qqmldelegatemodel.cpp

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// Copyright (C) 2020 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
 
#include "qqmldelegatemodel_p_p.h"
 
#include <QtQml/qqmlinfo.h>
 
#include <private/qqmlabstractdelegatecomponent_p.h>
#include <private/qquickpackage_p.h>
#include <private/qmetaobjectbuilder_p.h>
#include <private/qqmladaptormodel_p.h>
#include <private/qqmlanybinding_p.h>
#include <private/qqmlchangeset_p.h>
#include <private/qqmlengine_p.h>
#include <private/qqmlcomponent_p.h>
#include <private/qqmlpropertytopropertybinding_p.h>
#include <private/qjsvalue_p.h>
 
#include <private/qv4value_p.h>
#include <private/qv4functionobject_p.h>
#include <private/qv4objectiterator_p.h>
 
QT_BEGIN_NAMESPACE
 
Q_LOGGING_CATEGORY(lcItemViewDelegateRecycling, "qt.qml.delegatemodel.recycling")
 
class QQmlDelegateModelItem;
 
namespace QV4 {
 
namespace Heap {
 
struct DelegateModelGroupFunction : FunctionObject {
    void init(ExecutionEngine *engine, uint flag, QV4::ReturnedValue (*code)(QQmlDelegateModelItem *item, uint flag, const QV4::Value &arg));
 
    QV4::ReturnedValue (*code)(QQmlDelegateModelItem *item, uint flag, const QV4::Value &arg);
    uint flag;
};
 
struct QQmlDelegateModelGroupChange : Object {
    void init() { Object::init(); }
 
    QQmlChangeSet::ChangeData change;
};
 
struct QQmlDelegateModelGroupChangeArray : Object {
    void init(const QVector<QQmlChangeSet::Change> &changes);
    void destroy() {
        delete changes;
        Object::destroy();
    }
 
    QVector<QQmlChangeSet::Change> *changes;
};
 
 
}
 
struct DelegateModelGroupFunction : QV4::FunctionObject
{
    V4_OBJECT2(DelegateModelGroupFunction, FunctionObject)
 
    static Heap::DelegateModelGroupFunction *create(
            QV4::ExecutionEngine *engine, uint flag,
            QV4::ReturnedValue (*code)(QQmlDelegateModelItem *, uint, const QV4::Value &))
    {
        return engine->memoryManager->allocate<DelegateModelGroupFunction>(engine, flag, code);
    }
 
    static ReturnedValue virtualCall(const QV4::FunctionObject *that, const Value *thisObject, const Value *argv, int argc)
    {
        QV4::Scope scope(that->engine());
        QV4::Scoped<DelegateModelGroupFunction> f(scope, static_cast<const DelegateModelGroupFunction *>(that));
        QV4::Scoped<QQmlDelegateModelItemObject> o(scope, thisObject);
        if (!o)
            return scope.engine->throwTypeError(QStringLiteral("Not a valid DelegateModel object"));
 
        QV4::ScopedValue v(scope, argc ? argv[0] : Value::undefinedValue());
        return f->d()->code(o->d()->item, f->d()->flag, v);
    }
};
 
void Heap::DelegateModelGroupFunction::init(
        QV4::ExecutionEngine *engine, uint flag,
        QV4::ReturnedValue (*code)(QQmlDelegateModelItem *item, uint flag, const QV4::Value &arg))
{
    QV4::Heap::FunctionObject::init(engine, QStringLiteral("DelegateModelGroupFunction"));
    this->flag = flag;
    this->code = code;
}
 
}
 
DEFINE_OBJECT_VTABLE(QV4::DelegateModelGroupFunction);
 
 
 
class QQmlDelegateModelEngineData : public QV4::ExecutionEngine::Deletable
{
public:
    QQmlDelegateModelEngineData(QV4::ExecutionEngine *v4);
    ~QQmlDelegateModelEngineData();
 
    QV4::ReturnedValue array(QV4::ExecutionEngine *engine,
                             const QVector<QQmlChangeSet::Change> &changes);
 
    QV4::PersistentValue changeProto;
};
 
V4_DEFINE_EXTENSION(QQmlDelegateModelEngineData, qdmEngineData)
 
 
void QQmlDelegateModelPartsMetaObject::propertyCreated(int, QMetaPropertyBuilder &prop)
{
    prop.setWritable(false);
}
 
QVariant QQmlDelegateModelPartsMetaObject::initialValue(int id)
{
    QQmlDelegateModelParts *parts = static_cast<QQmlDelegateModelParts *>(object());
    QQmlPartsModel *m = new QQmlPartsModel(
            parts->model, QString::fromUtf8(name(id)), parts);
    parts->models.append(m);
    return QVariant::fromValue(static_cast<QObject *>(m));
}
 
QQmlDelegateModelParts::QQmlDelegateModelParts(QQmlDelegateModel *parent)
: QObject(parent), model(parent)
{
    new QQmlDelegateModelPartsMetaObject(this);
}
 
//---------------------------------------------------------------------------
 
 
QQmlDelegateModelPrivate::QQmlDelegateModelPrivate(QQmlContext *ctxt)
    : m_delegateChooser(nullptr)
    , m_cacheMetaType(nullptr)
    , m_context(ctxt)
    , m_parts(nullptr)
    , m_filterGroup(QStringLiteral("items"))
    , m_count(0)
    , m_groupCount(Compositor::MinimumGroupCount)
    , m_compositorGroup(Compositor::Cache)
    , m_complete(false)
    , m_delegateValidated(false)
    , m_reset(false)
    , m_transaction(false)
    , m_incubatorCleanupScheduled(false)
    , m_waitingToFetchMore(false)
    , m_cacheItems(nullptr)
    , m_items(nullptr)
    , m_persistedItems(nullptr)
{
}
 
QQmlDelegateModelPrivate::~QQmlDelegateModelPrivate()
{
    qDeleteAll(m_finishedIncubating);
 
    // Free up all items in the pool
    drainReusableItemsPool(0);
 
    if (m_cacheMetaType)
        m_cacheMetaType->release();
}
 
int QQmlDelegateModelPrivate::adaptorModelCount() const
{
    // QQmlDelegateModel currently only support list models.
    // So even if a model is a table model, only the first
    // column will be used.
    return m_adaptorModel.rowCount();
}
 
void QQmlDelegateModelPrivate::requestMoreIfNecessary()
{
    Q_Q(QQmlDelegateModel);
    if (!m_waitingToFetchMore && m_adaptorModel.canFetchMore()) {
        m_waitingToFetchMore = true;
        QCoreApplication::postEvent(q, new QEvent(QEvent::UpdateRequest));
    }
}
 
void QQmlDelegateModelPrivate::init()
{
    Q_Q(QQmlDelegateModel);
    m_compositor.setRemoveGroups(Compositor::GroupMask & ~Compositor::PersistedFlag);
 
    m_items = new QQmlDelegateModelGroup(QStringLiteral("items"), q, Compositor::Default, q);
    m_items->setDefaultInclude(true);
    m_persistedItems = new QQmlDelegateModelGroup(QStringLiteral("persistedItems"), q, Compositor::Persisted, q);
    QQmlDelegateModelGroupPrivate::get(m_items)->emitters.insert(this);
}
 
QQmlDelegateModel::QQmlDelegateModel()
    : QQmlDelegateModel(nullptr, nullptr)
{
}
 
QQmlDelegateModel::QQmlDelegateModel(QQmlContext *ctxt, QObject *parent)
: QQmlInstanceModel(*(new QQmlDelegateModelPrivate(ctxt)), parent)
{
    Q_D(QQmlDelegateModel);
    d->init();
}
 
QQmlDelegateModel::~QQmlDelegateModel()
{
    Q_D(QQmlDelegateModel);
    d->disconnectFromAbstractItemModel();
    d->m_adaptorModel.setObject(nullptr);
 
    for (QQmlDelegateModelItem *cacheItem : std::as_const(d->m_cache)) {
        if (cacheItem->object) {
            delete cacheItem->object;
 
            cacheItem->object = nullptr;
            cacheItem->contextData.reset();
            cacheItem->scriptRef -= 1;
        } else if (cacheItem->incubationTask) {
            // Both the incubationTask and the object may hold a scriptRef,
            // but if both are present, only one scriptRef is held in total.
            cacheItem->scriptRef -= 1;
        }
 
        cacheItem->groups &= ~Compositor::UnresolvedFlag;
        cacheItem->objectRef = 0;
 
        if (cacheItem->incubationTask) {
            d->releaseIncubator(cacheItem->incubationTask);
            cacheItem->incubationTask->vdm = nullptr;
            cacheItem->incubationTask = nullptr;
        }
 
        if (!cacheItem->isReferenced())
            delete cacheItem;
    }
}
 
 
void QQmlDelegateModel::classBegin()
{
    Q_D(QQmlDelegateModel);
    if (!d->m_context)
        d->m_context = qmlContext(this);
}
 
void QQmlDelegateModel::componentComplete()
{
    Q_D(QQmlDelegateModel);
    d->m_complete = true;
 
    int defaultGroups = 0;
    QStringList groupNames;
    groupNames.append(QStringLiteral("items"));
    groupNames.append(QStringLiteral("persistedItems"));
    if (QQmlDelegateModelGroupPrivate::get(d->m_items)->defaultInclude)
        defaultGroups |= Compositor::DefaultFlag;
    if (QQmlDelegateModelGroupPrivate::get(d->m_persistedItems)->defaultInclude)
        defaultGroups |= Compositor::PersistedFlag;
    for (int i = Compositor::MinimumGroupCount; i < d->m_groupCount; ++i) {
        QString name = d->m_groups[i]->name();
        if (name.isEmpty()) {
            d->m_groups[i] = d->m_groups[d->m_groupCount - 1];
            --d->m_groupCount;
            --i;
        } else if (name.at(0).isUpper()) {
            qmlWarning(d->m_groups[i]) << QQmlDelegateModelGroup::tr("Group names must start with a lower case letter");
            d->m_groups[i] = d->m_groups[d->m_groupCount - 1];
            --d->m_groupCount;
            --i;
        } else {
            groupNames.append(name);
 
            QQmlDelegateModelGroupPrivate *group = QQmlDelegateModelGroupPrivate::get(d->m_groups[i]);
            group->setModel(this, Compositor::Group(i));
            if (group->defaultInclude)
                defaultGroups |= (1 << i);
        }
    }
 
    d->m_cacheMetaType = new QQmlDelegateModelItemMetaType(
                d->m_context->engine()->handle(), this, groupNames);
 
    d->m_compositor.setGroupCount(d->m_groupCount);
    d->m_compositor.setDefaultGroups(defaultGroups);
    d->updateFilterGroup();
 
    while (!d->m_pendingParts.isEmpty())
        static_cast<QQmlPartsModel *>(d->m_pendingParts.first())->updateFilterGroup();
 
    QVector<Compositor::Insert> inserts;
    d->m_count = d->adaptorModelCount();
    d->m_compositor.append(
            &d->m_adaptorModel,
            0,
            d->m_count,
            defaultGroups | Compositor::AppendFlag | Compositor::PrependFlag,
            &inserts);
    d->itemsInserted(inserts);
    d->emitChanges();
    d->requestMoreIfNecessary();
}
 
QVariant QQmlDelegateModel::model() const
{
    Q_D(const QQmlDelegateModel);
    return d->m_adaptorModel.model();
}
 
void QQmlDelegateModelPrivate::connectToAbstractItemModel()
{
    Q_Q(QQmlDelegateModel);
    if (!m_adaptorModel.adaptsAim())
        return;
 
    auto aim = m_adaptorModel.aim();
 
    QObject::connect(aim, &QAbstractItemModel::rowsInserted, q, &QQmlDelegateModel::_q_rowsInserted);
    QObject::connect(aim, &QAbstractItemModel::rowsRemoved, q, &QQmlDelegateModel::_q_rowsRemoved);
    QObject::connect(aim, &QAbstractItemModel::rowsAboutToBeRemoved, q, &QQmlDelegateModel::_q_rowsAboutToBeRemoved);
    QObject::connect(aim, &QAbstractItemModel::columnsInserted, q, &QQmlDelegateModel::_q_columnsInserted);
    QObject::connect(aim, &QAbstractItemModel::columnsRemoved, q, &QQmlDelegateModel::_q_columnsRemoved);
    QObject::connect(aim, &QAbstractItemModel::columnsMoved, q, &QQmlDelegateModel::_q_columnsMoved);
    QObject::connect(aim, &QAbstractItemModel::dataChanged, q, &QQmlDelegateModel::_q_dataChanged);
    QObject::connect(aim, &QAbstractItemModel::rowsMoved, q, &QQmlDelegateModel::_q_rowsMoved);
    QObject::connect(aim, &QAbstractItemModel::modelAboutToBeReset, q, &QQmlDelegateModel::_q_modelAboutToBeReset);
    QObject::connect(aim, &QAbstractItemModel::layoutChanged, q, &QQmlDelegateModel::_q_layoutChanged);
}
 
void QQmlDelegateModelPrivate::disconnectFromAbstractItemModel()
{
    Q_Q(QQmlDelegateModel);
    if (!m_adaptorModel.adaptsAim())
        return;
 
    auto aim = m_adaptorModel.aim();
 
    QObject::disconnect(aim, &QAbstractItemModel::rowsInserted, q, &QQmlDelegateModel::_q_rowsInserted);
    QObject::disconnect(aim, &QAbstractItemModel::rowsAboutToBeRemoved, q, &QQmlDelegateModel::_q_rowsAboutToBeRemoved);
    QObject::disconnect(aim, &QAbstractItemModel::rowsRemoved, q, &QQmlDelegateModel::_q_rowsRemoved);
    QObject::disconnect(aim, &QAbstractItemModel::columnsInserted, q, &QQmlDelegateModel::_q_columnsInserted);
    QObject::disconnect(aim, &QAbstractItemModel::columnsRemoved, q, &QQmlDelegateModel::_q_columnsRemoved);
    QObject::disconnect(aim, &QAbstractItemModel::columnsMoved, q, &QQmlDelegateModel::_q_columnsMoved);
    QObject::disconnect(aim, &QAbstractItemModel::dataChanged, q, &QQmlDelegateModel::_q_dataChanged);
    QObject::disconnect(aim, &QAbstractItemModel::rowsMoved, q, &QQmlDelegateModel::_q_rowsMoved);
    QObject::disconnect(aim, &QAbstractItemModel::modelAboutToBeReset, q, &QQmlDelegateModel::_q_modelAboutToBeReset);
    QObject::disconnect(aim, &QAbstractItemModel::layoutChanged, q, &QQmlDelegateModel::_q_layoutChanged);
}
 
void QQmlDelegateModel::setModel(const QVariant &model)
{
    Q_D(QQmlDelegateModel);
 
    if (d->m_complete)
        _q_itemsRemoved(0, d->m_count);
 
    d->disconnectFromAbstractItemModel();
    d->m_adaptorModel.setModel(model);
    d->connectToAbstractItemModel();
 
    d->m_adaptorModel.replaceWatchedRoles(QList<QByteArray>(), d->m_watchedRoles);
    for (int i = 0; d->m_parts && i < d->m_parts->models.size(); ++i) {
        d->m_adaptorModel.replaceWatchedRoles(
                QList<QByteArray>(), d->m_parts->models.at(i)->watchedRoles());
    }
 
    if (d->m_complete) {
        _q_itemsInserted(0, d->adaptorModelCount());
        d->requestMoreIfNecessary();
    }
}
 
QQmlComponent *QQmlDelegateModel::delegate() const
{
    Q_D(const QQmlDelegateModel);
    return d->m_delegate;
}
 
void QQmlDelegateModel::setDelegate(QQmlComponent *delegate)
{
    Q_D(QQmlDelegateModel);
    if (d->m_transaction) {
        qmlWarning(this) << tr("The delegate of a DelegateModel cannot be changed within onUpdated.");
        return;
    }
    if (d->m_delegate == delegate)
        return;
    if (d->m_complete)
        _q_itemsRemoved(0, d->m_count);
    d->m_delegate.setObject(delegate, this);
    d->m_delegateValidated = false;
    if (d->m_delegateChooser)
        QObject::disconnect(d->m_delegateChooserChanged);
 
    d->m_delegateChooser = nullptr;
    if (delegate) {
        QQmlAbstractDelegateComponent *adc =
                qobject_cast<QQmlAbstractDelegateComponent *>(delegate);
        if (adc) {
            d->m_delegateChooser = adc;
            d->m_delegateChooserChanged = connect(adc, &QQmlAbstractDelegateComponent::delegateChanged, this,
                                               [d](){ d->delegateChanged(); });
        }
    }
    if (d->m_complete) {
        _q_itemsInserted(0, d->adaptorModelCount());
        d->requestMoreIfNecessary();
    }
    emit delegateChanged();
}
 
QVariant QQmlDelegateModel::rootIndex() const
{
    Q_D(const QQmlDelegateModel);
    return QVariant::fromValue(QModelIndex(d->m_adaptorModel.rootIndex));
}
 
void QQmlDelegateModel::setRootIndex(const QVariant &root)
{
    Q_D(QQmlDelegateModel);
 
    QModelIndex modelIndex = qvariant_cast<QModelIndex>(root);
    const bool changed = d->m_adaptorModel.rootIndex != modelIndex;
    if (changed || !d->m_adaptorModel.isValid()) {
        const int oldCount = d->m_count;
        d->m_adaptorModel.rootIndex = modelIndex;
        if (!d->m_adaptorModel.isValid() && d->m_adaptorModel.aim()) {
            // The previous root index was invalidated, so we need to reconnect the model.
            d->disconnectFromAbstractItemModel();
            d->m_adaptorModel.setModel(d->m_adaptorModel.list.list());
            d->connectToAbstractItemModel();
        }
        if (d->m_adaptorModel.canFetchMore())
            d->m_adaptorModel.fetchMore();
        if (d->m_complete) {
            const int newCount = d->adaptorModelCount();
            if (oldCount)
                _q_itemsRemoved(0, oldCount);
            if (newCount)
                _q_itemsInserted(0, newCount);
        }
        if (changed)
            emit rootIndexChanged();
    }
}
 
QVariant QQmlDelegateModel::modelIndex(int idx) const
{
    Q_D(const QQmlDelegateModel);
    return d->m_adaptorModel.modelIndex(idx);
}
 
QVariant QQmlDelegateModel::parentModelIndex() const
{
    Q_D(const QQmlDelegateModel);
    return d->m_adaptorModel.parentModelIndex();
}
 
int QQmlDelegateModel::count() const
{
    Q_D(const QQmlDelegateModel);
    if (!d->m_delegate)
        return 0;
    return d->m_compositor.count(d->m_compositorGroup);
}
 
QQmlDelegateModel::ReleaseFlags QQmlDelegateModelPrivate::release(QObject *object, QQmlInstanceModel::ReusableFlag reusableFlag)
{
    if (!object)
        return QQmlDelegateModel::ReleaseFlags{};
 
    QQmlDelegateModelItem *cacheItem = QQmlDelegateModelItem::dataForObject(object);
    if (!cacheItem)
        return QQmlDelegateModel::ReleaseFlags{};
 
    if (!cacheItem->releaseObject())
        return QQmlDelegateModel::Referenced;
 
    if (reusableFlag == QQmlInstanceModel::Reusable) {
        removeCacheItem(cacheItem);
        m_reusableItemsPool.insertItem(cacheItem);
        emit q_func()->itemPooled(cacheItem->index, cacheItem->object);
        return QQmlInstanceModel::Pooled;
    }
 
    destroyCacheItem(cacheItem);
    return QQmlInstanceModel::Destroyed;
}
 
void QQmlDelegateModelPrivate::destroyCacheItem(QQmlDelegateModelItem *cacheItem)
{
    emitDestroyingItem(cacheItem->object);
    cacheItem->destroyObject();
    if (cacheItem->incubationTask) {
        releaseIncubator(cacheItem->incubationTask);
        cacheItem->incubationTask = nullptr;
    }
    cacheItem->Dispose();
}
 
/*
  Returns ReleaseStatus flags.
*/
QQmlDelegateModel::ReleaseFlags QQmlDelegateModel::release(QObject *item, QQmlInstanceModel::ReusableFlag reusableFlag)
{
    Q_D(QQmlDelegateModel);
    QQmlInstanceModel::ReleaseFlags stat = d->release(item, reusableFlag);
    return stat;
}
 
// Cancel a requested async item
void QQmlDelegateModel::cancel(int index)
{
    Q_D(QQmlDelegateModel);
    if (index < 0 || index >= d->m_compositor.count(d->m_compositorGroup)) {
        qWarning() << "DelegateModel::cancel: index out range" << index << d->m_compositor.count(d->m_compositorGroup);
        return;
    }
 
    Compositor::iterator it = d->m_compositor.find(d->m_compositorGroup, index);
    QQmlDelegateModelItem *cacheItem = it->inCache() ? d->m_cache.at(it.cacheIndex()) : 0;
    if (cacheItem) {
        if (cacheItem->incubationTask && !cacheItem->isObjectReferenced()) {
            d->releaseIncubator(cacheItem->incubationTask);
            cacheItem->incubationTask = nullptr;
 
            if (cacheItem->object) {
                QObject *object = cacheItem->object;
                cacheItem->destroyObject();
                if (QQuickPackage *package = qmlobject_cast<QQuickPackage *>(object))
                    d->emitDestroyingPackage(package);
                else
                    d->emitDestroyingItem(object);
            }
 
            cacheItem->scriptRef -= 1;
        }
        if (!cacheItem->isReferenced()) {
            d->m_compositor.clearFlags(
                        Compositor::Cache, it.cacheIndex(), 1, Compositor::CacheFlag);
            d->m_cache.removeAt(it.cacheIndex());
            delete cacheItem;
            Q_ASSERT(d->m_cache.size() == d->m_compositor.count(Compositor::Cache));
        }
    }
}
 
void QQmlDelegateModelPrivate::group_append(
        QQmlListProperty<QQmlDelegateModelGroup> *property, QQmlDelegateModelGroup *group)
{
    QQmlDelegateModelPrivate *d = static_cast<QQmlDelegateModelPrivate *>(property->data);
    if (d->m_complete)
        return;
    if (d->m_groupCount == Compositor::MaximumGroupCount) {
        qmlWarning(d->q_func()) << QQmlDelegateModel::tr("The maximum number of supported DelegateModelGroups is 8");
        return;
    }
    d->m_groups[d->m_groupCount] = group;
    d->m_groupCount += 1;
}
 
qsizetype QQmlDelegateModelPrivate::group_count(
        QQmlListProperty<QQmlDelegateModelGroup> *property)
{
    QQmlDelegateModelPrivate *d = static_cast<QQmlDelegateModelPrivate *>(property->data);
    return d->m_groupCount - 1;
}
 
QQmlDelegateModelGroup *QQmlDelegateModelPrivate::group_at(
        QQmlListProperty<QQmlDelegateModelGroup> *property, qsizetype index)
{
    QQmlDelegateModelPrivate *d = static_cast<QQmlDelegateModelPrivate *>(property->data);
    return index >= 0 && index < d->m_groupCount - 1
            ? d->m_groups[index + 1]
            : nullptr;
}
 
QQmlListProperty<QQmlDelegateModelGroup> QQmlDelegateModel::groups()
{
    Q_D(QQmlDelegateModel);
    return QQmlListProperty<QQmlDelegateModelGroup>(
            this,
            d,
            QQmlDelegateModelPrivate::group_append,
            QQmlDelegateModelPrivate::group_count,
            QQmlDelegateModelPrivate::group_at,
            nullptr, nullptr, nullptr);
}
 
QQmlDelegateModelGroup *QQmlDelegateModel::items()
{
    Q_D(QQmlDelegateModel);
    return d->m_items;
}
 
QQmlDelegateModelGroup *QQmlDelegateModel::persistedItems()
{
    Q_D(QQmlDelegateModel);
    return d->m_persistedItems;
}
 
QString QQmlDelegateModel::filterGroup() const
{
    Q_D(const QQmlDelegateModel);
    return d->m_filterGroup;
}
 
void QQmlDelegateModel::setFilterGroup(const QString &group)
{
    Q_D(QQmlDelegateModel);
 
    if (d->m_transaction) {
        qmlWarning(this) << tr("The group of a DelegateModel cannot be changed within onChanged");
        return;
    }
 
    if (d->m_filterGroup != group) {
        d->m_filterGroup = group;
        d->updateFilterGroup();
        emit filterGroupChanged();
    }
}
 
void QQmlDelegateModel::resetFilterGroup()
{
    setFilterGroup(QStringLiteral("items"));
}
 
void QQmlDelegateModelPrivate::updateFilterGroup()
{
    Q_Q(QQmlDelegateModel);
    if (!m_cacheMetaType)
        return;
 
    QQmlListCompositor::Group previousGroup = m_compositorGroup;
    m_compositorGroup = Compositor::Default;
    for (int i = 1; i < m_groupCount; ++i) {
        if (m_filterGroup == m_cacheMetaType->groupNames.at(i - 1)) {
            m_compositorGroup = Compositor::Group(i);
            break;
        }
    }
 
    QQmlDelegateModelGroupPrivate::get(m_groups[m_compositorGroup])->emitters.insert(this);
    if (m_compositorGroup != previousGroup) {
        QVector<QQmlChangeSet::Change> removes;
        QVector<QQmlChangeSet::Change> inserts;
        m_compositor.transition(previousGroup, m_compositorGroup, &removes, &inserts);
 
        QQmlChangeSet changeSet;
        changeSet.move(removes, inserts);
        emit q->modelUpdated(changeSet, false);
 
        if (changeSet.difference() != 0)
            emit q->countChanged();
 
        if (m_parts) {
            auto partsCopy = m_parts->models; // deliberate; this may alter m_parts
            for (QQmlPartsModel *model : std::as_const(partsCopy))
                model->updateFilterGroup(m_compositorGroup, changeSet);
        }
    }
}
 
QObject *QQmlDelegateModel::parts()
{
    Q_D(QQmlDelegateModel);
    if (!d->m_parts)
        d->m_parts = new QQmlDelegateModelParts(this);
    return d->m_parts;
}
 
const QAbstractItemModel *QQmlDelegateModel::abstractItemModel() const
{
    Q_D(const QQmlDelegateModel);
    return d->m_adaptorModel.adaptsAim() ? d->m_adaptorModel.aim() : nullptr;
}
 
void QQmlDelegateModelPrivate::emitCreatedPackage(QQDMIncubationTask *incubationTask, QQuickPackage *package)
{
    for (int i = 1; i < m_groupCount; ++i)
        QQmlDelegateModelGroupPrivate::get(m_groups[i])->createdPackage(incubationTask->index[i], package);
}
 
void QQmlDelegateModelPrivate::emitInitPackage(QQDMIncubationTask *incubationTask, QQuickPackage *package)
{
    for (int i = 1; i < m_groupCount; ++i)
        QQmlDelegateModelGroupPrivate::get(m_groups[i])->initPackage(incubationTask->index[i], package);
}
 
void QQmlDelegateModelPrivate::emitDestroyingPackage(QQuickPackage *package)
{
    for (int i = 1; i < m_groupCount; ++i)
        QQmlDelegateModelGroupPrivate::get(m_groups[i])->destroyingPackage(package);
}
 
static bool isDoneIncubating(QQmlIncubator::Status status)
{
     return status == QQmlIncubator::Ready || status == QQmlIncubator::Error;
}
 
void QQDMIncubationTask::initializeRequiredProperties(QQmlDelegateModelItem *modelItemToIncubate, QObject *object)
{
    // QQmlObjectCreator produces a private internal context.
    // We can always attach the extra object there.
    QQmlData *d = QQmlData::get(object);
    if (auto contextData = d ? d->context : nullptr)
        contextData->setExtraObject(modelItemToIncubate);
 
    Q_ASSERT(modelItemToIncubate->delegate);
    const bool isBound = QQmlComponentPrivate::get(modelItemToIncubate->delegate)->isBound();
 
    auto incubatorPriv = QQmlIncubatorPrivate::get(this);
    if (incubatorPriv->hadTopLevelRequiredProperties()) {
        // If we have required properties, we clear the context object
        // so that the model role names are not polluting the context.
        // Unless the context is bound, in which case we have never set the context object.
        if (incubating && !isBound) {
            Q_ASSERT(incubating->contextData);
            incubating->contextData->setContextObject(nullptr);
        }
        if (proxyContext) {
            proxyContext->setContextObject(nullptr);
        }
 
        // Retrieve the metaObject before the potential return so that the accessors have a chance
        // to perform some finalization in case they produce a dynamic metaobject. Here we know for
        // sure that we are using required properties.
        const QMetaObject *qmlMetaObject = modelItemToIncubate->metaObject();
 
        if (incubatorPriv->requiredProperties()->empty())
            return;
        RequiredProperties *requiredProperties = incubatorPriv->requiredProperties();
 
        // if a required property was not in the model, it might still be a static property of the
        // QQmlDelegateModelItem or one of its derived classes this is the case for index, row,
        // column, model and more
        // the most derived subclasses of QQmlDelegateModelItem are QQmlDMAbstractItemModelData and
        // QQmlDMObjectData at depth 2, so 4 should be plenty
        QVarLengthArray<QPair<const QMetaObject *, QObject *>, 4> mos;
        // we first check the dynamic meta object for properties originating from the model
        // contains abstractitemmodelproperties
        mos.push_back(qMakePair(qmlMetaObject, modelItemToIncubate));
        auto delegateModelItemSubclassMO = qmlMetaObject->superClass();
        mos.push_back(qMakePair(delegateModelItemSubclassMO, modelItemToIncubate));
 
        while (strcmp(delegateModelItemSubclassMO->className(),
                      modelItemToIncubate->staticMetaObject.className())) {
            delegateModelItemSubclassMO = delegateModelItemSubclassMO->superClass();
            mos.push_back(qMakePair(delegateModelItemSubclassMO, modelItemToIncubate));
        }
        if (proxiedObject)
            mos.push_back(qMakePair(proxiedObject->metaObject(), proxiedObject));
 
        QQmlEngine *engine = QQmlEnginePrivate::get(incubatorPriv->enginePriv);
        QV4::ExecutionEngine *v4 = engine->handle();
        QV4::Scope scope(v4);
 
        for (const auto &metaObjectAndObject : mos) {
            const QMetaObject *mo = metaObjectAndObject.first;
            QObject *itemOrProxy = metaObjectAndObject.second;
            QV4::Scoped<QV4::QmlContext> qmlContext(scope);
 
            for (int i = mo->propertyOffset(); i < mo->propertyCount() + mo->propertyOffset(); ++i) {
                auto prop = mo->property(i);
                if (!prop.name())
                    continue;
                const QString propName = QString::fromUtf8(prop.name());
                bool wasInRequired = false;
                QQmlProperty targetProp = QQmlComponentPrivate::removePropertyFromRequired(
                            object, propName, requiredProperties,
                            engine, &wasInRequired);
                if (wasInRequired) {
                    QQmlAnyBinding binding;
                    binding = new QQmlPropertyToPropertyBinding(
                            engine, itemOrProxy, i, targetProp.object(), targetProp.index());
                    binding.installOn(targetProp);
                }
            }
        }
    } else {
        if (!isBound)
            modelItemToIncubate->contextData->setContextObject(modelItemToIncubate);
        if (proxiedObject)
            proxyContext->setContextObject(proxiedObject);
 
        // Retrieve the metaObject() once so that the accessors have a chance to perform some
        // finalization in case they produce a dynamic metaobject. For example, they might be
        // inclined to create a propertyCache now because there are no required properties and any
        // revisioned properties should be hidden after all. Here is the first time we know for
        // sure whether we are using context properties.
        modelItemToIncubate->metaObject();
    }
}
 
void QQDMIncubationTask::statusChanged(Status status)
{
    if (vdm) {
        vdm->incubatorStatusChanged(this, status);
    } else if (isDoneIncubating(status)) {
        Q_ASSERT(incubating);
        // The model was deleted from under our feet, cleanup ourselves
        delete incubating->object;
        incubating->object = nullptr;
        incubating->contextData.reset();
        incubating->scriptRef = 0;
        incubating->deleteLater();
    }
}
 
void QQmlDelegateModelPrivate::releaseIncubator(QQDMIncubationTask *incubationTask)
{
    Q_Q(QQmlDelegateModel);
    if (!incubationTask->isError())
        incubationTask->clear();
    m_finishedIncubating.append(incubationTask);
    if (!m_incubatorCleanupScheduled) {
        m_incubatorCleanupScheduled = true;
        QCoreApplication::postEvent(q, new QEvent(QEvent::User));
    }
}
 
void QQmlDelegateModelPrivate::reuseItem(QQmlDelegateModelItem *item, int newModelIndex, int newGroups)
{
    Q_ASSERT(item->object);
 
    // Update/reset which groups the item belongs to
    item->groups = newGroups;
 
    // Update context property index (including row and column) on the delegate
    // item, and inform the application about it. For a list, the row is the same
    // as the index, and the column is always 0. We set alwaysEmit to true, to
    // force all bindings to be reevaluated, even if the index didn't change.
    const bool alwaysEmit = true;
    item->setModelIndex(newModelIndex, newModelIndex, 0, alwaysEmit);
 
    // Notify the application that all 'dynamic'/role-based context data has
    // changed as well (their getter function will use the updated index).
    auto const itemAsList = QList<QQmlDelegateModelItem *>() << item;
    auto const updateAllRoles = QVector<int>();
    m_adaptorModel.notify(itemAsList, newModelIndex, 1, updateAllRoles);
 
    if (QQmlDelegateModelAttached *att = static_cast<QQmlDelegateModelAttached *>(
                qmlAttachedPropertiesObject<QQmlDelegateModel>(item->object, false))) {
        // Update currentIndex of the attached DelegateModel object
        // to the index the item has in the cache.
        att->resetCurrentIndex();
        // emitChanges will emit both group-, and index changes to the application
        att->emitChanges();
    }
 
    // Inform the view that the item is recycled. This will typically result
    // in the view updating its own attached delegate item properties.
    emit q_func()->itemReused(newModelIndex, item->object);
}
 
void QQmlDelegateModelPrivate::drainReusableItemsPool(int maxPoolTime)
{
    m_reusableItemsPool.drain(maxPoolTime, [this](QQmlDelegateModelItem *cacheItem){ destroyCacheItem(cacheItem); });
}
 
void QQmlDelegateModel::drainReusableItemsPool(int maxPoolTime)
{
    d_func()->drainReusableItemsPool(maxPoolTime);
}
 
int QQmlDelegateModel::poolSize()
{
    return d_func()->m_reusableItemsPool.size();
}
 
QQmlComponent *QQmlDelegateModelPrivate::resolveDelegate(int index)
{
    if (!m_delegateChooser)
        return m_delegate;
 
    QQmlComponent *delegate = nullptr;
    QQmlAbstractDelegateComponent *chooser = m_delegateChooser;
 
    do {
        delegate = chooser->delegate(&m_adaptorModel, index);
        chooser = qobject_cast<QQmlAbstractDelegateComponent *>(delegate);
    } while (chooser);
 
    return delegate;
}
 
void QQmlDelegateModelPrivate::addCacheItem(QQmlDelegateModelItem *item, Compositor::iterator it)
{
    m_cache.insert(it.cacheIndex(), item);
    m_compositor.setFlags(it, 1, Compositor::CacheFlag);
    Q_ASSERT(m_cache.size() == m_compositor.count(Compositor::Cache));
}
 
void QQmlDelegateModelPrivate::removeCacheItem(QQmlDelegateModelItem *cacheItem)
{
    int cidx = m_cache.lastIndexOf(cacheItem);
    if (cidx >= 0) {
        m_compositor.clearFlags(Compositor::Cache, cidx, 1, Compositor::CacheFlag);
        m_cache.removeAt(cidx);
    }
    Q_ASSERT(m_cache.size() == m_compositor.count(Compositor::Cache));
}
 
void QQmlDelegateModelPrivate::incubatorStatusChanged(QQDMIncubationTask *incubationTask, QQmlIncubator::Status status)
{
    if (!isDoneIncubating(status))
        return;
 
    const QList<QQmlError> incubationTaskErrors = incubationTask->errors();
 
    QQmlDelegateModelItem *cacheItem = incubationTask->incubating;
    cacheItem->incubationTask = nullptr;
    incubationTask->incubating = nullptr;
    releaseIncubator(incubationTask);
 
    if (status == QQmlIncubator::Ready) {
        cacheItem->referenceObject();
        if (QQuickPackage *package = qmlobject_cast<QQuickPackage *>(cacheItem->object))
            emitCreatedPackage(incubationTask, package);
        else
            emitCreatedItem(incubationTask, cacheItem->object);
        cacheItem->releaseObject();
    } else if (status == QQmlIncubator::Error) {
        qmlInfo(m_delegate, incubationTaskErrors + m_delegate->errors()) << "Cannot create delegate";
    }
 
    if (!cacheItem->isObjectReferenced()) {
        if (QQuickPackage *package = qmlobject_cast<QQuickPackage *>(cacheItem->object))
            emitDestroyingPackage(package);
        else
            emitDestroyingItem(cacheItem->object);
        delete cacheItem->object;
        cacheItem->object = nullptr;
        cacheItem->scriptRef -= 1;
        cacheItem->contextData.reset();
 
        if (!cacheItem->isReferenced()) {
            removeCacheItem(cacheItem);
            delete cacheItem;
        }
    }
}
 
void QQDMIncubationTask::setInitialState(QObject *o)
{
    vdm->setInitialState(this, o);
}
 
void QQmlDelegateModelPrivate::setInitialState(QQDMIncubationTask *incubationTask, QObject *o)
{
    QQmlDelegateModelItem *cacheItem = incubationTask->incubating;
    incubationTask->initializeRequiredProperties(incubationTask->incubating, o);
    cacheItem->object = o;
 
    if (QQuickPackage *package = qmlobject_cast<QQuickPackage *>(cacheItem->object))
        emitInitPackage(incubationTask, package);
    else
        emitInitItem(incubationTask, cacheItem->object);
}
 
static QQmlRefPointer<QQmlContextData> initProxy(QQmlDelegateModelItem *cacheItem)
{
    QQmlAdaptorModelProxyInterface *proxy
            = qobject_cast<QQmlAdaptorModelProxyInterface *>(cacheItem);
    if (!proxy)
        return cacheItem->contextData;
 
    QQmlRefPointer<QQmlContextData> ctxt = QQmlContextData::createChild(cacheItem->contextData);
    QObject *proxied = proxy->proxiedObject();
    cacheItem->incubationTask->proxiedObject = proxied;
    cacheItem->incubationTask->proxyContext = ctxt;
    ctxt->setContextObject(cacheItem);
    // We don't own the proxied object. We need to clear it if it goes away.
    QObject::connect(proxied, &QObject::destroyed,
                     cacheItem, &QQmlDelegateModelItem::childContextObjectDestroyed);
    return ctxt;
}
 
QObject *QQmlDelegateModelPrivate::object(Compositor::Group group, int index, QQmlIncubator::IncubationMode incubationMode)
{
    if (!m_delegate || index < 0 || index >= m_compositor.count(group)) {
        qWarning() << "DelegateModel::item: index out range" << index << m_compositor.count(group);
        return nullptr;
    } else if (!m_context || !m_context->isValid()) {
        return nullptr;
    }
 
    Compositor::iterator it = m_compositor.find(group, index);
    const auto flags = it->flags;
    const auto modelIndex = it.modelIndex();
 
    QQmlDelegateModelItem *cacheItem = it->inCache() ? m_cache.at(it.cacheIndex()) : 0;
 
    if (!cacheItem || !cacheItem->delegate) {
        QQmlComponent *delegate = resolveDelegate(modelIndex);
        if (!delegate)
            return nullptr;
 
        if (!cacheItem) {
            cacheItem = m_reusableItemsPool.takeItem(delegate, index);
            if (cacheItem) {
                // Move the pooled item back into the cache, update
                // all related properties, and return the object (which
                // has already been incubated, otherwise it wouldn't be in the pool).
                addCacheItem(cacheItem, it);
                reuseItem(cacheItem, index, flags);
                cacheItem->referenceObject();
 
                if (index == m_compositor.count(group) - 1)
                    requestMoreIfNecessary();
                return cacheItem->object;
            }
 
            // Since we could't find an available item in the pool, we create a new one
            cacheItem = m_adaptorModel.createItem(m_cacheMetaType, modelIndex);
            if (!cacheItem)
                return nullptr;
 
            cacheItem->groups = flags;
            addCacheItem(cacheItem, it);
        }
 
        cacheItem->delegate = delegate;
    }
 
    // Bump the reference counts temporarily so neither the content data or the delegate object
    // are deleted if incubatorStatusChanged() is called synchronously.
    cacheItem->scriptRef += 1;
    cacheItem->referenceObject();
 
    if (cacheItem->incubationTask) {
        bool sync = (incubationMode == QQmlIncubator::Synchronous || incubationMode == QQmlIncubator::AsynchronousIfNested);
        if (sync && cacheItem->incubationTask->incubationMode() == QQmlIncubator::Asynchronous) {
            // previously requested async - now needed immediately
            cacheItem->incubationTask->forceCompletion();
        }
    } else if (!cacheItem->object) {
        QQmlContext *creationContext = cacheItem->delegate->creationContext();
 
        cacheItem->scriptRef += 1;
 
        cacheItem->incubationTask = new QQDMIncubationTask(this, incubationMode);
        cacheItem->incubationTask->incubating = cacheItem;
        cacheItem->incubationTask->clear();
 
        for (int i = 1; i < m_groupCount; ++i)
            cacheItem->incubationTask->index[i] = it.index[i];
 
        const QQmlRefPointer<QQmlContextData> componentContext
                = QQmlContextData::get(creationContext  ? creationContext : m_context.data());
        QQmlComponentPrivate *cp = QQmlComponentPrivate::get(cacheItem->delegate);
 
        if (cp->isBound()) {
            cacheItem->contextData = componentContext;
 
            // Ignore return value of initProxy. We want to know the proxy when assigning required
            // properties, but we don't want it to pollute our context. The context is bound.
            if (m_adaptorModel.hasProxyObject())
                initProxy(cacheItem);
 
            cp->incubateObject(
                        cacheItem->incubationTask,
                        cacheItem->delegate,
                        m_context->engine(),
                        componentContext,
                        QQmlContextData::get(m_context));
        } else {
            QQmlRefPointer<QQmlContextData> ctxt
                    = QQmlContextData::createRefCounted(componentContext);
            ctxt->setContextObject(cacheItem);
            cacheItem->contextData = ctxt;
 
            if (m_adaptorModel.hasProxyObject())
                ctxt = initProxy(cacheItem);
 
            cp->incubateObject(
                        cacheItem->incubationTask,
                        cacheItem->delegate,
                        m_context->engine(),
                        ctxt,
                        QQmlContextData::get(m_context));
        }
    }
 
    if (index == m_compositor.count(group) - 1)
        requestMoreIfNecessary();
 
    // Remove the temporary reference count.
    cacheItem->scriptRef -= 1;
    if (cacheItem->object && (!cacheItem->incubationTask || isDoneIncubating(cacheItem->incubationTask->status())))
        return cacheItem->object;
 
    if (cacheItem->objectRef > 0)
        cacheItem->releaseObject();
 
    if (!cacheItem->isReferenced()) {
        removeCacheItem(cacheItem);
        delete cacheItem;
    }
 
    return nullptr;
}
 
/*
  If asynchronous is true or the component is being loaded asynchronously due
  to an ancestor being loaded asynchronously, object() may return 0.  In this
  case createdItem() will be emitted when the object is available.  The object
  at this stage does not have any references, so object() must be called again
  to ensure a reference is held.  Any call to object() which returns a valid object
  must be matched by a call to release() in order to destroy the object.
*/
QObject *QQmlDelegateModel::object(int index, QQmlIncubator::IncubationMode incubationMode)
{
    Q_D(QQmlDelegateModel);
    if (!d->m_delegate || index < 0 || index >= d->m_compositor.count(d->m_compositorGroup)) {
        qWarning() << "DelegateModel::item: index out range" << index << d->m_compositor.count(d->m_compositorGroup);
        return nullptr;
    }
 
    return d->object(d->m_compositorGroup, index, incubationMode);
}
 
QQmlIncubator::Status QQmlDelegateModel::incubationStatus(int index)
{
    Q_D(QQmlDelegateModel);
    if (d->m_compositor.count(d->m_compositorGroup) <= index)
        return QQmlIncubator::Null;
    Compositor::iterator it = d->m_compositor.find(d->m_compositorGroup, index);
    if (!it->inCache())
        return QQmlIncubator::Null;
 
    if (auto incubationTask = d->m_cache.at(it.cacheIndex())->incubationTask)
        return incubationTask->status();
 
    return QQmlIncubator::Ready;
}
 
QVariant QQmlDelegateModelPrivate::variantValue(QQmlListCompositor::Group group, int index, const QString &name)
{
    Compositor::iterator it = m_compositor.find(group, index);
    if (QQmlAdaptorModel *model = it.list<QQmlAdaptorModel>()) {
        QString role = name;
        int dot = name.indexOf(QLatin1Char('.'));
        if (dot > 0)
            role = name.left(dot);
        QVariant value = model->value(it.modelIndex(), role);
        while (dot > 0) {
            QObject *obj = qvariant_cast<QObject*>(value);
            if (!obj)
                return QVariant();
            const int from = dot + 1;
            dot = name.indexOf(QLatin1Char('.'), from);
            value = obj->property(QStringView{name}.mid(from, dot - from).toUtf8());
        }
        return value;
    }
    return QVariant();
}
 
QVariant QQmlDelegateModel::variantValue(int index, const QString &role)
{
    Q_D(QQmlDelegateModel);
    return d->variantValue(d->m_compositorGroup, index, role);
}
 
int QQmlDelegateModel::indexOf(QObject *item, QObject *) const
{
    Q_D(const QQmlDelegateModel);
    if (QQmlDelegateModelItem *cacheItem = QQmlDelegateModelItem::dataForObject(item))
        return cacheItem->groupIndex(d->m_compositorGroup);
    return -1;
}
 
void QQmlDelegateModel::setWatchedRoles(const QList<QByteArray> &roles)
{
    Q_D(QQmlDelegateModel);
    d->m_adaptorModel.replaceWatchedRoles(d->m_watchedRoles, roles);
    d->m_watchedRoles = roles;
}
 
void QQmlDelegateModelPrivate::addGroups(
        Compositor::iterator from, int count, Compositor::Group group, int groupFlags)
{
    QVector<Compositor::Insert> inserts;
    m_compositor.setFlags(from, count, group, groupFlags, &inserts);
    itemsInserted(inserts);
    emitChanges();
}
 
void QQmlDelegateModelPrivate::removeGroups(
        Compositor::iterator from, int count, Compositor::Group group, int groupFlags)
{
    QVector<Compositor::Remove> removes;
    m_compositor.clearFlags(from, count, group, groupFlags, &removes);
    itemsRemoved(removes);
    emitChanges();
}
 
void QQmlDelegateModelPrivate::setGroups(
        Compositor::iterator from, int count, Compositor::Group group, int groupFlags)
{
    QVector<Compositor::Remove> removes;
    QVector<Compositor::Insert> inserts;
 
    m_compositor.setFlags(from, count, group, groupFlags, &inserts);
    itemsInserted(inserts);
    const int removeFlags = ~groupFlags & Compositor::GroupMask;
 
    from = m_compositor.find(from.group, from.index[from.group]);
    m_compositor.clearFlags(from, count, group, removeFlags, &removes);
    itemsRemoved(removes);
    emitChanges();
}
 
bool QQmlDelegateModel::event(QEvent *e)
{
    Q_D(QQmlDelegateModel);
    if (e->type() == QEvent::UpdateRequest) {
        d->m_waitingToFetchMore = false;
        d->m_adaptorModel.fetchMore();
    } else if (e->type() == QEvent::User) {
        d->m_incubatorCleanupScheduled = false;
        qDeleteAll(d->m_finishedIncubating);
        d->m_finishedIncubating.clear();
    }
    return QQmlInstanceModel::event(e);
}
 
void QQmlDelegateModelPrivate::itemsChanged(const QVector<Compositor::Change> &changes)
{
    if (!m_delegate)
        return;
 
    QVarLengthArray<QVector<QQmlChangeSet::Change>, Compositor::MaximumGroupCount> translatedChanges(m_groupCount);
 
    for (const Compositor::Change &change : changes) {
        for (int i = 1; i < m_groupCount; ++i) {
            if (change.inGroup(i)) {
                translatedChanges[i].append(QQmlChangeSet::Change(change.index[i], change.count));
            }
        }
    }
 
    for (int i = 1; i < m_groupCount; ++i)
        QQmlDelegateModelGroupPrivate::get(m_groups[i])->changeSet.change(translatedChanges.at(i));
}
 
void QQmlDelegateModel::_q_itemsChanged(int index, int count, const QVector<int> &roles)
{
    Q_D(QQmlDelegateModel);
    if (count <= 0 || !d->m_complete)
        return;
 
    if (d->m_adaptorModel.notify(d->m_cache, index, count, roles)) {
        QVector<Compositor::Change> changes;
        d->m_compositor.listItemsChanged(&d->m_adaptorModel, index, count, &changes);
        d->itemsChanged(changes);
        d->emitChanges();
    }
    const bool needToCheckDelegateChoiceInvalidation = d->m_delegateChooser && !roles.isEmpty();
    if (!needToCheckDelegateChoiceInvalidation)
        return;
 
    // here, we only really can handle AIM based models, because only there
    // we can do something sensible with roles
    if (!d->m_adaptorModel.adaptsAim())
        return;
 
    const auto aim = d->m_adaptorModel.aim();
    const auto choiceRole = d->m_delegateChooser->role().toUtf8();
    const auto &roleNames = aim->roleNames();
    auto it = std::find_if(roles.begin(), roles.end(), [&](int role) {
        return roleNames[role] == choiceRole;
    });
    if (it == roles.end())
        return;
 
    // Compare handleModelReset - we're doing a more localized version
 
    /* A role change affecting the DelegateChoice is equivalent to removing all
       affected items (including  invalidating their cache entries) and afterwards
       reinserting them.
    */
    QVector<Compositor::Remove> removes;
    QVector<Compositor::Insert> inserts;
    d->m_compositor.listItemsRemoved(&d->m_adaptorModel, index, count, &removes);
    const QList<QQmlDelegateModelItem *> cache = d->m_cache;
    for (QQmlDelegateModelItem *item : cache)
        item->referenceObject();
    for (const auto& removed: removes) {
        if (!d->m_cache.isSharedWith(cache))
            break;
        QQmlDelegateModelItem *item = cache.value(removed.cacheIndex(), nullptr);
        if (!d->m_cache.contains(item))
            continue;
        if (item->modelIndex() != -1)
            item->setModelIndex(-1, -1, -1);
    }
    for (QQmlDelegateModelItem *item : cache)
        item->releaseObject();
    d->m_compositor.listItemsInserted(&d->m_adaptorModel, index, count, &inserts);
    d->itemsMoved(removes, inserts);
    d->emitChanges();
}
 
static void incrementIndexes(QQmlDelegateModelItem *cacheItem, int count, const int *deltas)
{
    if (QQDMIncubationTask *incubationTask = cacheItem->incubationTask) {
        for (int i = 1; i < count; ++i)
            incubationTask->index[i] += deltas[i];
    }
    if (QQmlDelegateModelAttached *attached = cacheItem->attached) {
        for (int i = 1; i < qMin<int>(count, Compositor::MaximumGroupCount); ++i)
            attached->m_currentIndex[i] += deltas[i];
    }
}
 
void QQmlDelegateModelPrivate::itemsInserted(
        const QVector<Compositor::Insert> &inserts,
        QVarLengthArray<QVector<QQmlChangeSet::Change>, Compositor::MaximumGroupCount> *translatedInserts,
        QHash<int, QList<QQmlDelegateModelItem *> > *movedItems)
{
    int cacheIndex = 0;
 
    int inserted[Compositor::MaximumGroupCount];
    for (int i = 1; i < m_groupCount; ++i)
        inserted[i] = 0;
 
    for (const Compositor::Insert &insert : inserts) {
        for (; cacheIndex < insert.cacheIndex(); ++cacheIndex)
            incrementIndexes(m_cache.at(cacheIndex), m_groupCount, inserted);
 
        for (int i = 1; i < m_groupCount; ++i) {
            if (insert.inGroup(i)) {
                (*translatedInserts)[i].append(
                        QQmlChangeSet::Change(insert.index[i], insert.count, insert.moveId));
                inserted[i] += insert.count;
            }
        }
 
        if (!insert.inCache())
            continue;
 
        if (movedItems && insert.isMove()) {
            QList<QQmlDelegateModelItem *> items = movedItems->take(insert.moveId);
            Q_ASSERT(items.size() == insert.count);
            m_cache = m_cache.mid(0, insert.cacheIndex())
                    + items + m_cache.mid(insert.cacheIndex());
        }
        if (insert.inGroup()) {
            for (int offset = 0; cacheIndex < insert.cacheIndex() + insert.count;
                 ++cacheIndex, ++offset) {
                QQmlDelegateModelItem *cacheItem = m_cache.at(cacheIndex);
                cacheItem->groups |= insert.flags & Compositor::GroupMask;
 
                if (QQDMIncubationTask *incubationTask = cacheItem->incubationTask) {
                    for (int i = 1; i < m_groupCount; ++i)
                        incubationTask->index[i] = cacheItem->groups & (1 << i)
                                ? insert.index[i] + offset
                                : insert.index[i];
                }
                if (QQmlDelegateModelAttached *attached = cacheItem->attached) {
                    for (int i = 1; i < m_groupCount; ++i)
                        attached->m_currentIndex[i] = cacheItem->groups & (1 << i)
                                ? insert.index[i] + offset
                                : insert.index[i];
                }
            }
        } else {
            cacheIndex = insert.cacheIndex() + insert.count;
        }
    }
    for (const QList<QQmlDelegateModelItem *> cache = m_cache; cacheIndex < cache.size(); ++cacheIndex)
        incrementIndexes(cache.at(cacheIndex), m_groupCount, inserted);
}
 
void QQmlDelegateModelPrivate::itemsInserted(const QVector<Compositor::Insert> &inserts)
{
    QVarLengthArray<QVector<QQmlChangeSet::Change>, Compositor::MaximumGroupCount> translatedInserts(m_groupCount);
    itemsInserted(inserts, &translatedInserts);
    Q_ASSERT(m_cache.size() == m_compositor.count(Compositor::Cache));
    if (!m_delegate)
        return;
 
    for (int i = 1; i < m_groupCount; ++i)
        QQmlDelegateModelGroupPrivate::get(m_groups[i])->changeSet.insert(translatedInserts.at(i));
}
 
void QQmlDelegateModel::_q_itemsInserted(int index, int count)
{
 
    Q_D(QQmlDelegateModel);
    if (count <= 0 || !d->m_complete)
        return;
 
    d->m_count += count;
 
    const QList<QQmlDelegateModelItem *> cache = d->m_cache;
    for (int i = 0, c = cache.size();  i < c; ++i) {
        QQmlDelegateModelItem *item = cache.at(i);
        // layout change triggered by changing the modelIndex might have
        // already invalidated this item in d->m_cache and deleted it.
        if (!d->m_cache.isSharedWith(cache) && !d->m_cache.contains(item))
            continue;
 
        if (item->modelIndex() >= index) {
            const int newIndex = item->modelIndex() + count;
            const int row = newIndex;
            const int column = 0;
            item->setModelIndex(newIndex, row, column);
        }
    }
 
    QVector<Compositor::Insert> inserts;
    d->m_compositor.listItemsInserted(&d->m_adaptorModel, index, count, &inserts);
    d->itemsInserted(inserts);
    d->emitChanges();
}
 
//### This method should be split in two. It will remove delegates, and it will re-render the list.
// When e.g. QQmlListModel::remove is called, the removal of the delegates should be done on
// QAbstractItemModel::rowsAboutToBeRemoved, and the re-rendering on
// QAbstractItemModel::rowsRemoved. Currently both are done on the latter signal. The problem is
// that the destruction of an item will emit a changed signal that ends up at the delegate, which
// in turn will try to load the data from the model (which should have already freed it), resulting
// in a use-after-free. See QTBUG-59256.
void QQmlDelegateModelPrivate::itemsRemoved(
        const QVector<Compositor::Remove> &removes,
        QVarLengthArray<QVector<QQmlChangeSet::Change>, Compositor::MaximumGroupCount> *translatedRemoves,
        QHash<int, QList<QQmlDelegateModelItem *> > *movedItems)
{
    int cacheIndex = 0;
    int removedCache = 0;
 
    int removed[Compositor::MaximumGroupCount];
    for (int i = 1; i < m_groupCount; ++i)
        removed[i] = 0;
 
    for (const Compositor::Remove &remove : removes) {
        for (; cacheIndex < remove.cacheIndex() && cacheIndex < m_cache.size(); ++cacheIndex)
            incrementIndexes(m_cache.at(cacheIndex), m_groupCount, removed);
 
        for (int i = 1; i < m_groupCount; ++i) {
            if (remove.inGroup(i)) {
                (*translatedRemoves)[i].append(
                        QQmlChangeSet::Change(remove.index[i], remove.count, remove.moveId));
                removed[i] -= remove.count;
            }
        }
 
        if (!remove.inCache())
            continue;
 
        if (movedItems && remove.isMove()) {
            movedItems->insert(remove.moveId, m_cache.mid(remove.cacheIndex(), remove.count));
            QList<QQmlDelegateModelItem *>::const_iterator begin = m_cache.constBegin() + remove.cacheIndex();
            QList<QQmlDelegateModelItem *>::const_iterator end = begin + remove.count;
            m_cache.erase(begin, end);
        } else {
            for (; cacheIndex < remove.cacheIndex() + remove.count - removedCache; ++cacheIndex) {
                QQmlDelegateModelItem *cacheItem = m_cache.at(cacheIndex);
                if (remove.inGroup(Compositor::Persisted) && cacheItem->objectRef == 0 && cacheItem->object) {
                    QObject *object = cacheItem->object;
                    cacheItem->destroyObject();
                    if (QQuickPackage *package = qmlobject_cast<QQuickPackage *>(object))
                        emitDestroyingPackage(package);
                    else
                        emitDestroyingItem(object);
                    cacheItem->scriptRef -= 1;
                }
                if (!cacheItem->isReferenced() && !remove.inGroup(Compositor::Persisted)) {
                    m_compositor.clearFlags(Compositor::Cache, cacheIndex, 1, Compositor::CacheFlag);
                    m_cache.removeAt(cacheIndex);
                    delete cacheItem;
                    --cacheIndex;
                    ++removedCache;
                    Q_ASSERT(m_cache.size() == m_compositor.count(Compositor::Cache));
                } else if (remove.groups() == cacheItem->groups) {
                    cacheItem->groups = 0;
                    if (QQDMIncubationTask *incubationTask = cacheItem->incubationTask) {
                        for (int i = 1; i < m_groupCount; ++i)
                            incubationTask->index[i] = -1;
                    }
                    if (QQmlDelegateModelAttached *attached = cacheItem->attached) {
                        for (int i = 1; i < m_groupCount; ++i)
                            attached->m_currentIndex[i] = -1;
                    }
                } else {
                    if (QQDMIncubationTask *incubationTask = cacheItem->incubationTask) {
                        if (!cacheItem->isObjectReferenced()) {
                            releaseIncubator(cacheItem->incubationTask);
                            cacheItem->incubationTask = nullptr;
                            if (cacheItem->object) {
                                QObject *object = cacheItem->object;
                                cacheItem->destroyObject();
                                if (QQuickPackage *package = qmlobject_cast<QQuickPackage *>(object))
                                    emitDestroyingPackage(package);
                                else
                                    emitDestroyingItem(object);
                            }
                            cacheItem->scriptRef -= 1;
                        } else {
                            for (int i = 1; i < m_groupCount; ++i) {
                                if (remove.inGroup(i))
                                    incubationTask->index[i] = remove.index[i];
                            }
                        }
                    }
                    if (QQmlDelegateModelAttached *attached = cacheItem->attached) {
                        for (int i = 1; i < m_groupCount; ++i) {
                            if (remove.inGroup(i))
                                attached->m_currentIndex[i] = remove.index[i];
                        }
                    }
                    cacheItem->groups &= ~remove.flags;
                }
            }
        }
    }
 
    for (const QList<QQmlDelegateModelItem *> cache = m_cache; cacheIndex < cache.size(); ++cacheIndex)
        incrementIndexes(cache.at(cacheIndex), m_groupCount, removed);
}
 
void QQmlDelegateModelPrivate::itemsRemoved(const QVector<Compositor::Remove> &removes)
{
    QVarLengthArray<QVector<QQmlChangeSet::Change>, Compositor::MaximumGroupCount> translatedRemoves(m_groupCount);
    itemsRemoved(removes, &translatedRemoves);
    Q_ASSERT(m_cache.size() == m_compositor.count(Compositor::Cache));
    if (!m_delegate)
        return;
 
    for (int i = 1; i < m_groupCount; ++i)
       QQmlDelegateModelGroupPrivate::get(m_groups[i])->changeSet.remove(translatedRemoves.at(i));
}
 
void QQmlDelegateModel::_q_itemsRemoved(int index, int count)
{
    Q_D(QQmlDelegateModel);
    if (count <= 0|| !d->m_complete)
        return;
 
    d->m_count -= count;
    Q_ASSERT(d->m_count >= 0);
    const QList<QQmlDelegateModelItem *> cache = d->m_cache;
    //Prevents items being deleted in remove loop
    for (QQmlDelegateModelItem *item : cache)
        item->referenceObject();
 
    for (int i = 0, c = cache.size();  i < c; ++i) {
        QQmlDelegateModelItem *item = cache.at(i);
        // layout change triggered by removal of a previous item might have
        // already invalidated this item in d->m_cache and deleted it
        if (!d->m_cache.isSharedWith(cache) && !d->m_cache.contains(item))
            continue;
 
        if (item->modelIndex() >= index + count) {
            const int newIndex = item->modelIndex() - count;
            const int row = newIndex;
            const int column = 0;
            item->setModelIndex(newIndex, row, column);
        } else if (item->modelIndex() >= index) {
            item->setModelIndex(-1, -1, -1);
        }
    }
    //Release items which are referenced before the loop
    for (QQmlDelegateModelItem *item : cache)
        item->releaseObject();
 
    QVector<Compositor::Remove> removes;
    d->m_compositor.listItemsRemoved(&d->m_adaptorModel, index, count, &removes);
    d->itemsRemoved(removes);
 
    d->emitChanges();
}
 
void QQmlDelegateModelPrivate::itemsMoved(
        const QVector<Compositor::Remove> &removes, const QVector<Compositor::Insert> &inserts)
{
    QHash<int, QList<QQmlDelegateModelItem *> > movedItems;
 
    QVarLengthArray<QVector<QQmlChangeSet::Change>, Compositor::MaximumGroupCount> translatedRemoves(m_groupCount);
    itemsRemoved(removes, &translatedRemoves, &movedItems);
 
    QVarLengthArray<QVector<QQmlChangeSet::Change>, Compositor::MaximumGroupCount> translatedInserts(m_groupCount);
    itemsInserted(inserts, &translatedInserts, &movedItems);
    Q_ASSERT(m_cache.size() == m_compositor.count(Compositor::Cache));
    Q_ASSERT(movedItems.isEmpty());
    if (!m_delegate)
        return;
 
    for (int i = 1; i < m_groupCount; ++i) {
        QQmlDelegateModelGroupPrivate::get(m_groups[i])->changeSet.move(
                    translatedRemoves.at(i),
                    translatedInserts.at(i));
    }
}
 
void QQmlDelegateModel::_q_itemsMoved(int from, int to, int count)
{
    Q_D(QQmlDelegateModel);
    if (count <= 0 || !d->m_complete)
        return;
 
    const int minimum = qMin(from, to);
    const int maximum = qMax(from, to) + count;
    const int difference = from > to ? count : -count;
 
    const QList<QQmlDelegateModelItem *> cache = d->m_cache;
    for (int i = 0, c = cache.size();  i < c; ++i) {
        QQmlDelegateModelItem *item = cache.at(i);
        // layout change triggered by changing the modelIndex might have
        // already invalidated this item in d->m_cache and deleted it.
        if (!d->m_cache.isSharedWith(cache) && !d->m_cache.contains(item))
            continue;
 
        if (item->modelIndex() >= from && item->modelIndex() < from + count) {
            const int newIndex = item->modelIndex() - from + to;
            const int row = newIndex;
            const int column = 0;
            item->setModelIndex(newIndex, row, column);
        } else if (item->modelIndex() >= minimum && item->modelIndex() < maximum) {
            const int newIndex = item->modelIndex() + difference;
            const int row = newIndex;
            const int column = 0;
            item->setModelIndex(newIndex, row, column);
        }
    }
 
    QVector<Compositor::Remove> removes;
    QVector<Compositor::Insert> inserts;
    d->m_compositor.listItemsMoved(&d->m_adaptorModel, from, to, count, &removes, &inserts);
    d->itemsMoved(removes, inserts);
    d->emitChanges();
}
 
void QQmlDelegateModelPrivate::emitModelUpdated(const QQmlChangeSet &changeSet, bool reset)
{
    Q_Q(QQmlDelegateModel);
    emit q->modelUpdated(changeSet, reset);
    if (changeSet.difference() != 0)
        emit q->countChanged();
}
 
void QQmlDelegateModelPrivate::delegateChanged(bool add, bool remove)
{
    Q_Q(QQmlDelegateModel);
    if (!m_complete)
        return;
 
    if (m_transaction) {
        qmlWarning(q) << QQmlDelegateModel::tr("The delegates of a DelegateModel cannot be changed within onUpdated.");
        return;
    }
 
    if (remove) {
        for (int i = 1; i < m_groupCount; ++i) {
            QQmlDelegateModelGroupPrivate::get(m_groups[i])->changeSet.remove(
                    0, m_compositor.count(Compositor::Group(i)));
        }
    }
    if (add) {
        for (int i = 1; i < m_groupCount; ++i) {
            QQmlDelegateModelGroupPrivate::get(m_groups[i])->changeSet.insert(
                    0, m_compositor.count(Compositor::Group(i)));
        }
    }
    emitChanges();
}
 
void QQmlDelegateModelPrivate::emitChanges()
{
    if (m_transaction || !m_complete || !m_context || !m_context->isValid())
        return;
 
    m_transaction = true;
    QV4::ExecutionEngine *engine = m_context->engine()->handle();
    for (int i = 1; i < m_groupCount; ++i)
        QQmlDelegateModelGroupPrivate::get(m_groups[i])->emitChanges(engine);
    m_transaction = false;
 
    const bool reset = m_reset;
    m_reset = false;
    for (int i = 1; i < m_groupCount; ++i)
        QQmlDelegateModelGroupPrivate::get(m_groups[i])->emitModelUpdated(reset);
 
    // emitChanges may alter m_cache and delete items
    QVarLengthArray<QPointer<QQmlDelegateModelAttached>> attachedObjects;
    attachedObjects.reserve(m_cache.length());
    for (const QQmlDelegateModelItem *cacheItem : std::as_const(m_cache))
        attachedObjects.append(cacheItem->attached);
 
    for (const QPointer<QQmlDelegateModelAttached> &attached : std::as_const(attachedObjects)) {
        if (attached && attached->m_cacheItem)
            attached->emitChanges();
    }
}
 
void QQmlDelegateModel::_q_modelAboutToBeReset()
{
    auto aim = static_cast<QAbstractItemModel *>(sender());
    auto oldRoleNames = aim->roleNames();
    // this relies on the fact that modelAboutToBeReset must be followed
    // by a modelReset signal before any further modelAboutToBeReset can occur
    QObject::connect(aim, &QAbstractItemModel::modelReset, this, [&, oldRoleNames](){
        auto aim = static_cast<QAbstractItemModel *>(sender());
        if (oldRoleNames == aim->roleNames()) {
            // if the rolenames stayed the same (most common case), then we don't have
            // to throw away all the setup that we did
            handleModelReset();
        } else {
            // If they did change, we give up and just start from scratch via setMode
            setModel(QVariant::fromValue(model()));
            // but we still have to call handleModelReset, otherwise views will
            // not refresh
            handleModelReset();
        }
    }, Qt::SingleShotConnection);
}
 
void QQmlDelegateModel::handleModelReset()
{
    Q_D(QQmlDelegateModel);
    if (!d->m_delegate)
        return;
 
    int oldCount = d->m_count;
    d->m_adaptorModel.rootIndex = QModelIndex();
 
    if (d->m_complete) {
        d->m_count = d->adaptorModelCount();
 
        const QList<QQmlDelegateModelItem *> cache = d->m_cache;
        for (QQmlDelegateModelItem *item : cache)
            item->referenceObject();
 
        for (int i = 0, c = cache.size();  i < c; ++i) {
            QQmlDelegateModelItem *item = cache.at(i);
            // layout change triggered by changing the modelIndex might have
            // already invalidated this item in d->m_cache and deleted it.
            if (!d->m_cache.isSharedWith(cache) && !d->m_cache.contains(item))
                continue;
 
            if (item->modelIndex() != -1)
                item->setModelIndex(-1, -1, -1);
        }
 
        for (QQmlDelegateModelItem *item : cache)
            item->releaseObject();
        QVector<Compositor::Remove> removes;
        QVector<Compositor::Insert> inserts;
        if (oldCount)
            d->m_compositor.listItemsRemoved(&d->m_adaptorModel, 0, oldCount, &removes);
        if (d->m_count)
            d->m_compositor.listItemsInserted(&d->m_adaptorModel, 0, d->m_count, &inserts);
        d->itemsMoved(removes, inserts);
        d->m_reset = true;
 
        if (d->m_adaptorModel.canFetchMore())
            d->m_adaptorModel.fetchMore();
 
        d->emitChanges();
    }
    emit rootIndexChanged();
}
 
void QQmlDelegateModel::_q_rowsInserted(const QModelIndex &parent, int begin, int end)
{
    Q_D(QQmlDelegateModel);
    if (parent == d->m_adaptorModel.rootIndex)
        _q_itemsInserted(begin, end - begin + 1);
}
 
void QQmlDelegateModel::_q_rowsAboutToBeRemoved(const QModelIndex &parent, int begin, int end)
{
    Q_D(QQmlDelegateModel);
    if (!d->m_adaptorModel.rootIndex.isValid())
        return;
    const QModelIndex index = d->m_adaptorModel.rootIndex;
    if (index.parent() == parent && index.row() >= begin && index.row() <= end) {
        const int oldCount = d->m_count;
        d->m_count = 0;
        d->disconnectFromAbstractItemModel();
        d->m_adaptorModel.invalidateModel();
 
        if (d->m_complete && oldCount > 0) {
            QVector<Compositor::Remove> removes;
            d->m_compositor.listItemsRemoved(&d->m_adaptorModel, 0, oldCount, &removes);
            d->itemsRemoved(removes);
            d->emitChanges();
        }
    }
}
 
void QQmlDelegateModel::_q_rowsRemoved(const QModelIndex &parent, int begin, int end)
{
    Q_D(QQmlDelegateModel);
    if (parent == d->m_adaptorModel.rootIndex)
        _q_itemsRemoved(begin, end - begin + 1);
}
 
void QQmlDelegateModel::_q_rowsMoved(
        const QModelIndex &sourceParent, int sourceStart, int sourceEnd,
        const QModelIndex &destinationParent, int destinationRow)
{
   Q_D(QQmlDelegateModel);
    const int count = sourceEnd - sourceStart + 1;
    if (destinationParent == d->m_adaptorModel.rootIndex && sourceParent == d->m_adaptorModel.rootIndex) {
        _q_itemsMoved(sourceStart, sourceStart > destinationRow ? destinationRow : destinationRow - count, count);
    } else if (sourceParent == d->m_adaptorModel.rootIndex) {
        _q_itemsRemoved(sourceStart, count);
    } else if (destinationParent == d->m_adaptorModel.rootIndex) {
        _q_itemsInserted(destinationRow, count);
    }
}
 
void QQmlDelegateModel::_q_columnsInserted(const QModelIndex &parent, int begin, int end)
{
    Q_D(QQmlDelegateModel);
    Q_UNUSED(end);
    if (parent == d->m_adaptorModel.rootIndex && begin == 0) {
        // mark all items as changed
        _q_itemsChanged(0, d->m_count, QVector<int>());
    }
}
 
void QQmlDelegateModel::_q_columnsRemoved(const QModelIndex &parent, int begin, int end)
{
    Q_D(QQmlDelegateModel);
    Q_UNUSED(end);
    if (parent == d->m_adaptorModel.rootIndex && begin == 0) {
        // mark all items as changed
        _q_itemsChanged(0, d->m_count, QVector<int>());
    }
}
 
void QQmlDelegateModel::_q_columnsMoved(const QModelIndex &parent, int start, int end,
                                        const QModelIndex &destination, int column)
{
    Q_D(QQmlDelegateModel);
    Q_UNUSED(end);
    if ((parent == d->m_adaptorModel.rootIndex && start == 0)
        || (destination == d->m_adaptorModel.rootIndex && column == 0)) {
        // mark all items as changed
        _q_itemsChanged(0, d->m_count, QVector<int>());
    }
}
 
void QQmlDelegateModel::_q_dataChanged(const QModelIndex &begin, const QModelIndex &end, const QVector<int> &roles)
{
    Q_D(QQmlDelegateModel);
    if (begin.parent() == d->m_adaptorModel.rootIndex)
        _q_itemsChanged(begin.row(), end.row() - begin.row() + 1, roles);
}
 
bool QQmlDelegateModel::isDescendantOf(const QPersistentModelIndex& desc, const QList< QPersistentModelIndex >& parents) const
{
    for (int i = 0, c = parents.size(); i < c; ++i) {
        for (QPersistentModelIndex parent = desc; parent.isValid(); parent = parent.parent()) {
            if (parent == parents[i])
                return true;
        }
    }
 
    return false;
}
 
void QQmlDelegateModel::_q_layoutChanged(const QList<QPersistentModelIndex> &parents, QAbstractItemModel::LayoutChangeHint hint)
{
    Q_D(QQmlDelegateModel);
    if (!d->m_complete)
        return;
 
    if (hint == QAbstractItemModel::VerticalSortHint) {
        if (!parents.isEmpty() && d->m_adaptorModel.rootIndex.isValid() && !isDescendantOf(d->m_adaptorModel.rootIndex, parents)) {
            return;
        }
 
        // mark all items as changed
        _q_itemsChanged(0, d->m_count, QVector<int>());
 
    } else if (hint == QAbstractItemModel::HorizontalSortHint) {
        // Ignored
    } else {
        // We don't know what's going on, so reset the model
        handleModelReset();
    }
}
 
QQmlDelegateModelAttached *QQmlDelegateModel::qmlAttachedProperties(QObject *obj)
{
    if (QQmlDelegateModelItem *cacheItem = QQmlDelegateModelItem::dataForObject(obj)) {
        cacheItem->attached = new QQmlDelegateModelAttached(cacheItem, obj);
        return cacheItem->attached;
    }
    return new QQmlDelegateModelAttached(obj);
}
 
QQmlDelegateModelPrivate::InsertionResult
QQmlDelegateModelPrivate::insert(Compositor::insert_iterator &before, const QV4::Value &object, int groups)
{
    if (!m_context || !m_context->isValid())
        return InsertionResult::Error;
 
    QQmlDelegateModelItem *cacheItem = m_adaptorModel.createItem(m_cacheMetaType, -1);
    if (!cacheItem)
        return InsertionResult::Error;
    if (!object.isObject())
        return InsertionResult::Error;
 
    QV4::ExecutionEngine *v4 = object.as<QV4::Object>()->engine();
    QV4::Scope scope(v4);
    QV4::ScopedObject o(scope, object);
    if (!o)
        return InsertionResult::Error;
 
    QV4::ObjectIterator it(scope, o, QV4::ObjectIterator::EnumerableOnly);
    QV4::ScopedValue propertyName(scope);
    QV4::ScopedValue v(scope);
    const auto oldCache = m_cache;
    while (1) {
        propertyName = it.nextPropertyNameAsString(v);
        if (propertyName->isNull())
            break;
        cacheItem->setValue(
                    propertyName->toQStringNoThrow(),
                    QV4::ExecutionEngine::toVariant(v, QMetaType {}));
    }
    const bool cacheModified = !m_cache.isSharedWith(oldCache);
    if (cacheModified)
        return InsertionResult::Retry;
 
    cacheItem->groups = groups | Compositor::UnresolvedFlag | Compositor::CacheFlag;
 
    // Must be before the new object is inserted into the cache or its indexes will be adjusted too.
    itemsInserted(QVector<Compositor::Insert>(1, Compositor::Insert(before, 1, cacheItem->groups & ~Compositor::CacheFlag)));
 
    m_cache.insert(before.cacheIndex(), cacheItem);
    m_compositor.insert(before, nullptr, 0, 1, cacheItem->groups);
 
    return InsertionResult::Success;
}
 
//============================================================================
 
QQmlDelegateModelItemMetaType::QQmlDelegateModelItemMetaType(
        QV4::ExecutionEngine *engine, QQmlDelegateModel *model, const QStringList &groupNames)
    : model(model)
    , groupCount(groupNames.size() + 1)
    , v4Engine(engine)
    , metaObject(nullptr)
    , groupNames(groupNames)
{
}
 
QQmlDelegateModelItemMetaType::~QQmlDelegateModelItemMetaType()
{
    if (metaObject)
        metaObject->release();
}
 
void QQmlDelegateModelItemMetaType::initializeMetaObject()
{
    QMetaObjectBuilder builder;
    builder.setFlags(DynamicMetaObject);
    builder.setClassName(QQmlDelegateModelAttached::staticMetaObject.className());
    builder.setSuperClass(&QQmlDelegateModelAttached::staticMetaObject);
 
    int notifierId = 0;
    for (int i = 0; i < groupNames.size(); ++i, ++notifierId) {
        QString propertyName = QLatin1String("in") + groupNames.at(i);
        propertyName.replace(2, 1, propertyName.at(2).toUpper());
        builder.addSignal("__" + propertyName.toUtf8() + "Changed()");
        QMetaPropertyBuilder propertyBuilder = builder.addProperty(
                propertyName.toUtf8(), "bool", notifierId);
        propertyBuilder.setWritable(true);
    }
    for (int i = 0; i < groupNames.size(); ++i, ++notifierId) {
        const QString propertyName = groupNames.at(i) + QLatin1String("Index");
        builder.addSignal("__" + propertyName.toUtf8() + "Changed()");
        QMetaPropertyBuilder propertyBuilder = builder.addProperty(
                propertyName.toUtf8(), "int", notifierId);
        propertyBuilder.setWritable(true);
    }
 
    metaObject = new QQmlDelegateModelAttachedMetaObject(this, builder.toMetaObject());
}
 
void QQmlDelegateModelItemMetaType::initializePrototype()
{
    QV4::Scope scope(v4Engine);
 
    QV4::ScopedObject proto(scope, v4Engine->newObject());
    proto->defineAccessorProperty(QStringLiteral("model"), QQmlDelegateModelItem::get_model, nullptr);
    proto->defineAccessorProperty(QStringLiteral("groups"), QQmlDelegateModelItem::get_groups, QQmlDelegateModelItem::set_groups);
    QV4::ScopedString s(scope);
    QV4::ScopedProperty p(scope);
 
    s = v4Engine->newString(QStringLiteral("isUnresolved"));
    QV4::ScopedFunctionObject f(scope);
    QV4::ExecutionEngine *engine = scope.engine;
    p->setGetter((f = QV4::DelegateModelGroupFunction::create(engine, 30, QQmlDelegateModelItem::get_member)));
    p->setSetter(nullptr);
    proto->insertMember(s, p, QV4::Attr_Accessor|QV4::Attr_NotConfigurable|QV4::Attr_NotEnumerable);
 
    s = v4Engine->newString(QStringLiteral("inItems"));
    p->setGetter((f = QV4::DelegateModelGroupFunction::create(engine, QQmlListCompositor::Default, QQmlDelegateModelItem::get_member)));
    p->setSetter((f = QV4::DelegateModelGroupFunction::create(engine, QQmlListCompositor::Default, QQmlDelegateModelItem::set_member)));
    proto->insertMember(s, p, QV4::Attr_Accessor|QV4::Attr_NotConfigurable|QV4::Attr_NotEnumerable);
 
    s = v4Engine->newString(QStringLiteral("inPersistedItems"));
    p->setGetter((f = QV4::DelegateModelGroupFunction::create(engine, QQmlListCompositor::Persisted, QQmlDelegateModelItem::get_member)));
    p->setSetter((f = QV4::DelegateModelGroupFunction::create(engine, QQmlListCompositor::Persisted, QQmlDelegateModelItem::set_member)));
    proto->insertMember(s, p, QV4::Attr_Accessor|QV4::Attr_NotConfigurable|QV4::Attr_NotEnumerable);
 
    s = v4Engine->newString(QStringLiteral("itemsIndex"));
    p->setGetter((f = QV4::DelegateModelGroupFunction::create(engine, QQmlListCompositor::Default, QQmlDelegateModelItem::get_index)));
    proto->insertMember(s, p, QV4::Attr_Accessor|QV4::Attr_NotConfigurable|QV4::Attr_NotEnumerable);
 
    s = v4Engine->newString(QStringLiteral("persistedItemsIndex"));
    p->setGetter((f = QV4::DelegateModelGroupFunction::create(engine, QQmlListCompositor::Persisted, QQmlDelegateModelItem::get_index)));
    p->setSetter(nullptr);
    proto->insertMember(s, p, QV4::Attr_Accessor|QV4::Attr_NotConfigurable|QV4::Attr_NotEnumerable);
 
    for (int i = 2; i < groupNames.size(); ++i) {
        QString propertyName = QLatin1String("in") + groupNames.at(i);
        propertyName.replace(2, 1, propertyName.at(2).toUpper());
        s = v4Engine->newString(propertyName);
        p->setGetter((f = QV4::DelegateModelGroupFunction::create(engine, i + 1, QQmlDelegateModelItem::get_member)));
        p->setSetter((f = QV4::DelegateModelGroupFunction::create(engine, i + 1, QQmlDelegateModelItem::set_member)));
        proto->insertMember(s, p, QV4::Attr_Accessor|QV4::Attr_NotConfigurable|QV4::Attr_NotEnumerable);
    }
    for (int i = 2; i < groupNames.size(); ++i) {
        const QString propertyName = groupNames.at(i) + QLatin1String("Index");
        s = v4Engine->newString(propertyName);
        p->setGetter((f = QV4::DelegateModelGroupFunction::create(engine, i + 1, QQmlDelegateModelItem::get_index)));
        p->setSetter(nullptr);
        proto->insertMember(s, p, QV4::Attr_Accessor|QV4::Attr_NotConfigurable|QV4::Attr_NotEnumerable);
    }
    modelItemProto.set(v4Engine, proto);
}
 
int QQmlDelegateModelItemMetaType::parseGroups(const QStringList &groups) const
{
    int groupFlags = 0;
    for (const QString &groupName : groups) {
        int index = groupNames.indexOf(groupName);
        if (index != -1)
            groupFlags |= 2 << index;
    }
    return groupFlags;
}
 
int QQmlDelegateModelItemMetaType::parseGroups(const QV4::Value &groups) const
{
    int groupFlags = 0;
    QV4::Scope scope(v4Engine);
 
    QV4::ScopedString s(scope, groups);
    if (s) {
        const QString groupName = s->toQString();
        int index = groupNames.indexOf(groupName);
        if (index != -1)
            groupFlags |= 2 << index;
        return groupFlags;
    }
 
    QV4::ScopedArrayObject array(scope, groups);
    if (array) {
        QV4::ScopedValue v(scope);
        uint arrayLength = array->getLength();
        for (uint i = 0; i < arrayLength; ++i) {
            v = array->get(i);
            const QString groupName = v->toQString();
            int index = groupNames.indexOf(groupName);
            if (index != -1)
                groupFlags |= 2 << index;
        }
    }
    return groupFlags;
}
 
QV4::ReturnedValue QQmlDelegateModelItem::get_model(const QV4::FunctionObject *b, const QV4::Value *thisObject, const QV4::Value *, int)
{
    QV4::Scope scope(b);
    QV4::Scoped<QQmlDelegateModelItemObject> o(scope, thisObject->as<QQmlDelegateModelItemObject>());
    if (!o)
        return b->engine()->throwTypeError(QStringLiteral("Not a valid DelegateModel object"));
    if (!o->d()->item->metaType->model)
        RETURN_UNDEFINED();
 
    return o->d()->item->get();
}
 
QV4::ReturnedValue QQmlDelegateModelItem::get_groups(const QV4::FunctionObject *b, const QV4::Value *thisObject, const QV4::Value *, int)
{
    QV4::Scope scope(b);
    QV4::Scoped<QQmlDelegateModelItemObject> o(scope, thisObject->as<QQmlDelegateModelItemObject>());
    if (!o)
        return scope.engine->throwTypeError(QStringLiteral("Not a valid DelegateModel object"));
 
    QStringList groups;
    for (int i = 1; i < o->d()->item->metaType->groupCount; ++i) {
        if (o->d()->item->groups & (1 << i))
            groups.append(o->d()->item->metaType->groupNames.at(i - 1));
    }
 
    return scope.engine->fromVariant(groups);
}
 
QV4::ReturnedValue QQmlDelegateModelItem::set_groups(const QV4::FunctionObject *b, const QV4::Value *thisObject, const QV4::Value *argv, int argc)
{
    QV4::Scope scope(b);
    QV4::Scoped<QQmlDelegateModelItemObject> o(scope, thisObject->as<QQmlDelegateModelItemObject>());
    if (!o)
        return scope.engine->throwTypeError(QStringLiteral("Not a valid DelegateModel object"));
 
    if (!argc)
        THROW_TYPE_ERROR();
 
    if (!o->d()->item->metaType->model)
        RETURN_UNDEFINED();
    QQmlDelegateModelPrivate *model = QQmlDelegateModelPrivate::get(o->d()->item->metaType->model);
 
    const int groupFlags = model->m_cacheMetaType->parseGroups(argv[0]);
    const int cacheIndex = model->m_cache.indexOf(o->d()->item);
    Compositor::iterator it = model->m_compositor.find(Compositor::Cache, cacheIndex);
    model->setGroups(it, 1, Compositor::Cache, groupFlags);
    return QV4::Encode::undefined();
}
 
QV4::ReturnedValue QQmlDelegateModelItem::get_member(QQmlDelegateModelItem *thisItem, uint flag, const QV4::Value &)
{
    return QV4::Encode(bool(thisItem->groups & (1 << flag)));
}
 
QV4::ReturnedValue QQmlDelegateModelItem::set_member(QQmlDelegateModelItem *cacheItem, uint flag, const QV4::Value &arg)
{
    if (!cacheItem->metaType->model)
        return QV4::Encode::undefined();
 
    QQmlDelegateModelPrivate *model = QQmlDelegateModelPrivate::get(cacheItem->metaType->model);
 
    bool member = arg.toBoolean();
    uint groupFlag = (1 << flag);
    if (member == ((cacheItem->groups & groupFlag) != 0))
        return QV4::Encode::undefined();
 
    const int cacheIndex = model->m_cache.indexOf(cacheItem);
    Compositor::iterator it = model->m_compositor.find(Compositor::Cache, cacheIndex);
    if (member)
        model->addGroups(it, 1, Compositor::Cache, groupFlag);
    else
        model->removeGroups(it, 1, Compositor::Cache, groupFlag);
    return QV4::Encode::undefined();
}
 
QV4::ReturnedValue QQmlDelegateModelItem::get_index(QQmlDelegateModelItem *thisItem, uint flag, const QV4::Value &)
{
    return QV4::Encode((int)thisItem->groupIndex(Compositor::Group(flag)));
}
 
void QQmlDelegateModelItem::childContextObjectDestroyed(QObject *childContextObject)
{
    if (!contextData)
        return;
 
    for (QQmlRefPointer<QQmlContextData> ctxt = contextData->childContexts(); ctxt;
         ctxt = ctxt->nextChild()) {
        if (ctxt->contextObject() == childContextObject)
            ctxt->setContextObject(nullptr);
    }
}
 
 
//---------------------------------------------------------------------------
 
DEFINE_OBJECT_VTABLE(QQmlDelegateModelItemObject);
 
void QV4::Heap::QQmlDelegateModelItemObject::destroy()
{
    item->Dispose();
    Object::destroy();
}
 
 
QQmlDelegateModelItem::QQmlDelegateModelItem(
        const QQmlRefPointer<QQmlDelegateModelItemMetaType> &metaType,
        QQmlAdaptorModel::Accessors *accessor,
        int modelIndex, int row, int column)
    : v4(metaType->v4Engine)
    , metaType(metaType)
    , contextData(nullptr)
    , object(nullptr)
    , attached(nullptr)
    , incubationTask(nullptr)
    , delegate(nullptr)
    , poolTime(0)
    , objectRef(0)
    , scriptRef(0)
    , groups(0)
    , index(modelIndex)
    , row(row)
    , column(column)
{
    if (accessor->propertyCache) {
        // The property cache in the accessor is common for all the model
        // items in the model it wraps. It describes available model roles,
        // together with revisioned properties like row, column and index, all
        // which should be available in the delegate. We assign this cache to the
        // model item so that the QML engine can use the revision information
        // when resolving the properties (rather than falling back to just
        // inspecting the QObject in the model item directly).
        QQmlData::get(this, true)->propertyCache = accessor->propertyCache;
    }
}
 
QQmlDelegateModelItem::~QQmlDelegateModelItem()
{
    Q_ASSERT(scriptRef == 0);
    Q_ASSERT(objectRef == 0);
    Q_ASSERT(!object);
 
    if (incubationTask) {
        if (metaType->model)
            QQmlDelegateModelPrivate::get(metaType->model)->releaseIncubator(incubationTask);
        else
            delete incubationTask;
    }
}
 
void QQmlDelegateModelItem::Dispose()
{
    --scriptRef;
    if (isReferenced())
        return;
 
    if (metaType->model) {
        QQmlDelegateModelPrivate *model = QQmlDelegateModelPrivate::get(metaType->model);
        model->removeCacheItem(this);
    }
    delete this;
}
 
void QQmlDelegateModelItem::setModelIndex(int idx, int newRow, int newColumn, bool alwaysEmit)
{
    const int prevIndex = index;
    const int prevRow = row;
    const int prevColumn = column;
 
    index = idx;
    row = newRow;
    column = newColumn;
 
    if (idx != prevIndex || alwaysEmit)
        emit modelIndexChanged();
    if (row != prevRow || alwaysEmit)
        emit rowChanged();
    if (column != prevColumn || alwaysEmit)
        emit columnChanged();
}
 
void QQmlDelegateModelItem::destroyObject()
{
    Q_ASSERT(object);
    Q_ASSERT(contextData);
 
    QQmlData *data = QQmlData::get(object);
    Q_ASSERT(data);
    if (data->ownContext) {
        data->ownContext->clearContext();
        if (data->ownContext->contextObject() == object)
            data->ownContext->setContextObject(nullptr);
        data->ownContext = nullptr;
        data->context = nullptr;
    }
    /* QTBUG-87228: when destroying object at the application exit, the deferred
     * parent by setting it to QCoreApplication instance if it's nullptr, so
     * deletion won't work. Not to leak memory, make sure our object has a that
     * the parent claims the object at the end of the lifetime. When not at the
     * application exit, normal event loop will handle the deferred deletion
     * earlier.
     */
    if (object->parent() == nullptr)
        object->setParent(QCoreApplication::instance());
    object->deleteLater();
 
    if (attached) {
        attached->m_cacheItem = nullptr;
        attached = nullptr;
    }
 
    contextData.reset();
    object = nullptr;
}
 
QQmlDelegateModelItem *QQmlDelegateModelItem::dataForObject(QObject *object)
{
    QQmlData *d = QQmlData::get(object);
    if (!d)
        return nullptr;
 
    QQmlRefPointer<QQmlContextData> context = d->context;
    if (!context || !context->isValid())
        return nullptr;
 
    if (QObject *extraObject = context->extraObject())
        return qobject_cast<QQmlDelegateModelItem *>(extraObject);
 
    for (context = context->parent(); context; context = context->parent()) {
        if (QObject *extraObject = context->extraObject())
            return qobject_cast<QQmlDelegateModelItem *>(extraObject);
        if (QQmlDelegateModelItem *cacheItem = qobject_cast<QQmlDelegateModelItem *>(
                context->contextObject())) {
            return cacheItem;
        }
    }
    return nullptr;
}
 
int QQmlDelegateModelItem::groupIndex(Compositor::Group group)
{
    if (QQmlDelegateModelPrivate * const model = metaType->model
            ? QQmlDelegateModelPrivate::get(metaType->model)
            : nullptr) {
        return model->m_compositor.find(Compositor::Cache, model->m_cache.indexOf(this)).index[group];
    }
    return -1;
}
 
//---------------------------------------------------------------------------
 
QQmlDelegateModelAttachedMetaObject::QQmlDelegateModelAttachedMetaObject(
        QQmlDelegateModelItemMetaType *metaType, QMetaObject *metaObject)
    : metaType(metaType)
    , metaObject(metaObject)
    , memberPropertyOffset(QQmlDelegateModelAttached::staticMetaObject.propertyCount())
    , indexPropertyOffset(QQmlDelegateModelAttached::staticMetaObject.propertyCount() + metaType->groupNames.size())
{
    // Don't reference count the meta-type here as that would create a circular reference.
    // Instead we rely the fact that the meta-type's reference count can't reach 0 without first
    // destroying all delegates with attached objects.
    *static_cast<QMetaObject *>(this) = *metaObject;
}
 
QQmlDelegateModelAttachedMetaObject::~QQmlDelegateModelAttachedMetaObject()
{
    ::free(metaObject);
}
 
void QQmlDelegateModelAttachedMetaObject::objectDestroyed(QObject *)
{
    release();
}
 
int QQmlDelegateModelAttachedMetaObject::metaCall(QObject *object, QMetaObject::Call call, int _id, void **arguments)
{
    QQmlDelegateModelAttached *attached = static_cast<QQmlDelegateModelAttached *>(object);
    if (call == QMetaObject::ReadProperty) {
        if (_id >= indexPropertyOffset) {
            Compositor::Group group = Compositor::Group(_id - indexPropertyOffset + 1);
            *static_cast<int *>(arguments[0]) = attached->m_currentIndex[group];
            return -1;
        } else if (_id >= memberPropertyOffset) {
            Compositor::Group group = Compositor::Group(_id - memberPropertyOffset + 1);
            *static_cast<bool *>(arguments[0]) = attached->m_cacheItem->groups & (1 << group);
            return -1;
        }
    } else if (call == QMetaObject::WriteProperty) {
        if (_id >= memberPropertyOffset) {
            if (!metaType->model)
                return -1;
            QQmlDelegateModelPrivate *model = QQmlDelegateModelPrivate::get(metaType->model);
            Compositor::Group group = Compositor::Group(_id - memberPropertyOffset + 1);
            const int groupFlag = 1 << group;
            const bool member = attached->m_cacheItem->groups & groupFlag;
            if (member && !*static_cast<bool *>(arguments[0])) {
                Compositor::iterator it = model->m_compositor.find(
                        group, attached->m_currentIndex[group]);
                model->removeGroups(it, 1, group, groupFlag);
            } else if (!member && *static_cast<bool *>(arguments[0])) {
                for (int i = 1; i < metaType->groupCount; ++i) {
                    if (attached->m_cacheItem->groups & (1 << i)) {
                        Compositor::iterator it = model->m_compositor.find(
                                Compositor::Group(i), attached->m_currentIndex[i]);
                        model->addGroups(it, 1, Compositor::Group(i), groupFlag);
                        break;
                    }
                }
            }
            return -1;
        }
    }
    return attached->qt_metacall(call, _id, arguments);
}
 
QQmlDelegateModelAttached::QQmlDelegateModelAttached(QObject *parent)
    : m_cacheItem(nullptr)
    , m_previousGroups(0)
{
    QQml_setParent_noEvent(this, parent);
}
 
QQmlDelegateModelAttached::QQmlDelegateModelAttached(
        QQmlDelegateModelItem *cacheItem, QObject *parent)
    : m_cacheItem(cacheItem)
    , m_previousGroups(cacheItem->groups)
{
    QQml_setParent_noEvent(this, parent);
    resetCurrentIndex();
    // Let m_previousIndex be equal to m_currentIndex
    std::copy(std::begin(m_currentIndex), std::end(m_currentIndex), std::begin(m_previousIndex));
 
    if (!cacheItem->metaType->metaObject)
        cacheItem->metaType->initializeMetaObject();
 
    QObjectPrivate::get(this)->metaObject = cacheItem->metaType->metaObject;
    cacheItem->metaType->metaObject->addref();
}
 
void QQmlDelegateModelAttached::resetCurrentIndex()
{
    if (QQDMIncubationTask *incubationTask = m_cacheItem->incubationTask) {
        for (int i = 1; i < qMin<int>(m_cacheItem->metaType->groupCount, Compositor::MaximumGroupCount); ++i)
            m_currentIndex[i] = incubationTask->index[i];
    } else {
        QQmlDelegateModelPrivate * const model = QQmlDelegateModelPrivate::get(m_cacheItem->metaType->model);
        Compositor::iterator it = model->m_compositor.find(
                Compositor::Cache, model->m_cache.indexOf(m_cacheItem));
        for (int i = 1; i < m_cacheItem->metaType->groupCount; ++i)
            m_currentIndex[i] = it.index[i];
    }
}
 
void QQmlDelegateModelAttached::setInPersistedItems(bool inPersisted)
{
    setInGroup(QQmlListCompositor::Persisted, inPersisted);
}
 
bool QQmlDelegateModelAttached::inPersistedItems() const
{
    if (!m_cacheItem)
        return false;
    const uint groupFlag = (1 << QQmlListCompositor::Persisted);
    return m_cacheItem->groups & groupFlag;
}
 
int QQmlDelegateModelAttached::persistedItemsIndex() const
{
    if (!m_cacheItem)
        return -1;
    return m_cacheItem->groupIndex(QQmlListCompositor::Persisted);
}
 
void QQmlDelegateModelAttached::setInGroup(QQmlListCompositor::Group group, bool inGroup)
{
    if (!(m_cacheItem && m_cacheItem->metaType && m_cacheItem->metaType->model))
        return;
    QQmlDelegateModelPrivate *model = QQmlDelegateModelPrivate::get(m_cacheItem->metaType->model);
    const uint groupFlag = (1 << group);
    if (inGroup == bool(m_cacheItem->groups & groupFlag))
        return;
 
    const int cacheIndex = model->m_cache.indexOf(m_cacheItem);
    Compositor::iterator it = model->m_compositor.find(Compositor::Cache, cacheIndex);
    if (inGroup)
        model->addGroups(it, 1, Compositor::Cache, groupFlag);
    else
        model->removeGroups(it, 1, Compositor::Cache, groupFlag);
    // signal emission happens in add-/removeGroups
}
 
void QQmlDelegateModelAttached::setInItems(bool inItems)
{
    setInGroup(QQmlListCompositor::Default, inItems);
}
 
bool QQmlDelegateModelAttached::inItems() const
{
    if (!m_cacheItem)
        return false;
    const uint groupFlag = (1 << QQmlListCompositor::Default);
    return m_cacheItem->groups & groupFlag;
}
 
int QQmlDelegateModelAttached::itemsIndex() const
{
    if (!m_cacheItem)
        return -1;
    return m_cacheItem->groupIndex(QQmlListCompositor::Default);
}
 
QQmlDelegateModel *QQmlDelegateModelAttached::model() const
{
    return m_cacheItem ? m_cacheItem->metaType->model : nullptr;
}
 
QStringList QQmlDelegateModelAttached::groups() const
{
    QStringList groups;
 
    if (!m_cacheItem)
        return groups;
    for (int i = 1; i < m_cacheItem->metaType->groupCount; ++i) {
        if (m_cacheItem->groups & (1 << i))
            groups.append(m_cacheItem->metaType->groupNames.at(i - 1));
    }
    return groups;
}
 
void QQmlDelegateModelAttached::setGroups(const QStringList &groups)
{
    if (!m_cacheItem)
        return;
 
    QQmlDelegateModelPrivate *model = QQmlDelegateModelPrivate::get(m_cacheItem->metaType->model);
 
    const int groupFlags = model->m_cacheMetaType->parseGroups(groups);
    const int cacheIndex = model->m_cache.indexOf(m_cacheItem);
    Compositor::iterator it = model->m_compositor.find(Compositor::Cache, cacheIndex);
    model->setGroups(it, 1, Compositor::Cache, groupFlags);
}
 
bool QQmlDelegateModelAttached::isUnresolved() const
{
    if (!m_cacheItem)
        return false;
 
    return m_cacheItem->groups & Compositor::UnresolvedFlag;
}
 
void QQmlDelegateModelAttached::emitChanges()
{
    const int groupChanges = m_previousGroups ^ m_cacheItem->groups;
    m_previousGroups = m_cacheItem->groups;
 
    int indexChanges = 0;
    const int groupCount = m_cacheItem->metaType->groupCount;
    for (int i = 1; i < groupCount; ++i) {
        if (m_previousIndex[i] != m_currentIndex[i]) {
            m_previousIndex[i] = m_currentIndex[i];
            indexChanges |= (1 << i);
        }
    }
 
    // Don't access m_cacheItem anymore once we've started sending signals.
    // We don't own it and someone might delete it.
 
    int notifierId = 0;
    const QMetaObject *meta = metaObject();
    for (int i = 1; i < groupCount; ++i, ++notifierId) {
        if (groupChanges & (1 << i))
            QMetaObject::activate(this, meta, notifierId, nullptr);
    }
    for (int i = 1; i < groupCount; ++i, ++notifierId) {
        if (indexChanges & (1 << i))
            QMetaObject::activate(this, meta, notifierId, nullptr);
    }
 
    if (groupChanges)
        emit groupsChanged();
}
 
//============================================================================
 
void QQmlDelegateModelGroupPrivate::setModel(QQmlDelegateModel *m, Compositor::Group g)
{
    Q_ASSERT(!model);
    model = m;
    group = g;
}
 
bool QQmlDelegateModelGroupPrivate::isChangedConnected()
{
    Q_Q(QQmlDelegateModelGroup);
    IS_SIGNAL_CONNECTED(q, QQmlDelegateModelGroup, changed, (const QJSValue &,const QJSValue &));
}
 
void QQmlDelegateModelGroupPrivate::emitChanges(QV4::ExecutionEngine *v4)
{
    Q_Q(QQmlDelegateModelGroup);
    if (isChangedConnected() && !changeSet.isEmpty()) {
        emit q->changed(QJSValuePrivate::fromReturnedValue(
                            qdmEngineData(v4)->array(v4, changeSet.removes())),
                        QJSValuePrivate::fromReturnedValue(
                            qdmEngineData(v4)->array(v4, changeSet.inserts())));
    }
    if (changeSet.difference() != 0)
        emit q->countChanged();
}
 
void QQmlDelegateModelGroupPrivate::emitModelUpdated(bool reset)
{
    for (QQmlDelegateModelGroupEmitterList::iterator it = emitters.begin(); it != emitters.end(); ++it)
        it->emitModelUpdated(changeSet, reset);
    changeSet.clear();
}
 
typedef QQmlDelegateModelGroupEmitterList::iterator GroupEmitterListIt;
 
void QQmlDelegateModelGroupPrivate::createdPackage(int index, QQuickPackage *package)
{
    for (GroupEmitterListIt it = emitters.begin(), end = emitters.end(); it != end; ++it)
        it->createdPackage(index, package);
}
 
void QQmlDelegateModelGroupPrivate::initPackage(int index, QQuickPackage *package)
{
    for (GroupEmitterListIt it = emitters.begin(), end = emitters.end(); it != end; ++it)
        it->initPackage(index, package);
}
 
void QQmlDelegateModelGroupPrivate::destroyingPackage(QQuickPackage *package)
{
    for (GroupEmitterListIt it = emitters.begin(), end = emitters.end(); it != end; ++it)
        it->destroyingPackage(package);
}
 
QQmlDelegateModelGroup::QQmlDelegateModelGroup(QObject *parent)
    : QObject(*new QQmlDelegateModelGroupPrivate, parent)
{
}
 
QQmlDelegateModelGroup::QQmlDelegateModelGroup(
        const QString &name, QQmlDelegateModel *model, int index, QObject *parent)
    : QQmlDelegateModelGroup(parent)
{
    Q_D(QQmlDelegateModelGroup);
    d->name = name;
    d->setModel(model, Compositor::Group(index));
}
 
QQmlDelegateModelGroup::~QQmlDelegateModelGroup()
{
}
 
QString QQmlDelegateModelGroup::name() const
{
    Q_D(const QQmlDelegateModelGroup);
    return d->name;
}
 
void QQmlDelegateModelGroup::setName(const QString &name)
{
    Q_D(QQmlDelegateModelGroup);
    if (d->model)
        return;
    if (d->name != name) {
        d->name = name;
        emit nameChanged();
    }
}
 
int QQmlDelegateModelGroup::count() const
{
    Q_D(const QQmlDelegateModelGroup);
    if (!d->model)
        return 0;
    return QQmlDelegateModelPrivate::get(d->model)->m_compositor.count(d->group);
}
 
bool QQmlDelegateModelGroup::defaultInclude() const
{
    Q_D(const QQmlDelegateModelGroup);
    return d->defaultInclude;
}
 
void QQmlDelegateModelGroup::setDefaultInclude(bool include)
{
    Q_D(QQmlDelegateModelGroup);
    if (d->defaultInclude != include) {
        d->defaultInclude = include;
 
        if (d->model) {
            if (include)
                QQmlDelegateModelPrivate::get(d->model)->m_compositor.setDefaultGroup(d->group);
            else
                QQmlDelegateModelPrivate::get(d->model)->m_compositor.clearDefaultGroup(d->group);
        }
        emit defaultIncludeChanged();
    }
}
 
QJSValue QQmlDelegateModelGroup::get(int index)
{
    Q_D(QQmlDelegateModelGroup);
    if (!d->model)
        return QJSValue();
 
    QQmlDelegateModelPrivate *model = QQmlDelegateModelPrivate::get(d->model);
    if (!model->m_context || !model->m_context->isValid()) {
        return QJSValue();
    } else if (index < 0 || index >= model->m_compositor.count(d->group)) {
        qmlWarning(this) << tr("get: index out of range");
        return QJSValue();
    }
 
    Compositor::iterator it = model->m_compositor.find(d->group, index);
    QQmlDelegateModelItem *cacheItem = it->inCache()
            ? model->m_cache.at(it.cacheIndex())
            : 0;
 
    if (!cacheItem) {
        cacheItem = model->m_adaptorModel.createItem(
                model->m_cacheMetaType, it.modelIndex());
        if (!cacheItem)
            return QJSValue();
        cacheItem->groups = it->flags;
 
        model->m_cache.insert(it.cacheIndex(), cacheItem);
        model->m_compositor.setFlags(it, 1, Compositor::CacheFlag);
    }
 
    if (model->m_cacheMetaType->modelItemProto.isUndefined())
        model->m_cacheMetaType->initializePrototype();
    QV4::ExecutionEngine *v4 = model->m_cacheMetaType->v4Engine;
    QV4::Scope scope(v4);
    ++cacheItem->scriptRef;
    QV4::ScopedObject o(scope, v4->memoryManager->allocate<QQmlDelegateModelItemObject>(cacheItem));
    QV4::ScopedObject p(scope, model->m_cacheMetaType->modelItemProto.value());
    o->setPrototypeOf(p);
 
    return QJSValuePrivate::fromReturnedValue(o->asReturnedValue());
}
 
bool QQmlDelegateModelGroupPrivate::parseIndex(const QV4::Value &value, int *index, Compositor::Group *group) const
{
    if (value.isNumber()) {
        *index = value.toInt32();
        return true;
    }
 
    if (!value.isObject())
        return false;
 
    QV4::ExecutionEngine *v4 = value.as<QV4::Object>()->engine();
    QV4::Scope scope(v4);
    QV4::Scoped<QQmlDelegateModelItemObject> object(scope, value);
 
    if (object) {
        QQmlDelegateModelItem * const cacheItem = object->d()->item;
        if (QQmlDelegateModelPrivate *model = cacheItem->metaType->model
                ? QQmlDelegateModelPrivate::get(cacheItem->metaType->model)
                : nullptr) {
            *index = model->m_cache.indexOf(cacheItem);
            *group = Compositor::Cache;
            return true;
        }
    }
    return false;
}
 
void QQmlDelegateModelGroup::insert(QQmlV4FunctionPtr args)
{
    Q_D(QQmlDelegateModelGroup);
    QQmlDelegateModelPrivate *model = QQmlDelegateModelPrivate::get(d->model);
 
    int index = model->m_compositor.count(d->group);
    Compositor::Group group = d->group;
 
    if (args->length() == 0)
        return;
 
    int  i = 0;
    QV4::Scope scope(args->v4engine());
    QV4::ScopedValue v(scope, (*args)[i]);
    if (d->parseIndex(v, &index, &group)) {
        if (index < 0 || index > model->m_compositor.count(group)) {
            qmlWarning(this) << tr("insert: index out of range");
            return;
        }
        if (++i == args->length())
            return;
        v = (*args)[i];
    }
 
    if (v->as<QV4::ArrayObject>())
        return;
 
    int groups = 1 << d->group;
    if (++i < args->length()) {
        QV4::ScopedValue val(scope, (*args)[i]);
        groups |= model->m_cacheMetaType->parseGroups(val);
    }
 
    if (v->as<QV4::Object>()) {
        auto insertionResult = QQmlDelegateModelPrivate::InsertionResult::Retry;
        do {
            Compositor::insert_iterator before = index < model->m_compositor.count(group)
                    ? model->m_compositor.findInsertPosition(group, index)
                    : model->m_compositor.end();
            insertionResult = model->insert(before, v, groups);
        } while (insertionResult == QQmlDelegateModelPrivate::InsertionResult::Retry);
        if (insertionResult == QQmlDelegateModelPrivate::InsertionResult::Success)
            model->emitChanges();
    }
}
 
void QQmlDelegateModelGroup::create(QQmlV4FunctionPtr args)
{
    Q_D(QQmlDelegateModelGroup);
    if (!d->model)
        return;
 
    if (args->length() == 0)
        return;
 
    QQmlDelegateModelPrivate *model = QQmlDelegateModelPrivate::get(d->model);
 
    int index = model->m_compositor.count(d->group);
    Compositor::Group group = d->group;
 
    int  i = 0;
    QV4::Scope scope(args->v4engine());
    QV4::ScopedValue v(scope, (*args)[i]);
    if (d->parseIndex(v, &index, &group))
        ++i;
 
    if (i < args->length() && index >= 0 && index <= model->m_compositor.count(group)) {
        v = (*args)[i];
        if (v->as<QV4::Object>()) {
            int groups = 1 << d->group;
            if (++i < args->length()) {
                QV4::ScopedValue val(scope, (*args)[i]);
                groups |= model->m_cacheMetaType->parseGroups(val);
            }
 
            auto insertionResult = QQmlDelegateModelPrivate::InsertionResult::Retry;
            do {
                Compositor::insert_iterator before = index < model->m_compositor.count(group)
                        ? model->m_compositor.findInsertPosition(group, index)
                        : model->m_compositor.end();
 
                index = before.index[d->group];
                group = d->group;
 
                insertionResult = model->insert(before, v, groups);
            } while (insertionResult == QQmlDelegateModelPrivate::InsertionResult::Retry);
            if (insertionResult == QQmlDelegateModelPrivate::InsertionResult::Error)
                return;
        }
    }
    if (index < 0 || index >= model->m_compositor.count(group)) {
        qmlWarning(this) << tr("create: index out of range");
        return;
    }
 
    QObject *object = model->object(group, index, QQmlIncubator::AsynchronousIfNested);
    if (object) {
        QVector<Compositor::Insert> inserts;
        Compositor::iterator it = model->m_compositor.find(group, index);
        model->m_compositor.setFlags(it, 1, d->group, Compositor::PersistedFlag, &inserts);
        model->itemsInserted(inserts);
        model->m_cache.at(it.cacheIndex())->releaseObject();
    }
 
    args->setReturnValue(QV4::QObjectWrapper::wrap(args->v4engine(), object));
    model->emitChanges();
}
 
void QQmlDelegateModelGroup::resolve(QQmlV4FunctionPtr args)
{
    Q_D(QQmlDelegateModelGroup);
    if (!d->model)
        return;
 
    QQmlDelegateModelPrivate *model = QQmlDelegateModelPrivate::get(d->model);
 
    if (args->length() < 2)
        return;
 
    int from = -1;
    int to = -1;
    Compositor::Group fromGroup = d->group;
    Compositor::Group toGroup = d->group;
 
    QV4::Scope scope(args->v4engine());
    QV4::ScopedValue v(scope, (*args)[0]);
    if (d->parseIndex(v, &from, &fromGroup)) {
        if (from < 0 || from >= model->m_compositor.count(fromGroup)) {
            qmlWarning(this) << tr("resolve: from index out of range");
            return;
        }
    } else {
        qmlWarning(this) << tr("resolve: from index invalid");
        return;
    }
 
    v = (*args)[1];
    if (d->parseIndex(v, &to, &toGroup)) {
        if (to < 0 || to >= model->m_compositor.count(toGroup)) {
            qmlWarning(this) << tr("resolve: to index out of range");
            return;
        }
    } else {
        qmlWarning(this) << tr("resolve: to index invalid");
        return;
    }
 
    Compositor::iterator fromIt = model->m_compositor.find(fromGroup, from);
    Compositor::iterator toIt = model->m_compositor.find(toGroup, to);
 
    if (!fromIt->isUnresolved()) {
        qmlWarning(this) << tr("resolve: from is not an unresolved item");
        return;
    }
    if (!toIt->list) {
        qmlWarning(this) << tr("resolve: to is not a model item");
        return;
    }
 
    const int unresolvedFlags = fromIt->flags;
    const int resolvedFlags = toIt->flags;
    const int resolvedIndex = toIt.modelIndex();
    void * const resolvedList = toIt->list;
 
    QQmlDelegateModelItem *cacheItem = model->m_cache.at(fromIt.cacheIndex());
    cacheItem->groups &= ~Compositor::UnresolvedFlag;
 
    if (toIt.cacheIndex() > fromIt.cacheIndex())
        toIt.decrementIndexes(1, unresolvedFlags);
    if (!toIt->inGroup(fromGroup) || toIt.index[fromGroup] > from)
        from += 1;
 
    model->itemsMoved(
            QVector<Compositor::Remove>(1, Compositor::Remove(fromIt, 1, unresolvedFlags, 0)),
            QVector<Compositor::Insert>(1, Compositor::Insert(toIt, 1, unresolvedFlags, 0)));
    model->itemsInserted(
            QVector<Compositor::Insert>(1, Compositor::Insert(toIt, 1, (resolvedFlags & ~unresolvedFlags) | Compositor::CacheFlag)));
    toIt.incrementIndexes(1, resolvedFlags | unresolvedFlags);
    model->itemsRemoved(QVector<Compositor::Remove>(1, Compositor::Remove(toIt, 1, resolvedFlags)));
 
    model->m_compositor.setFlags(toGroup, to, 1, unresolvedFlags & ~Compositor::UnresolvedFlag);
    model->m_compositor.clearFlags(fromGroup, from, 1, unresolvedFlags);
 
    if (resolvedFlags & Compositor::CacheFlag)
        model->m_compositor.insert(
                    Compositor::Cache, toIt.cacheIndex(), resolvedList,
                    resolvedIndex, 1, Compositor::CacheFlag);
 
    Q_ASSERT(model->m_cache.size() == model->m_compositor.count(Compositor::Cache));
 
    if (!cacheItem->isReferenced()) {
        Q_ASSERT(toIt.cacheIndex() == model->m_cache.indexOf(cacheItem));
        model->m_cache.removeAt(toIt.cacheIndex());
        model->m_compositor.clearFlags(
                    Compositor::Cache, toIt.cacheIndex(), 1, Compositor::CacheFlag);
        delete cacheItem;
        Q_ASSERT(model->m_cache.size() == model->m_compositor.count(Compositor::Cache));
    } else {
        cacheItem->resolveIndex(model->m_adaptorModel, resolvedIndex);
        if (cacheItem->attached)
            cacheItem->attached->emitUnresolvedChanged();
    }
 
    model->emitChanges();
}
 
void QQmlDelegateModelGroup::remove(QQmlV4FunctionPtr args)
{
    Q_D(QQmlDelegateModelGroup);
    if (!d->model)
        return;
    Compositor::Group group = d->group;
    int index = -1;
    int count = 1;
 
    if (args->length() == 0)
        return;
 
    int i = 0;
    QV4::Scope scope(args->v4engine());
    QV4::ScopedValue v(scope, (*args)[0]);
    if (!d->parseIndex(v, &index, &group)) {
        qmlWarning(this) << tr("remove: invalid index");
        return;
    }
 
    if (++i < args->length()) {
        v = (*args)[i];
        if (v->isNumber())
            count = v->toInt32();
    }
 
    QQmlDelegateModelPrivate *model = QQmlDelegateModelPrivate::get(d->model);
    if (index < 0 || index >= model->m_compositor.count(group)) {
        qmlWarning(this) << tr("remove: index out of range");
    } else if (count != 0) {
        Compositor::iterator it = model->m_compositor.find(group, index);
        if (count < 0 || count > model->m_compositor.count(d->group) - it.index[d->group]) {
            qmlWarning(this) << tr("remove: invalid count");
        } else {
            model->removeGroups(it, count, d->group, 1 << d->group);
        }
    }
}
 
bool QQmlDelegateModelGroupPrivate::parseGroupArgs(
        QQmlV4FunctionPtr args, Compositor::Group *group, int *index, int *count, int *groups) const
{
    if (!model || !QQmlDelegateModelPrivate::get(model)->m_cacheMetaType)
        return false;
 
    if (args->length() < 2)
        return false;
 
    int i = 0;
    QV4::Scope scope(args->v4engine());
    QV4::ScopedValue v(scope, (*args)[i]);
    if (!parseIndex(v, index, group))
        return false;
 
    v = (*args)[++i];
    if (v->isNumber()) {
        *count = v->toInt32();
 
        if (++i == args->length())
            return false;
        v = (*args)[i];
    }
 
    *groups = QQmlDelegateModelPrivate::get(model)->m_cacheMetaType->parseGroups(v);
 
    return true;
}
 
void QQmlDelegateModelGroup::addGroups(QQmlV4FunctionPtr args)
{
    Q_D(QQmlDelegateModelGroup);
    Compositor::Group group = d->group;
    int index = -1;
    int count = 1;
    int groups = 0;
 
    if (!d->parseGroupArgs(args, &group, &index, &count, &groups))
        return;
 
    QQmlDelegateModelPrivate *model = QQmlDelegateModelPrivate::get(d->model);
    if (index < 0 || index >= model->m_compositor.count(group)) {
        qmlWarning(this) << tr("addGroups: index out of range");
    } else if (count != 0) {
        Compositor::iterator it = model->m_compositor.find(group, index);
        if (count < 0 || count > model->m_compositor.count(d->group) - it.index[d->group]) {
            qmlWarning(this) << tr("addGroups: invalid count");
        } else {
            model->addGroups(it, count, d->group, groups);
        }
    }
}
 
void QQmlDelegateModelGroup::removeGroups(QQmlV4FunctionPtr args)
{
    Q_D(QQmlDelegateModelGroup);
    Compositor::Group group = d->group;
    int index = -1;
    int count = 1;
    int groups = 0;
 
    if (!d->parseGroupArgs(args, &group, &index, &count, &groups))
        return;
 
    QQmlDelegateModelPrivate *model = QQmlDelegateModelPrivate::get(d->model);
    if (index < 0 || index >= model->m_compositor.count(group)) {
        qmlWarning(this) << tr("removeGroups: index out of range");
    } else if (count != 0) {
        Compositor::iterator it = model->m_compositor.find(group, index);
        if (count < 0 || count > model->m_compositor.count(d->group) - it.index[d->group]) {
            qmlWarning(this) << tr("removeGroups: invalid count");
        } else {
            model->removeGroups(it, count, d->group, groups);
        }
    }
}
 
void QQmlDelegateModelGroup::setGroups(QQmlV4FunctionPtr args)
{
    Q_D(QQmlDelegateModelGroup);
    Compositor::Group group = d->group;
    int index = -1;
    int count = 1;
    int groups = 0;
 
    if (!d->parseGroupArgs(args, &group, &index, &count, &groups))
        return;
 
    QQmlDelegateModelPrivate *model = QQmlDelegateModelPrivate::get(d->model);
    if (index < 0 || index >= model->m_compositor.count(group)) {
        qmlWarning(this) << tr("setGroups: index out of range");
    } else if (count != 0) {
        Compositor::iterator it = model->m_compositor.find(group, index);
        if (count < 0 || count > model->m_compositor.count(d->group) - it.index[d->group]) {
            qmlWarning(this) << tr("setGroups: invalid count");
        } else {
            model->setGroups(it, count, d->group, groups);
        }
    }
}
 
void QQmlDelegateModelGroup::move(QQmlV4FunctionPtr args)
{
    Q_D(QQmlDelegateModelGroup);
 
    if (args->length() < 2)
        return;
 
    Compositor::Group fromGroup = d->group;
    Compositor::Group toGroup = d->group;
    int from = -1;
    int to = -1;
    int count = 1;
 
    QV4::Scope scope(args->v4engine());
    QV4::ScopedValue v(scope, (*args)[0]);
    if (!d->parseIndex(v, &from, &fromGroup)) {
        qmlWarning(this) << tr("move: invalid from index");
        return;
    }
 
    v = (*args)[1];
    if (!d->parseIndex(v, &to, &toGroup)) {
        qmlWarning(this) << tr("move: invalid to index");
        return;
    }
 
    if (args->length() > 2) {
        v = (*args)[2];
        if (v->isNumber())
            count = v->toInt32();
    }
 
    QQmlDelegateModelPrivate *model = QQmlDelegateModelPrivate::get(d->model);
 
    if (count < 0) {
        qmlWarning(this) << tr("move: invalid count");
    } else if (from < 0 || from + count > model->m_compositor.count(fromGroup)) {
        qmlWarning(this) << tr("move: from index out of range");
    } else if (!model->m_compositor.verifyMoveTo(fromGroup, from, toGroup, to, count, d->group)) {
        qmlWarning(this) << tr("move: to index out of range");
    } else if (count > 0) {
        QVector<Compositor::Remove> removes;
        QVector<Compositor::Insert> inserts;
 
        model->m_compositor.move(fromGroup, from, toGroup, to, count, d->group, &removes, &inserts);
        model->itemsMoved(removes, inserts);
        model->emitChanges();
    }
 
}
 
//============================================================================
 
QQmlPartsModel::QQmlPartsModel(QQmlDelegateModel *model, const QString &part, QObject *parent)
    : QQmlInstanceModel(*new QObjectPrivate, parent)
    , m_model(model)
    , m_part(part)
    , m_compositorGroup(Compositor::Cache)
    , m_inheritGroup(true)
{
    QQmlDelegateModelPrivate *d = QQmlDelegateModelPrivate::get(m_model);
    if (d->m_cacheMetaType) {
        QQmlDelegateModelGroupPrivate::get(d->m_groups[1])->emitters.insert(this);
        m_compositorGroup = Compositor::Default;
    } else {
        d->m_pendingParts.insert(this);
    }
}
 
QQmlPartsModel::~QQmlPartsModel()
{
}
 
QString QQmlPartsModel::filterGroup() const
{
    if (m_inheritGroup)
        return m_model->filterGroup();
    return m_filterGroup;
}
 
void QQmlPartsModel::setFilterGroup(const QString &group)
{
    if (QQmlDelegateModelPrivate::get(m_model)->m_transaction) {
        qmlWarning(this) << tr("The group of a DelegateModel cannot be changed within onChanged");
        return;
    }
 
    if (m_filterGroup != group || m_inheritGroup) {
        m_filterGroup = group;
        m_inheritGroup = false;
        updateFilterGroup();
 
        emit filterGroupChanged();
    }
}
 
void QQmlPartsModel::resetFilterGroup()
{
    if (!m_inheritGroup) {
        m_inheritGroup = true;
        updateFilterGroup();
        emit filterGroupChanged();
    }
}
 
void QQmlPartsModel::updateFilterGroup()
{
    QQmlDelegateModelPrivate *model = QQmlDelegateModelPrivate::get(m_model);
    if (!model->m_cacheMetaType)
        return;
 
    if (m_inheritGroup) {
        if (m_filterGroup == model->m_filterGroup)
            return;
        m_filterGroup = model->m_filterGroup;
    }
 
    QQmlListCompositor::Group previousGroup = m_compositorGroup;
    m_compositorGroup = Compositor::Default;
    QQmlDelegateModelGroupPrivate::get(model->m_groups[Compositor::Default])->emitters.insert(this);
    for (int i = 1; i < model->m_groupCount; ++i) {
        if (m_filterGroup == model->m_cacheMetaType->groupNames.at(i - 1)) {
            m_compositorGroup = Compositor::Group(i);
            break;
        }
    }
 
    QQmlDelegateModelGroupPrivate::get(model->m_groups[m_compositorGroup])->emitters.insert(this);
    if (m_compositorGroup != previousGroup) {
        QVector<QQmlChangeSet::Change> removes;
        QVector<QQmlChangeSet::Change> inserts;
        model->m_compositor.transition(previousGroup, m_compositorGroup, &removes, &inserts);
 
        QQmlChangeSet changeSet;
        changeSet.move(removes, inserts);
        if (!changeSet.isEmpty())
            emit modelUpdated(changeSet, false);
 
        if (changeSet.difference() != 0)
            emit countChanged();
    }
}
 
void QQmlPartsModel::updateFilterGroup(
        Compositor::Group group, const QQmlChangeSet &changeSet)
{
    if (!m_inheritGroup)
        return;
 
    m_compositorGroup = group;
    QQmlDelegateModelGroupPrivate::get(QQmlDelegateModelPrivate::get(m_model)->m_groups[m_compositorGroup])->emitters.insert(this);
 
    if (!changeSet.isEmpty())
        emit modelUpdated(changeSet, false);
 
    if (changeSet.difference() != 0)
        emit countChanged();
 
    emit filterGroupChanged();
}
 
int QQmlPartsModel::count() const
{
    QQmlDelegateModelPrivate *model = QQmlDelegateModelPrivate::get(m_model);
    return model->m_delegate
            ? model->m_compositor.count(m_compositorGroup)
            : 0;
}
 
bool QQmlPartsModel::isValid() const
{
    return m_model->isValid();
}
 
QObject *QQmlPartsModel::object(int index, QQmlIncubator::IncubationMode incubationMode)
{
    QQmlDelegateModelPrivate *model = QQmlDelegateModelPrivate::get(m_model);
 
    if (!model->m_delegate || index < 0 || index >= model->m_compositor.count(m_compositorGroup)) {
        qWarning() << "DelegateModel::item: index out range" << index << model->m_compositor.count(m_compositorGroup);
        return nullptr;
    }
 
    QObject *object = model->object(m_compositorGroup, index, incubationMode);
 
    if (QQuickPackage *package = qmlobject_cast<QQuickPackage *>(object)) {
        QObject *part = package->part(m_part);
        if (!part)
            return nullptr;
        m_packaged.insert(part, package);
        return part;
    }
 
    model->release(object);
    if (!model->m_delegateValidated) {
        if (object)
            qmlWarning(model->m_delegate) << tr("Delegate component must be Package type.");
        model->m_delegateValidated = true;
    }
 
    return nullptr;
}
 
QQmlInstanceModel::ReleaseFlags QQmlPartsModel::release(QObject *item, ReusableFlag)
{
    QQmlInstanceModel::ReleaseFlags flags;
 
    auto it = m_packaged.find(item);
    if (it != m_packaged.end()) {
        QQuickPackage *package = *it;
        QQmlDelegateModelPrivate *model = QQmlDelegateModelPrivate::get(m_model);
        flags = model->release(package);
        m_packaged.erase(it);
        if (!m_packaged.contains(item))
            flags &= ~Referenced;
        if (flags & Destroyed)
            QQmlDelegateModelPrivate::get(m_model)->emitDestroyingPackage(package);
    }
    return flags;
}
 
QVariant QQmlPartsModel::variantValue(int index, const QString &role)
{
    return QQmlDelegateModelPrivate::get(m_model)->variantValue(m_compositorGroup, index, role);
}
 
void QQmlPartsModel::setWatchedRoles(const QList<QByteArray> &roles)
{
    QQmlDelegateModelPrivate *model = QQmlDelegateModelPrivate::get(m_model);
    model->m_adaptorModel.replaceWatchedRoles(m_watchedRoles, roles);
    m_watchedRoles = roles;
}
 
QQmlIncubator::Status QQmlPartsModel::incubationStatus(int index)
{
    QQmlDelegateModelPrivate *model = QQmlDelegateModelPrivate::get(m_model);
    Compositor::iterator it = model->m_compositor.find(model->m_compositorGroup, index);
    if (!it->inCache())
        return QQmlIncubator::Null;
 
    if (auto incubationTask = model->m_cache.at(it.cacheIndex())->incubationTask)
        return incubationTask->status();
 
    return QQmlIncubator::Ready;
}
 
int QQmlPartsModel::indexOf(QObject *item, QObject *) const
{
    auto it = m_packaged.find(item);
    if (it != m_packaged.end()) {
        if (QQmlDelegateModelItem *cacheItem = QQmlDelegateModelItem::dataForObject(*it))
            return cacheItem->groupIndex(m_compositorGroup);
    }
    return -1;
}
 
void QQmlPartsModel::createdPackage(int index, QQuickPackage *package)
{
    emit createdItem(index, package->part(m_part));
}
 
void QQmlPartsModel::initPackage(int index, QQuickPackage *package)
{
    if (m_modelUpdatePending)
        m_pendingPackageInitializations << index;
    else
        emit initItem(index, package->part(m_part));
}
 
void QQmlPartsModel::destroyingPackage(QQuickPackage *package)
{
    QObject *item = package->part(m_part);
    Q_ASSERT(!m_packaged.contains(item));
    emit destroyingItem(item);
}
 
void QQmlPartsModel::emitModelUpdated(const QQmlChangeSet &changeSet, bool reset)
{
    m_modelUpdatePending = false;
    emit modelUpdated(changeSet, reset);
    if (changeSet.difference() != 0)
        emit countChanged();
 
    QQmlDelegateModelPrivate *model = QQmlDelegateModelPrivate::get(m_model);
    QVector<int> pendingPackageInitializations;
    qSwap(pendingPackageInitializations, m_pendingPackageInitializations);
    for (int index : pendingPackageInitializations) {
        if (!model->m_delegate || index < 0 || index >= model->m_compositor.count(m_compositorGroup))
            continue;
        QObject *object = model->object(m_compositorGroup, index, QQmlIncubator::Asynchronous);
        if (QQuickPackage *package = qmlobject_cast<QQuickPackage *>(object))
            emit initItem(index, package->part(m_part));
        model->release(object);
    }
}
 
void QQmlReusableDelegateModelItemsPool::insertItem(QQmlDelegateModelItem *modelItem)
{
    // Currently, the only way for a view to reuse items is to call release()
    // in the model class with the second argument explicitly set to
    // QQmlReuseableDelegateModelItemsPool::Reusable. If the released item is
    // no longer referenced, it will be added to the pool. Reusing of items can
    // be specified per item, in case certain items cannot be recycled. A
    // QQmlDelegateModelItem knows which delegate its object was created from.
    // So when we are about to create a new item, we first check if the pool
    // contains an item based on the same delegate from before. If so, we take
    // it out of the pool (instead of creating a new item), and update all its
    // context properties and attached properties.
 
    // When a view is recycling items, it should call drain() regularly. As
    // there is currently no logic to 'hibernate' items in the pool, they are
    // only meant to rest there for a short while, ideally only from the time
    // e.g a row is unloaded on one side of the view, and until a new row is
    // loaded on the opposite side. Between these times, the application will
    // see the item as fully functional and 'alive' (just not visible on
    // screen). Since this time is supposed to be short, we don't take any
    // action to notify the application about it, since we don't want to
    // trigger any bindings that can disturb performance.
 
    // A recommended time for calling drain() is each time a view has finished
    // loading e.g a new row or column. If there are more items in the pool
    // after that, it means that the view most likely doesn't need them anytime
    // soon. Those items should be destroyed to reduce resource consumption.
 
    // Depending on if a view is a list or a table, it can sometimes be
    // performant to keep items in the pool for a bit longer than one "row
    // out/row in" cycle. E.g for a table, if the number of visible rows in a
    // view is much larger than the number of visible columns. In that case, if
    // you flick out a row, and then flick in a column, you would throw away a
    // lot of items in the pool if completely draining it. The reason is that
    // unloading a row places more items in the pool than what ends up being
    // recycled when loading a new column. And then, when you next flick in a
    // new row, you would need to load all those drained items again from
    // scratch. For that reason, you can specify a maxPoolTime to the
    // drainReusableItemsPool() that allows you to keep items in the pool for a
    // bit longer, effectively keeping more items in circulation. A recommended
    // maxPoolTime would be equal to the number of dimensions in the view,
    // which means 1 for a list view and 2 for a table view. If you specify 0,
    // all items will be drained.
 
    Q_ASSERT(!modelItem->incubationTask);
    Q_ASSERT(!modelItem->isObjectReferenced());
    Q_ASSERT(modelItem->object);
    Q_ASSERT(modelItem->delegate);
 
    modelItem->poolTime = 0;
    m_reusableItemsPool.append(modelItem);
 
    qCDebug(lcItemViewDelegateRecycling)
            << "item:" << modelItem
            << "delegate:" << modelItem->delegate
            << "index:" << modelItem->modelIndex()
            << "row:" << modelItem->modelRow()
            << "column:" << modelItem->modelColumn()
            << "pool size:" << m_reusableItemsPool.size();
}
 
QQmlDelegateModelItem *QQmlReusableDelegateModelItemsPool::takeItem(const QQmlComponent *delegate, int newIndexHint)
{
    // Find the oldest item in the pool that was made from the same delegate as
    // the given argument, remove it from the pool, and return it.
    for (auto it = m_reusableItemsPool.begin(); it != m_reusableItemsPool.end(); ++it) {
        if ((*it)->delegate != delegate)
            continue;
        auto modelItem = *it;
        m_reusableItemsPool.erase(it);
 
        qCDebug(lcItemViewDelegateRecycling)
                << "item:" << modelItem
                << "delegate:" << delegate
                << "old index:" << modelItem->modelIndex()
                << "old row:" << modelItem->modelRow()
                << "old column:" << modelItem->modelColumn()
                << "new index:" << newIndexHint
                << "pool size:" << m_reusableItemsPool.size();
 
        return modelItem;
    }
 
    qCDebug(lcItemViewDelegateRecycling)
            << "no available item for delegate:" << delegate
            << "new index:" << newIndexHint
            << "pool size:" << m_reusableItemsPool.size();
 
    return nullptr;
}
 
void QQmlReusableDelegateModelItemsPool::drain(int maxPoolTime, std::function<void(QQmlDelegateModelItem *cacheItem)> releaseItem)
{
    // Rather than releasing all pooled items upon a call to this function, each
    // item has a poolTime. The poolTime specifies for how many loading cycles an item
    // has been resting in the pool. And for each invocation of this function, poolTime
    // will increase. If poolTime is equal to, or exceeds, maxPoolTime, it will be removed
    // from the pool and released. This way, the view can tweak a bit for how long
    // items should stay in "circulation", even if they are not recycled right away.
    qCDebug(lcItemViewDelegateRecycling) << "pool size before drain:" << m_reusableItemsPool.size();
 
    for (auto it = m_reusableItemsPool.begin(); it != m_reusableItemsPool.end();) {
        auto modelItem = *it;
        modelItem->poolTime++;
        if (modelItem->poolTime <= maxPoolTime) {
            ++it;
        } else {
            it = m_reusableItemsPool.erase(it);
            releaseItem(modelItem);
        }
    }
 
    qCDebug(lcItemViewDelegateRecycling) << "pool size after drain:" << m_reusableItemsPool.size();
}
 
//============================================================================
 
struct QQmlDelegateModelGroupChange : QV4::Object
{
    V4_OBJECT2(QQmlDelegateModelGroupChange, QV4::Object)
 
    static QV4::Heap::QQmlDelegateModelGroupChange *create(QV4::ExecutionEngine *e) {
        return e->memoryManager->allocate<QQmlDelegateModelGroupChange>();
    }
 
    static QV4::ReturnedValue method_get_index(const QV4::FunctionObject *b, const QV4::Value *thisObject, const QV4::Value *, int) {
        QV4::Scope scope(b);
        QV4::Scoped<QQmlDelegateModelGroupChange> that(scope, thisObject->as<QQmlDelegateModelGroupChange>());
        if (!that)
            THROW_TYPE_ERROR();
        return QV4::Encode(that->d()->change.index);
    }
    static QV4::ReturnedValue method_get_count(const QV4::FunctionObject *b, const QV4::Value *thisObject, const QV4::Value *, int) {
        QV4::Scope scope(b);
        QV4::Scoped<QQmlDelegateModelGroupChange> that(scope, thisObject->as<QQmlDelegateModelGroupChange>());
        if (!that)
            THROW_TYPE_ERROR();
        return QV4::Encode(that->d()->change.count);
    }
    static QV4::ReturnedValue method_get_moveId(const QV4::FunctionObject *b, const QV4::Value *thisObject, const QV4::Value *, int) {
        QV4::Scope scope(b);
        QV4::Scoped<QQmlDelegateModelGroupChange> that(scope, thisObject->as<QQmlDelegateModelGroupChange>());
        if (!that)
            THROW_TYPE_ERROR();
        if (that->d()->change.moveId < 0)
            RETURN_UNDEFINED();
        return QV4::Encode(that->d()->change.moveId);
    }
};
 
DEFINE_OBJECT_VTABLE(QQmlDelegateModelGroupChange);
 
struct QQmlDelegateModelGroupChangeArray : public QV4::Object
{
    V4_OBJECT2(QQmlDelegateModelGroupChangeArray, QV4::Object)
    V4_NEEDS_DESTROY
public:
    static QV4::Heap::QQmlDelegateModelGroupChangeArray *create(QV4::ExecutionEngine *engine, const QVector<QQmlChangeSet::Change> &changes)
    {
        return engine->memoryManager->allocate<QQmlDelegateModelGroupChangeArray>(changes);
    }
 
    quint32 count() const { return d()->changes->size(); }
    const QQmlChangeSet::Change &at(int index) const { return d()->changes->at(index); }
 
    static QV4::ReturnedValue virtualGet(const QV4::Managed *m, QV4::PropertyKey id, const QV4::Value *receiver, bool *hasProperty)
    {
        if (id.isArrayIndex()) {
            uint index = id.asArrayIndex();
            Q_ASSERT(m->as<QQmlDelegateModelGroupChangeArray>());
            QV4::ExecutionEngine *v4 = static_cast<const QQmlDelegateModelGroupChangeArray *>(m)->engine();
            QV4::Scope scope(v4);
            QV4::Scoped<QQmlDelegateModelGroupChangeArray> array(scope, static_cast<const QQmlDelegateModelGroupChangeArray *>(m));
 
            if (index >= array->count()) {
                if (hasProperty)
                    *hasProperty = false;
                return QV4::Value::undefinedValue().asReturnedValue();
            }
 
            const QQmlChangeSet::Change &change = array->at(index);
 
            QV4::ScopedObject changeProto(scope, qdmEngineData(v4)->changeProto.value());
            QV4::Scoped<QQmlDelegateModelGroupChange> object(scope, QQmlDelegateModelGroupChange::create(v4));
            object->setPrototypeOf(changeProto);
            object->d()->change = change;
 
            if (hasProperty)
                *hasProperty = true;
            return object.asReturnedValue();
        }
 
        Q_ASSERT(m->as<QQmlDelegateModelGroupChangeArray>());
        const QQmlDelegateModelGroupChangeArray *array = static_cast<const QQmlDelegateModelGroupChangeArray *>(m);
 
        if (id == array->engine()->id_length()->propertyKey()) {
            if (hasProperty)
                *hasProperty = true;
            return QV4::Encode(array->count());
        }
 
        return Object::virtualGet(m, id, receiver, hasProperty);
    }
};
 
void QV4::Heap::QQmlDelegateModelGroupChangeArray::init(const QVector<QQmlChangeSet::Change> &changes)
{
    Object::init();
    this->changes = new QVector<QQmlChangeSet::Change>(changes);
    QV4::Scope scope(internalClass->engine);
    QV4::ScopedObject o(scope, this);
    o->setArrayType(QV4::Heap::ArrayData::Custom);
}
 
DEFINE_OBJECT_VTABLE(QQmlDelegateModelGroupChangeArray);
 
QQmlDelegateModelEngineData::QQmlDelegateModelEngineData(QV4::ExecutionEngine *v4)
{
    QV4::Scope scope(v4);
 
    QV4::ScopedObject proto(scope, v4->newObject());
    proto->defineAccessorProperty(QStringLiteral("index"), QQmlDelegateModelGroupChange::method_get_index, nullptr);
    proto->defineAccessorProperty(QStringLiteral("count"), QQmlDelegateModelGroupChange::method_get_count, nullptr);
    proto->defineAccessorProperty(QStringLiteral("moveId"), QQmlDelegateModelGroupChange::method_get_moveId, nullptr);
    changeProto.set(v4, proto);
}
 
QQmlDelegateModelEngineData::~QQmlDelegateModelEngineData()
{
}
 
QV4::ReturnedValue QQmlDelegateModelEngineData::array(QV4::ExecutionEngine *v4,
                                                      const QVector<QQmlChangeSet::Change> &changes)
{
    QV4::Scope scope(v4);
    QV4::ScopedObject o(scope, QQmlDelegateModelGroupChangeArray::create(v4, changes));
    return o.asReturnedValue();
}
 
QT_END_NAMESPACE
 
#include "moc_qqmldelegatemodel_p_p.cpp"
 
#include "moc_qqmldelegatemodel_p.cpp"