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//===----------------------------------------------------------------------===//
//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See https://llvm.org/LICENSE.txt for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
//
//===----------------------------------------------------------------------===//
#ifndef _LIBCPP___ALGORITHM_INPLACE_MERGE_H
#define _LIBCPP___ALGORITHM_INPLACE_MERGE_H
#include <__algorithm/comp.h>
#include <__algorithm/comp_ref_type.h>
#include <__algorithm/lower_bound.h>
#include <__algorithm/min.h>
#include <__algorithm/move.h>
#include <__algorithm/rotate.h>
#include <__algorithm/upper_bound.h>
#include <__config>
#include <__iterator/advance.h>
#include <__iterator/distance.h>
#include <__iterator/iterator_traits.h>
#include <__iterator/reverse_iterator.h>
#include <__utility/swap.h>
#include <memory>
#if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
# pragma GCC system_header
#endif
_LIBCPP_PUSH_MACROS
#include <__undef_macros>
_LIBCPP_BEGIN_NAMESPACE_STD
template <class _Predicate>
class __invert // invert the sense of a comparison
{
private:
_Predicate __p_;
public:
_LIBCPP_INLINE_VISIBILITY __invert() {}
_LIBCPP_INLINE_VISIBILITY
explicit __invert(_Predicate __p) : __p_(__p) {}
template <class _T1>
_LIBCPP_INLINE_VISIBILITY
bool operator()(const _T1& __x) {return !__p_(__x);}
template <class _T1, class _T2>
_LIBCPP_INLINE_VISIBILITY
bool operator()(const _T1& __x, const _T2& __y) {return __p_(__y, __x);}
};
template <class _Compare, class _InputIterator1, class _InputIterator2,
class _OutputIterator>
void __half_inplace_merge(_InputIterator1 __first1, _InputIterator1 __last1,
_InputIterator2 __first2, _InputIterator2 __last2,
_OutputIterator __result, _Compare __comp)
{
for (; __first1 != __last1; ++__result)
{
if (__first2 == __last2)
{
_VSTD::move(__first1, __last1, __result);
return;
}
if (__comp(*__first2, *__first1))
{
*__result = _VSTD::move(*__first2);
++__first2;
}
else
{
*__result = _VSTD::move(*__first1);
++__first1;
}
}
// __first2 through __last2 are already in the right spot.
}
template <class _Compare, class _BidirectionalIterator>
void
__buffered_inplace_merge(_BidirectionalIterator __first, _BidirectionalIterator __middle, _BidirectionalIterator __last,
_Compare __comp, typename iterator_traits<_BidirectionalIterator>::difference_type __len1,
typename iterator_traits<_BidirectionalIterator>::difference_type __len2,
typename iterator_traits<_BidirectionalIterator>::value_type* __buff)
{
typedef typename iterator_traits<_BidirectionalIterator>::value_type value_type;
__destruct_n __d(0);
unique_ptr<value_type, __destruct_n&> __h2(__buff, __d);
if (__len1 <= __len2)
{
value_type* __p = __buff;
for (_BidirectionalIterator __i = __first; __i != __middle; __d.template __incr<value_type>(), (void) ++__i, (void) ++__p)
::new ((void*)__p) value_type(_VSTD::move(*__i));
_VSTD::__half_inplace_merge<_Compare>(__buff, __p, __middle, __last, __first, __comp);
}
else
{
value_type* __p = __buff;
for (_BidirectionalIterator __i = __middle; __i != __last; __d.template __incr<value_type>(), (void) ++__i, (void) ++__p)
::new ((void*)__p) value_type(_VSTD::move(*__i));
typedef reverse_iterator<_BidirectionalIterator> _RBi;
typedef reverse_iterator<value_type*> _Rv;
typedef __invert<_Compare> _Inverted;
_VSTD::__half_inplace_merge<_Inverted>(_Rv(__p), _Rv(__buff),
_RBi(__middle), _RBi(__first),
_RBi(__last), _Inverted(__comp));
}
}
template <class _Compare, class _BidirectionalIterator>
void
__inplace_merge(_BidirectionalIterator __first, _BidirectionalIterator __middle, _BidirectionalIterator __last,
_Compare __comp, typename iterator_traits<_BidirectionalIterator>::difference_type __len1,
typename iterator_traits<_BidirectionalIterator>::difference_type __len2,
typename iterator_traits<_BidirectionalIterator>::value_type* __buff, ptrdiff_t __buff_size)
{
typedef typename iterator_traits<_BidirectionalIterator>::difference_type difference_type;
while (true)
{
// if __middle == __last, we're done
if (__len2 == 0)
return;
if (__len1 <= __buff_size || __len2 <= __buff_size)
return _VSTD::__buffered_inplace_merge<_Compare>
(__first, __middle, __last, __comp, __len1, __len2, __buff);
// shrink [__first, __middle) as much as possible (with no moves), returning if it shrinks to 0
for (; true; ++__first, (void) --__len1)
{
if (__len1 == 0)
return;
if (__comp(*__middle, *__first))
break;
}
// __first < __middle < __last
// *__first > *__middle
// partition [__first, __m1) [__m1, __middle) [__middle, __m2) [__m2, __last) such that
// all elements in:
// [__first, __m1) <= [__middle, __m2)
// [__middle, __m2) < [__m1, __middle)
// [__m1, __middle) <= [__m2, __last)
// and __m1 or __m2 is in the middle of its range
_BidirectionalIterator __m1; // "median" of [__first, __middle)
_BidirectionalIterator __m2; // "median" of [__middle, __last)
difference_type __len11; // distance(__first, __m1)
difference_type __len21; // distance(__middle, __m2)
// binary search smaller range
if (__len1 < __len2)
{ // __len >= 1, __len2 >= 2
__len21 = __len2 / 2;
__m2 = __middle;
_VSTD::advance(__m2, __len21);
__m1 = _VSTD::__upper_bound<_Compare>(__first, __middle, *__m2, __comp);
__len11 = _VSTD::distance(__first, __m1);
}
else
{
if (__len1 == 1)
{ // __len1 >= __len2 && __len2 > 0, therefore __len2 == 1
// It is known *__first > *__middle
swap(*__first, *__middle);
return;
}
// __len1 >= 2, __len2 >= 1
__len11 = __len1 / 2;
__m1 = __first;
_VSTD::advance(__m1, __len11);
__m2 = std::lower_bound(__middle, __last, *__m1, __comp);
__len21 = _VSTD::distance(__middle, __m2);
}
difference_type __len12 = __len1 - __len11; // distance(__m1, __middle)
difference_type __len22 = __len2 - __len21; // distance(__m2, __last)
// [__first, __m1) [__m1, __middle) [__middle, __m2) [__m2, __last)
// swap middle two partitions
__middle = _VSTD::rotate(__m1, __middle, __m2);
// __len12 and __len21 now have swapped meanings
// merge smaller range with recursive call and larger with tail recursion elimination
if (__len11 + __len21 < __len12 + __len22)
{
_VSTD::__inplace_merge<_Compare>(__first, __m1, __middle, __comp, __len11, __len21, __buff, __buff_size);
// _VSTD::__inplace_merge<_Compare>(__middle, __m2, __last, __comp, __len12, __len22, __buff, __buff_size);
__first = __middle;
__middle = __m2;
__len1 = __len12;
__len2 = __len22;
}
else
{
_VSTD::__inplace_merge<_Compare>(__middle, __m2, __last, __comp, __len12, __len22, __buff, __buff_size);
// _VSTD::__inplace_merge<_Compare>(__first, __m1, __middle, __comp, __len11, __len21, __buff, __buff_size);
__last = __middle;
__middle = __m1;
__len1 = __len11;
__len2 = __len21;
}
}
}
template <class _BidirectionalIterator, class _Compare>
inline _LIBCPP_INLINE_VISIBILITY
void
inplace_merge(_BidirectionalIterator __first, _BidirectionalIterator __middle, _BidirectionalIterator __last,
_Compare __comp)
{
typedef typename iterator_traits<_BidirectionalIterator>::value_type value_type;
typedef typename iterator_traits<_BidirectionalIterator>::difference_type difference_type;
difference_type __len1 = _VSTD::distance(__first, __middle);
difference_type __len2 = _VSTD::distance(__middle, __last);
difference_type __buf_size = _VSTD::min(__len1, __len2);
pair<value_type*, ptrdiff_t> __buf = _VSTD::get_temporary_buffer<value_type>(__buf_size);
unique_ptr<value_type, __return_temporary_buffer> __h(__buf.first);
typedef typename __comp_ref_type<_Compare>::type _Comp_ref;
return _VSTD::__inplace_merge<_Comp_ref>(__first, __middle, __last, __comp, __len1, __len2,
__buf.first, __buf.second);
}
template <class _BidirectionalIterator>
inline _LIBCPP_INLINE_VISIBILITY
void
inplace_merge(_BidirectionalIterator __first, _BidirectionalIterator __middle, _BidirectionalIterator __last)
{
_VSTD::inplace_merge(__first, __middle, __last,
__less<typename iterator_traits<_BidirectionalIterator>::value_type>());
}
_LIBCPP_END_NAMESPACE_STD
_LIBCPP_POP_MACROS
#endif // _LIBCPP___ALGORITHM_INPLACE_MERGE_H
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