Sprout/sprout/algorithm/minmax_element.hpp

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#ifndef SPROUT_ALGORITHM_MINMAX_ELEMENT_HPP
#define SPROUT_ALGORITHM_MINMAX_ELEMENT_HPP
#include <iterator>
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#include <type_traits>
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#include <sprout/config.hpp>
#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>
#include <sprout/utility/pair/access.hpp>
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#include HDR_FUNCTIONAL_SSCRISK_CEL_OR_SPROUT
namespace sprout {
namespace detail {
template<typename InputIteratorPair, typename Compare>
inline SPROUT_CONSTEXPR InputIteratorPair
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iter_minmax_pair(InputIteratorPair const& a, InputIteratorPair const& b, Compare comp) {
return InputIteratorPair(
comp(*sprout::first(b), *sprout::first(a)) ? sprout::first(b) : sprout::first(a),
comp(*sprout::second(a), *sprout::second(b)) ? sprout::second(b) : sprout::second(a)
);
}
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template<typename InputIteratorPair, typename InputIterator, typename Compare>
inline SPROUT_CONSTEXPR InputIteratorPair
iter_minmax(InputIteratorPair const& a, InputIterator b, Compare comp) {
return InputIteratorPair(
comp(*b, *sprout::first(a)) ? b : sprout::first(a),
comp(*sprout::second(a), *b) ? b : sprout::second(a)
);
}
template<typename RandomAccessIterator, typename Compare>
inline SPROUT_CONSTEXPR sprout::pair<RandomAccessIterator, RandomAccessIterator>
minmax_element_impl_ra(
RandomAccessIterator first, RandomAccessIterator last, Compare comp,
typename std::iterator_traits<RandomAccessIterator>::difference_type pivot
)
{
return pivot == 0 ? sprout::pair<RandomAccessIterator, RandomAccessIterator>(first, first)
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: sprout::detail::iter_minmax_pair(
sprout::detail::minmax_element_impl_ra(
first, sprout::next(first, pivot), comp,
pivot / 2
),
sprout::detail::minmax_element_impl_ra(
sprout::next(first, pivot), last, comp,
(sprout::distance(first, last) - pivot) / 2
),
comp
)
;
}
template<typename RandomAccessIterator, typename Compare>
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inline SPROUT_CONSTEXPR typename std::enable_if<
sprout::is_constant_distance_iterator<RandomAccessIterator>::value,
sprout::pair<RandomAccessIterator, RandomAccessIterator>
>::type
minmax_element(
RandomAccessIterator first, RandomAccessIterator last, Compare comp,
std::random_access_iterator_tag*
)
{
return first == last ? sprout::pair<RandomAccessIterator, RandomAccessIterator>(last, last)
: sprout::detail::minmax_element_impl_ra(
first, last, comp,
sprout::distance(first, last) / 2
)
;
}
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template<typename ForwardIterator, typename Compare>
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inline SPROUT_CONSTEXPR sprout::pair<ForwardIterator, sprout::pair<ForwardIterator, ForwardIterator> >
minmax_element_impl_1(
sprout::pair<ForwardIterator, sprout::pair<ForwardIterator, ForwardIterator> > const& current,
ForwardIterator last, Compare comp, typename std::iterator_traits<ForwardIterator>::difference_type n
)
{
typedef sprout::pair<ForwardIterator, sprout::pair<ForwardIterator, ForwardIterator> > type;
return current.first == last ? current
: n == 1 ? type(sprout::next(current.first), sprout::detail::iter_minmax(current.second, current.first, comp))
: sprout::detail::minmax_element_impl_1(
sprout::detail::minmax_element_impl_1(
current,
last, comp, n / 2
),
last, comp, n - n / 2
)
;
}
template<typename ForwardIterator, typename Compare>
inline SPROUT_CONSTEXPR sprout::pair<ForwardIterator, sprout::pair<ForwardIterator, ForwardIterator> >
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minmax_element_impl(
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sprout::pair<ForwardIterator, sprout::pair<ForwardIterator, ForwardIterator> > const& current,
ForwardIterator last, Compare comp, typename std::iterator_traits<ForwardIterator>::difference_type n
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)
{
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typedef sprout::pair<ForwardIterator, sprout::pair<ForwardIterator, ForwardIterator> > type;
return current.first == last ? current
: sprout::detail::minmax_element_impl(
sprout::detail::minmax_element_impl_1(
current,
last, comp, n
),
last, comp, n * 2
)
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;
}
template<typename ForwardIterator, typename Compare>
inline SPROUT_CONSTEXPR sprout::pair<ForwardIterator, ForwardIterator>
minmax_element(
ForwardIterator first, ForwardIterator last, Compare comp,
void*
)
{
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typedef sprout::pair<ForwardIterator, sprout::pair<ForwardIterator, ForwardIterator> > type;
return first == last ? sprout::pair<ForwardIterator, ForwardIterator>(first, first)
: sprout::detail::minmax_element_impl(type(sprout::next(first), sprout::pair<ForwardIterator, ForwardIterator>(first, first)), last, comp, 1).second
;
}
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} // namespace detail
// 25.4.7 Minimum and maximum
//
// recursion depth:
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// O(log N)
//
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template<typename ForwardIterator, typename Compare>
inline SPROUT_CONSTEXPR sprout::pair<ForwardIterator, ForwardIterator>
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minmax_element(ForwardIterator first, ForwardIterator last, Compare comp) {
typedef typename std::iterator_traits<ForwardIterator>::iterator_category* category;
return sprout::detail::minmax_element(first, last, comp, category());
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}
template<typename ForwardIterator>
inline SPROUT_CONSTEXPR sprout::pair<ForwardIterator, ForwardIterator>
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minmax_element(ForwardIterator first, ForwardIterator last) {
return sprout::minmax_element(
first, last,
NS_SSCRISK_CEL_OR_SPROUT::less<typename std::iterator_traits<ForwardIterator>::value_type>()
);
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}
} // namespace sprout
#endif // #ifndef SPROUT_ALGORITHM_MINMAX_ELEMENT_HPP