Function validate_instance

src/db/db/dbLayoutQuery.cc:674–681

  }

  void validate_instance ()
  {
    //  during modification or delete, instances may vanish while iterating,
    //  hence we need to check during iteration
    while (m_inst != m_inst_end && !mp_parent->is_valid (instance ())) {
      ++m_inst;
    }
  }

  void next_valid_instance ()
  {