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boost/iterator/reverse_iterator.hpp

// (C) Copyright David Abrahams 2002.
// (C) Copyright Jeremy Siek    2002.
// (C) Copyright Thomas Witt    2002.
// Distributed under the Boost Software License, Version 1.0. (See
// accompanying file LICENSE_1_0.txt or copy at
// http://www.boost.org/LICENSE_1_0.txt)
#ifndef BOOST_REVERSE_ITERATOR_23022003THW_HPP
#define BOOST_REVERSE_ITERATOR_23022003THW_HPP

#include <boost/next_prior.hpp>
#include <boost/iterator.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() { --this->base_reference(); }
      void decrement() { ++this->base_reference(); }

      void advance(typename super_t::difference_type n)
      {
          this->base_reference() += -n;
      }

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

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

} // namespace boost

#endif // BOOST_REVERSE_ITERATOR_23022003THW_HPP