Sprout/sprout/algorithm/upper_bound.hpp
2016-04-01 23:37:48 +09:00

55 lines
2 KiB
C++

/*=============================================================================
Copyright (c) 2011 RiSK (sscrisk)
https://github.com/sscrisk/CEL---ConstExpr-Library
Copyright (c) 2011-2016 Bolero MURAKAMI
https://github.com/bolero-MURAKAMI/Sprout
Distributed under the Boost Software License, Version 1.0. (See accompanying
file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
=============================================================================*/
#ifndef SPROUT_ALGORITHM_UPPER_BOUND_HPP
#define SPROUT_ALGORITHM_UPPER_BOUND_HPP
#include <iterator>
#include <sprout/config.hpp>
#include <sprout/iterator/next.hpp>
#include <sprout/iterator/distance.hpp>
#include <sprout/functional/less.hpp>
namespace sprout {
namespace detail {
template<typename ForwardIterator, typename T, typename Compare>
inline SPROUT_CONSTEXPR ForwardIterator
upper_bound(
ForwardIterator const& first, typename std::iterator_traits<ForwardIterator>::difference_type len,
T const& value, Compare comp
)
{
return len == 0 ? first
: comp(value, *sprout::next(first, len / 2))
? sprout::detail::upper_bound(first, len / 2, value, comp)
: sprout::detail::upper_bound(sprout::next(first, len / 2 + 1), len - (len / 2 + 1), value, comp)
;
}
} // namespace detail
// 25.4.3.2 upper_bound
//
// recursion depth:
// O(log N)
//
template<typename ForwardIterator, typename T, typename Compare>
inline SPROUT_CONSTEXPR ForwardIterator
upper_bound(ForwardIterator first, ForwardIterator last, T const& value, Compare comp) {
return sprout::detail::upper_bound(first, sprout::distance(first, last), value, comp);
}
template<typename ForwardIterator, typename T>
inline SPROUT_CONSTEXPR ForwardIterator
upper_bound(ForwardIterator first, ForwardIterator last, T const& value) {
return sprout::upper_bound(first, last, value, sprout::less<>());
}
} // namespace sprout
#endif // #ifndef SPROUT_ALGORITHM_UPPER_BOUND_HPP