fix recursion depth: is_heap, is_heap_until

This commit is contained in:
bolero-MURAKAMI 2012-12-16 18:20:24 +09:00
parent 0201107eec
commit 86f68671a1
5 changed files with 232 additions and 21 deletions

View file

@ -1,42 +1,70 @@
#ifndef SPROUT_ALGORITHM_IS_HEAP_UNTIL_HPP
#define SPROUT_ALGORITHM_IS_HEAP_UNTIL_HPP
#include <cstddef>
#include <iterator>
#include <sprout/config.hpp>
#include <sprout/iterator/operation.hpp>
#include HDR_ITERATOR_SSCRISK_CEL_OR_SPROUT
#include HDR_FUNCTIONAL_SSCRISK_CEL_OR_SPROUT
namespace sprout {
// Copyright (C) 2011 RiSK (sscrisk)
namespace detail {
template<typename RandomAccessIterator, typename Compare>
inline SPROUT_CONSTEXPR typename std::iterator_traits<RandomAccessIterator>::difference_type
is_heap_until_impl(
RandomAccessIterator it, Compare comp,
typename std::iterator_traits<RandomAccessIterator>::difference_type first, typename std::iterator_traits<RandomAccessIterator>::difference_type last,
typename std::iterator_traits<RandomAccessIterator>::difference_type pivot, typename std::iterator_traits<RandomAccessIterator>::difference_type found
)
{
return found != first ? found
: pivot == 0 ? (!comp(it[first], it[(first - 1) / 2]) ? first : last)
: sprout::detail::is_heap_until_impl(
it, comp, first + pivot, last,
((last - first) - pivot) / 2,
sprout::detail::is_heap_until_impl(
it, comp, first, first + pivot,
pivot / 2,
first
)
)
;
}
template<typename RandomAccessIterator, typename Compare>
inline SPROUT_CONSTEXPR RandomAccessIterator
is_heap_until_impl(
RandomAccessIterator first, RandomAccessIterator last, Compare comp,
std::size_t n
typename std::iterator_traits<RandomAccessIterator>::difference_type size
)
{
return sprout::next(first, n) == last || !comp(first[n], first[(n - 1) / 2]) ? sprout::next(first, n)
: sprout::detail::is_heap_until_impl(first, last, comp, n + 1)
return size < 2 ? last
: sprout::next(first, sprout::detail::is_heap_until_impl(first, comp, 1, size, (size - 1) / 2, 1))
;
}
} // namespace detail
// 25.4.6.5 is_heap
template<typename RandomAccessIterator>
inline SPROUT_CONSTEXPR RandomAccessIterator
is_heap_until(RandomAccessIterator first, RandomAccessIterator last) {
return sprout::is_heap_until(first, last, NS_SSCRISK_CEL_OR_SPROUT::less<decltype(*first)>());
}
//
// recursion depth:
// O(log N)
//
template<typename RandomAccessIterator, typename Compare>
inline SPROUT_CONSTEXPR RandomAccessIterator
is_heap_until(RandomAccessIterator first, RandomAccessIterator last, Compare comp) {
return NS_SSCRISK_CEL_OR_SPROUT::distance(first, last) < 2 ? last
: sprout::detail::is_heap_until_impl(first, last, comp, 1)
;
return sprout::detail::is_heap_until_impl(
first, last, comp,
NS_SSCRISK_CEL_OR_SPROUT::distance(first, last)
);
}
template<typename RandomAccessIterator>
inline SPROUT_CONSTEXPR RandomAccessIterator
is_heap_until(RandomAccessIterator first, RandomAccessIterator last) {
return sprout::is_heap_until(
first, last,
NS_SSCRISK_CEL_OR_SPROUT::less<typename std::iterator_traits<RandomAccessIterator>::value_type>()
);
}
} // namespace sprout