/* Some basic iterator stuff */

namespace {

  template<class T>
  struct ListEntry
  {
    ListEntry* prev, *next;
    T val;
  };

  template<class T>
  class ListIter
  {
    ListEntry<T>* entry;
  public:
    ListIter(ListEntry<T>* entry)
      : entry(entry)
    {}
    T& operator*() const
    {
      return entry->val;
    }
    ListIter& operator++()
    {
      entry = entry->next;
      return *this;
    }
    ListIter operator++(int)
    {
      ListIter cpy = *this;
      ++(*this);
      return cpy;
    }
  };
}