// 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(
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SinglePassIterator first
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, SinglePassIterator last
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, single_pass_traversal_tag
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)
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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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++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(
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RandomAccessIterator first
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, RandomAccessIterator last
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, random_access_traversal_tag
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)
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{
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return last - first;
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}
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}
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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(
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first, last, typename iterator_traversal<SinglePassIterator>::type()
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);
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}
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}
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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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