mirror of
https://github.com/bolero-MURAKAMI/Sprout
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74 lines
2.6 KiB
C++
74 lines
2.6 KiB
C++
#ifndef SPROUT_ALGORITHM_COUNT_HPP
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#define SPROUT_ALGORITHM_COUNT_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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#include HDR_ITERATOR_SSCRISK_CEL_OR_SPROUT
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namespace sprout {
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namespace detail {
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template<typename RandomAccessIterator, typename T>
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inline SPROUT_CONSTEXPR typename std::iterator_traits<RandomAccessIterator>::difference_type
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count_impl_ra(
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RandomAccessIterator first, RandomAccessIterator last, T const& value,
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typename std::iterator_traits<RandomAccessIterator>::difference_type pivot
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)
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{
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return pivot == 0 ? (*first == value ? 1 : 0)
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: sprout::detail::count_impl_ra(
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first, sprout::next(first, pivot), value,
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pivot / 2
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)
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+ sprout::detail::count_impl_ra(
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sprout::next(first, pivot), last, value,
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(NS_SSCRISK_CEL_OR_SPROUT::distance(first, last) - pivot) / 2
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)
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;
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}
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template<typename RandomAccessIterator, typename T>
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inline SPROUT_CONSTEXPR typename std::iterator_traits<RandomAccessIterator>::difference_type
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count(
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RandomAccessIterator first, RandomAccessIterator last, T const& value,
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std::random_access_iterator_tag*
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)
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{
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return first == last ? 0
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: sprout::detail::count_impl_ra(first, last, value, NS_SSCRISK_CEL_OR_SPROUT::distance(first, last) / 2)
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;
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}
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// Copyright (C) 2011 RiSK (sscrisk)
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template<typename InputIterator, typename T>
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inline SPROUT_CONSTEXPR typename std::iterator_traits<InputIterator>::difference_type
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count_impl(InputIterator first, InputIterator last, T const& value) {
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return first == last ? 0
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: (*first == value ? 1 : 0) + sprout::detail::count_impl(sprout::next(first), last, value)
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;
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}
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template<typename InputIterator, typename T>
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inline SPROUT_CONSTEXPR typename std::iterator_traits<InputIterator>::difference_type
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count(
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InputIterator first, InputIterator last, T const& value,
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void*
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)
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{
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return sprout::detail::count_impl(first, last, value);
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}
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} //namespace detail
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// 25.2.9 Count
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//
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// recursion depth:
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// [first, last) is RandomAccessIterator -> O(log N)
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// otherwise -> O(N)
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//
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template<typename InputIterator, typename T>
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inline SPROUT_CONSTEXPR typename std::iterator_traits<InputIterator>::difference_type
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count(InputIterator first, InputIterator last, T const& value) {
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typedef typename std::iterator_traits<InputIterator>::iterator_category* category;
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return sprout::detail::count(first, last, value, category());
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}
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} // namespace sprout
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#endif // #ifndef SPROUT_ALGORITHM_COUNT_HPP
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