qconcatenatetablesproxymodel.cpp

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// Copyright (C) 2016 Klarälvdalens Datakonsult AB, a KDAB Group company, info@kdab.com, author David Faure <david.faure@kdab.com>
// SPDX-License-Identifier: LicenseRef-Qt-Commercial OR LGPL-3.0-only OR GPL-2.0-only OR GPL-3.0-only
 
#include "qconcatenatetablesproxymodel.h"
#include <private/qabstractitemmodel_p.h>
#include "qsize.h"
#include "qmap.h"
#include "qdebug.h"
 
QT_BEGIN_NAMESPACE
 
class QConcatenateTablesProxyModelPrivate : public QAbstractItemModelPrivate
{
    Q_DECLARE_PUBLIC(QConcatenateTablesProxyModel);
 
public:
    QConcatenateTablesProxyModelPrivate();
 
    int computeRowsPrior(const QAbstractItemModel *sourceModel) const;
 
    struct SourceModelForRowResult
    {
        SourceModelForRowResult() : sourceModel(nullptr), sourceRow(-1) {}
        QAbstractItemModel *sourceModel;
        int sourceRow;
    };
    SourceModelForRowResult sourceModelForRow(int row) const;
 
    void _q_slotRowsAboutToBeInserted(const QModelIndex &, int start, int end);
    void _q_slotRowsInserted(const QModelIndex &, int start, int end);
    void _q_slotRowsAboutToBeRemoved(const QModelIndex &, int start, int end);
    void _q_slotRowsRemoved(const QModelIndex &, int start, int end);
    void _q_slotColumnsAboutToBeInserted(const QModelIndex &parent, int start, int end);
    void _q_slotColumnsInserted(const QModelIndex &parent, int, int);
    void _q_slotColumnsAboutToBeRemoved(const QModelIndex &parent, int start, int end);
    void _q_slotColumnsRemoved(const QModelIndex &parent, int, int);
    void _q_slotDataChanged(const QModelIndex &from, const QModelIndex &to, const QList<int> &roles);
    void _q_slotSourceLayoutAboutToBeChanged(const QList<QPersistentModelIndex> &sourceParents, QAbstractItemModel::LayoutChangeHint hint);
    void _q_slotSourceLayoutChanged(const QList<QPersistentModelIndex> &sourceParents, QAbstractItemModel::LayoutChangeHint hint);
    void _q_slotModelAboutToBeReset();
    void _q_slotModelReset();
    int columnCountAfterChange(const QAbstractItemModel *model, int newCount) const;
    int calculatedColumnCount() const;
    void updateColumnCount();
    bool mapDropCoordinatesToSource(int row, int column, const QModelIndex &parent,
                                    int *sourceRow, int *sourceColumn, QModelIndex *sourceParent, QAbstractItemModel **sourceModel) const;
 
    QList<QAbstractItemModel *> m_models;
    int m_rowCount; // have to maintain it here since we can't compute during model destruction
    int m_columnCount;
 
    // for columns{AboutToBe,}{Inserted,Removed}
    int m_newColumnCount;
 
    // for layoutAboutToBeChanged/layoutChanged
    QList<QPersistentModelIndex> layoutChangePersistentIndexes;
    QList<QModelIndex> layoutChangeProxyIndexes;
};
 
QConcatenateTablesProxyModelPrivate::QConcatenateTablesProxyModelPrivate()
    : m_rowCount(0),
      m_columnCount(0),
      m_newColumnCount(0)
{
}
 
QConcatenateTablesProxyModel::QConcatenateTablesProxyModel(QObject *parent)
    : QAbstractItemModel(*new QConcatenateTablesProxyModelPrivate, parent)
{
}
 
QConcatenateTablesProxyModel::~QConcatenateTablesProxyModel()
{
}
 
QModelIndex QConcatenateTablesProxyModel::mapFromSource(const QModelIndex &sourceIndex) const
{
    Q_D(const QConcatenateTablesProxyModel);
    if (!sourceIndex.isValid())
        return QModelIndex();
    const QAbstractItemModel *sourceModel = sourceIndex.model();
    if (!d->m_models.contains(const_cast<QAbstractItemModel *>(sourceModel))) {
        qWarning("QConcatenateTablesProxyModel: index from wrong model passed to mapFromSource");
        Q_ASSERT(!"QConcatenateTablesProxyModel: index from wrong model passed to mapFromSource");
        return QModelIndex();
    }
    if (sourceIndex.column() >= d->m_columnCount)
        return QModelIndex();
    int rowsPrior = d_func()->computeRowsPrior(sourceModel);
    return createIndex(rowsPrior + sourceIndex.row(), sourceIndex.column(), sourceIndex.internalPointer());
}
 
QModelIndex QConcatenateTablesProxyModel::mapToSource(const QModelIndex &proxyIndex) const
{
    Q_D(const QConcatenateTablesProxyModel);
    Q_ASSERT(checkIndex(proxyIndex));
    if (!proxyIndex.isValid())
        return QModelIndex();
    if (proxyIndex.model() != this) {
        qWarning("QConcatenateTablesProxyModel: index from wrong model passed to mapToSource");
        Q_ASSERT(!"QConcatenateTablesProxyModel: index from wrong model passed to mapToSource");
        return QModelIndex();
    }
    const int row = proxyIndex.row();
    const auto result = d->sourceModelForRow(row);
    if (!result.sourceModel)
        return QModelIndex();
    return result.sourceModel->index(result.sourceRow, proxyIndex.column());
}
 
QVariant QConcatenateTablesProxyModel::data(const QModelIndex &index, int role) const
{
    const QModelIndex sourceIndex = mapToSource(index);
    Q_ASSERT(checkIndex(index, CheckIndexOption::IndexIsValid));
    if (!sourceIndex.isValid())
        return QVariant();
    return sourceIndex.data(role);
}
 
bool QConcatenateTablesProxyModel::setData(const QModelIndex &index, const QVariant &value, int role)
{
    Q_ASSERT(checkIndex(index, CheckIndexOption::IndexIsValid));
    const QModelIndex sourceIndex = mapToSource(index);
    Q_ASSERT(sourceIndex.isValid());
    const auto sourceModel = const_cast<QAbstractItemModel *>(sourceIndex.model());
    return sourceModel->setData(sourceIndex, value, role);
}
 
QMap<int, QVariant> QConcatenateTablesProxyModel::itemData(const QModelIndex &proxyIndex) const
{
    Q_ASSERT(checkIndex(proxyIndex));
    const QModelIndex sourceIndex = mapToSource(proxyIndex);
    Q_ASSERT(sourceIndex.isValid());
    return sourceIndex.model()->itemData(sourceIndex);
}
 
bool QConcatenateTablesProxyModel::setItemData(const QModelIndex &proxyIndex, const QMap<int, QVariant> &roles)
{
    Q_ASSERT(checkIndex(proxyIndex));
    const QModelIndex sourceIndex = mapToSource(proxyIndex);
    Q_ASSERT(sourceIndex.isValid());
    const auto sourceModel = const_cast<QAbstractItemModel *>(sourceIndex.model());
    return sourceModel->setItemData(sourceIndex, roles);
}
 
Qt::ItemFlags QConcatenateTablesProxyModel::flags(const QModelIndex &index) const
{
    Q_D(const QConcatenateTablesProxyModel);
    if (d->m_models.isEmpty())
        return Qt::NoItemFlags;
    Q_ASSERT(checkIndex(index));
    if (!index.isValid())
        return d->m_models.at(0)->flags(index);
    const QModelIndex sourceIndex = mapToSource(index);
    Q_ASSERT(sourceIndex.isValid());
    return sourceIndex.model()->flags(sourceIndex);
}
 
QVariant QConcatenateTablesProxyModel::headerData(int section, Qt::Orientation orientation, int role) const
{
    Q_D(const QConcatenateTablesProxyModel);
    if (d->m_models.isEmpty())
        return QVariant();
    switch (orientation) {
        case Qt::Horizontal:
            return d->m_models.at(0)->headerData(section, orientation, role);
        case Qt::Vertical: {
            const auto result = d->sourceModelForRow(section);
            Q_ASSERT(result.sourceModel);
            return result.sourceModel->headerData(result.sourceRow, orientation, role);
        }
    }
    return QVariant();
}
 
int QConcatenateTablesProxyModel::columnCount(const QModelIndex &parent) const
{
    Q_D(const QConcatenateTablesProxyModel);
    if (parent.isValid())
        return 0; // flat model
    return d->m_columnCount;
}
 
QModelIndex QConcatenateTablesProxyModel::index(int row, int column, const QModelIndex &parent) const
{
    Q_D(const QConcatenateTablesProxyModel);
    Q_ASSERT(hasIndex(row, column, parent));
    if (!hasIndex(row, column, parent))
        return QModelIndex();
    Q_ASSERT(checkIndex(parent, QAbstractItemModel::CheckIndexOption::ParentIsInvalid)); // flat model
    const auto result = d->sourceModelForRow(row);
    Q_ASSERT(result.sourceModel);
    return mapFromSource(result.sourceModel->index(result.sourceRow, column));
}
 
QModelIndex QConcatenateTablesProxyModel::parent(const QModelIndex &index) const
{
    Q_UNUSED(index);
    return QModelIndex(); // flat model, no hierarchy
}
 
int QConcatenateTablesProxyModel::rowCount(const QModelIndex &parent) const
{
    Q_D(const QConcatenateTablesProxyModel);
    if (parent.isValid())
        return 0; // flat model
    return d->m_rowCount;
}
 
QStringList QConcatenateTablesProxyModel::mimeTypes() const
{
    Q_D(const QConcatenateTablesProxyModel);
    if (d->m_models.isEmpty())
        return QStringList();
    return d->m_models.at(0)->mimeTypes();
}
 
QMimeData *QConcatenateTablesProxyModel::mimeData(const QModelIndexList &indexes) const
{
    Q_D(const QConcatenateTablesProxyModel);
    if (indexes.isEmpty())
        return nullptr;
    const QModelIndex firstIndex = indexes.first();
    Q_ASSERT(checkIndex(firstIndex, CheckIndexOption::IndexIsValid));
    const auto result = d->sourceModelForRow(firstIndex.row());
    QModelIndexList sourceIndexes;
    sourceIndexes.reserve(indexes.size());
    for (const QModelIndex &index : indexes) {
        const QModelIndex sourceIndex = mapToSource(index);
        Q_ASSERT(sourceIndex.model() == result.sourceModel); // see documentation above
        sourceIndexes.append(sourceIndex);
    }
    return result.sourceModel->mimeData(sourceIndexes);
}
 
 
bool QConcatenateTablesProxyModelPrivate::mapDropCoordinatesToSource(int row, int column, const QModelIndex &parent,
                                                                     int *sourceRow, int *sourceColumn, QModelIndex *sourceParent, QAbstractItemModel **sourceModel) const
{
    Q_Q(const QConcatenateTablesProxyModel);
    *sourceColumn = column;
    if (!parent.isValid()) {
        // Drop after the last item
        if (row == -1 || row == m_rowCount) {
            *sourceRow = -1;
            *sourceModel = m_models.constLast();
            return true;
        }
        // Drop between toplevel items
        const auto result = sourceModelForRow(row);
        Q_ASSERT(result.sourceModel);
        *sourceRow = result.sourceRow;
        *sourceModel = result.sourceModel;
        return true;
    } else {
        if (row > -1)
            return false; // flat model, no dropping as new children of items
        // Drop onto item
        const int targetRow = parent.row();
        const auto result = sourceModelForRow(targetRow);
        Q_ASSERT(result.sourceModel);
        const QModelIndex sourceIndex = q->mapToSource(parent);
        *sourceRow = -1;
        *sourceParent = sourceIndex;
        *sourceModel = result.sourceModel;
        return true;
    }
}
 
bool QConcatenateTablesProxyModel::canDropMimeData(const QMimeData *data, Qt::DropAction action, int row, int column, const QModelIndex &parent) const
{
    Q_D(const QConcatenateTablesProxyModel);
    if (d->m_models.isEmpty())
        return false;
 
    int sourceRow, sourceColumn;
    QModelIndex sourceParent;
    QAbstractItemModel *sourceModel;
    if (!d->mapDropCoordinatesToSource(row, column, parent, &sourceRow, &sourceColumn, &sourceParent, &sourceModel))
        return false;
    return sourceModel->canDropMimeData(data, action, sourceRow, sourceColumn, sourceParent);
}
 
bool QConcatenateTablesProxyModel::dropMimeData(const QMimeData *data, Qt::DropAction action, int row, int column, const QModelIndex &parent)
{
    Q_D(const QConcatenateTablesProxyModel);
    if (d->m_models.isEmpty())
        return false;
    int sourceRow, sourceColumn;
    QModelIndex sourceParent;
    QAbstractItemModel *sourceModel;
    if (!d->mapDropCoordinatesToSource(row, column, parent, &sourceRow, &sourceColumn, &sourceParent, &sourceModel))
        return false;
 
    return sourceModel->dropMimeData(data, action, sourceRow, sourceColumn, sourceParent);
}
 
QSize QConcatenateTablesProxyModel::span(const QModelIndex &index) const
{
    Q_D(const QConcatenateTablesProxyModel);
    Q_ASSERT(checkIndex(index));
    if (d->m_models.isEmpty() || !index.isValid())
        return QSize();
    const QModelIndex sourceIndex = mapToSource(index);
    Q_ASSERT(sourceIndex.isValid());
    return sourceIndex.model()->span(sourceIndex);
}
 
QList<QAbstractItemModel *> QConcatenateTablesProxyModel::sourceModels() const
{
    Q_D(const QConcatenateTablesProxyModel);
    return d->m_models.toList();
}
 
void QConcatenateTablesProxyModel::addSourceModel(QAbstractItemModel *sourceModel)
{
    Q_D(QConcatenateTablesProxyModel);
    Q_ASSERT(sourceModel);
    Q_ASSERT(!d->m_models.contains(sourceModel));
    connect(sourceModel, SIGNAL(dataChanged(QModelIndex,QModelIndex,QList<int>)), this, SLOT(_q_slotDataChanged(QModelIndex,QModelIndex,QList<int>)));
    connect(sourceModel, SIGNAL(rowsInserted(QModelIndex,int,int)), this, SLOT(_q_slotRowsInserted(QModelIndex,int,int)));
    connect(sourceModel, SIGNAL(rowsRemoved(QModelIndex,int,int)), this, SLOT(_q_slotRowsRemoved(QModelIndex,int,int)));
    connect(sourceModel, SIGNAL(rowsAboutToBeInserted(QModelIndex,int,int)), this, SLOT(_q_slotRowsAboutToBeInserted(QModelIndex,int,int)));
    connect(sourceModel, SIGNAL(rowsAboutToBeRemoved(QModelIndex,int,int)), this, SLOT(_q_slotRowsAboutToBeRemoved(QModelIndex,int,int)));
 
    connect(sourceModel, SIGNAL(columnsInserted(QModelIndex,int,int)), this, SLOT(_q_slotColumnsInserted(QModelIndex,int,int)));
    connect(sourceModel, SIGNAL(columnsRemoved(QModelIndex,int,int)), this, SLOT(_q_slotColumnsRemoved(QModelIndex,int,int)));
    connect(sourceModel, SIGNAL(columnsAboutToBeInserted(QModelIndex,int,int)), this, SLOT(_q_slotColumnsAboutToBeInserted(QModelIndex,int,int)));
    connect(sourceModel, SIGNAL(columnsAboutToBeRemoved(QModelIndex,int,int)), this, SLOT(_q_slotColumnsAboutToBeRemoved(QModelIndex,int,int)));
 
    connect(sourceModel, SIGNAL(layoutAboutToBeChanged(QList<QPersistentModelIndex>, QAbstractItemModel::LayoutChangeHint)),
            this, SLOT(_q_slotSourceLayoutAboutToBeChanged(QList<QPersistentModelIndex>, QAbstractItemModel::LayoutChangeHint)));
    connect(sourceModel, SIGNAL(layoutChanged(QList<QPersistentModelIndex>, QAbstractItemModel::LayoutChangeHint)),
            this, SLOT(_q_slotSourceLayoutChanged(QList<QPersistentModelIndex>, QAbstractItemModel::LayoutChangeHint)));
    connect(sourceModel, SIGNAL(modelAboutToBeReset()), this, SLOT(_q_slotModelAboutToBeReset()));
    connect(sourceModel, SIGNAL(modelReset()), this, SLOT(_q_slotModelReset()));
 
    const int newRows = sourceModel->rowCount();
    if (newRows > 0)
        beginInsertRows(QModelIndex(), d->m_rowCount, d->m_rowCount + newRows - 1);
    d->m_rowCount += newRows;
    d->m_models.append(sourceModel);
    if (newRows > 0)
        endInsertRows();
 
    d->updateColumnCount();
}
 
void QConcatenateTablesProxyModel::removeSourceModel(QAbstractItemModel *sourceModel)
{
    Q_D(QConcatenateTablesProxyModel);
    Q_ASSERT(d->m_models.contains(sourceModel));
    disconnect(sourceModel, nullptr, this, nullptr);
 
    const int rowsRemoved = sourceModel->rowCount();
    const int rowsPrior = d->computeRowsPrior(sourceModel);   // location of removed section
 
    if (rowsRemoved > 0)
        beginRemoveRows(QModelIndex(), rowsPrior, rowsPrior + rowsRemoved - 1);
    d->m_models.removeOne(sourceModel);
    d->m_rowCount -= rowsRemoved;
    if (rowsRemoved > 0)
        endRemoveRows();
 
    d->updateColumnCount();
}
 
void QConcatenateTablesProxyModelPrivate::_q_slotRowsAboutToBeInserted(const QModelIndex &parent, int start, int end)
{
    Q_Q(QConcatenateTablesProxyModel);
    if (parent.isValid()) // not supported, the proxy is a flat model
        return;
    const QAbstractItemModel * const model = static_cast<QAbstractItemModel *>(q->sender());
    const int rowsPrior = computeRowsPrior(model);
    q->beginInsertRows(QModelIndex(), rowsPrior + start, rowsPrior + end);
}
 
void QConcatenateTablesProxyModelPrivate::_q_slotRowsInserted(const QModelIndex &parent, int start, int end)
{
    Q_Q(QConcatenateTablesProxyModel);
    if (parent.isValid()) // flat model
        return;
    m_rowCount += end - start + 1;
    q->endInsertRows();
}
 
void QConcatenateTablesProxyModelPrivate::_q_slotRowsAboutToBeRemoved(const QModelIndex &parent, int start, int end)
{
    Q_Q(QConcatenateTablesProxyModel);
    if (parent.isValid()) // flat model
        return;
    const QAbstractItemModel * const model = static_cast<QAbstractItemModel *>(q->sender());
    const int rowsPrior = computeRowsPrior(model);
    q->beginRemoveRows(QModelIndex(), rowsPrior + start, rowsPrior + end);
}
 
void QConcatenateTablesProxyModelPrivate::_q_slotRowsRemoved(const QModelIndex &parent, int start, int end)
{
    Q_Q(QConcatenateTablesProxyModel);
    if (parent.isValid()) // flat model
        return;
    m_rowCount -= end - start + 1;
    q->endRemoveRows();
}
 
void QConcatenateTablesProxyModelPrivate::_q_slotColumnsAboutToBeInserted(const QModelIndex &parent, int start, int end)
{
    Q_Q(QConcatenateTablesProxyModel);
    if (parent.isValid()) // flat model
        return;
    const QAbstractItemModel * const model = static_cast<QAbstractItemModel *>(q->sender());
    const int oldColCount = model->columnCount();
    const int newColCount = columnCountAfterChange(model, oldColCount + end - start + 1);
    Q_ASSERT(newColCount >= oldColCount);
    if (newColCount > oldColCount)
        // If the underlying models have a different number of columns (example: 2 and 3), inserting 2 columns in
        // the first model leads to inserting only one column in the proxy, since qMin(2+2,3) == 3.
        q->beginInsertColumns(QModelIndex(), start, qMin(end, start + newColCount - oldColCount - 1));
    m_newColumnCount = newColCount;
}
 
void QConcatenateTablesProxyModelPrivate::_q_slotColumnsInserted(const QModelIndex &parent, int start, int end)
{
    Q_UNUSED(start);
    Q_UNUSED(end);
    Q_Q(QConcatenateTablesProxyModel);
    if (parent.isValid()) // flat model
        return;
    if (m_newColumnCount != m_columnCount) {
        m_columnCount = m_newColumnCount;
        q->endInsertColumns();
    }
}
 
void QConcatenateTablesProxyModelPrivate::_q_slotColumnsAboutToBeRemoved(const QModelIndex &parent, int start, int end)
{
    Q_Q(QConcatenateTablesProxyModel);
    if (parent.isValid()) // flat model
        return;
    const QAbstractItemModel * const model = static_cast<QAbstractItemModel *>(q->sender());
    const int oldColCount = model->columnCount();
    const int newColCount = columnCountAfterChange(model, oldColCount - (end - start + 1));
    Q_ASSERT(newColCount <= oldColCount);
    if (newColCount < oldColCount)
        q->beginRemoveColumns(QModelIndex(), start, qMax(end, start + oldColCount - newColCount - 1));
    m_newColumnCount = newColCount;
}
 
void QConcatenateTablesProxyModelPrivate::_q_slotColumnsRemoved(const QModelIndex &parent, int start, int end)
{
    Q_Q(QConcatenateTablesProxyModel);
    Q_UNUSED(start);
    Q_UNUSED(end);
    if (parent.isValid()) // flat model
        return;
    if (m_newColumnCount != m_columnCount) {
        m_columnCount = m_newColumnCount;
        q->endRemoveColumns();
    }
}
 
void QConcatenateTablesProxyModelPrivate::_q_slotDataChanged(const QModelIndex &from, const QModelIndex &to, const QList<int> &roles)
{
    Q_Q(QConcatenateTablesProxyModel);
    Q_ASSERT(from.isValid());
    Q_ASSERT(to.isValid());
    if (from.column() >= m_columnCount)
        return;
    QModelIndex adjustedTo = to;
    if (to.column() >= m_columnCount)
        adjustedTo = to.siblingAtColumn(m_columnCount - 1);
    const QModelIndex myFrom = q->mapFromSource(from);
    Q_ASSERT(q->checkIndex(myFrom, QAbstractItemModel::CheckIndexOption::IndexIsValid));
    const QModelIndex myTo = q->mapFromSource(adjustedTo);
    Q_ASSERT(q->checkIndex(myTo, QAbstractItemModel::CheckIndexOption::IndexIsValid));
    emit q->dataChanged(myFrom, myTo, roles);
}
 
void QConcatenateTablesProxyModelPrivate::_q_slotSourceLayoutAboutToBeChanged(const QList<QPersistentModelIndex> &sourceParents, QAbstractItemModel::LayoutChangeHint hint)
{
    Q_Q(QConcatenateTablesProxyModel);
 
    if (!sourceParents.isEmpty() && !sourceParents.contains(QModelIndex()))
        return;
 
    emit q->layoutAboutToBeChanged({}, hint);
 
    const QModelIndexList persistentIndexList = q->persistentIndexList();
    layoutChangePersistentIndexes.reserve(persistentIndexList.size());
    layoutChangeProxyIndexes.reserve(persistentIndexList.size());
 
    for (const QModelIndex &proxyPersistentIndex : persistentIndexList) {
        layoutChangeProxyIndexes.append(proxyPersistentIndex);
        Q_ASSERT(proxyPersistentIndex.isValid());
        const QPersistentModelIndex srcPersistentIndex = q->mapToSource(proxyPersistentIndex);
        Q_ASSERT(srcPersistentIndex.isValid());
        layoutChangePersistentIndexes << srcPersistentIndex;
    }
}
 
void QConcatenateTablesProxyModelPrivate::_q_slotSourceLayoutChanged(const QList<QPersistentModelIndex> &sourceParents, QAbstractItemModel::LayoutChangeHint hint)
{
    Q_Q(QConcatenateTablesProxyModel);
    if (!sourceParents.isEmpty() && !sourceParents.contains(QModelIndex()))
        return;
    for (int i = 0; i < layoutChangeProxyIndexes.size(); ++i) {
        const QModelIndex proxyIdx = layoutChangeProxyIndexes.at(i);
        const QModelIndex newProxyIdx = q->mapFromSource(layoutChangePersistentIndexes.at(i));
        q->changePersistentIndex(proxyIdx, newProxyIdx);
    }
 
    layoutChangePersistentIndexes.clear();
    layoutChangeProxyIndexes.clear();
 
    emit q->layoutChanged({}, hint);
}
 
void QConcatenateTablesProxyModelPrivate::_q_slotModelAboutToBeReset()
{
    Q_Q(QConcatenateTablesProxyModel);
    Q_ASSERT(m_models.contains(const_cast<QAbstractItemModel *>(static_cast<const QAbstractItemModel *>(q->sender()))));
    q->beginResetModel();
    // A reset might reduce both rowCount and columnCount, and we can't notify of both at the same time,
    // and notifying of one after the other leaves an intermediary invalid situation.
    // So the only safe choice is to forward it as a full reset.
}
 
void QConcatenateTablesProxyModelPrivate::_q_slotModelReset()
{
    Q_Q(QConcatenateTablesProxyModel);
    Q_ASSERT(m_models.contains(const_cast<QAbstractItemModel *>(static_cast<const QAbstractItemModel *>(q->sender()))));
    m_columnCount = calculatedColumnCount();
    m_rowCount = computeRowsPrior(nullptr);
    q->endResetModel();
}
 
int QConcatenateTablesProxyModelPrivate::calculatedColumnCount() const
{
    if (m_models.isEmpty())
        return 0;
 
    const auto it = std::min_element(m_models.begin(), m_models.end(), [](const QAbstractItemModel* model1, const QAbstractItemModel* model2) {
                        return model1->columnCount() < model2->columnCount();
                    });
    return (*it)->columnCount();
}
 
void QConcatenateTablesProxyModelPrivate::updateColumnCount()
{
    Q_Q(QConcatenateTablesProxyModel);
    const int newColumnCount = calculatedColumnCount();
    const int columnDiff = newColumnCount - m_columnCount;
    if (columnDiff > 0) {
        q->beginInsertColumns(QModelIndex(), m_columnCount, m_columnCount + columnDiff - 1);
        m_columnCount = newColumnCount;
        q->endInsertColumns();
    } else if (columnDiff < 0) {
        const int lastColumn = m_columnCount - 1;
        q->beginRemoveColumns(QModelIndex(), lastColumn + columnDiff + 1, lastColumn);
        m_columnCount = newColumnCount;
        q->endRemoveColumns();
    }
}
 
int QConcatenateTablesProxyModelPrivate::columnCountAfterChange(const QAbstractItemModel *model, int newCount) const
{
    int newColumnCount = 0;
    for (int i = 0; i < m_models.size(); ++i) {
        const QAbstractItemModel *mod = m_models.at(i);
        const int colCount = mod == model ? newCount : mod->columnCount();
        if (i == 0)
            newColumnCount = colCount;
        else
            newColumnCount = qMin(colCount, newColumnCount);
    }
    return newColumnCount;
}
 
int QConcatenateTablesProxyModelPrivate::computeRowsPrior(const QAbstractItemModel *sourceModel) const
{
    int rowsPrior = 0;
    for (const QAbstractItemModel *model : m_models) {
        if (model == sourceModel)
            break;
        rowsPrior += model->rowCount();
    }
    return rowsPrior;
}
 
QConcatenateTablesProxyModelPrivate::SourceModelForRowResult QConcatenateTablesProxyModelPrivate::sourceModelForRow(int row) const
{
    QConcatenateTablesProxyModelPrivate::SourceModelForRowResult result;
    int rowCount = 0;
    for (QAbstractItemModel *model : m_models) {
        const int subRowCount = model->rowCount();
        if (rowCount + subRowCount > row) {
            result.sourceModel = model;
            break;
        }
        rowCount += subRowCount;
    }
    result.sourceRow = row - rowCount;
    return result;
}
 
QT_END_NAMESPACE
 
#include "moc_qconcatenatetablesproxymodel.cpp"