Sprout/sprout/algorithm/any_of_equal.hpp
2013-02-26 16:14:04 +09:00

109 lines
3.5 KiB
C++

#ifndef SPROUT_ALGORITHM_ANY_OF_EQUAL_HPP
#define SPROUT_ALGORITHM_ANY_OF_EQUAL_HPP
#include <iterator>
#include <type_traits>
#include <sprout/config.hpp>
#include <sprout/iterator/operation.hpp>
#include <sprout/iterator/type_traits/category.hpp>
#include <sprout/utility/pair/pair.hpp>
namespace sprout {
namespace detail {
template<typename RandomAccessIterator, typename T>
inline SPROUT_CONSTEXPR bool
any_of_equal_impl_ra(
RandomAccessIterator first, RandomAccessIterator last, T const& value,
typename std::iterator_traits<RandomAccessIterator>::difference_type pivot
)
{
return pivot == 0 ? *first == value
: sprout::detail::any_of_equal_impl_ra(
first, sprout::next(first, pivot), value,
pivot / 2
)
|| sprout::detail::any_of_equal_impl_ra(
sprout::next(first, pivot), last, value,
(sprout::distance(first, last) - pivot) / 2
)
;
}
template<typename RandomAccessIterator, typename T>
inline SPROUT_CONSTEXPR typename std::enable_if<
sprout::is_constant_distance_iterator<RandomAccessIterator>::value,
bool
>::type
any_of_equal(
RandomAccessIterator first, RandomAccessIterator last, T const& value,
std::random_access_iterator_tag*
)
{
return first == last ? false
: sprout::detail::any_of_equal_impl_ra(first, last, value, sprout::distance(first, last) / 2)
;
}
template<typename InputIterator, typename T>
inline SPROUT_CONSTEXPR sprout::pair<InputIterator, bool>
any_of_equal_impl_1(
sprout::pair<InputIterator, bool> const& current,
InputIterator last, T const& value, typename std::iterator_traits<InputIterator>::difference_type n
)
{
typedef sprout::pair<InputIterator, bool> type;
return current.second || current.first == last ? current
: n == 1 ? *current.first == value ? type(current.first, true) : type(sprout::next(current.first), false)
: sprout::detail::any_of_equal_impl_1(
sprout::detail::any_of_equal_impl_1(
current,
last, value, n / 2
),
last, value, n - n / 2
)
;
}
template<typename InputIterator, typename T>
inline SPROUT_CONSTEXPR sprout::pair<InputIterator, bool>
any_of_equal_impl(
sprout::pair<InputIterator, bool> const& current,
InputIterator last, T const& value, typename std::iterator_traits<InputIterator>::difference_type n
)
{
typedef sprout::pair<InputIterator, bool> type;
return current.second || current.first == last ? current
: sprout::detail::any_of_equal_impl(
sprout::detail::any_of_equal_impl_1(
current,
last, value, n
),
last, value, n * 2
)
;
}
template<typename InputIterator, typename T>
inline SPROUT_CONSTEXPR bool
any_of_equal(
InputIterator first, InputIterator last, T const& value,
std::input_iterator_tag*
)
{
typedef sprout::pair<InputIterator, bool> type;
return sprout::detail::any_of_equal_impl(type(first, false), last, value, 1).second;
}
} // namespace detail
//
// any_of_equal
//
// recursion depth:
// O(log N)
//
template<typename InputIterator, typename T>
inline SPROUT_CONSTEXPR bool
any_of_equal(InputIterator first, InputIterator last, T const& value) {
typedef typename std::iterator_traits<InputIterator>::iterator_category* category;
return sprout::detail::any_of_equal(first, last, value, category());
}
} // namespace sprout
#endif // #ifndef SPROUT_ALGORITHM_ANY_OF_EQUAL_HPP