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https://github.com/bolero-MURAKAMI/Sprout.git
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74 lines
2.7 KiB
C++
74 lines
2.7 KiB
C++
#ifndef SPROUT_ITERATOR_DISTANCE_HPP
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#define SPROUT_ITERATOR_DISTANCE_HPP
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#include <iterator>
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#include <type_traits>
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#include <sprout/config.hpp>
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#include <sprout/iterator/next.hpp>
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#include <sprout/adl/not_found.hpp>
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namespace sprout_adl {
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sprout::not_found_via_adl iterator_distance(...);
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} // namespace sprout_adl
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namespace sprout {
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namespace iterator_detail {
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template<typename RandomAccessIterator>
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inline SPROUT_CONSTEXPR typename std::enable_if<
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!std::is_pointer<RandomAccessIterator>::value,
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typename std::iterator_traits<RandomAccessIterator>::difference_type
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>::type
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iterator_distance(RandomAccessIterator first, RandomAccessIterator last, std::random_access_iterator_tag*) {
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return last - first;
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}
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// Copyright (C) 2011 RiSK (sscrisk)
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template<typename InputIterator>
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inline SPROUT_CONSTEXPR typename std::iterator_traits<InputIterator>::difference_type
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iterator_distance_impl(InputIterator first, InputIterator last) {
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return first == last ? 0
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: 1 + sprout::iterator_detail::iterator_distance_impl(sprout::next(first), last)
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;
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}
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template<typename InputIterator>
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inline SPROUT_CONSTEXPR typename std::iterator_traits<InputIterator>::difference_type
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iterator_distance(InputIterator first, InputIterator last, void*) {
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return sprout::iterator_detail::iterator_distance_impl(first, last);
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}
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template<typename InputIterator>
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inline SPROUT_CONSTEXPR typename std::iterator_traits<InputIterator>::difference_type
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iterator_distance(InputIterator first, InputIterator last) {
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typedef typename std::iterator_traits<InputIterator>::iterator_category* category;
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return sprout::iterator_detail::iterator_distance(first, last, category());
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}
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} // namespace iterator_detail
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} // namespace sprout
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namespace sprout_iterator_detail {
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template<typename InputIterator>
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inline SPROUT_CONSTEXPR typename std::iterator_traits<InputIterator>::difference_type
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distance(InputIterator first, InputIterator last) {
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using sprout::iterator_detail::iterator_distance;
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using sprout_adl::iterator_distance;
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return iterator_distance(first, last);
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}
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} // namespace sprout_iterator_detail
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namespace sprout {
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//
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// distance
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//
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// effect:
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// ADL callable iterator_distance(first, last) -> iterator_distance(first, last)
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// [first, last) is RandomAccessIterator && not Pointer -> last - first
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// otherwise -> linearly count: first to last
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//
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template<typename InputIterator>
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inline SPROUT_CONSTEXPR typename std::iterator_traits<InputIterator>::difference_type
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distance(InputIterator first, InputIterator last) {
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return sprout_iterator_detail::distance(first, last);
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}
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} // namespace sprout
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#endif // #ifndef SPROUT_ITERATOR_DISTANCE_HPP
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