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++ // Copyright (C) 2024 The Qt Company Ltd.
++ // SPDX-License-Identifier: LicenseRef-Qt-Commercial OR BSD-3-Clause
++
++ #include "spreadformula.h"
++ #include "datamodel.h"
++ #include "spreadkey.h"
++ #include "spreadrole.h"
++ #include "spreadmodel.h"
++
++ bool Formula::includesLoop(SpreadModel *model, const DataModel *dataModel, QSet<int> *history) const
++ {
++ if (m_operator == Operator::Invalid)
++ return false;
++
++ if (history == nullptr) {
++ QSet<int> history;
++ return includesLoop(model, dataModel, &history);
++ }
++
++ if (m_operator == Operator::Sum) {
++ SpreadKey top_left = dataModel->getKey(m_cellIds.first);
++ SpreadKey bottom_right = dataModel->getKey(m_cellIds.second);
++ if (bottom_right.first < top_left.first)
++ std::swap(top_left.first, bottom_right.first);
++ if (bottom_right.second < top_left.second)
++ std::swap(top_left.second, bottom_right.second);
++ for (int row = top_left.first; row <= bottom_right.first; ++row) {
++ for (int column = top_left.second; column <= bottom_right.second; ++column) {
++ const int id = dataModel->getId(SpreadKey{row, column});
++ if (history->find(id) != history->end())
++ return true;
++ const QString edit_text = dataModel->getData(id, spread::Role::Edit).toString();
++ const Formula formula = model->parseFormulaString(edit_text);
++ if (!formula.isValid())
++ continue;
++ auto it = history->insert(id);
++ if (formula.includesLoop(model, dataModel, history))
++ return true;
++ auto cit = spread::make_const(*history, it);
++ history->erase(cit);
++ }
++ }
++ } else {
++ const int id_1 = m_cellIds.first;
++ if (history->find(id_1) != history->end())
++ return true;
++ const QString edit_text = dataModel->getData(id_1, spread::Role::Edit).toString();
++ const Formula formula = model->parseFormulaString(edit_text);
++ if (!formula.isValid())
++ return false;
++ auto it = history->insert(id_1);
++ if (formula.includesLoop(model, dataModel, history))
++ return true;
++ auto cit = spread::make_const(*history, it);
++ history->erase(cit);
++
++ if (m_operator != Operator::Assign) {
++ const int id_2 = m_cellIds.second;
++ if (history->find(id_2) != history->end())
++ return true;
++ const QString edit_text = dataModel->getData(id_2, spread::Role::Edit).toString();
++ const Formula formula = model->parseFormulaString(edit_text);
++ if (!formula.isValid())
++ return false;
++ auto it = history->insert(id_2);
++ if (formula.includesLoop(model, dataModel, history))
++ return true;
++ auto cit = spread::make_const(*history, it);
++ history->erase(cit);
++ }
++ }
++
++ return false;
++ }