// Copyright (C) 2017 Michel Morin. // // 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_ITERATOR_ADVANCE_HPP #define BOOST_ITERATOR_ADVANCE_HPP #include <boost/config.hpp> #include <boost/iterator/iterator_categories.hpp> namespace boost { namespace iterators { namespace detail { template <typename InputIterator, typename Distance> inline BOOST_CXX14_CONSTEXPR void advance_impl( InputIterator& it , Distance n , incrementable_traversal_tag ) { while (n > 0) { ++it; --n; } } template <typename BidirectionalIterator, typename Distance> inline BOOST_CXX14_CONSTEXPR void advance_impl( BidirectionalIterator& it , Distance n , bidirectional_traversal_tag ) { if (n >= 0) { while (n > 0) { ++it; --n; } } else { while (n < 0) { --it; ++n; } } } template <typename RandomAccessIterator, typename Distance> inline BOOST_CXX14_CONSTEXPR void advance_impl( RandomAccessIterator& it , Distance n , random_access_traversal_tag ) { it += n; } } namespace advance_adl_barrier { template <typename InputIterator, typename Distance> inline BOOST_CXX14_CONSTEXPR void advance(InputIterator& it, Distance n) { detail::advance_impl( it, n, typename iterator_traversal<InputIterator>::type() ); } } using namespace advance_adl_barrier; } // namespace iterators using namespace iterators::advance_adl_barrier; } // namespace boost #endif