/*
 * (C) Copyright Neal D. Becker (2004)
 * Permission to copy, use, modify, sell and distribute this software
 * is granted provided this copyright notice appears in all copies.
 * This software is provided "as is" without express or implied
 * warranty, and with no claim as to its suitability for any purpose.
*/

#ifndef zippy_iterator_H
#define zippy_iterator_H

#include <boost/iterator/iterator_facade.hpp>
#include <boost/utility.hpp>	// next
#include <iterator>

//! Cont is a container type.  It is a container of iterators.
template<class Cont>
class zippy_iterator
  : public boost::iterator_facade<zippy_iterator<Cont>,
				  typename std::iterator_traits<typename Cont::value_type>::value_type,
				  boost::forward_traversal_tag>
{
public:

  typedef typename Cont::value_type iter_t;
  typedef typename std::iterator_traits<iter_t>::value_type value_t;

  typedef typename Cont::iterator cit;

  explicit zippy_iterator (Cont c) : cont (c), cont_iter (cont.begin()) {}

  template<typename OtherCont>
  zippy_iterator& operator= (const zippy_iterator<OtherCont>& z) {
    cont = z.cont;
    cont_iter = boost::next (cont.begin(), std::distance (const_cast<cit> (z.cont.begin()), const_cast<cit> (z.cont_iter)));
  }

  template<typename OtherCont>
  zippy_iterator (const zippy_iterator<OtherCont>& z) :
    cont (z.cont),
    cont_iter (boost::next (cont.begin(), std::distance (const_cast<cit> (z.cont.begin()), const_cast<cit> (z.cont_iter))))
  { }

  zippy_iterator (const zippy_iterator<Cont>& z) :
    cont (z.cont),
    cont_iter (boost::next (cont.begin(), std::distance (const_cast<cit> (z.cont.begin()), const_cast<cit> (z.cont_iter))))
  { }

  value_t& dereference() const { return **cont_iter; }

  void increment() {
    (*cont_iter)++;
    cont_iter++;
    if (cont_iter == cont.end())
      cont_iter = cont.begin();
  }

  bool equal (zippy_iterator const& other) const {
    return std::equal (cont.begin(), cont.end(), other.cont.begin());
  }

private:

  Cont cont;
  typename Cont::iterator cont_iter;

};

template<typename Cont_t>
inline zippy_iterator<Cont_t> make_zippy_iterator (Cont_t cont) {
  return zippy_iterator<Cont_t> (cont);
}

#endif