forked from boostorg/iterator
60 lines
1.6 KiB
C++
60 lines
1.6 KiB
C++
// Copyright (C) 2017 Michel Morin.
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//
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// Distributed under the Boost Software License, Version 1.0.
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// (See accompanying file LICENSE_1_0.txt or copy at
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// http://www.boost.org/LICENSE_1_0.txt)
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#ifndef BOOST_ITERATOR_DISTANCE_HPP
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#define BOOST_ITERATOR_DISTANCE_HPP
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#include <boost/config.hpp>
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#include <boost/iterator/iterator_categories.hpp>
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#include <boost/iterator/iterator_traits.hpp>
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namespace boost {
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namespace iterators {
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namespace detail {
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template< typename SinglePassIterator >
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inline BOOST_CXX14_CONSTEXPR typename iterator_difference< SinglePassIterator >::type
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distance_impl(SinglePassIterator first, SinglePassIterator last, single_pass_traversal_tag)
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{
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typename iterator_difference< SinglePassIterator >::type n = 0;
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while (first != last)
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{
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++first;
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++n;
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}
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return n;
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}
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template< typename RandomAccessIterator >
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inline BOOST_CXX14_CONSTEXPR typename iterator_difference< RandomAccessIterator >::type
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distance_impl(RandomAccessIterator first, RandomAccessIterator last, random_access_traversal_tag)
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{
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return last - first;
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}
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} // namespace detail
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namespace distance_adl_barrier {
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template< typename SinglePassIterator >
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inline BOOST_CXX14_CONSTEXPR typename iterator_difference< SinglePassIterator >::type
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distance(SinglePassIterator first, SinglePassIterator last)
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{
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return detail::distance_impl(first, last, typename iterator_traversal< SinglePassIterator >::type());
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}
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} // namespace distance_adl_barrier
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using namespace distance_adl_barrier;
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} // namespace iterators
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using namespace iterators::distance_adl_barrier;
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} // namespace boost
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#endif
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