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QListView: avoid quadratic complexity in selectedIndexes().

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Use std::remove_if(), which is linear, instead of looping
over erase(it), which turns the loop quadratic.

Reorder condition: call cheap non-virtual QModelIndex::column()
first, then virtuals parent(), and isIndexHidden().

Change-Id: Id46ee1297b91906332eeca98f69372ef887ac330
Reviewed-by: Marc Mutz <marc.mutz@kdab.com>
Reviewed-by: Edward Welbourne <edward.welbourne@theqtcompany.com>
This commit is contained in:
Anton Kudryavtsev 2016-02-17 12:26:43 +03:00
parent d392826959
commit ad9340de99
1 changed files with 5 additions and 7 deletions
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12
src/widgets/itemviews/qlistview.cpp
View File

@ -1440,13 +1440,11 @@ QModelIndexList QListView::selectedIndexes() const
return QModelIndexList();
QModelIndexList viewSelected = d->selectionModel->selectedIndexes();
for (int i = 0; i < viewSelected.count();) {
const QModelIndex &index = viewSelected.at(i);
if (!isIndexHidden(index) && index.parent() == d->root && index.column() == d->column)
++i;
else
viewSelected.removeAt(i);
}
auto ignorable = [this, d](const QModelIndex &index) {
return index.column() != d->column || index.parent() != d->root || isIndexHidden(index);
};
viewSelected.erase(std::remove_if(viewSelected.begin(), viewSelected.end(), ignorable),
viewSelected.end());
return viewSelected;
}