iterator/include/boost/iterator/reverse_iterator.hpp

// (C) Copyright David Abrahams 2002.
// (C) Copyright Jeremy Siek    2002.
// (C) Copyright Thomas Witt    2002.
// 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 BOOST_REVERSE_ITERATOR_23022003THW_HPP
#define BOOST_REVERSE_ITERATOR_23022003THW_HPP

#include <boost/iterator.hpp>
#include <boost/utility.hpp>
#include <boost/iterator/iterator_adaptor.hpp>

namespace boost
{

  //
  //
  //
  template <class Iterator>
  class reverse_iterator :
    public iterator_adaptor< reverse_iterator<Iterator>, Iterator >
  {
    typedef iterator_adaptor< reverse_iterator<Iterator>, Iterator > super_t;

    friend class iterator_core_access;

  public:
    reverse_iterator() {}

    explicit reverse_iterator(Iterator x) 
      : super_t(x) {}

    template<class OtherIterator>
    reverse_iterator(
        reverse_iterator<OtherIterator> const& r
      , typename enable_if_convertible<OtherIterator, Iterator>::type* = 0
    )
      : super_t(r.base())
    {}

  private:
    typename super_t::reference dereference() const { return *boost::prior(this->base()); }
    
    void increment() { super_t::decrement(); }
    void decrement() { super_t::increment(); }

    void advance(typename super_t::difference_type n)
    {
      super_t::advance(-n);
    }

    template <class OtherIterator>
    typename super_t::difference_type
    distance_to(reverse_iterator<OtherIterator> const& y) const
    {
      return -super_t::distance_to(y);
    }
  };

  template <class BidirectionalIterator>
  reverse_iterator<BidirectionalIterator> make_reverse_iterator(BidirectionalIterator x)
  {
      return reverse_iterator<BidirectionalIterator>(x);
  }

} // namespace boost

#endif // BOOST_REVERSE_ITERATOR_23022003THW_HPP