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