Line data    Source code

       1             : // Copyright (C) 2017 Michel Morin.
       2             : //
       3             : // Distributed under the Boost Software License, Version 1.0.
       4             : // (See accompanying file LICENSE_1_0.txt or copy at
       5             : // http://www.boost.org/LICENSE_1_0.txt)
       6             : 
       7             : #ifndef BOOST_ITERATOR_DISTANCE_HPP
       8             : #define BOOST_ITERATOR_DISTANCE_HPP
       9             : 
      10             : #include <boost/config.hpp>
      11             : #include <boost/iterator/iterator_categories.hpp>
      12             : #include <boost/iterator/iterator_traits.hpp>
      13             : 
      14             : namespace boost {
      15             : namespace iterators {
      16             : 
      17             :     namespace detail {
      18             :         template <typename SinglePassIterator>
      19             :         inline BOOST_CXX14_CONSTEXPR typename iterator_difference<SinglePassIterator>::type
      20             :         distance_impl(
      21             :             SinglePassIterator first
      22             :           , SinglePassIterator last
      23             :           , single_pass_traversal_tag
      24             :         )
      25             :         {
      26             :             typename iterator_difference<SinglePassIterator>::type n = 0;
      27             :             while (first != last) {
      28             :                 ++first;
      29             :                 ++n;
      30             :             }
      31             :             return n;
      32             :         }
      33             : 
      34             :         template <typename RandomAccessIterator>
      35             :         inline BOOST_CXX14_CONSTEXPR typename iterator_difference<RandomAccessIterator>::type
      36           0 :         distance_impl(
      37             :             RandomAccessIterator first
      38             :           , RandomAccessIterator last
      39             :           , random_access_traversal_tag
      40             :         )
      41             :         {
      42           0 :             return last - first;
      43             :         }
      44             :     }
      45             : 
      46             :     namespace distance_adl_barrier {
      47             :         template <typename SinglePassIterator>
      48             :         inline BOOST_CXX14_CONSTEXPR typename iterator_difference<SinglePassIterator>::type
      49           0 :         distance(SinglePassIterator first, SinglePassIterator last)
      50             :         {
      51           0 :             return detail::distance_impl(
      52             :                 first, last, typename iterator_traversal<SinglePassIterator>::type()
      53             :             );
      54             :         }
      55             :     }
      56             : 
      57             :     using namespace distance_adl_barrier;
      58             : 
      59             : } // namespace iterators
      60             : 
      61             : using namespace iterators::distance_adl_barrier;
      62             : 
      63             : } // namespace boost
      64             : 
      65             : #endif