    return name_;
  }
  
  void DBCFile::parseExtraInfo(const QString &content) {
    static QRegularExpression bo_regexp(R"(^BO_ (\w+) (\w+) *: (\w+) (\w+))");
    static QRegularExpression sg_regexp(R"(^SG_ (\w+) : (\d+)\|(\d+)@(\d+)([\+|\-]) \(([0-9.+\-eE]+),([0-9.+\-eE]+)\) \[([0-9.+\-eE]+)\|([0-9.+\-eE]+)\] \"(.*)\" (.*))");
    static QRegularExpression sgm_regexp(R"(^SG_ (\w+) (\w+) *: (\d+)\|(\d+)@(\d+)([\+|\-]) \(([0-9.+\-eE]+),([0-9.+\-eE]+)\) \[([0-9.+\-eE]+)\|([0-9.+\-eE]+)\] \"(.*)\" (.*))");
    static QRegularExpression sg_comment_regexp(R"(^CM_ SG_ *(\w+) *(\w+) *\"(.*)\";)");
 
</s> remove     } else {
 </s> add     } else if (!dbc_file->isEmpty()) { </s> remove   assert(dbc()->dbcCount() > 0);
  auto &[_, dbc_file] = dbc()->dbc_files.first();

  QString fn = QFileDialog::getSaveFileName(this, tr("Save File"), QDir::cleanPath(settings.last_dir + "/untitled.dbc"), tr("DBC (*.dbc)"));
  if (!fn.isEmpty()) {
    dbc_file->saveAs(fn);
 </s> add   for (auto &[s, dbc_file] : dbc()->dbc_files) {
    if (dbc_file->isEmpty()) continue;
    QString fn = QFileDialog::getSaveFileName(this, tr("Save File"), QDir::cleanPath(settings.last_dir + "/untitled.dbc"), tr("DBC (*.dbc)"));
    if (!fn.isEmpty()) {
      dbc_file->saveAs(fn);
    } </s> remove   if (dbc()->dbcCount() > 1) {
 </s> add   int cnt = dbc()->nonEmptyDBCCount();
  save_dbc->setEnabled(cnt > 0);

  if (cnt > 1) {
bool DBCFile::isEmpty() const {
  return (signalCount() == 0) && name().isEmpty();
}

    return name_;
  }
  
bool DBCFile::isEmpty() const {
  return (signalCount() == 0) && name().isEmpty();
}

  void DBCFile::parseExtraInfo(const QString &content) {
    static QRegularExpression bo_regexp(R"(^BO_ (\w+) (\w+) *: (\w+) (\w+))");
    static QRegularExpression sg_regexp(R"(^SG_ (\w+) : (\d+)\|(\d+)@(\d+)([\+|\-]) \(([0-9.+\-eE]+),([0-9.+\-eE]+)\) \[([0-9.+\-eE]+)\|([0-9.+\-eE]+)\] \"(.*)\" (.*))");
    static QRegularExpression sgm_regexp(R"(^SG_ (\w+) (\w+) *: (\d+)\|(\d+)@(\d+)([\+|\-]) \(([0-9.+\-eE]+),([0-9.+\-eE]+)\) \[([0-9.+\-eE]+)\|([0-9.+\-eE]+)\] \"(.*)\" (.*))");
    static QRegularExpression sg_comment_regexp(R"(^CM_ SG_ *(\w+) *(\w+) *\"(.*)\";)");
keep keep add keep keep keep keep keep
 cabana: do not try to save empty wildcard DBC (#27898)

* cabana: do not try to save empty wildcard DBC

* use reference 
tools/cabana/dbc/dbcfile.cc