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/////////////////////////////////////////////////////////////////////////////
//
// (C) Copyright Ion Gaztanaga  2014-2014
//
// 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)
//
// See http://www.boost.org/libs/intrusive for documentation.
//
/////////////////////////////////////////////////////////////////////////////

#ifndef BOOST_INTRUSIVE_DETAIL_ITERATOR_HPP
#define BOOST_INTRUSIVE_DETAIL_ITERATOR_HPP

#ifndef BOOST_CONFIG_HPP
#  include <boost/config.hpp>
#endif

#if defined(BOOST_HAS_PRAGMA_ONCE)
#  pragma once
#endif

#include <cstddef>
#include <boost/intrusive/detail/std_fwd.hpp>
#include <boost/move/detail/iterator_traits.hpp>
#include <boost/move/detail/meta_utils_core.hpp>

namespace boost {
namespace intrusive {

using boost::movelib::iterator_traits;

////////////////////
//    iterator
////////////////////
template<class Category, class T, class Distance, class Pointer = T*, class Reference = T&>
struct iterator
{
   typedef Category  iterator_category;
   typedef T         value_type;
   typedef Distance  difference_type;
   typedef Pointer   pointer;
   typedef Reference reference;
};

////////////////////////////////////////
//    iterator_[dis|en]able_if_tag
////////////////////////////////////////
template<class I, class Tag, class R = void>
struct iterator_enable_if_tag
   : ::boost::move_detail::enable_if_c
      < ::boost::move_detail::is_same
         < typename boost::intrusive::iterator_traits<I>::iterator_category 
         , Tag
         >::value
         , R>
{};

template<class I, class Tag, class R = void>
struct iterator_disable_if_tag
   : ::boost::move_detail::enable_if_c
      < !::boost::move_detail::is_same
         < typename boost::intrusive::iterator_traits<I>::iterator_category 
         , Tag
         >::value
         , R>
{};

////////////////////////////////////////
//    iterator_[dis|en]able_if_tag_difference_type
////////////////////////////////////////
template<class I, class Tag>
struct iterator_enable_if_tag_difference_type
   : iterator_enable_if_tag<I, Tag, typename boost::intrusive::iterator_traits<I>::difference_type>
{};

template<class I, class Tag>
struct iterator_disable_if_tag_difference_type
   : iterator_disable_if_tag<I, Tag, typename boost::intrusive::iterator_traits<I>::difference_type>
{};

////////////////////
//    advance
////////////////////
template<class InputIt, class Distance> inline
typename iterator_enable_if_tag<InputIt, std::input_iterator_tag>::type
   iterator_advance(InputIt& it, Distance n)
{
   while(n--)
	   ++it;
}

template<class InputIt, class Distance> inline
typename iterator_enable_if_tag<InputIt, std::forward_iterator_tag>::type
   iterator_advance(InputIt& it, Distance n)
{
   while(n--)
	   ++it;
}

template<class InputIt, class Distance> inline
typename iterator_enable_if_tag<InputIt, std::bidirectional_iterator_tag>::type
   iterator_advance(InputIt& it, Distance n)
{
   for (; 0 < n; --n)
	   ++it;
   for (; n < 0; ++n)
	   --it;
}

template<class InputIt, class Distance> inline
typename iterator_enable_if_tag<InputIt, std::random_access_iterator_tag>::type
   iterator_advance(InputIt& it, Distance n)
{
   it += n;
}

////////////////////
//    distance
////////////////////
template<class InputIt> inline
typename iterator_disable_if_tag_difference_type
   <InputIt, std::random_access_iterator_tag>::type
      iterator_distance(InputIt first, InputIt last)
{
   typename iterator_traits<InputIt>::difference_type off = 0;
   while(first != last){
	   ++off;
      ++first;
   }
   return off;
}

template<class InputIt> inline
typename iterator_enable_if_tag_difference_type
   <InputIt, std::random_access_iterator_tag>::type
      iterator_distance(InputIt first, InputIt last)
{
   typename iterator_traits<InputIt>::difference_type off = last - first;
   return off;
}

} //namespace intrusive
} //namespace boost

#endif //BOOST_INTRUSIVE_DETAIL_ITERATOR_HPP