std::max(a, b.metaMethod().parameterCount());
            });
        }
 
        QObjectPrivate::connect(signalObject, signalIndex, receiver, slot, Qt::AutoConnection);
    } else {
        slot->maxNumArguments = std::numeric_limits<qsizetype>::max();
        qCDebug(lcObjectConnect,
               "Could not find receiver of the connection, using sender as receiver. Disconnect "
               "explicitly (or delete the sender) to make sure the connection is removed.");
        QObjectPrivate::connect(signalObject, signalIndex, signalObject, slot, Qt::AutoConnection);
    }
 
    RETURN_UNDEFINED();
}
 
ReturnedValue QObjectWrapper::method_disconnect(const FunctionObject *b, const Value *thisObject, const Value *argv, int argc)
{
    Scope scope(b);
 
    if (argc == 0)
        THROW_GENERIC_ERROR("Function.prototype.disconnect: no arguments given");
 
    std::pair<QObject *, int> signalInfo = extractQtSignal(*thisObject);
    QObject *signalObject = signalInfo.first;
    int signalIndex = signalInfo.second;
 
    if (signalIndex == -1)
        THROW_GENERIC_ERROR("Function.prototype.disconnect: this object is not a signal");
 
    if (!signalObject)
        THROW_GENERIC_ERROR("Function.prototype.disconnect: cannot disconnect from deleted QObject");
 
    if (signalIndex < 0 || signalObject->metaObject()->method(signalIndex).methodType() != QMetaMethod::Signal)
        THROW_GENERIC_ERROR("Function.prototype.disconnect: this object is not a signal");
 
    ScopedFunctionObject functionValue(scope);
    ScopedValue functionThisValue(scope, Encode::undefined());
 
    if (argc == 1) {
        functionValue = argv[0];
    } else if (argc >= 2) {
        functionThisValue = argv[0];
        functionValue = argv[1];
    }
 
    if (!functionValue)
        THROW_GENERIC_ERROR("Function.prototype.disconnect: target is not a function");
 
    if (!functionThisValue->isUndefined() && !functionThisValue->isObject())
        THROW_GENERIC_ERROR("Function.prototype.disconnect: target this is not an object");
 
    std::pair<QObject *, int> functionData = QObjectMethod::extractQtMethod(functionValue);
 
    void *a[] = {
        scope.engine,
        functionValue.ptr,
        functionThisValue.ptr,
        functionData.first,
        &functionData.second
    };
 
    QObject *receiver = nullptr;
 
    if (functionData.first)
        receiver = functionData.first;
    else if (auto qobjectWrapper = functionThisValue->as<QV4::QObjectWrapper>())
        receiver = qobjectWrapper->object();
    else if (auto typeWrapper = functionThisValue->as<QV4::QQmlTypeWrapper>())
        receiver = typeWrapper->object();
 
    if (receiver) {
        QObjectPrivate::disconnect(signalObject, signalIndex, receiver,
                                   reinterpret_cast<void **>(&a));
    } else {
        QObjectPrivate::disconnect(signalObject, signalIndex, signalObject,
                                   reinterpret_cast<void **>(&a));
    }
 
    RETURN_UNDEFINED();
}
 
static void markChildQObjectsRecursively(QObject *parent, MarkStack *markStack)
{
    QQueue<QObject *> queue;
    queue.append(parent->children());
 
    while (!queue.isEmpty()) {
        QObject *child = queue.dequeue();
        if (!child)
            continue;
        QObjectWrapper::markWrapper(child, markStack);
        queue.append(child->children());
    }
}
 
// returns true if and only if an object was recorded
static bool recordObjectForCompilationUnits(
        QObject *o, const QQmlRefPointer<QV4::ExecutableCompilationUnit> &compilationUnit,
        MemoryManager::ObjectsForCompilationUnit *recorded)
{
    Q_ASSERT(compilationUnit);
    Q_ASSERT(o);
    Q_ASSERT(recorded);
 
    const auto &baseUnit = compilationUnit->baseCompilationUnit();
    Q_ASSERT(baseUnit);
 
    for (const auto &unit : recorded->compilationUnits) {
        if (baseUnit == unit) {
            recorded->objects.push_back(o);
            return true;
        }
    }
 
    return false;
}
 
// returns true if and only if an object was recorded
static bool recordVMEObjectForCompilationUnits(
        QObject *o, const QQmlVMEMetaObject *vme,
        MemoryManager::ObjectsForCompilationUnit *recorded)
{
    for (; vme; vme = vme->parentVMEMetaObject()) {
        if (recordObjectForCompilationUnits(o, vme->compilationUnit(), recorded))
            return true;
    }
 
    return false;
}
 
void Heap::QObjectWrapper::markObjects(Heap::Base *that, MarkStack *markStack)
{
    Object::markObjects(that, markStack);
 
    QObject *o = static_cast<QObjectWrapper *>(that)->object();
    if (!o)
        return;
 
    const auto markChildrenRecursivelyGuard = qScopeGuard([o, markStack]() {
        // Children usually don't need to be marked, the gc keeps them alive.
        // But in the rare case of a "floating" QObject without a parent that
        // _gets_ marked (we've been called here!) then we also need to
        // propagate the marking down to the children recursively.
        if (!o->parent())
            markChildQObjectsRecursively(o, markStack);
    });
 
    QQmlData *ddata = QQmlData::get(o);
    if (!ddata)
        return;
 
    if (ddata->hasVMEMetaObject) {
        if (auto *vme = static_cast<QQmlVMEMetaObject *>(QObjectPrivate::get(o)->metaObject)) {
            vme->mark(markStack);
            if (auto *recorded = markStack->engine()->memoryManager->m_recordedObjects) {
                // ddata->compilationUnit can be different from the VME compilation units
                // if the "topmost" instantiation of the object is inaddressible.
                if (!recordVMEObjectForCompilationUnits(o, vme, recorded)
                        && ddata->compilationUnit != vme->compilationUnit()) {
                    recordObjectForCompilationUnits(o, ddata->compilationUnit, recorded);
                }
            }
        }
    } else if (const auto &cu = ddata->compilationUnit) {
        // Objects without a VMEMetaObject are identified via QQmlData::compilationUnit.
        if (auto *recorded = markStack->engine()->memoryManager->m_recordedObjects)
            recordObjectForCompilationUnits(o, cu, recorded);
    }
 
    if (!ddata->hasConstWrapper || !that->internalClass->engine->m_multiplyWrappedQObjects)
        return;
 
    // mark the const wrapper if our engine has interacted with it at some point
    Scope scope(that->internalClass->engine);
    Scoped<QV4::QObjectWrapper> constWrapper(
            scope, scope.engine->m_multiplyWrappedQObjects->value(static_cast<const QObject *>(o)));
 
    if (!constWrapper)
        return;
 
    if (that != constWrapper->d()) {
        // We've got the non-const wrapper. Also mark the const one.
        constWrapper->mark(markStack);
        return;
    }
 
    // We've got the const wrapper. Also mark the non-const one
    if (ddata->jsEngineId == scope.engine->m_engineId)
        ddata->jsWrapper.markOnce(markStack);
    else
        scope.engine->m_multiplyWrappedQObjects->mark(o, markStack);
}
 
void QObjectWrapper::destroyObject(bool lastCall)
{
    Heap::QObjectWrapper *h = d();
    Q_ASSERT(h->internalClass);
 
    if (QObject *o = h->object()) {
        QQmlData *ddata = QQmlData::get(o, false);
        if (ddata) {
            if (!o->parent() && !ddata->indestructible) {
                if (ddata && ddata->ownContext) {
                    Q_ASSERT(ddata->ownContext.data() == ddata->context);
                    ddata->ownContext->deepClearContextObject(o);
                    ddata->ownContext.reset();
                    ddata->context = nullptr;
                }
 
                // This object is notionally destroyed now. It might still live until the next
                // event loop iteration, but it won't need its connections, CU, or deferredData
                // anymore.
 
                ddata->isQueuedForDeletion = true;
                ddata->disconnectNotifiers(QQmlData::DeleteNotifyList::No);
                ddata->compilationUnit.reset();
 
                qDeleteAll(ddata->deferredData);
                ddata->deferredData.clear();
 
                if (lastCall)
                    delete o;
                else
                    o->deleteLater();
            } else {
                // If the object is C++-owned, we still have to release the weak reference we have
                // to it. If the "main" wrapper is not ours, we should leave it alone, though.
                if (ddata->jsWrapper.as<QObjectWrapper>() == this)
                    ddata->jsWrapper.clear();
            }
        }
    }
 
    h->destroy();
}
 
 
DEFINE_OBJECT_VTABLE(QObjectWrapper);
 
template<typename Retrieve>
int MatchVariant(QMetaType conversionMetaType, Retrieve &&retrieve) {
    if (conversionMetaType == QMetaType::fromType<QVariant>())
        return 0;
 
    const QMetaType type = retrieve();
    if (type == conversionMetaType)
        return 0;
 
    if (const QMetaObject *conversionMetaObject = conversionMetaType.metaObject()) {
        if (const QMetaObject *mo = type.metaObject(); mo && mo->inherits(conversionMetaObject))
            return 1;
    }
 
    if (QMetaType::canConvert(type, conversionMetaType)) {
        if (conversionMetaType == QMetaType::fromType<QJSValue>()
                || conversionMetaType == QMetaType::fromType<double>()
                || conversionMetaType == QMetaType::fromType<QString>()) {
            // Unspecific conversions receive lower score. You can convert anything
            // to QString or double via toString() and valueOf(), respectively.
            // And anything can be wrapped into QJSValue, but that's inefficient.
            return 6;
        }
 
        // We have an explicitly defined conversion method to a non-boring type.
        return 5;
    }
 
    return 10;
};
 
/*
    Returns the match score for converting \a actual to be of type \a conversionType.  A
    zero score means "perfect match" whereas a higher score is worse.
 
    The conversion table is copied out of the \l QScript::callQtMethod() function.
*/
static int MatchScore(const Value &actual, QMetaType conversionMetaType)
{
    const int conversionType = conversionMetaType.id();
    const auto convertibleScore = [&](QMetaType actualType) {
        // There are a number of things we can do in JavaScript to subvert this, but
        // if the conversion is not explicitly defined in C++, we don't want to prioritize it.
        if (!QMetaType::canConvert(actualType, conversionMetaType))
            return 10;
 
        // You can convert anything to QJSValue, but that's inefficient.
        // If we have a better option, we should use it.
        if (conversionMetaType == QMetaType::fromType<QJSValue>())
            return 9;
 
        // You can also convert anything to QVariant, but that's also suboptimal.
        // You can convert anything to string or double via toString() and valueOf().
        // Those are also rather unspecific.
        switch (conversionType) {
        case QMetaType::QVariant:
        case QMetaType::Double:
        case QMetaType::QString:
            return 9;
        default:
            break;
        }
 
        // We have an explicitly defined conversion method to a non-boring type.
        return 8;
    };
 
    if (actual.isNumber()) {
        switch (conversionType) {
        case QMetaType::Double:
            return 0;
        case QMetaType::Float:
            return 1;
        case QMetaType::LongLong:
        case QMetaType::ULongLong:
            return 2;
        case QMetaType::Long:
        case QMetaType::ULong:
            return 3;
        case QMetaType::Int:
        case QMetaType::UInt:
            return 4;
        case QMetaType::Short:
        case QMetaType::UShort:
            return 5;
            break;
        case QMetaType::Char:
        case QMetaType::UChar:
            return 6;
        case QMetaType::QJsonValue:
            return 5;
        default:
            return convertibleScore(actual.isInteger()
                                            ? QMetaType::fromType<int>()
                                            : QMetaType::fromType<double>());
        }
    } else if (actual.isString()) {
        switch (conversionType) {
        case QMetaType::QString:
            return 0;
        case QMetaType::QJsonValue:
            return 5;
        case QMetaType::QUrl:
            return 6; // we like to convert strings to URLs in QML
        case QMetaType::Double:
        case QMetaType::Float:
        case QMetaType::LongLong:
        case QMetaType::ULongLong:
        case QMetaType::Int:
        case QMetaType::UInt:
        case QMetaType::Short:
        case QMetaType::UShort:
        case QMetaType::Char:
        case QMetaType::UChar:
            // QMetaType can natively convert strings to numbers.
            // However, in the general case it's of course extremely lossy.
            return 10;
        default:
            return convertibleScore(QMetaType::fromType<QString>());
        }
    } else if (actual.isBoolean()) {
        switch (conversionType) {
        case QMetaType::Bool:
            return 0;
        case QMetaType::QJsonValue:
            return 5;
        default:
            return convertibleScore(QMetaType::fromType<bool>());
        }
    } else if (actual.as<DateObject>()) {
        switch (conversionType) {
        case QMetaType::QDateTime:
            return 0;
        case QMetaType::QDate:
            return 1;
        case QMetaType::QTime:
            return 2;
        default:
            return convertibleScore(QMetaType::fromType<QDateTime>());
        }
    } else if (actual.as<RegExpObject>()) {
        switch (conversionType) {
#if QT_CONFIG(regularexpression)
        case QMetaType::QRegularExpression:
            return 0;
        default:
            return convertibleScore(QMetaType::fromType<QRegularExpression>());
#else
        default:
            return convertibleScore(QMetaType());
#endif
        }
    } else if (actual.as<ArrayBuffer>()) {
        switch (conversionType) {
        case QMetaType::QByteArray:
            return 0;
        default:
            return convertibleScore(QMetaType::fromType<QByteArray>());
        }
    } else if (actual.as<ArrayObject>()) {
        switch (conversionType) {
        case QMetaType::QJsonArray:
            return 3;
        case QMetaType::QStringList:
        case QMetaType::QVariantList:
            return 5;
        case QMetaType::QVector4D:
        case QMetaType::QMatrix4x4:
            return 6;
        case QMetaType::QVector3D:
            return 7;
        default:
            return convertibleScore(QMetaType());
        }
    } else if (actual.isNull()) {
        switch (conversionType) {
        case QMetaType::Nullptr:
        case QMetaType::VoidStar:
        case QMetaType::QObjectStar:
        case QMetaType::QJsonValue:
            return 0;
        default: {
            if (conversionMetaType.flags().testFlag(QMetaType::IsPointer))
                return 0;
            else
                return convertibleScore(QMetaType());
        }
        }
    } else if (const Object *obj = actual.as<Object>()) {
        if (const VariantObject *variantObject = obj->as<VariantObject>()) {
            return MatchVariant(conversionMetaType, [variantObject]() {
                return variantObject->d()->data().metaType();
            });
        }
 
        if (const QObjectWrapper *wrapper = obj->as<QObjectWrapper>()) {
            switch (conversionType) {
            case QMetaType::QObjectStar:
                return 0;
            default:
                if (conversionMetaType.flags() & QMetaType::PointerToQObject) {
                    QObject *wrapped = wrapper->object();
                    if (!wrapped)
                        return 0;
                    if (qmlobject_can_cpp_cast(wrapped, conversionMetaType.metaObject()))
                        return 0;
                }
            }
 
            return convertibleScore(QMetaType::fromType<QObject *>());
        }
 
        if (const QQmlTypeWrapper *wrapper = obj->as<QQmlTypeWrapper>()) {
            const QQmlType type = wrapper->d()->type();
            if (type.isSingleton()) {
                const QMetaType metaType = type.typeId();
                if (metaType == conversionMetaType)
                    return 0;
 
                if (conversionMetaType.flags() & QMetaType::PointerToQObject
                    && metaType.flags() & QMetaType::PointerToQObject
                    && type.metaObject()->inherits(conversionMetaType.metaObject())) {
                        return 0;
                }
            } else if (QObject *object = wrapper->object()) {
                if (conversionMetaType.flags() & QMetaType::PointerToQObject
                    && qmlobject_can_cpp_cast(object, conversionMetaType.metaObject())) {
                        return 0;
                }
            }
 
            return convertibleScore(QMetaType());
        }
 
        if (const Sequence *sequence = obj->as<Sequence>()) {
            const QMetaType sequenceType = SequencePrototype::metaTypeForSequence(sequence);
            if (sequenceType == conversionMetaType)
                return 1;
 
            return convertibleScore(sequenceType);
        }
 
        if (const QQmlValueTypeWrapper *wrapper = obj->as<QQmlValueTypeWrapper>()) {
            return MatchVariant(conversionMetaType, [wrapper]() {
                return wrapper->d()->isVariant()
                           ? wrapper->toVariant().metaType()
                           : wrapper->type();
            });
        }
 
        if (conversionMetaType == QMetaType::fromType<QJSValue>())
            return 0;
 
        switch (conversionType) {
        case QMetaType::QJsonObject:
        case QMetaType::QVariantMap:
            return 5;
        default:
            break;
        }
 
    }
 
    return convertibleScore(QMetaType());
}
 
static int numDefinedArguments(CallData *callArgs)
{
    int numDefinedArguments = callArgs->argc();
    while (numDefinedArguments > 0
           && callArgs->args[numDefinedArguments - 1].type() == StaticValue::Undefined_Type) {
        --numDefinedArguments;
    }
    return numDefinedArguments;
}
 
static bool requiresStrictArguments(const QQmlObjectOrGadget &object)
{
    const QMetaObject *metaObject = object.metaObject();
    const int indexOfClassInfo = metaObject->indexOfClassInfo("QML.StrictArguments");
    return indexOfClassInfo != -1
            && metaObject->classInfo(indexOfClassInfo).value() == QByteArrayView("true");
}
 
static ReturnedValue doConvertReturnValue(ExecutionEngine *engine, QMetaType type, const void *data)
{
    if (type.flags() & QMetaType::PointerToQObject) {
        // We consider QObjects returned from invokables as owned by the QML engine unless
        // explicitly configured otherwise.
        if (QObject *object = *static_cast<QObject *const *>(data))
            QQmlData::get(object, true)->setImplicitDestructible();
    }
    return engine->fromData(type, data);
}
 
static ReturnedValue doConvertReturnValue(ExecutionEngine *engine, const QVariant &value)
{
    // QVariant is treated as transparent when returned. That means we still adopt
    // QObjects if they're wrapped in QVariant. See above.
    return doConvertReturnValue(engine, value.metaType(), value.constData());
}
 
ReturnedValue QObjectMethod::callPrecise(
        const QQmlObjectOrGadget &object, const QQmlPropertyData &data, ExecutionEngine *engine,
        CallData *callArgs, QMetaObject::Call callType)
{
    const auto constructReturnValue = [&](QMetaType returnType, void *returnValue) {
        // If we construct a value in place, we mustn't initialize the memory before that.
        if (callType != QMetaObject::ConstructInPlace)
            defaultConstructReturnValue(returnType, returnValue);
    };
 
    const auto convertReturnValue
            = [&](ExecutionEngine *engine, QMetaType returnType, void *returnValue) {
 
        // In contrast to other invocations of convertAndCall() we do not want to create
        // a URL object from a QUrl here like metaTypeFromJS does. This is for compatibility.
        // URL objects are proper, specified, objects that behave different from our variant
        // objects when it comes to equality comparisons.
 
        const ReturnedValue result = returnType == QMetaType::fromType<QVariant>()
                ? doConvertReturnValue(engine, *reinterpret_cast<const QVariant *>(returnValue))
                : doConvertReturnValue(engine, returnType, returnValue);
 
        // NB: A type can be both a PointerToQObject and NeedsDestruction if the user registers
        //     such a thing explicitly. We respect that.
        if (returnType.flags() & QMetaType::NeedsDestruction)
            returnType.destruct(returnValue);
        return result;
    };
 
    const auto conversionErrorHandler = [&](QMetaType argumentType, void *argument, int ii) {
        // We've checked the number of arguments before
        Q_ASSERT(ii < callArgs->argc());
 
        if (argumentType == QMetaType::fromType<QJSManagedValue>()) {
            // We have an engine here. So we can conjure up a QJSManagedValue for anything.
            *static_cast<QJSManagedValue *>(argument)
                    = QJSManagedValuePrivate::create(engine, callArgs->args[ii].asValue<Value>());
            return true;
        }
 
        if ((argumentType.flags() & QMetaType::PointerToQObject)
                && callArgs->args[ii].isUndefined()) {
            // TODO: QObjectMethod silently converts undefined to null when you pass undefined
            //       to a method that accepts some QObject-derived. This is wrong because
            //       undefined is certainly not null. We accept it for compatibility.
            *static_cast<QObject **>(argument) = nullptr;
            return true;
        }
 
        // TODO: QObjectMethod is allowed to use QVariant conversion.
        //       This is wrong because we can't see the converters at compile time.
        //       It only exists for compatibility with old versions of Qt.
        const QVariant v = ExecutionEngine::toVariant(
                callArgs->args[ii].asValue<Value>(), argumentType);
        if (QMetaType::convert(v.metaType(), v.constData(), argumentType, argument))
            return true;
 
        qWarning() << QString::fromLatin1("Could not convert argument %1 from %2 to %3")
                              .arg(ii)
                              .arg(callArgs->args[ii].asValue<Value>().toQStringNoThrow())
                              .arg(argumentType.name());
        const StackTrace stack = engine->stackTrace();
        for (const StackFrame &frame : stack) {
            qWarning() << "\t" << frame.function + QLatin1Char('@') + frame.source + (frame.line > 0
                    ? (QLatin1Char(':') + QString::number(frame.line))
                    : QString());
 
        }
 
        if (object.metaObject()->method(data.coreIndex()).methodType() == QMetaMethod::Signal) {
            qWarning() << "Passing incompatible arguments to signals is not supported.";
            return defaultConversionErrorHandler(argumentType, argument, ii);
        }
 
        engine->throwTypeError(QLatin1String(
                "Passing incompatible arguments to C++ functions from JavaScript is not allowed."));
        return false;
    };
 
    QString unknownTypeError;
 
    const auto handleTooManyArguments = [&](int expectedArguments) {
        if (requiresStrictArguments(object)) {
            engine->throwError(QStringLiteral("Too many arguments"));
            return false;
        }
 
        const auto stackTrace = engine->stackTrace();
        if (stackTrace.isEmpty()) {
            qWarning().nospace().noquote()
                    << "When matching arguments for "
                    << object.className() << "::" << data.name(object.metaObject()) << "():";
        } else {
            const StackFrame frame = stackTrace.first();
            qWarning().noquote() << frame.function + QLatin1Char('@') + frame.source
                            + (frame.line > 0 ? (QLatin1Char(':') + QString::number(frame.line))
                                              : QString());
        }
 
        qWarning().noquote() << QStringLiteral("Too many arguments, ignoring %1")
                                        .arg(callArgs->argc() - expectedArguments);
        return true;
    };
 
    const int definedArgumentCount = numDefinedArguments(callArgs);
 
    if (data.hasArguments()) {
        QQmlMetaObject::ArgTypeStorage<10> storage;
 
        const bool ok = data.isConstructor()
                ? object.constructorReturnAndParameterTypes(
                          data, &storage, &unknownTypeError)
                : object.methodReturnAndParameterTypes(
                          data, &storage, &unknownTypeError);
        if (!ok)
            return engine->throwError(unknownTypeError);
 
        const int expectedArgumentCount = storage.size() - 1;
        if (callArgs->argc() < expectedArgumentCount)
            return engine->throwError(QLatin1String("Insufficient arguments"));
 
        if (definedArgumentCount > expectedArgumentCount
                && !handleTooManyArguments(expectedArgumentCount)) {
            return Encode::undefined();
        }
 
        return QV4::convertAndCall(
                engine, storage.constData(), storage.size(),
                std::as_const(callArgs)->argValues<Value>(), expectedArgumentCount,
                [&](void **argData, const QMetaType *types, int argc) {
            Q_UNUSED(types);
            Q_UNUSED(argc);
            object.metacall(callType, data.coreIndex(), argData);
        }, constructReturnValue, convertReturnValue, conversionErrorHandler);
    }
 
    if (definedArgumentCount > 0 && !handleTooManyArguments(0))
        return Encode::undefined();
 
    const QMetaType returnType = object.methodReturnType(data, &unknownTypeError);
    if (!returnType.isValid())
        return engine->throwError(unknownTypeError);
 
    return QV4::convertAndCall(
            engine, &returnType, 1, nullptr, 0,
            [&](void **argData, const QMetaType *types, int argc) {
        Q_UNUSED(types);
        Q_UNUSED(argc);
        object.metacall(callType, data.coreIndex(), argData);
    }, constructReturnValue, convertReturnValue, conversionErrorHandler);
}
 
/*
Resolve the overloaded method to call.  The algorithm works conceptually like this:
    1.  Resolve the set of overloads it is *possible* to call.
        Impossible overloads include those that have too many parameters or have parameters
        of unknown type.
    2.  Filter the set of overloads to only contain those with the closest number of
        parameters.
        For example, if we are called with 3 parameters and there are 2 overloads that
        take 2 parameters and one that takes 3, eliminate the 2 parameter overloads.
    3.  Find the best remaining overload based on its match score.
        If two or more overloads have the same match score, return the last one. The match
        score is constructed by adding the matchScore() result for each of the parameters.
*/
const QQmlPropertyData *QObjectMethod::resolveOverloaded(
            const QQmlObjectOrGadget &object, const QQmlPropertyData *methods, int methodCount,
            ExecutionEngine *engine, CallData *callArgs)
{
    const int argumentCount = callArgs->argc();
    const int definedArgumentCount = numDefinedArguments(callArgs);
 
    const QQmlPropertyData *best = nullptr;
    int bestParameterScore = INT_MAX;
    int bestMaxMatchScore = INT_MAX;
    int bestSumMatchScore = INT_MAX;
 
    Scope scope(engine);
    ScopedValue v(scope);
 
    for (int i = 0; i < methodCount; ++i) {
        const QQmlPropertyData *attempt = methods + i;
 
        if (lcOverloadResolution().isDebugEnabled()) {
            const QQmlPropertyData &candidate = methods[i];
            const QMetaMethod m = candidate.isConstructor()
                                  ? object.metaObject()->constructor(candidate.coreIndex())
                                  : object.metaObject()->method(candidate.coreIndex());
            qCDebug(lcOverloadResolution) << "::: considering signature" << m.methodSignature();
        }
 
        // QQmlV4Function overrides anything that doesn't provide the exact number of arguments
        int methodParameterScore = 1;
        // QQmlV4Function overrides the "no idea" option, which is 10
        int maxMethodMatchScore = 9;
        // QQmlV4Function cannot provide a best sum of match scores as we don't match the arguments
        int sumMethodMatchScore = bestSumMatchScore;
 
        if (!attempt->isV4Function()) {
            QQmlMetaObject::ArgTypeStorage<9> storage;
            int methodArgumentCount = 0;
            if (attempt->hasArguments()) {
                if (attempt->isConstructor()) {
                    if (!object.constructorParameterTypes(*attempt, &storage, nullptr)) {
                        qCDebug(lcOverloadResolution, "rejected, could not get ctor argument types");
                        continue;
                    }
                } else {
                    if (!object.methodParameterTypes(*attempt, &storage, nullptr)) {
                        qCDebug(lcOverloadResolution, "rejected, could not get ctor argument types");
                        continue;
                    }
                }
                methodArgumentCount = storage.size();
            }
 
            if (methodArgumentCount > argumentCount) {
                qCDebug(lcOverloadResolution, "rejected, insufficient arguments");
                continue; // We don't have sufficient arguments to call this method
            }
 
            methodParameterScore = (definedArgumentCount == methodArgumentCount)
                    ? 0
                    : (definedArgumentCount - methodArgumentCount + 1);
            if (methodParameterScore > bestParameterScore) {
                qCDebug(lcOverloadResolution) << "rejected, score too bad. own" << methodParameterScore << "vs best:" << bestParameterScore;
                continue; // We already have a better option
            }
 
            maxMethodMatchScore = 0;
            sumMethodMatchScore = 0;
            for (int ii = 0; ii < methodArgumentCount; ++ii) {
                const int score = MatchScore((v = Value::fromStaticValue(callArgs->args[ii])),
                                             storage[ii]);
                maxMethodMatchScore = qMax(maxMethodMatchScore, score);
                sumMethodMatchScore += score;
            }
        }
 
        if (bestParameterScore > methodParameterScore || bestMaxMatchScore > maxMethodMatchScore
                || (bestParameterScore == methodParameterScore
                    && bestMaxMatchScore == maxMethodMatchScore
                    && bestSumMatchScore > sumMethodMatchScore)) {
            best = attempt;
            bestParameterScore = methodParameterScore;
            bestMaxMatchScore = maxMethodMatchScore;
            bestSumMatchScore = sumMethodMatchScore;
            qCDebug(lcOverloadResolution) << "updated best" << "bestParameterScore" << bestParameterScore  << "\n"
                                          << "bestMaxMatchScore" << bestMaxMatchScore  << "\n"
                                          << "bestSumMatchScore" << bestSumMatchScore  << "\n";
        } else {
            qCDebug(lcOverloadResolution) << "did not update best\n"
                                          << "bestParameterScore" << bestParameterScore << "\t"
                                          << "methodParameterScore" << methodParameterScore << "\n"
                                          << "bestMaxMatchScore" << bestMaxMatchScore << "\t"
                                          << "maxMethodMatchScore" << maxMethodMatchScore << "\n"
                                          << "bestSumMatchScore" << bestSumMatchScore << "\t"
                                          << "sumMethodMatchScore" << sumMethodMatchScore << "\n";
        }
 
        if (bestParameterScore == 0 && bestMaxMatchScore == 0) {
            qCDebug(lcOverloadResolution, "perfect match");
            break; // We can't get better than that
        }
 
    };
 
    if (best && best->isValid()) {
        return best;
    } else {
        QString error = QLatin1String("Unable to determine callable overload.  Candidates are:");
        for (int i = 0; i < methodCount; ++i) {
            const QQmlPropertyData &candidate = methods[i];
            const QMetaMethod m = candidate.isConstructor()
                                  ? object.metaObject()->constructor(candidate.coreIndex())
                                  : object.metaObject()->method(candidate.coreIndex());
            error += u"\n    " + QString::fromUtf8(m.methodSignature());
        }
 
        engine->throwError(error);
        return nullptr;
    }
}
 
static bool ExactMatch(QMetaType passed, QMetaType required, const void *data)
{
    if (required == QMetaType::fromType<QVariant>()
            || required == QMetaType::fromType<QJSValue>()
            || required == QMetaType::fromType<QJSManagedValue>()) {
        return true;
    }
 
    if (data) {
        if (passed == QMetaType::fromType<QVariant>())
            passed = static_cast<const QVariant *>(data)->metaType();
        else if (passed == QMetaType::fromType<QJSPrimitiveValue>())
            passed = static_cast<const QJSPrimitiveValue *>(data)->metaType();
    }
 
    if (passed == required)
        return true;
 
    if (required == QMetaType::fromType<QJSPrimitiveValue>()) {
        switch (passed.id()) {
        case QMetaType::UnknownType:
        case QMetaType::Nullptr:
        case QMetaType::Bool:
        case QMetaType::Int:
        case QMetaType::Double:
        case QMetaType::QString:
            return true;
        default:
            break;
        }
    }
 
    return false;
}
 
bool QObjectMethod::isExactMatch(
        const QMetaMethod &method, void **argv, int argc, const QMetaType *types)
{
    if (types[0].isValid() && !ExactMatch(method.returnMetaType(), types[0], nullptr))
        return false;
 
    if (method.parameterCount() != argc)
        return false;
 
    for (int i = 0; i < argc; ++i) {
        if (!ExactMatch(types[i + 1], method.parameterMetaType(i), argv[i + 1]))
            return false;
    }
 
    return true;
}
 
const QQmlPropertyData *QObjectMethod::resolveOverloaded(
        const QQmlPropertyData *methods, int methodCount,
        void **argv, int argc, const QMetaType *types)
{
    // We only accept exact matches here. Everything else goes through the JavaScript conversion.
    for (int i = 0; i < methodCount; ++i) {
        const QQmlPropertyData *attempt = methods + i;
        if (isExactMatch(attempt->metaMethod(), argv, argc, types))
            return attempt;
    }
 
    return nullptr;
}
 
ReturnedValue QObjectMethod::create(ExecutionEngine *engine, Heap::Object *wrapper, int index)
{
    Scope valueScope(engine);
    Scoped<QObjectMethod> method(
            valueScope,
            engine->memoryManager->allocate<QObjectMethod>(engine, wrapper, index));
    return method.asReturnedValue();
}
 
ReturnedValue QObjectMethod::create(
        ExecutionEngine *engine, Heap::QQmlValueTypeWrapper *valueType, int index)
{
    Scope valueScope(engine);
    Scoped<QObjectMethod> method(
            valueScope,
            engine->memoryManager->allocate<QObjectMethod>(engine, valueType, index));
    return method.asReturnedValue();
}
 
ReturnedValue QObjectMethod::create(
        ExecutionEngine *engine, Heap::QObjectMethod *cloneFrom,
        Heap::Object *wrapper, Heap::Object *object)
{
    Scope valueScope(engine);
 
    Scoped<QQmlValueTypeWrapper> valueTypeWrapper(valueScope);
    if (cloneFrom->wrapper) {
        Scoped<QQmlValueTypeWrapper> ref(valueScope, cloneFrom->wrapper);
        if (ref) {
            valueTypeWrapper = QQmlValueTypeWrapper::create(engine, ref->d(), wrapper);
        } else {
            // We cannot re-attach a plain QQmlValueTypeWrapper because don't we know what
            // value we should operate on. Without knowledge of the property the value
            // was read from, we cannot load the value from the given object.
            return Encode::undefined();
        }
    }
 
    Scoped<QObjectMethod> method(
            valueScope,
            engine->memoryManager->allocate<QV4::QObjectMethod>(
                    engine, valueTypeWrapper ? valueTypeWrapper->d() : object, cloneFrom->index));
 
    method->d()->methodCount = cloneFrom->methodCount;
 
    Q_ASSERT(method->d()->methods == nullptr);
    switch (cloneFrom->methodCount) {
    case 0:
        Q_ASSERT(cloneFrom->methods == nullptr);
        break;
    case 1:
        Q_ASSERT(cloneFrom->methods
                 == reinterpret_cast<QQmlPropertyData *>(&cloneFrom->_singleMethod));
        method->d()->methods = reinterpret_cast<QQmlPropertyData *>(&method->d()->_singleMethod);
        *method->d()->methods = *cloneFrom->methods;
        break;
    default:
        Q_ASSERT(cloneFrom->methods != nullptr);
        method->d()->methods = new QQmlPropertyData[cloneFrom->methodCount];
        memcpy(method->d()->methods, cloneFrom->methods,
               cloneFrom->methodCount * sizeof(QQmlPropertyData));
        break;
    }
 
    return method.asReturnedValue();
}
 
void Heap::QObjectMethod::init(QV4::ExecutionEngine *engine, Object *object, int methodIndex)
{
    Heap::FunctionObject::init(engine);
    wrapper.set(engine, object);
    index = methodIndex;
}
 
const QMetaObject *Heap::QObjectMethod::metaObject() const
{
    Scope scope(internalClass->engine);
 
    if (Scoped<QV4::QQmlValueTypeWrapper> valueWrapper(scope, wrapper); valueWrapper)
        return valueWrapper->metaObject();
    if (QObject *self = object())
        return self->metaObject();
 
    return nullptr;
}
 
QObject *Heap::QObjectMethod::object() const
{
    Scope scope(internalClass->engine);
 
    if (Scoped<QV4::QObjectWrapper> objectWrapper(scope, wrapper); objectWrapper)
        return objectWrapper->object();
    if (Scoped<QV4::QQmlTypeWrapper> typeWrapper(scope, wrapper); typeWrapper)
        return typeWrapper->object();
    return nullptr;
}
 
bool Heap::QObjectMethod::isDetached() const
{
    if (!wrapper)
        return true;
 
    QV4::Scope scope(internalClass->engine);
    if (Scoped<QV4::QQmlValueTypeWrapper> valueWrapper(scope, wrapper); valueWrapper)
        return valueWrapper->d()->object() == nullptr;
 
    return false;
}
 
bool Heap::QObjectMethod::isAttachedTo(QObject *o) const
{
    QV4::Scope scope(internalClass->engine);
    if (Scoped<QV4::QObjectWrapper> objectWrapper(scope, wrapper); objectWrapper)
        return objectWrapper->object() == o;
    if (Scoped<QV4::QQmlTypeWrapper> typeWrapper(scope, wrapper); typeWrapper)
        return typeWrapper->object() == o;
 
    if (Scoped<QV4::QQmlValueTypeWrapper> valueWrapper(scope, wrapper); valueWrapper) {
        QV4::Scope scope(wrapper->internalClass->engine);
        if (QV4::Scoped<QV4::QObjectWrapper> qobject(scope, valueWrapper->d()->object()); qobject)
            return qobject->object() == o;
        if (QV4::Scoped<QV4::QQmlTypeWrapper> type(scope, valueWrapper->d()->object()); type)
            return type->object() == o;
 
        // Attached to some nested value type or sequence object
        return false;
    }
 
    return false;
}
 
Heap::QObjectMethod::ThisObjectMode Heap::QObjectMethod::checkThisObject(
        const QMetaObject *thisMeta) const
{
    // Check that the metaobject matches.
 
    if (!thisMeta) {
        // You can only get a detached method via a lookup, and then you have a thisObject.
        Q_ASSERT(wrapper);
        return Included;
    }
 
    const auto check = [&](const QMetaObject *included) {
        const auto stackFrame = internalClass->engine->currentStackFrame;
        if (stackFrame && !stackFrame->v4Function->executableCompilationUnit()
                ->nativeMethodsAcceptThisObjects()) {
            qCWarning(lcMethodBehavior,
                      "%s:%d: Calling C++ methods with 'this' objects different from the one "
                      "they were retrieved from is broken, due to historical reasons. The "
                      "original object is used as 'this' object. You can allow the given "
                      "'this' object to be used by setting "
                      "'pragma NativeMethodBehavior: AcceptThisObject'",
                      qPrintable(stackFrame->source()), stackFrame->lineNumber());
            return Included;
        }
 
        // destroy() and toString() can be called on all QObjects, but not on gadgets.
        if (index < 0)
            return thisMeta->inherits(&QObject::staticMetaObject) ? Explicit : Invalid;
 
        // Find the base type the method belongs to.
        int methodOffset = included->methodOffset();
        while (true) {
            if (included == thisMeta)
                return Explicit;
 
            if (methodOffset <= index)
                return thisMeta->inherits(included) ? Explicit : Invalid;
 
            included = included->superClass();
            Q_ASSERT(included);
            methodOffset -= QMetaObjectPrivate::get(included)->methodCount;
        };
 
        Q_UNREACHABLE_RETURN(Invalid);
    };
 
    if (const QMetaObject *meta = metaObject())
        return check(meta);
 
    // If the QObjectMethod is detached, we can only have gotten here via a lookup.
    // The lookup checks that the QQmlPropertyCache matches.
    return Explicit;
}
 
QString Heap::QObjectMethod::name() const
{
    if (index == QV4::QObjectMethod::DestroyMethod)
        return QStringLiteral("destroy");
    else if (index == QV4::QObjectMethod::ToStringMethod)
        return QStringLiteral("toString");
 
    const QMetaObject *mo = metaObject();
    if (!mo)
        return QString();
 
    int methodOffset = mo->methodOffset();
    while (methodOffset > index) {
        mo = mo->superClass();
        methodOffset -= QMetaObjectPrivate::get(mo)->methodCount;
    }
 
    return "%1::%2"_L1.arg(QLatin1StringView{mo->className()},
                           QLatin1StringView{mo->method(index).name()});
}
 
void Heap::QObjectMethod::ensureMethodsCache(const QMetaObject *thisMeta)
{
    if (methods) {
        Q_ASSERT(methodCount > 0);
        return;
    }
 
    const QMetaObject *mo = metaObject();
 
    if (!mo)
        mo = thisMeta;
 
    Q_ASSERT(mo);
 
    int methodOffset = mo->methodOffset();
    while (methodOffset > index) {
        mo = mo->superClass();
        methodOffset -= QMetaObjectPrivate::get(mo)->methodCount;
    }
    QVarLengthArray<QQmlPropertyData, 9> resolvedMethods;
    QQmlPropertyData dummy;
    QMetaMethod method = mo->method(index);
    dummy.load(method);
    dummy.setMetaObject(mo);
    resolvedMethods.append(dummy);
    // Look for overloaded methods
    QByteArray methodName = method.name();
    for (int ii = index - 1; ii >= methodOffset; --ii) {
        if (methodName == mo->method(ii).name()) {
            method = mo->method(ii);
            dummy.load(method);
            resolvedMethods.append(dummy);
        }
    }
    if (resolvedMethods.size() > 1) {
        methods = new QQmlPropertyData[resolvedMethods.size()];
        memcpy(methods, resolvedMethods.data(), resolvedMethods.size()*sizeof(QQmlPropertyData));
        methodCount = resolvedMethods.size();
    } else {
        methods = reinterpret_cast<QQmlPropertyData *>(&_singleMethod);
        *methods = resolvedMethods.at(0);
        methodCount = 1;
    }
 
    Q_ASSERT(methodCount > 0);
}
 
ReturnedValue QObjectMethod::method_toString(ExecutionEngine *engine, QObject *o) const
{
    return engine->newString(
                QObjectWrapper::objectToString(
                    engine, o ? o->metaObject() : d()->metaObject(), o))->asReturnedValue();
}
 
ReturnedValue QObjectMethod::method_destroy(
        ExecutionEngine *engine, QObject *o, const Value *args, int argc) const
{
    method_destroy(engine, o, argc > 0 ? args[0].toInt32() : 0);
    return Encode::undefined();
}
 
bool QObjectMethod::method_destroy(ExecutionEngine *engine, QObject *o, int delay) const
{
    if (!o)
        return true;
 
    if (QQmlData::keepAliveDuringGarbageCollection(o)) {
        engine->throwError(QStringLiteral("Invalid attempt to destroy() an indestructible object"));
        return false;
    }
 
    if (delay > 0)
        QTimer::singleShot(delay, o, &QObject::deleteLater);
    else
        o->deleteLater();
 
    return true;
}
 
ReturnedValue QObjectMethod::virtualCall(
        const FunctionObject *m, const Value *thisObject, const Value *argv, int argc)
{
    const QObjectMethod *This = static_cast<const QObjectMethod*>(m);
    return This->callInternal(thisObject, argv, argc);
}
 
void QObjectMethod::virtualCallWithMetaTypes(
        const FunctionObject *m, QObject *thisObject, void **argv, const QMetaType *types, int argc)
{
    const QObjectMethod *This = static_cast<const QObjectMethod*>(m);
    This->callInternalWithMetaTypes(thisObject, argv, types, argc);
}
 
ReturnedValue QObjectMethod::callInternal(const Value *thisObject, const Value *argv, int argc) const
{
    ExecutionEngine *v4 = engine();
 
    const QMetaObject *thisMeta = nullptr;
 
    QObject *o = nullptr;
    Heap::QQmlValueTypeWrapper *valueWrapper = nullptr;
    if (const QObjectWrapper *w = thisObject->as<QObjectWrapper>()) {
        thisMeta = w->metaObject();
        o = w->object();
    } else if (const QQmlTypeWrapper *w = thisObject->as<QQmlTypeWrapper>()) {
        thisMeta = w->metaObject();
        o = w->object();
    } else if (const QQmlValueTypeWrapper *w = thisObject->as<QQmlValueTypeWrapper>()) {
        thisMeta = w->metaObject();
        valueWrapper = w->d();
    }
 
    Heap::QObjectMethod::ThisObjectMode mode = Heap::QObjectMethod::Invalid;
    if (o && o == d()->object()) {
        mode = Heap::QObjectMethod::Explicit;
        // Nothing to do; objects are the same. This should be common
    } else if (valueWrapper && valueWrapper == d()->wrapper) {
        mode = Heap::QObjectMethod::Explicit;
        // Nothing to do; gadgets are the same. This should be somewhat common
    } else {
        mode = d()->checkThisObject(thisMeta);
        if (mode == Heap::QObjectMethod::Invalid) {
            v4->throwError(QLatin1String("Cannot call method %1 on %2").arg(
                           d()->name(), thisObject->toQStringNoThrow()));
            return Encode::undefined();
        }
    }
 
    QQmlObjectOrGadget object = [&](){
        if (mode == Heap::QObjectMethod::Included) {
            QV4::Scope scope(v4);
            if (QV4::Scoped<QV4::QObjectWrapper> qobject(scope, d()->wrapper); qobject)
                return QQmlObjectOrGadget(qobject->object());
            if (QV4::Scoped<QV4::QQmlTypeWrapper> type(scope, d()->wrapper); type)
                return QQmlObjectOrGadget(type->object());
            if (QV4::Scoped<QV4::QQmlValueTypeWrapper> value(scope, d()->wrapper); value) {
                valueWrapper = value->d();
                return QQmlObjectOrGadget(valueWrapper->metaObject(), valueWrapper->gadgetPtr());
            }
            Q_UNREACHABLE();
        } else {
            if (o)
                return QQmlObjectOrGadget(o);
 
            Q_ASSERT(valueWrapper);
            if (!valueWrapper->enforcesLocation())
                QV4::ReferenceObject::readReference(valueWrapper);
            return QQmlObjectOrGadget(thisMeta, valueWrapper->gadgetPtr());
        }
    }();
 
    if (object.isNull())
        return Encode::undefined();
 
    if (d()->index == DestroyMethod)
        return method_destroy(v4, object.qObject(), argv, argc);
    else if (d()->index == ToStringMethod) {
        if (Q_UNLIKELY(qt_v4NativeCallHookEnabled)) {
            const QMetaObject *meta = object.metaObject();
            if (meta && meta->indexOfMethod("toString()") >= 0)
                qt_v4AboutToCallNativeMethodHook(meta);
        }
        return method_toString(v4, object.qObject());
    }
 
    d()->ensureMethodsCache(thisMeta);
 
    Scope scope(v4);
    JSCallData cData(thisObject, argv, argc);
    CallData *callData = cData.callData(scope);
 
    const QQmlPropertyData *method = d()->methods;
 
    // If we call the method, we have to write back any value type references afterwards.
    // The method might change the value.
    const auto doCall = [&](const auto &call) {
        if (!method->isConstant()) {
            if (valueWrapper && valueWrapper->isReference()) {
                ScopedValue rv(scope, call());
                valueWrapper->writeBack();
                return rv->asReturnedValue();
            }
        }
 
        return call();
    };
 
    if (d()->methodCount != 1) {
        Q_ASSERT(d()->methodCount > 0);
        method = resolveOverloaded(object, d()->methods, d()->methodCount, v4, callData);
        if (method == nullptr)
            return Encode::undefined();
    }
 
    if (Q_UNLIKELY(qt_v4NativeCallHookEnabled))
        qt_v4AboutToCallNativeMethodHook(object.metaObject());
 
    if (method->isV4Function()) {
        return doCall([&]() {
            ScopedValue rv(scope, Value::undefinedValue());
            QQmlV4Function func(callData, rv, v4);
            QQmlV4FunctionPtr funcptr = &func;
 
            void *args[] = { nullptr, &funcptr };
            object.metacall(QMetaObject::InvokeMetaMethod, method->coreIndex(), args);
 
            return rv->asReturnedValue();
        });
    }
 
    return doCall([&]() { return callPrecise(object, *method, v4, callData); });
}
 
struct ToStringMetaMethod
{
    constexpr int parameterCount() const { return 0; }
    constexpr QMetaType returnMetaType() const { return QMetaType::fromType<QString>(); }
    constexpr QMetaType parameterMetaType(int) const { return QMetaType(); }
};
 
void QObjectMethod::callInternalWithMetaTypes(
        QObject *thisObject, void **argv, const QMetaType *types, int argc) const
{
    ExecutionEngine *v4 = engine();
 
    const QMetaObject *thisMeta = nullptr;
    Heap::QQmlValueTypeWrapper *valueWrapper = nullptr;
 
    if (thisObject) {
        thisMeta = thisObject->metaObject();
    } else {
        Q_ASSERT(Value::fromHeapObject(d()->wrapper).as<QQmlValueTypeWrapper>());
        valueWrapper = d()->wrapper.cast<Heap::QQmlValueTypeWrapper>();
        thisMeta = valueWrapper->metaObject();
    }
 
    QQmlObjectOrGadget object = [&](){
        if (thisObject)
            return QQmlObjectOrGadget(thisObject);
 
        Scope scope(v4);
        Scoped<QQmlValueTypeWrapper> wrapper(scope, d()->wrapper);
        Q_ASSERT(wrapper);
 
        Heap::QQmlValueTypeWrapper *valueWrapper = wrapper->d();
        if (!valueWrapper->enforcesLocation())
            QV4::ReferenceObject::readReference(valueWrapper);
        return QQmlObjectOrGadget(thisMeta, valueWrapper->gadgetPtr());
    }();
 
    if (object.isNull())
        return;
 
    if (d()->index == DestroyMethod) {
        // method_destroy will use at most one argument
        QV4::convertAndCall(
                v4, thisObject, argv, types, std::min(argc, 1),
                [this, v4, object](const Value *thisObject, const Value *argv, int argc) {
                    Q_UNUSED(thisObject);
                    return method_destroy(v4, object.qObject(), argv, argc);
                });
        return;
    }
 
    if (d()->index == ToStringMethod) {
        const ToStringMetaMethod metaMethod;
        QV4::coerceAndCall(
                v4, &metaMethod, argv, types, argc,
                [v4, thisMeta, object](void **argv, int) {
            if (!argv[0])
                return;
            *static_cast<QString *>(argv[0])
                    = QObjectWrapper::objectToString(v4, thisMeta, object.qObject());
        });
        return;
    }
 
    d()->ensureMethodsCache(thisMeta);
 
    const QQmlPropertyData *method = d()->methods;
    if (d()->methodCount != 1) {
        Q_ASSERT(d()->methodCount > 0);
        method = resolveOverloaded(d()->methods, d()->methodCount, argv, argc, types);
    }
 
    if (!method || method->isV4Function()) {
        QV4::convertAndCall(
                v4, thisObject, argv, types, argc,
                [this](const Value *thisObject, const Value *argv, int argc) {
                    return callInternal(thisObject, argv, argc);
                });
    } else {
        const QMetaMethod metaMethod = method->metaMethod();
        QV4::coerceAndCall(
                v4, &metaMethod, argv, types, argc,
                [v4, object, valueWrapper, method](void **argv, int argc) {
            Q_UNUSED(argc);
 
            // If we call the method, we have to write back any value type references afterwards.
            // The method might change the value.
            object.metacall(QMetaObject::InvokeMetaMethod, method->coreIndex(), argv);
            if (!method->isConstant()) {
                if (valueWrapper && valueWrapper->isReference())
                    valueWrapper->writeBack();
            }
 
            // If the method returns a QObject* we need to track it on the JS heap
            // (if it's destructible).
            QObject *qobjectPtr = nullptr;
            const QMetaType resultType = method->propType();
            if (argv[0]) {
                if (resultType.flags() & QMetaType::PointerToQObject) {
                    qobjectPtr = *static_cast<QObject **>(argv[0]);
                } else if (resultType == QMetaType::fromType<QVariant>()) {
                    const QVariant *result = static_cast<const QVariant *>(argv[0]);
                    const QMetaType variantType = result->metaType();
                    if (variantType.flags() & QMetaType::PointerToQObject)
                        qobjectPtr = *static_cast<QObject *const *>(result->data());
                }
            }
 
            if (qobjectPtr) {
                QQmlData *ddata = QQmlData::get(qobjectPtr, true);
                if (!ddata->explicitIndestructibleSet) {
                    ddata->indestructible = false;
                    QObjectWrapper::ensureWrapper(v4, qobjectPtr);
                }
            }
        });
    }
}
 
DEFINE_OBJECT_VTABLE(QObjectMethod);
 
void Heap::QmlSignalHandler::init(QObject *object, int signalIndex)
{
    Object::init();
    this->signalIndex = signalIndex;
    setObject(object);
}
 
DEFINE_OBJECT_VTABLE(QmlSignalHandler);
 
ReturnedValue QmlSignalHandler::call(const Value *thisObject, const Value *argv, int argc) const
{
    const QString handlerName = QQmlSignalNames::signalNameToHandlerName(
            object()->metaObject()->method(signalIndex()).name());
    qCWarning(lcSignalHandler).noquote()
            << QStringLiteral("Property '%1' of object %2 is a signal handler. You should "
                              "not call it directly. Make it a proper function and call "
                              "that or emit the signal.")
                       .arg(handlerName, thisObject->toQStringNoThrow());
 
    Scope scope(engine());
    Scoped<QObjectMethod> method(
            scope, QObjectMethod::create(
                           scope.engine,
                           static_cast<Heap::QObjectWrapper *>(nullptr),
                           signalIndex()));
 
    return method->call(thisObject, argv, argc);
}
 
void QmlSignalHandler::initProto(ExecutionEngine *engine)
{
    if (engine->signalHandlerPrototype()->d_unchecked())
        return;
 
    Scope scope(engine);
    ScopedObject o(scope, engine->newObject());
    ScopedString connect(scope, engine->newIdentifier(QStringLiteral("connect")));
    ScopedString disconnect(scope, engine->newIdentifier(QStringLiteral("disconnect")));
    o->put(connect, ScopedValue(scope, engine->functionPrototype()->get(connect)));
    o->put(disconnect, ScopedValue(scope, engine->functionPrototype()->get(disconnect)));
 
    engine->jsObjects[ExecutionEngine::SignalHandlerProto] = o->d();
}
 
 
MultiplyWrappedQObjectMap::Iterator MultiplyWrappedQObjectMap::erase(
        MultiplyWrappedQObjectMap::Iterator it)
{
    const QObjectBiPointer key = it.key();
    const QObject *obj = key.isT1() ? key.asT1() : key.asT2();
    disconnect(obj, &QObject::destroyed, this, &MultiplyWrappedQObjectMap::removeDestroyedObject);
    return QHash<QObjectBiPointer, WeakValue>::erase(it);
}
 
void MultiplyWrappedQObjectMap::removeDestroyedObject(QObject *object)
{
    QHash<QObjectBiPointer, WeakValue>::remove(object);
    QHash<QObjectBiPointer, WeakValue>::remove(static_cast<const QObject *>(object));
}
 
} // namespace QV4
 
QT_END_NAMESPACE
 
#include "moc_qv4qobjectwrapper_p.cpp"