3rdparty/boost/boost/iterator/distance.hpp

   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         distance_impl(
  37             RandomAccessIterator first
  38           , RandomAccessIterator last
  39           , random_access_traversal_tag
  40         )
  41         {
  42             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         distance(SinglePassIterator first, SinglePassIterator last)
  50         {
  51             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