qitemselectionmodel.cpp

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// Copyright (C) 2021 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 "qitemselectionmodel.h"
#include "qitemselectionmodel_p.h"
 
#include <private/qitemselectionmodel_p.h>
#include <private/qabstractitemmodel_p.h>
#include <private/qduplicatetracker_p.h>
#include <private/qoffsetstringarray_p.h>
#include <qdebug.h>
 
#include <algorithm>
#include <functional>
 
QT_BEGIN_NAMESPACE
 
QT_IMPL_METATYPE_EXTERN(QItemSelectionRange)
QT_IMPL_METATYPE_EXTERN(QItemSelection)
 
 
bool QItemSelectionRange::intersects(const QItemSelectionRange &other) const
{
    // isValid() and parent() last since they are more expensive
    return (model() == other.model()
            && ((top() <= other.top() && bottom() >= other.top())
                || (top() >= other.top() && top() <= other.bottom()))
            && ((left() <= other.left() && right() >= other.left())
                || (left() >= other.left() && left() <= other.right()))
            && parent() == other.parent()
            && isValid() && other.isValid()
            );
}
 
QItemSelectionRange QItemSelectionRange::intersected(const QItemSelectionRange &other) const
{
    if (model() == other.model() && parent() == other.parent()) {
        QModelIndex topLeft = model()->index(qMax(top(), other.top()),
                                             qMax(left(), other.left()),
                                             other.parent());
        QModelIndex bottomRight = model()->index(qMin(bottom(), other.bottom()),
                                                 qMin(right(), other.right()),
                                                 other.parent());
        return QItemSelectionRange(topLeft, bottomRight);
    }
    return QItemSelectionRange();
}
 
static void rowLengthsFromRange(const QItemSelectionRange &range, QList<std::pair<QPersistentModelIndex, uint>> &result)
{
    if (range.isValid() && range.model()) {
        const QModelIndex topLeft = range.topLeft();
        const int bottom = range.bottom();
        const uint width = range.width();
        const int column = topLeft.column();
        for (int row = topLeft.row(); row <= bottom; ++row) {
            // We don't need to keep track of ItemIsSelectable and ItemIsEnabled here. That is
            // required in indexesFromRange() because that method is called from public API
            // which requires the limitation.
            result.emplace_back(topLeft.sibling(row, column), width);
        }
    }
}
 
static bool isSelectableAndEnabled(Qt::ItemFlags flags)
{
    return flags.testFlags(Qt::ItemIsSelectable | Qt::ItemIsEnabled);
}
 
template<typename ModelIndexContainer>
static void indexesFromRange(const QItemSelectionRange &range, ModelIndexContainer &result)
{
    if (range.isValid() && range.model()) {
        const QModelIndex topLeft = range.topLeft();
        const int bottom = range.bottom();
        const int right = range.right();
        for (int row = topLeft.row(); row <= bottom; ++row) {
            const QModelIndex columnLeader = topLeft.sibling(row, topLeft.column());
            for (int column = topLeft.column(); column <= right; ++column) {
                QModelIndex index = columnLeader.sibling(row, column);
                if (isSelectableAndEnabled(range.model()->flags(index)))
                    result.push_back(index);
            }
        }
    }
}
 
template<typename ModelIndexContainer>
static ModelIndexContainer qSelectionIndexes(const QItemSelection &selection)
{
    ModelIndexContainer result;
    for (const auto &range : selection)
        indexesFromRange(range, result);
    return result;
}
 
bool QItemSelectionRange::isEmpty() const
{
    if (!isValid() || !model())
        return true;
 
    for (int column = left(); column <= right(); ++column) {
        for (int row = top(); row <= bottom(); ++row) {
            QModelIndex index = model()->index(row, column, parent());
            if (isSelectableAndEnabled(model()->flags(index)))
                return false;
        }
    }
    return true;
}
 
QModelIndexList QItemSelectionRange::indexes() const
{
    QModelIndexList result;
    indexesFromRange(*this, result);
    return result;
}
 
QItemSelection::QItemSelection(const QModelIndex &topLeft, const QModelIndex &bottomRight)
{
    select(topLeft, bottomRight);
}
 
void QItemSelection::select(const QModelIndex &topLeft, const QModelIndex &bottomRight)
{
    if (!topLeft.isValid() || !bottomRight.isValid())
        return;
 
    if ((topLeft.model() != bottomRight.model())
        || topLeft.parent() != bottomRight.parent()) {
        qWarning("Can't select indexes from different model or with different parents");
        return;
    }
    if (topLeft.row() > bottomRight.row() || topLeft.column() > bottomRight.column()) {
        int top = qMin(topLeft.row(), bottomRight.row());
        int bottom = qMax(topLeft.row(), bottomRight.row());
        int left = qMin(topLeft.column(), bottomRight.column());
        int right = qMax(topLeft.column(), bottomRight.column());
        QModelIndex tl = topLeft.sibling(top, left);
        QModelIndex br = bottomRight.sibling(bottom, right);
        append(QItemSelectionRange(tl, br));
        return;
    }
    append(QItemSelectionRange(topLeft, bottomRight));
}
 
bool QItemSelection::contains(const QModelIndex &index) const
{
    if (isSelectableAndEnabled(index.flags())) {
        QList<QItemSelectionRange>::const_iterator it = begin();
        for (; it != end(); ++it)
            if ((*it).contains(index))
                return true;
    }
    return false;
}
 
QModelIndexList QItemSelection::indexes() const
{
    return qSelectionIndexes<QModelIndexList>(*this);
}
 
static QList<std::pair<QPersistentModelIndex, uint>> qSelectionPersistentRowLengths(const QItemSelection &sel)
{
    QList<std::pair<QPersistentModelIndex, uint>> result;
    for (const QItemSelectionRange &range : sel)
        rowLengthsFromRange(range, result);
    return result;
}
 
void QItemSelection::merge(const QItemSelection &other, QItemSelectionModel::SelectionFlags command)
{
    if (other.isEmpty() ||
          !(command & QItemSelectionModel::Select ||
          command & QItemSelectionModel::Deselect ||
          command & QItemSelectionModel::Toggle))
        return;
 
    QItemSelection newSelection;
    newSelection.reserve(other.size());
    // Collect intersections
    QItemSelection intersections;
    for (const auto &range : other) {
        if (!range.isValid())
            continue;
        newSelection.push_back(range);
        for (int t = 0; t < size(); ++t) {
            if (range.intersects(at(t)))
                intersections.append(at(t).intersected(range));
        }
    }
 
    //  Split the old (and new) ranges using the intersections
    for (int i = 0; i < intersections.size(); ++i) { // for each intersection
        for (int t = 0; t < size();) { // splitt each old range
            if (at(t).intersects(intersections.at(i))) {
                split(at(t), intersections.at(i), this);
                removeAt(t);
            } else {
                ++t;
            }
        }
        // only split newSelection if Toggle is specified
        for (int n = 0; (command & QItemSelectionModel::Toggle) && n < newSelection.size();) {
            if (newSelection.at(n).intersects(intersections.at(i))) {
                split(newSelection.at(n), intersections.at(i), &newSelection);
                newSelection.removeAt(n);
            } else {
                ++n;
            }
        }
    }
    // do not add newSelection for Deselect
    if (!(command & QItemSelectionModel::Deselect))
        operator+=(newSelection);
}
 
void QItemSelection::split(const QItemSelectionRange &range,
                           const QItemSelectionRange &other, QItemSelection *result)
{
    if (range.parent() != other.parent() || range.model() != other.model())
        return;
 
    QModelIndex parent = other.parent();
    int top = range.top();
    int left = range.left();
    int bottom = range.bottom();
    int right = range.right();
    int other_top = other.top();
    int other_left = other.left();
    int other_bottom = other.bottom();
    int other_right = other.right();
    const QAbstractItemModel *model = range.model();
    Q_ASSERT(model);
    if (other_top > top) {
        QModelIndex tl = model->index(top, left, parent);
        QModelIndex br = model->index(other_top - 1, right, parent);
        result->append(QItemSelectionRange(tl, br));
        top = other_top;
    }
    if (other_bottom < bottom) {
        QModelIndex tl = model->index(other_bottom + 1, left, parent);
        QModelIndex br = model->index(bottom, right, parent);
        result->append(QItemSelectionRange(tl, br));
        bottom = other_bottom;
    }
    if (other_left > left) {
        QModelIndex tl = model->index(top, left, parent);
        QModelIndex br = model->index(bottom, other_left - 1, parent);
        result->append(QItemSelectionRange(tl, br));
        left = other_left;
    }
    if (other_right < right) {
        QModelIndex tl = model->index(top, other_right + 1, parent);
        QModelIndex br = model->index(bottom, right, parent);
        result->append(QItemSelectionRange(tl, br));
        right = other_right;
    }
}
 
 
void QItemSelectionModelPrivate::initModel(QAbstractItemModel *m)
{
    Q_Q(QItemSelectionModel);
    const QAbstractItemModel *oldModel = model.valueBypassingBindings();
    if (oldModel == m)
        return;
 
    if (oldModel) {
        q->reset();
        disconnectModel();
    }
 
    // Caller has to call notify(), unless calling during construction (the common case).
    model.setValueBypassingBindings(m);
 
    if (m) {
        connections = std::array<QMetaObject::Connection, 12> {
            QObjectPrivate::connect(m, &QAbstractItemModel::rowsAboutToBeRemoved,
                                    this, &QItemSelectionModelPrivate::rowsAboutToBeRemoved),
            QObjectPrivate::connect(m, &QAbstractItemModel::columnsAboutToBeRemoved,
                                    this, &QItemSelectionModelPrivate::columnsAboutToBeRemoved),
            QObjectPrivate::connect(m, &QAbstractItemModel::rowsAboutToBeInserted,
                                    this, &QItemSelectionModelPrivate::rowsAboutToBeInserted),
            QObjectPrivate::connect(m, &QAbstractItemModel::columnsAboutToBeInserted,
                                    this, &QItemSelectionModelPrivate::columnsAboutToBeInserted),
            QObjectPrivate::connect(m, &QAbstractItemModel::rowsAboutToBeMoved,
                                    this, &QItemSelectionModelPrivate::triggerLayoutToBeChanged),
            QObjectPrivate::connect(m, &QAbstractItemModel::columnsAboutToBeMoved,
                                    this, &QItemSelectionModelPrivate::triggerLayoutToBeChanged),
            QObjectPrivate::connect(m, &QAbstractItemModel::rowsMoved,
                                    this, &QItemSelectionModelPrivate::triggerLayoutChanged),
            QObjectPrivate::connect(m, &QAbstractItemModel::columnsMoved,
                                    this, &QItemSelectionModelPrivate::triggerLayoutChanged),
            QObjectPrivate::connect(m, &QAbstractItemModel::layoutAboutToBeChanged,
                                    this, &QItemSelectionModelPrivate::layoutAboutToBeChanged),
            QObjectPrivate::connect(m, &QAbstractItemModel::layoutChanged,
                                    this, &QItemSelectionModelPrivate::layoutChanged),
            QObject::connect(m, &QAbstractItemModel::modelReset,
                             q, &QItemSelectionModel::reset),
            QObjectPrivate::connect(m, &QAbstractItemModel::destroyed,
                                    this, &QItemSelectionModelPrivate::modelDestroyed)
        };
    }
}
 
void QItemSelectionModelPrivate::disconnectModel()
{
    for (auto &connection : connections)
        QObject::disconnect(connection);
}
 
QItemSelection QItemSelectionModelPrivate::expandSelection(const QItemSelection &selection,
                                                           QItemSelectionModel::SelectionFlags command) const
{
    if (selection.isEmpty() && !((command & QItemSelectionModel::Rows) ||
                                 (command & QItemSelectionModel::Columns)))
        return selection;
 
    QItemSelection expanded;
    if (command & QItemSelectionModel::Rows) {
        for (int i = 0; i < selection.size(); ++i) {
            QModelIndex parent = selection.at(i).parent();
            int colCount = model->columnCount(parent);
            QModelIndex tl = model->index(selection.at(i).top(), 0, parent);
            QModelIndex br = model->index(selection.at(i).bottom(), colCount - 1, parent);
            //we need to merge because the same row could have already been inserted
            expanded.merge(QItemSelection(tl, br), QItemSelectionModel::Select);
        }
    }
    if (command & QItemSelectionModel::Columns) {
        for (int i = 0; i < selection.size(); ++i) {
            QModelIndex parent = selection.at(i).parent();
            int rowCount = model->rowCount(parent);
            QModelIndex tl = model->index(0, selection.at(i).left(), parent);
            QModelIndex br = model->index(rowCount - 1, selection.at(i).right(), parent);
            //we need to merge because the same column could have already been inserted
            expanded.merge(QItemSelection(tl, br), QItemSelectionModel::Select);
        }
    }
    return expanded;
}
 
void QItemSelectionModelPrivate::rowsAboutToBeRemoved(const QModelIndex &parent,
                                                         int start, int end)
{
    Q_Q(QItemSelectionModel);
    Q_ASSERT(start <= end);
    finalize();
 
    // update current index
    if (currentIndex.isValid() && parent == currentIndex.parent()
        && currentIndex.row() >= start && currentIndex.row() <= end) {
        QModelIndex old = currentIndex;
        if (start > 0) {
            // there are rows left above the change
            currentIndex = model->index(start - 1, old.column(), parent);
        } else if (model.value() && end < model->rowCount(parent) - 1) {
            // there are rows left below the change
            currentIndex = model->index(end + 1, old.column(), parent);
        } else {
            // there are no rows left in the table
            currentIndex = QModelIndex();
        }
        emit q->currentChanged(currentIndex, old);
        emit q->currentRowChanged(currentIndex, old);
        if (currentIndex.column() != old.column())
            emit q->currentColumnChanged(currentIndex, old);
    }
 
    QItemSelection deselected;
    QItemSelection newParts;
    bool indexesOfSelectionChanged = false;
    QItemSelection::iterator it = ranges.begin();
    while (it != ranges.end()) {
        if (it->topLeft().parent() != parent) {  // Check parents until reaching root or contained in range
            QModelIndex itParent = it->topLeft().parent();
            while (itParent.isValid() && itParent.parent() != parent)
                itParent = itParent.parent();
 
            if (itParent.isValid() && start <= itParent.row() && itParent.row() <= end) {
                deselected.append(*it);
                it = ranges.erase(it);
            } else {
                if (itParent.isValid() && end < itParent.row())
                    indexesOfSelectionChanged = true;
                ++it;
            }
        } else if (start <= it->bottom() && it->bottom() <= end    // Full inclusion
                   && start <= it->top() && it->top() <= end) {
            deselected.append(*it);
            it = ranges.erase(it);
        } else if (start <= it->top() && it->top() <= end) {      // Top intersection
            deselected.append(QItemSelectionRange(it->topLeft(), model->index(end, it->right(), it->parent())));
            *it = QItemSelectionRange(model->index(end + 1, it->left(), it->parent()), it->bottomRight());
            ++it;
        } else if (start <= it->bottom() && it->bottom() <= end) {    // Bottom intersection
            deselected.append(QItemSelectionRange(model->index(start, it->left(), it->parent()), it->bottomRight()));
            *it = QItemSelectionRange(it->topLeft(), model->index(start - 1, it->right(), it->parent()));
            ++it;
        } else if (it->top() < start && end < it->bottom()) { // Middle intersection
            // If the parent contains (1, 2, 3, 4, 5, 6, 7, 8) and [3, 4, 5, 6] is selected,
            // and [4, 5] is removed, we need to split [3, 4, 5, 6] into [3], [4, 5] and [6].
            // [4, 5] is appended to deselected, and [3] and [6] remain part of the selection
            // in ranges.
            const QItemSelectionRange removedRange(model->index(start, it->left(), it->parent()),
                                                    model->index(end, it->right(), it->parent()));
            deselected.append(removedRange);
            QItemSelection::split(*it, removedRange, &newParts);
            it = ranges.erase(it);
        } else if (end < it->top()) { // deleted row before selection
            indexesOfSelectionChanged = true;
            ++it;
        } else {
            ++it;
        }
    }
    ranges.append(newParts);
 
    if (!deselected.isEmpty() || indexesOfSelectionChanged)
        emit q->selectionChanged(QItemSelection(), deselected);
}
 
void QItemSelectionModelPrivate::columnsAboutToBeRemoved(const QModelIndex &parent,
                                                            int start, int end)
{
    Q_Q(QItemSelectionModel);
 
    // update current index
    if (currentIndex.isValid() && parent == currentIndex.parent()
        && currentIndex.column() >= start && currentIndex.column() <= end) {
        QModelIndex old = currentIndex;
        if (start > 0) {
            // there are columns to the left of the change
            currentIndex = model->index(old.row(), start - 1, parent);
        } else if (model.value() && end < model->columnCount() - 1) {
            // there are columns to the right of the change
            currentIndex = model->index(old.row(), end + 1, parent);
        } else {
            // there are no columns left in the table
            currentIndex = QModelIndex();
        }
        emit q->currentChanged(currentIndex, old);
        if (currentIndex.row() != old.row())
            emit q->currentRowChanged(currentIndex, old);
        emit q->currentColumnChanged(currentIndex, old);
    }
 
    // update selections
    QModelIndex tl = model->index(0, start, parent);
    QModelIndex br = model->index(model->rowCount(parent) - 1, end, parent);
    q->select(QItemSelection(tl, br), QItemSelectionModel::Deselect);
    finalize();
}
 
void QItemSelectionModelPrivate::columnsAboutToBeInserted(const QModelIndex &parent,
                                                             int start, int end)
{
    Q_UNUSED(end);
    finalize();
    QList<QItemSelectionRange> split;
    QList<QItemSelectionRange>::iterator it = ranges.begin();
    for (; it != ranges.end(); ) {
        const QModelIndex &itParent = it->parent();
        if ((*it).isValid() && itParent == parent
            && (*it).left() < start && (*it).right() >= start) {
            QModelIndex bottomMiddle = model->index((*it).bottom(), start - 1, itParent);
            QItemSelectionRange left((*it).topLeft(), bottomMiddle);
            QModelIndex topMiddle = model->index((*it).top(), start, itParent);
            QItemSelectionRange right(topMiddle, (*it).bottomRight());
            it = ranges.erase(it);
            split.append(left);
            split.append(right);
        } else {
            ++it;
        }
    }
    ranges += split;
}
 
void QItemSelectionModelPrivate::rowsAboutToBeInserted(const QModelIndex &parent,
                                                          int start, int end)
{
    Q_Q(QItemSelectionModel);
    Q_UNUSED(end);
    finalize();
    QList<QItemSelectionRange> split;
    QList<QItemSelectionRange>::iterator it = ranges.begin();
    bool indexesOfSelectionChanged = false;
    for (; it != ranges.end(); ) {
        const QModelIndex &itParent = it->parent();
        if ((*it).isValid() && itParent == parent
            && (*it).top() < start && (*it).bottom() >= start) {
            QModelIndex middleRight = model->index(start - 1, (*it).right(), itParent);
            QItemSelectionRange top((*it).topLeft(), middleRight);
            QModelIndex middleLeft = model->index(start, (*it).left(), itParent);
            QItemSelectionRange bottom(middleLeft, (*it).bottomRight());
            it = ranges.erase(it);
            split.append(top);
            split.append(bottom);
        } else if ((*it).isValid() && itParent == parent      // insertion before selection
            && (*it).top() >= start) {
            indexesOfSelectionChanged = true;
            ++it;
        } else {
            ++it;
        }
    }
    ranges += split;
 
    if (indexesOfSelectionChanged)
        emit q->selectionChanged(QItemSelection(), QItemSelection());
}
 
void QItemSelectionModelPrivate::layoutAboutToBeChanged(const QList<QPersistentModelIndex> &,
                                                        QAbstractItemModel::LayoutChangeHint hint)
{
    savedPersistentIndexes.clear();
    savedPersistentCurrentIndexes.clear();
    savedPersistentRowLengths.clear();
    savedPersistentCurrentRowLengths.clear();
 
    // optimization for when all indexes are selected
    // (only if there is lots of items (1000) because this is not entirely correct)
    if (ranges.isEmpty() && currentSelection.size() == 1) {
        QItemSelectionRange range = currentSelection.constFirst();
        QModelIndex parent = range.parent();
        tableRowCount = model->rowCount(parent);
        tableColCount = model->columnCount(parent);
        if (tableRowCount * tableColCount > 1000
            && range.top() == 0
            && range.left() == 0
            && range.bottom() == tableRowCount - 1
            && range.right() == tableColCount - 1) {
            tableSelected = true;
            tableParent = parent;
            return;
        }
    }
    tableSelected = false;
 
    if (hint == QAbstractItemModel::VerticalSortHint) {
        // Special case when we know we're sorting vertically. We can assume that all indexes for columns
        // are displaced the same way, and therefore we only need to track an index from one column per
        // row with a QPersistentModelIndex together with the length of items to the right of it
        // which are displaced the same way.
        // An algorithm which contains the same assumption is used to process layoutChanged.
        savedPersistentRowLengths = qSelectionPersistentRowLengths(ranges);
        savedPersistentCurrentRowLengths = qSelectionPersistentRowLengths(currentSelection);
    } else {
        savedPersistentIndexes = qSelectionIndexes<QList<QPersistentModelIndex>>(ranges);
        savedPersistentCurrentIndexes = qSelectionIndexes<QList<QPersistentModelIndex>>(currentSelection);
    }
}
static QItemSelection mergeRowLengths(const QList<std::pair<QPersistentModelIndex, uint>> &rowLengths)
{
    if (rowLengths.isEmpty())
      return QItemSelection();
 
    QItemSelection result;
    int i = 0;
    while (i < rowLengths.size()) {
        const QPersistentModelIndex &tl = rowLengths.at(i).first;
        if (!tl.isValid()) {
            ++i;
            continue;
        }
        QPersistentModelIndex br = tl;
        const uint length = rowLengths.at(i).second;
        while (++i < rowLengths.size()) {
            const QPersistentModelIndex &next = rowLengths.at(i).first;
            if (!next.isValid())
                continue;
            const uint nextLength = rowLengths.at(i).second;
            if ((nextLength == length)
                && (next.row() == br.row() + 1)
                && (next.column() == br.column())
                && (next.parent() == br.parent())) {
                br = next;
            } else {
                break;
            }
        }
        result.append(QItemSelectionRange(tl, br.sibling(br.row(), br.column() + length - 1)));
    }
    return result;
}
 
static QItemSelection mergeIndexes(const QList<QPersistentModelIndex> &indexes)
{
    QItemSelection colSpans;
    // merge columns
    int i = 0;
    while (i < indexes.size()) {
        const QPersistentModelIndex &tl = indexes.at(i);
        if (!tl.isValid()) {
            ++i;
            continue;
        }
        QPersistentModelIndex br = tl;
        QModelIndex brParent = br.parent();
        int brRow = br.row();
        int brColumn = br.column();
        while (++i < indexes.size()) {
            const QPersistentModelIndex &next = indexes.at(i);
            if (!next.isValid())
                continue;
            const QModelIndex nextParent = next.parent();
            const int nextRow = next.row();
            const int nextColumn = next.column();
            if ((nextParent == brParent)
                 && (nextRow == brRow)
                 && (nextColumn == brColumn + 1)) {
                br = next;
                brParent = nextParent;
                brRow = nextRow;
                brColumn = nextColumn;
            } else {
                break;
            }
        }
        colSpans.append(QItemSelectionRange(tl, br));
    }
    // merge rows
    QItemSelection rowSpans;
    i = 0;
    while (i < colSpans.size()) {
        QModelIndex tl = colSpans.at(i).topLeft();
        QModelIndex br = colSpans.at(i).bottomRight();
        QModelIndex prevTl = tl;
        while (++i < colSpans.size()) {
            QModelIndex nextTl = colSpans.at(i).topLeft();
            QModelIndex nextBr = colSpans.at(i).bottomRight();
 
            if (nextTl.parent() != tl.parent())
                break; // we can't merge selection ranges from different parents
 
            if ((nextTl.column() == prevTl.column()) && (nextBr.column() == br.column())
                && (nextTl.row() == prevTl.row() + 1) && (nextBr.row() == br.row() + 1)) {
                br = nextBr;
                prevTl = nextTl;
            } else {
                break;
            }
        }
        rowSpans.append(QItemSelectionRange(tl, br));
    }
    return rowSpans;
}
 
static bool qt_PersistentModelIndexLessThan(const QPersistentModelIndex &i1, const QPersistentModelIndex &i2)
{
    const QModelIndex parent1 = i1.parent();
    const QModelIndex parent2 = i2.parent();
    return parent1 == parent2 ? i1 < i2 : parent1 < parent2;
}
 
void QItemSelectionModelPrivate::layoutChanged(const QList<QPersistentModelIndex> &, QAbstractItemModel::LayoutChangeHint hint)
{
    // special case for when all indexes are selected
    if (tableSelected && tableColCount == model->columnCount(tableParent)
        && tableRowCount == model->rowCount(tableParent)) {
        ranges.clear();
        currentSelection.clear();
        int bottom = tableRowCount - 1;
        int right = tableColCount - 1;
        QModelIndex tl = model->index(0, 0, tableParent);
        QModelIndex br = model->index(bottom, right, tableParent);
        currentSelection << QItemSelectionRange(tl, br);
        tableParent = QModelIndex();
        tableSelected = false;
        return;
    }
 
    if ((hint != QAbstractItemModel::VerticalSortHint && savedPersistentCurrentIndexes.isEmpty() && savedPersistentIndexes.isEmpty())
     || (hint == QAbstractItemModel::VerticalSortHint && savedPersistentRowLengths.isEmpty() && savedPersistentCurrentRowLengths.isEmpty())) {
        // either the selection was actually empty, or we
        // didn't get the layoutAboutToBeChanged() signal
        return;
    }
 
    // clear the "old" selection
    ranges.clear();
    currentSelection.clear();
 
    if (hint != QAbstractItemModel::VerticalSortHint) {
        // sort the "new" selection, as preparation for merging
        std::stable_sort(savedPersistentIndexes.begin(), savedPersistentIndexes.end(),
                         qt_PersistentModelIndexLessThan);
        std::stable_sort(savedPersistentCurrentIndexes.begin(), savedPersistentCurrentIndexes.end(),
                         qt_PersistentModelIndexLessThan);
 
        // update the selection by merging the individual indexes
        ranges = mergeIndexes(savedPersistentIndexes);
        currentSelection = mergeIndexes(savedPersistentCurrentIndexes);
 
        // release the persistent indexes
        savedPersistentIndexes.clear();
        savedPersistentCurrentIndexes.clear();
    } else {
        // sort the "new" selection, as preparation for merging
        std::stable_sort(savedPersistentRowLengths.begin(), savedPersistentRowLengths.end());
        std::stable_sort(savedPersistentCurrentRowLengths.begin(), savedPersistentCurrentRowLengths.end());
 
        // update the selection by merging the individual indexes
        ranges = mergeRowLengths(savedPersistentRowLengths);
        currentSelection = mergeRowLengths(savedPersistentCurrentRowLengths);
 
        // release the persistent indexes
        savedPersistentRowLengths.clear();
        savedPersistentCurrentRowLengths.clear();
    }
}
 
void QItemSelectionModelPrivate::modelDestroyed()
{
    model.setValueBypassingBindings(nullptr);
    disconnectModel();
    model.notify();
}
 
QItemSelectionModel::QItemSelectionModel(QAbstractItemModel *model)
    : QObject(*new QItemSelectionModelPrivate, model)
{
    d_func()->initModel(model);
}
 
QItemSelectionModel::QItemSelectionModel(QAbstractItemModel *model, QObject *parent)
    : QObject(*new QItemSelectionModelPrivate, parent)
{
    d_func()->initModel(model);
}
 
QItemSelectionModel::QItemSelectionModel(QItemSelectionModelPrivate &dd, QAbstractItemModel *model)
    : QObject(dd, model)
{
    dd.initModel(model);
}
 
QItemSelectionModel::~QItemSelectionModel()
{
}
 
void QItemSelectionModel::select(const QModelIndex &index, QItemSelectionModel::SelectionFlags command)
{
    QItemSelection selection(index, index);
    select(selection, command);
}
 
namespace {
namespace QtFunctionObjects {
struct IsNotValid {
    typedef bool result_type;
    struct is_transparent : std::true_type {};
    template <typename T>
    constexpr bool operator()(T &t) const noexcept(noexcept(t.isValid()))
    { return !t.isValid(); }
    template <typename T>
    constexpr bool operator()(T *t) const noexcept(noexcept(t->isValid()))
    { return !t->isValid(); }
};
}
} // unnamed namespace
 
void QItemSelectionModel::select(const QItemSelection &selection, QItemSelectionModel::SelectionFlags command)
{
    Q_D(QItemSelectionModel);
    if (!d->model.value()) {
        qWarning("QItemSelectionModel: Selecting when no model has been set will result in a no-op.");
        return;
    }
    if (command == NoUpdate)
        return;
 
    // store old selection
    QItemSelection sel = selection;
    // If d->ranges is non-empty when the source model is reset the persistent indexes
    // it contains will be invalid. We can't clear them in a modelReset slot because that might already
    // be too late if another model observer is connected to the same modelReset slot and is invoked first
    // it might call select() on this selection model before any such QItemSelectionModelPrivate::modelReset() slot
    // is invoked, so it would not be cleared yet. We clear it invalid ranges in it here.
    d->ranges.removeIf(QtFunctionObjects::IsNotValid());
 
    QItemSelection old = d->ranges;
    old.merge(d->currentSelection, d->currentCommand);
 
    // expand selection according to SelectionBehavior
    if (command & Rows || command & Columns)
        sel = d->expandSelection(sel, command);
 
    // clear ranges and currentSelection
    if (command & Clear) {
        d->ranges.clear();
        d->currentSelection.clear();
    }
 
    // merge and clear currentSelection if Current was not set (ie. start new currentSelection)
    if (!(command & Current))
        d->finalize();
 
    // update currentSelection
    if (command & Toggle || command & Select || command & Deselect) {
        d->currentCommand = command;
        d->currentSelection = sel;
    }
 
    // generate new selection, compare with old and emit selectionChanged()
    QItemSelection newSelection = d->ranges;
    newSelection.merge(d->currentSelection, d->currentCommand);
    emitSelectionChanged(newSelection, old);
}
 
void QItemSelectionModel::clear()
{
    clearSelection();
    clearCurrentIndex();
}
 
void QItemSelectionModel::clearCurrentIndex()
{
    Q_D(QItemSelectionModel);
    QModelIndex previous = d->currentIndex;
    d->currentIndex = QModelIndex();
    if (previous.isValid()) {
        emit currentChanged(d->currentIndex, previous);
        emit currentRowChanged(d->currentIndex, previous);
        emit currentColumnChanged(d->currentIndex, previous);
    }
}
 
void QItemSelectionModel::reset()
{
    const QSignalBlocker blocker(this);
    clear();
}
 
void QItemSelectionModel::clearSelection()
{
    Q_D(QItemSelectionModel);
    if (d->ranges.size() == 0 && d->currentSelection.size() == 0)
        return;
 
    select(QItemSelection(), Clear);
}
 
 
void QItemSelectionModel::setCurrentIndex(const QModelIndex &index, QItemSelectionModel::SelectionFlags command)
{
    Q_D(QItemSelectionModel);
    if (!d->model.value()) {
        qWarning("QItemSelectionModel: Setting the current index when no model has been set will result in a no-op.");
        return;
    }
    if (index == d->currentIndex) {
        if (command != NoUpdate)
            select(index, command); // select item
        return;
    }
    QPersistentModelIndex previous = d->currentIndex;
    d->currentIndex = index; // set current before emitting selection changed below
    if (command != NoUpdate)
        select(d->currentIndex, command); // select item
    emit currentChanged(d->currentIndex, previous);
    if (d->currentIndex.row() != previous.row() ||
            d->currentIndex.parent() != previous.parent())
        emit currentRowChanged(d->currentIndex, previous);
    if (d->currentIndex.column() != previous.column() ||
            d->currentIndex.parent() != previous.parent())
        emit currentColumnChanged(d->currentIndex, previous);
}
 
QModelIndex QItemSelectionModel::currentIndex() const
{
    return static_cast<QModelIndex>(d_func()->currentIndex);
}
 
bool QItemSelectionModel::isSelected(const QModelIndex &index) const
{
    Q_D(const QItemSelectionModel);
    if (d->model != index.model() || !index.isValid())
        return false;
 
    bool selected = false;
    //  search model ranges
    QList<QItemSelectionRange>::const_iterator it = d->ranges.begin();
    for (; it != d->ranges.end(); ++it) {
        if ((*it).isValid() && (*it).contains(index)) {
            selected = true;
            break;
        }
    }
 
    // check  currentSelection
    if (d->currentSelection.size()) {
        if ((d->currentCommand & Deselect) && selected)
            selected = !d->currentSelection.contains(index);
        else if (d->currentCommand & Toggle)
            selected ^= d->currentSelection.contains(index);
        else if ((d->currentCommand & Select) && !selected)
            selected = d->currentSelection.contains(index);
    }
 
    if (selected)
        return isSelectableAndEnabled(d->model->flags(index));
 
    return false;
}
 
bool QItemSelectionModel::isRowSelected(int row, const QModelIndex &parent) const
{
    Q_D(const QItemSelectionModel);
    if (!d->model.value())
        return false;
    if (parent.isValid() && d->model != parent.model())
        return false;
 
    // return false if row exist in currentSelection (Deselect)
    if (d->currentCommand & Deselect && d->currentSelection.size()) {
        for (int i=0; i<d->currentSelection.size(); ++i) {
            if (d->currentSelection.at(i).parent() == parent &&
                row >= d->currentSelection.at(i).top() &&
                row <= d->currentSelection.at(i).bottom())
                return false;
        }
    }
    // return false if ranges in both currentSelection and ranges
    // intersect and have the same row contained
    if (d->currentCommand & Toggle && d->currentSelection.size()) {
        for (int i=0; i<d->currentSelection.size(); ++i)
            if (d->currentSelection.at(i).top() <= row &&
                d->currentSelection.at(i).bottom() >= row)
                for (int j=0; j<d->ranges.size(); ++j)
                    if (d->ranges.at(j).top() <= row && d->ranges.at(j).bottom() >= row
                        && d->currentSelection.at(i).intersected(d->ranges.at(j)).isValid())
                        return false;
    }
 
    auto isSelectable = [&](int row, int column) {
        return isSelectableAndEnabled(d->model->index(row, column, parent).flags());
    };
 
    const int colCount = d->model->columnCount(parent);
    int unselectable = 0;
    // add ranges and currentSelection and check through them all
    QList<QItemSelectionRange>::const_iterator it;
    QList<QItemSelectionRange> joined = d->ranges;
    if (d->currentSelection.size())
        joined += d->currentSelection;
    for (int column = 0; column < colCount; ++column) {
        if (!isSelectable(row, column)) {
            ++unselectable;
            continue;
        }
 
        for (it = joined.constBegin(); it != joined.constEnd(); ++it) {
            if ((*it).contains(row, column, parent)) {
                for (int i = column; i <= (*it).right(); ++i) {
                    if (!isSelectable(row, i))
                        ++unselectable;
                }
 
                column = qMax(column, (*it).right());
                break;
            }
        }
        if (it == joined.constEnd())
            return false;
    }
    return unselectable < colCount;
}
 
bool QItemSelectionModel::isColumnSelected(int column, const QModelIndex &parent) const
{
    Q_D(const QItemSelectionModel);
    if (!d->model.value())
        return false;
    if (parent.isValid() && d->model != parent.model())
        return false;
 
    // return false if column exist in currentSelection (Deselect)
    if (d->currentCommand & Deselect && d->currentSelection.size()) {
        for (int i = 0; i < d->currentSelection.size(); ++i) {
            if (d->currentSelection.at(i).parent() == parent &&
                column >= d->currentSelection.at(i).left() &&
                column <= d->currentSelection.at(i).right())
                return false;
        }
    }
    // return false if ranges in both currentSelection and the selection model
    // intersect and have the same column contained
    if (d->currentCommand & Toggle && d->currentSelection.size()) {
        for (int i = 0; i < d->currentSelection.size(); ++i) {
            if (d->currentSelection.at(i).left() <= column &&
                d->currentSelection.at(i).right() >= column) {
                for (int j = 0; j < d->ranges.size(); ++j) {
                    if (d->ranges.at(j).left() <= column && d->ranges.at(j).right() >= column
                        && d->currentSelection.at(i).intersected(d->ranges.at(j)).isValid()) {
                        return false;
                    }
                }
            }
        }
    }
 
    auto isSelectable = [&](int row, int column) {
        return isSelectableAndEnabled(d->model->index(row, column, parent).flags());
    };
    const int rowCount = d->model->rowCount(parent);
    int unselectable = 0;
 
    // add ranges and currentSelection and check through them all
    QList<QItemSelectionRange>::const_iterator it;
    QList<QItemSelectionRange> joined = d->ranges;
    if (d->currentSelection.size())
        joined += d->currentSelection;
    for (int row = 0; row < rowCount; ++row) {
        if (!isSelectable(row, column)) {
            ++unselectable;
            continue;
        }
        for (it = joined.constBegin(); it != joined.constEnd(); ++it) {
            if ((*it).contains(row, column, parent)) {
                for (int i = row; i <= (*it).bottom(); ++i) {
                    if (!isSelectable(i, column)) {
                        ++unselectable;
                    }
                }
                row = qMax(row, (*it).bottom());
                break;
            }
        }
        if (it == joined.constEnd())
            return false;
    }
    return unselectable < rowCount;
}
 
bool QItemSelectionModel::rowIntersectsSelection(int row, const QModelIndex &parent) const
{
    Q_D(const QItemSelectionModel);
    if (!d->model.value())
        return false;
    if (parent.isValid() && d->model != parent.model())
         return false;
 
    QItemSelection sel = d->ranges;
    sel.merge(d->currentSelection, d->currentCommand);
    for (const QItemSelectionRange &range : std::as_const(sel)) {
        if (range.parent() != parent)
            return false;
        int top = range.top();
        int bottom = range.bottom();
        int left = range.left();
        int right = range.right();
        if (top <= row && bottom >= row) {
            for (int j = left; j <= right; j++) {
                if (isSelectableAndEnabled(d->model->index(row, j, parent).flags()))
                    return true;
            }
        }
    }
 
    return false;
}
 
bool QItemSelectionModel::columnIntersectsSelection(int column, const QModelIndex &parent) const
{
    Q_D(const QItemSelectionModel);
    if (!d->model.value())
        return false;
    if (parent.isValid() && d->model != parent.model())
        return false;
 
    QItemSelection sel = d->ranges;
    sel.merge(d->currentSelection, d->currentCommand);
    for (const QItemSelectionRange &range : std::as_const(sel)) {
        if (range.parent() != parent)
            return false;
        int top = range.top();
        int bottom = range.bottom();
        int left = range.left();
        int right = range.right();
        if (left <= column && right >= column) {
            for (int j = top; j <= bottom; j++) {
                if (isSelectableAndEnabled(d->model->index(j, column, parent).flags()))
                    return true;
            }
        }
    }
 
    return false;
}
 
static bool selectionIsEmpty(const QItemSelection &selection)
{
    return std::all_of(selection.begin(), selection.end(),
                       [](const QItemSelectionRange &r) { return r.isEmpty(); });
}
 
bool QItemSelectionModel::hasSelection() const
{
    Q_D(const QItemSelectionModel);
 
    // QTreeModel unfortunately sorts itself lazily.
    // When it sorts itself, it emits are layoutChanged signal.
    // This layoutChanged signal invalidates d->ranges here.
    // So QTreeModel must not sort itself while we are iterating over
    // d->ranges here. It sorts itself in executePendingOperations,
    // thus preventing the sort to happen inside of selectionIsEmpty below.
    // Sad story, read more in QTBUG-94546
    const QAbstractItemModel *model = QItemSelectionModel::model();
    if (model != nullptr) {
        auto model_p = static_cast<const QAbstractItemModelPrivate *>(QObjectPrivate::get(model));
        model_p->executePendingOperations();
    }
 
    if (d->currentCommand & (Toggle | Deselect)) {
        QItemSelection sel = d->ranges;
        sel.merge(d->currentSelection, d->currentCommand);
        return !selectionIsEmpty(sel);
    } else {
        return !(selectionIsEmpty(d->ranges) && selectionIsEmpty(d->currentSelection));
    }
}
 
QModelIndexList QItemSelectionModel::selectedIndexes() const
{
    Q_D(const QItemSelectionModel);
    QItemSelection selected = d->ranges;
    selected.merge(d->currentSelection, d->currentCommand);
    return selected.indexes();
}
 
struct RowOrColumnDefinition {
    QModelIndex parent;
    int rowOrColumn;
 
    friend bool operator==(const RowOrColumnDefinition &lhs, const RowOrColumnDefinition &rhs) noexcept
    { return lhs.parent == rhs.parent && lhs.rowOrColumn == rhs.rowOrColumn; }
    friend bool operator!=(const RowOrColumnDefinition &lhs, const RowOrColumnDefinition &rhs) noexcept
    { return !operator==(lhs, rhs); }
};
size_t qHash(const RowOrColumnDefinition &key, size_t seed = 0) noexcept
{
    QtPrivate::QHashCombine hash;
    seed = hash(seed, key.parent);
    seed = hash(seed, key.rowOrColumn);
    return seed;
}
 
QT_SPECIALIZE_STD_HASH_TO_CALL_QHASH_BY_CREF(RowOrColumnDefinition)
 
 
QModelIndexList QItemSelectionModel::selectedRows(int column) const
{
    QModelIndexList indexes;
 
    QDuplicateTracker<RowOrColumnDefinition> rowsSeen;
 
    const QItemSelection ranges = selection();
    for (int i = 0; i < ranges.size(); ++i) {
        const QItemSelectionRange &range = ranges.at(i);
        QModelIndex parent = range.parent();
        for (int row = range.top(); row <= range.bottom(); row++) {
            if (!rowsSeen.hasSeen({parent, row})) {
                if (isRowSelected(row, parent)) {
                    indexes.append(model()->index(row, column, parent));
                }
            }
        }
    }
 
    return indexes;
}
 
QModelIndexList QItemSelectionModel::selectedColumns(int row) const
{
    QModelIndexList indexes;
 
    QDuplicateTracker<RowOrColumnDefinition> columnsSeen;
 
    const QItemSelection ranges = selection();
    for (int i = 0; i < ranges.size(); ++i) {
        const QItemSelectionRange &range = ranges.at(i);
        QModelIndex parent = range.parent();
        for (int column = range.left(); column <= range.right(); column++) {
            if (!columnsSeen.hasSeen({parent, column})) {
                if (isColumnSelected(column, parent)) {
                    indexes.append(model()->index(row, column, parent));
                }
            }
        }
    }
 
    return indexes;
}
 
const QItemSelection QItemSelectionModel::selection() const
{
    Q_D(const QItemSelectionModel);
    QItemSelection selected = d->ranges;
    selected.merge(d->currentSelection, d->currentCommand);
    // make sure we have no invalid ranges
    // ###  should probably be handled more generic somewhere else
    selected.removeIf(QtFunctionObjects::IsNotValid());
    return selected;
}
 
QAbstractItemModel *QItemSelectionModel::model()
{
    return d_func()->model.value();
}
 
const QAbstractItemModel *QItemSelectionModel::model() const
{
    return d_func()->model.value();
}
 
QBindable<QAbstractItemModel *> QItemSelectionModel::bindableModel()
{
    return &d_func()->model;
}
 
void QItemSelectionModel::setModel(QAbstractItemModel *model)
{
    Q_D(QItemSelectionModel);
    d->model.removeBindingUnlessInWrapper();
    if (d->model.valueBypassingBindings() == model)
        return;
    d->initModel(model);
    d->model.notify();
}
 
void QItemSelectionModel::emitSelectionChanged(const QItemSelection &newSelection,
                                               const QItemSelection &oldSelection)
{
    // if both selections are empty or equal we return
    if ((oldSelection.isEmpty() && newSelection.isEmpty()) ||
        oldSelection == newSelection)
        return;
 
    // if either selection is empty we do not need to compare
    if (oldSelection.isEmpty() || newSelection.isEmpty()) {
        emit selectionChanged(newSelection, oldSelection);
        return;
    }
 
    QItemSelection deselected = oldSelection;
    QItemSelection selected = newSelection;
 
    // remove equal ranges
    bool advance;
    for (int o = 0; o < deselected.size(); ++o) {
        advance = true;
        for (int s = 0; s < selected.size() && o < deselected.size();) {
            if (deselected.at(o) == selected.at(s)) {
                deselected.removeAt(o);
                selected.removeAt(s);
                advance = false;
            } else {
                ++s;
            }
        }
        if (advance)
            ++o;
    }
 
    // find intersections
    QItemSelection intersections;
    for (int o = 0; o < deselected.size(); ++o) {
        for (int s = 0; s < selected.size(); ++s) {
            if (deselected.at(o).intersects(selected.at(s)))
                intersections.append(deselected.at(o).intersected(selected.at(s)));
        }
    }
 
    // compare remaining ranges with intersections and split them to find deselected and selected
    for (int i = 0; i < intersections.size(); ++i) {
        // split deselected
        for (int o = 0; o < deselected.size();) {
            if (deselected.at(o).intersects(intersections.at(i))) {
                QItemSelection::split(deselected.at(o), intersections.at(i), &deselected);
                deselected.removeAt(o);
            } else {
                ++o;
            }
        }
        // split selected
        for (int s = 0; s < selected.size();) {
            if (selected.at(s).intersects(intersections.at(i))) {
                QItemSelection::split(selected.at(s), intersections.at(i), &selected);
                selected.removeAt(s);
            } else {
                ++s;
            }
        }
    }
 
    if (!selected.isEmpty() || !deselected.isEmpty())
        emit selectionChanged(selected, deselected);
}
 
#ifndef QT_NO_DEBUG_STREAM
QDebug operator<<(QDebug dbg, const QItemSelectionRange &range)
{
    QDebugStateSaver saver(dbg);
    dbg.nospace() << "QItemSelectionRange(" << range.topLeft()
                  << ',' << range.bottomRight() << ')';
    return dbg;
}
#endif
 
QT_END_NAMESPACE
 
#include "moc_qitemselectionmodel.cpp"