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sort.h
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sort.h
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/* THOR - THOR Template Library
* Joshua M. Kriegshauser
*
* sort.h
*
* ** THOR INTERNAL FILE - NOT FOR APPLICATION USE **
*
* This file contains STL-compatible sort algorithms and commonly used predicates.
*/
#ifndef THOR_SORT_H
#define THOR_SORT_H
#pragma once
#ifndef THOR_FUNCTION_H
#include "function.h"
#endif
#ifndef THOR_TEMPORARY_BUFFER_H
#include "temporary_buffer.h"
#endif
namespace thor
{
// sort() implementation (using heap sort).
template <class T> less<T> __less_factory(T*)
{
return less<T>();
}
template<class T, class RandomAccessIterator, class Compare>
void __sort_inner(RandomAccessIterator first, thor_diff_type i, thor_diff_type count, Compare comp, T*)
{
thor_diff_type k = i * 2 + 1;
T save = *(first + i);
while (k < count)
{
if (k + 1 < count && comp(*(first + k), *(first + k + 1)))
{
++k;
}
if (!comp(save, *(first + k)))
{
break;
}
*(first + i) = *(first + k);
i = k;
k = i * 2 + 1;
}
*(first + i) = save;
}
template<class T, class RandomAccessIterator, class Compare>
void __sort_internal(RandomAccessIterator first, RandomAccessIterator last, Compare comp, T*)
{
//////////////////////////////////////////////////////////////////////////////////////////
// well optimized heap sort - special thanks to eternallyconfuzzled.com (Julienne Walker)
//////////////////////////////////////////////////////////////////////////////////////////
thor_diff_type sortCount = last - first;
THOR_DEBUG_ASSERT(sortCount >= 0);
thor_diff_type i = sortCount / 2;
while (i-- > 0)
{
__sort_inner(first, i, sortCount, comp, (T*)0);
}
while (--sortCount > 0)
{
thor::swap(*first, *(first + sortCount));
__sort_inner(first, 0, sortCount, comp, (T*)0);
}
}
template <class RandomAccessIterator>
void sort(RandomAccessIterator first, RandomAccessIterator last)
{
if (first != last)
{
__sort_internal(first, last, __less_factory(THOR_GET_VALUE_TYPE(first, RandomAccessIterator)), THOR_GET_VALUE_TYPE(first, RandomAccessIterator));
}
}
template <class RandomAccessIterator, class Compare>
void sort(RandomAccessIterator first, RandomAccessIterator last, Compare comp)
{
if (first != last)
{
__sort_internal(first, last, comp, THOR_GET_VALUE_TYPE(first, RandomAccessIterator));
}
}
// stable_sort() implementation (using merge sort).
template <class RandomAccessIterator, class T, class Compare>
void __unguarded_linear_insert(RandomAccessIterator last, T val, Compare comp)
{
RandomAccessIterator next = last;
--next;
while (comp(val, *next))
{
*last = *next;
last = next;
--next;
}
*last = val;
}
template <class RandomAccessIterator, class T, class Compare>
inline void __linear_insert(RandomAccessIterator first, RandomAccessIterator last, T val, Compare comp)
{
if (comp(val, *first))
{
thor::copy_backward(first, last, last + 1);
*first = val;
}
else
{
__unguarded_linear_insert(last, val, comp);
}
}
template <class RandomAccessIterator, class Compare>
void __insertion_sort(RandomAccessIterator first, RandomAccessIterator last, Compare comp)
{
if (first == last)
{
return;
}
for (RandomAccessIterator iter = first + 1; iter != last; ++iter)
{
__linear_insert(first, iter, *iter, comp);
}
}
template <class RandomAccessIterator1, class RandomAccessIterator2, class Compare>
void __merge_sort_loop(RandomAccessIterator1 first, RandomAccessIterator1 last, RandomAccessIterator2 result, difference_type step_size, Compare comp)
{
difference_type two_step = 2 * step_size;
while (last - first >= two_step)
{
result = thor::merge(first, first + step_size, first + step_size, first + two_step, result, comp);
first += two_step;
}
difference_type diff = last - first;
if (diff < step_size)
{
step_size = diff;
}
thor::merge(first, first + step_size, first + step_size, last, result, comp);
}
const int __default_chunk_size = 7;
template <class RandomAccessIterator, class Compare>
void __chunk_insertion_sort(RandomAccessIterator first, RandomAccessIterator last, difference_type chunk_size, Compare comp)
{
while (last - first >= chunk_size)
{
__insertion_sort(first, first + chunk_size, comp);
first += chunk_size;
}
__insertion_sort(first, last, comp);
}
template <class RandomAccessIterator, class T, class Compare>
void __merge_sort_buffer(RandomAccessIterator first, RandomAccessIterator last, T* buffer, Compare comp)
{
difference_type len = last - first;
T* buffer_last = buffer + len;
difference_type step_size = __default_chunk_size;
__chunk_insertion_sort(first, last, step_size, comp);
while (step_size < len)
{
__merge_sort_loop(first, last, buffer, step_size, comp);
step_size *= 2;
__merge_sort_loop(buffer, buffer_last, first, step_size, comp);
step_size *= 2;
}
}
template <class BidirectionalIterator1, class BidirectionalIterator2>
BidirectionalIterator1 __rotate_adaptive(BidirectionalIterator1 first,
BidirectionalIterator1 middle,
BidirectionalIterator1 last,
difference_type len1, difference_type len2,
BidirectionalIterator2 buffer,
difference_type buffer_size)
{
if (len1 > len2 && len2 <= buffer_size)
{
BidirectionalIterator2 buffer_end = thor::copy(middle, last, buffer);
thor::copy_backward(first, middle, last);
return thor::copy(buffer, buffer_end, first);
}
else if (len1 <= buffer_size)
{
BidirectionalIterator2 buffer_end = thor::copy(first, middle, buffer);
thor::copy(middle, last, first);
return thor::copy_backward(buffer, buffer_end, last);
}
else
{
return thor::rotate(first, middle, last);
}
}
template <class BidirectionalIterator1, class BidirectionalIterator2, class BidirectionalIterator3, class Compare>
BidirectionalIterator3 __merge_backward(BidirectionalIterator1 first1, BidirectionalIterator1 last1,
BidirectionalIterator2 first2, BidirectionalIterator2 last2,
BidirectionalIterator3 result, Compare comp)
{
if (first1 == last1)
{
return thor::copy_backward(first2, last2, result);
}
if (first2 == last2)
{
return thor::copy_backward(first1, last1, result);
}
--last1;
--last2;
for (;;)
{
if (comp(*last2, *last1))
{
*--result = *last1;
if (first1 == last1)
{
return thor::copy_backward(first2, ++last2, result);
}
--last1;
}
else
{
*--result = *last2;
if (first2 == last2)
{
return thor::copy_backward(first1, ++last1, result);
}
--last2;
}
}
}
template <class BidirectionalIterator, class T, class Compare>
void __merge_adaptive(BidirectionalIterator first,
BidirectionalIterator middle,
BidirectionalIterator last,
difference_type len1, difference_type len2,
T* buffer, difference_type buffer_size,
Compare comp)
{
if (len1 <= len2 && len1 <= buffer_size)
{
T* buffer_end = thor::copy(first, middle, buffer);
thor::merge(buffer, buffer_end, middle, last, first, comp);
}
else if (len2 <= buffer_size)
{
T* buffer_end = thor::copy(middle, last, buffer);
__merge_backward(first, middle, buffer, buffer_end, last, comp);
}
else
{
BidirectionalIterator first_cut = first;
BidirectionalIterator second_cut = middle;
difference_type len11 = 0;
difference_type len22 = 0;
if (len1 > len2)
{
len11 = len1 / 2;
thor::advance(first_cut, len11);
second_cut = thor::lower_bound(middle, last, *first_cut, comp);
len22 += thor::distance(middle, second_cut);
}
else
{
len22 = len2 / 2;
thor::advance(second_cut, len22);
first_cut = thor::upper_bound(first, middle, *second_cut, comp);
len11 += thor::distance(first, first_cut);
}
BidirectionalIterator new_middle =
__rotate_adaptive(first_cut, middle, second_cut, len1 - len11,
len22, buffer, buffer_size);
__merge_adaptive(first, first_cut, new_middle, len11,
len22, buffer, buffer_size, comp);
__merge_adaptive(new_middle, second_cut, last, len1 - len11,
len2 - len22, buffer, buffer_size, comp);
}
}
template<class T, class RandomAccessIterator, class Compare>
void __stable_sort_adaptive(RandomAccessIterator first, RandomAccessIterator last, T* p, difference_type s, Compare comp)
{
difference_type len = (last - first + 1) / 2;
RandomAccessIterator middle = first + len;
__merge_sort_buffer(first, middle, p, comp);
__merge_sort_buffer(middle, last, p, comp);
__merge_adaptive(first, middle, last, middle - first, last - middle, p, s, comp);
}
template<class T, class RandomAccessIterator, class Compare>
void __stable_sort_internal(RandomAccessIterator first, RandomAccessIterator last, Compare comp, T*)
{
__TemporaryBuffer<RandomAccessIterator, T> buf(first, last);
__stable_sort_adaptive(first, last, buf.begin(), buf.size(), comp);
}
template <class RandomAccessIterator>
void stable_sort(RandomAccessIterator first, RandomAccessIterator last)
{
if (first != last)
{
__stable_sort_internal(first, last, __less_factory(THOR_GET_VALUE_TYPE(first, RandomAccessIterator)), THOR_GET_VALUE_TYPE(first, RandomAccessIterator));
}
}
template <class RandomAccessIterator, class Compare>
void stable_sort(RandomAccessIterator first, RandomAccessIterator last, Compare comp)
{
if (first != last)
{
__stable_sort_internal(first, last, comp, THOR_GET_VALUE_TYPE(first, RandomAccessIterator));
}
}
}; // namespace thor
#endif