// In header: <boost/document/column.hpp>

template<typename Value> 
class column_iter : public boost::iterator_facade< column_iter< Cell >, Cell, boost::random_access_traversal_tag >
{
public:
  // construct/copy/destruct
  column_iter(std::shared_ptr< sheet_interface >, std::size_t, std::size_t);

  // public member functions
  void increment();
  void decrement();
  void advance(std::size_t);
  template<typename T> bool equal(column_iter< T > const &) const;
  template<typename T> std::size_t distance_to(column_iter< T > const &) const;
  Cell & dereference() const;
};