mirror of
https://github.com/bolero-MURAKAMI/Sprout
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41 lines
1.1 KiB
C++
41 lines
1.1 KiB
C++
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#ifndef SPROUT_DETAIL_ITERATOR_EXT_HPP
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#define SPROUT_DETAIL_ITERATOR_EXT_HPP
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#include <iterator>
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#include <sprout/config.hpp>
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#include <sprout/iterator/operation.hpp>
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namespace sprout {
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namespace detail {
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template<typename Iterator>
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SPROUT_CONSTEXPR typename std::iterator_traits<Iterator>::difference_type bidirectional_distance_impl(
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Iterator first1,
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Iterator first2,
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Iterator last,
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typename std::iterator_traits<Iterator>::difference_type current = 1
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)
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{
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return first1 == last ? current
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: first2 == last ? -current
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: sprout::detail::bidirectional_distance_impl(sprout::next(first1), sprout::prev(first2), last, current + 1)
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;
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}
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//
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// bidirectional_distance
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//
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template<typename Iterator>
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SPROUT_CONSTEXPR typename std::iterator_traits<Iterator>::difference_type bidirectional_distance(
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Iterator first,
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Iterator last
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)
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{
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return first == last ? 0
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: sprout::detail::bidirectional_distance_impl(sprout::next(first), sprout::prev(first), last)
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;
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}
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} // namespace detail
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} // namespace sprout
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#endif // #ifndef SPROUT_DETAIL_ITERATOR_EXT_HPP
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