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https://github.com/bolero-MURAKAMI/Sprout.git
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110 lines
3.5 KiB
C++
110 lines
3.5 KiB
C++
#ifndef SPROUT_ALGORITHM_FIND_IF_HPP
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#define SPROUT_ALGORITHM_FIND_IF_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/operation.hpp>
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#include <sprout/iterator/type_traits/is_iterator.hpp>
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#include <sprout/utility/pair/pair.hpp>
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namespace sprout {
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namespace detail {
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template<typename RandomAccessIterator, typename Predicate>
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inline SPROUT_CONSTEXPR RandomAccessIterator
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find_if_impl_ra(
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RandomAccessIterator first, RandomAccessIterator last, Predicate pred,
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typename std::iterator_traits<RandomAccessIterator>::difference_type pivot, RandomAccessIterator found
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)
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{
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return found != first ? found
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: pivot == 0 ? (pred(*first) ? first : last)
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: sprout::detail::find_if_impl_ra(
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sprout::next(first, pivot), last, pred,
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(sprout::distance(first, last) - pivot) / 2,
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sprout::detail::find_if_impl_ra(
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first, sprout::next(first, pivot), pred,
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pivot / 2,
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first
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)
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)
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;
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}
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template<typename RandomAccessIterator, typename Predicate>
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inline SPROUT_CONSTEXPR typename std::enable_if<
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sprout::is_constant_distance_iterator<RandomAccessIterator>::value,
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RandomAccessIterator
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>::type
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find_if(
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RandomAccessIterator first, RandomAccessIterator last, Predicate pred,
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std::random_access_iterator_tag*
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)
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{
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return first == last ? last
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: sprout::detail::find_if_impl_ra(first, last, pred, sprout::distance(first, last) / 2, first)
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;
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}
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template<typename InputIterator, typename Predicate>
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inline SPROUT_CONSTEXPR sprout::pair<InputIterator, bool>
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find_if_impl_1(
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sprout::pair<InputIterator, bool> const& current,
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InputIterator last, Predicate pred, typename std::iterator_traits<InputIterator>::difference_type n
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)
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{
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typedef sprout::pair<InputIterator, bool> type;
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return current.second || current.first == last ? current
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: n == 1 ? pred(*current.first) ? type(current.first, true) : type(sprout::next(current.first), false)
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: sprout::detail::find_if_impl_1(
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sprout::detail::find_if_impl_1(
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current,
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last, pred, n / 2
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),
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last, pred, n - n / 2
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)
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;
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}
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template<typename InputIterator, typename Predicate>
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inline SPROUT_CONSTEXPR sprout::pair<InputIterator, bool>
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find_if_impl(
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sprout::pair<InputIterator, bool> const& current,
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InputIterator last, Predicate pred, typename std::iterator_traits<InputIterator>::difference_type n
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)
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{
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typedef sprout::pair<InputIterator, bool> type;
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return current.second || current.first == last ? current
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: sprout::detail::find_if_impl(
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sprout::detail::find_if_impl_1(
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current,
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last, pred, n
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),
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last, pred, n * 2
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)
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;
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}
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template<typename InputIterator, typename Predicate>
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inline SPROUT_CONSTEXPR InputIterator
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find_if(
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InputIterator first, InputIterator last, Predicate pred,
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void*
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)
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{
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typedef sprout::pair<InputIterator, bool> type;
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return sprout::detail::find_if_impl(type(first, false), last, pred, 1).first;
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}
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} // namespace detail
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// 25.2.5 Find
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//
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// recursion depth:
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// O(log N)
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//
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template<typename InputIterator, typename Predicate>
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inline SPROUT_CONSTEXPR InputIterator
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find_if(InputIterator first, InputIterator last, Predicate pred) {
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typedef typename std::iterator_traits<InputIterator>::iterator_category* category;
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return sprout::detail::find_if(first, last, pred, category());
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}
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} // namespace sprout
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#endif // #ifndef SPROUT_ALGORITHM_FIND_IF_HPP
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