ceph/src/boost/boost/iterator/advance.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_ADVANCE_HPP
   8 #define BOOST_ITERATOR_ADVANCE_HPP
   9
  10 #include <boost/config.hpp>
  11 #include <boost/iterator/iterator_categories.hpp>
  12
  13 namespace boost {
  14 namespace iterators {
  15
  16     namespace detail {
  17         template <typename InputIterator, typename Distance>
  18         inline BOOST_CXX14_CONSTEXPR void
  19         advance_impl(
  20             InputIterator& it
  21           , Distance n
  22           , incrementable_traversal_tag
  23         )
  24         {
  25             while (n > 0) {
  26                 ++it;
  27                 --n;
  28             }
  29         }
  30
  31         template <typename BidirectionalIterator, typename Distance>
  32         inline BOOST_CXX14_CONSTEXPR void
  33         advance_impl(
  34             BidirectionalIterator& it
  35           , Distance n
  36           , bidirectional_traversal_tag
  37         )
  38         {
  39             if (n >= 0) {
  40                 while (n > 0) {
  41                     ++it;
  42                     --n;
  43                 }
  44             }
  45             else {
  46                 while (n < 0) {
  47                     --it;
  48                     ++n;
  49                 }
  50             }
  51         }
  52
  53         template <typename RandomAccessIterator, typename Distance>
  54         inline BOOST_CXX14_CONSTEXPR void
  55         advance_impl(
  56             RandomAccessIterator& it
  57           , Distance n
  58           , random_access_traversal_tag
  59         )
  60         {
  61             it += n;
  62         }
  63     }
  64
  65     namespace advance_adl_barrier {
  66         template <typename InputIterator, typename Distance>
  67         inline BOOST_CXX14_CONSTEXPR void
  68         advance(InputIterator& it, Distance n)
  69         {
  70             detail::advance_impl(
  71                 it, n, typename iterator_traversal<InputIterator>::type()
  72             );
  73         }
  74     }
  75
  76     using namespace advance_adl_barrier;
  77
  78 } // namespace iterators
  79
  80 using namespace iterators::advance_adl_barrier;
  81
  82 } // namespace boost
  83
  84 #endif