thevar1able/ClickHouse
1
0
Fork 0
mirror of https://github.com/ClickHouse/ClickHouse.git synced 2024-11-21 15:12:02 +00:00
Code Issues Packages Projects Releases Wiki Activity

Simplified implementation

Browse Source
This commit is contained in:
Maksim Kita 2022-02-08 10:03:29 +00:00
parent b536b27e15
commit 42792dec48
1 changed files with 24 additions and 34 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

58
base/base/sort.h
View File

@ -45,38 +45,12 @@ private:
template <typename Comparator>
using ComparatorWrapper = DebugLessComparator<Comparator>;
template <typename RandomIt, typename Compare>
void shuffleItemsInEqualRanges(RandomIt first, RandomIt last, Compare compare)
template <typename RandomIt>
void shuffle(RandomIt first, RandomIt last)
{
static pcg64 rng(getThreadId());
bool equal_range_started = false;
RandomIt equal_range_start_it;
while (true)
{
auto next = first + 1;
if (next == last)
break;
bool first_equal_second = compare(*first, *next) == compare(*next, *first);
if (equal_range_started && !first_equal_second)
{
std::shuffle(equal_range_start_it, next, rng);
equal_range_started = false;
}
else if (!equal_range_started && first_equal_second)
{
equal_range_started = true;
equal_range_start_it = first;
}
++first;
}
if (equal_range_started)
std::shuffle(equal_range_start_it, last, rng);
std::shuffle(first, last, rng);
}
#else
@ -100,17 +74,32 @@ void nth_element(RandomIt first, RandomIt nth, RandomIt last)
comparator compare;
ComparatorWrapper<comparator> compare_wrapper = compare;
#ifdef NDEBUG
::shuffle(first, last);
#endif
::miniselect::floyd_rivest_select(first, nth, last, compare_wrapper);
#ifdef NDEBUG
::shuffle(first, nth);
if (nth != last)
::shuffle(nth + 1, last);
#endif
}
template <typename RandomIt, typename Compare>
void partial_sort(RandomIt first, RandomIt middle, RandomIt last, Compare compare)
{
#ifdef NDEBUG
::shuffle(first, last);
#endif
ComparatorWrapper<Compare> compare_wrapper = compare;
::miniselect::floyd_rivest_partial_sort(first, middle, last, compare_wrapper);
#ifdef NDEBUG
::shuffleItemsInEqualRanges(first, middle, compare_wrapper);
::shuffle(middle, last);
#endif
}
@ -119,6 +108,7 @@ void partial_sort(RandomIt first, RandomIt middle, RandomIt last)
{
using value_type = typename std::iterator_traits<RandomIt>::value_type;
using comparator = std::less<value_type>;
::partial_sort(first, middle, last, comparator());
}
@ -127,12 +117,12 @@ void partial_sort(RandomIt first, RandomIt middle, RandomIt last)
template <typename RandomIt, typename Compare>
void sort(RandomIt first, RandomIt last, Compare compare)
{
#ifdef NDEBUG
::shuffle(first, last);
#endif
ComparatorWrapper<Compare> compare_wrapper = compare;
::pdqsort(first, last, compare_wrapper);
#ifdef NDEBUG
::shuffleItemsInEqualRanges(first, last, compare_wrapper);
#endif
}
template <typename RandomIt>