xref: /freebsd-src/contrib/llvm-project/libcxx/include/__algorithm/inplace_merge.h (revision 0fca6ea1d4eea4c934cfff25ac9ee8ad6fe95583)
1fe6060f1SDimitry Andric //===----------------------------------------------------------------------===//
2fe6060f1SDimitry Andric //
3fe6060f1SDimitry Andric // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
4fe6060f1SDimitry Andric // See https://llvm.org/LICENSE.txt for license information.
5fe6060f1SDimitry Andric // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
6fe6060f1SDimitry Andric //
7fe6060f1SDimitry Andric //===----------------------------------------------------------------------===//
8fe6060f1SDimitry Andric 
9fe6060f1SDimitry Andric #ifndef _LIBCPP___ALGORITHM_INPLACE_MERGE_H
10fe6060f1SDimitry Andric #define _LIBCPP___ALGORITHM_INPLACE_MERGE_H
11fe6060f1SDimitry Andric 
12fe6060f1SDimitry Andric #include <__algorithm/comp.h>
1304eeddc0SDimitry Andric #include <__algorithm/comp_ref_type.h>
14fcaf7f86SDimitry Andric #include <__algorithm/iterator_operations.h>
15fe6060f1SDimitry Andric #include <__algorithm/lower_bound.h>
16fe6060f1SDimitry Andric #include <__algorithm/min.h>
17fe6060f1SDimitry Andric #include <__algorithm/move.h>
18fe6060f1SDimitry Andric #include <__algorithm/rotate.h>
19fe6060f1SDimitry Andric #include <__algorithm/upper_bound.h>
2004eeddc0SDimitry Andric #include <__config>
21fcaf7f86SDimitry Andric #include <__functional/identity.h>
2281ad6265SDimitry Andric #include <__iterator/advance.h>
2381ad6265SDimitry Andric #include <__iterator/distance.h>
24fe6060f1SDimitry Andric #include <__iterator/iterator_traits.h>
2581ad6265SDimitry Andric #include <__iterator/reverse_iterator.h>
26bdd1243dSDimitry Andric #include <__memory/destruct_n.h>
27bdd1243dSDimitry Andric #include <__memory/temporary_buffer.h>
28bdd1243dSDimitry Andric #include <__memory/unique_ptr.h>
29bdd1243dSDimitry Andric #include <__utility/pair.h>
30bdd1243dSDimitry Andric #include <new>
31fe6060f1SDimitry Andric 
32fe6060f1SDimitry Andric #if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
33fe6060f1SDimitry Andric #  pragma GCC system_header
34fe6060f1SDimitry Andric #endif
35fe6060f1SDimitry Andric 
36fe6060f1SDimitry Andric _LIBCPP_PUSH_MACROS
37fe6060f1SDimitry Andric #include <__undef_macros>
38fe6060f1SDimitry Andric 
39fe6060f1SDimitry Andric _LIBCPP_BEGIN_NAMESPACE_STD
40fe6060f1SDimitry Andric 
41fe6060f1SDimitry Andric template <class _Predicate>
42fe6060f1SDimitry Andric class __invert // invert the sense of a comparison
43fe6060f1SDimitry Andric {
44fe6060f1SDimitry Andric private:
45fe6060f1SDimitry Andric   _Predicate __p_;
46cb14a3feSDimitry Andric 
47fe6060f1SDimitry Andric public:
485f757f3fSDimitry Andric   _LIBCPP_HIDE_FROM_ABI __invert() {}
49fe6060f1SDimitry Andric 
50cb14a3feSDimitry Andric   _LIBCPP_HIDE_FROM_ABI explicit __invert(_Predicate __p) : __p_(__p) {}
51fe6060f1SDimitry Andric 
52fe6060f1SDimitry Andric   template <class _T1>
53cb14a3feSDimitry Andric   _LIBCPP_HIDE_FROM_ABI bool operator()(const _T1& __x) {
54cb14a3feSDimitry Andric     return !__p_(__x);
55cb14a3feSDimitry Andric   }
56fe6060f1SDimitry Andric 
57fe6060f1SDimitry Andric   template <class _T1, class _T2>
58cb14a3feSDimitry Andric   _LIBCPP_HIDE_FROM_ABI bool operator()(const _T1& __x, const _T2& __y) {
59cb14a3feSDimitry Andric     return __p_(__y, __x);
60cb14a3feSDimitry Andric   }
61fe6060f1SDimitry Andric };
62fe6060f1SDimitry Andric 
63cb14a3feSDimitry Andric template <class _AlgPolicy,
64cb14a3feSDimitry Andric           class _Compare,
65cb14a3feSDimitry Andric           class _InputIterator1,
66cb14a3feSDimitry Andric           class _Sent1,
67cb14a3feSDimitry Andric           class _InputIterator2,
68cb14a3feSDimitry Andric           class _Sent2,
69cb14a3feSDimitry Andric           class _OutputIterator>
70cb14a3feSDimitry Andric _LIBCPP_HIDE_FROM_ABI void __half_inplace_merge(
71cb14a3feSDimitry Andric     _InputIterator1 __first1,
72cb14a3feSDimitry Andric     _Sent1 __last1,
73cb14a3feSDimitry Andric     _InputIterator2 __first2,
74cb14a3feSDimitry Andric     _Sent2 __last2,
75cb14a3feSDimitry Andric     _OutputIterator __result,
76cb14a3feSDimitry Andric     _Compare&& __comp) {
77cb14a3feSDimitry Andric   for (; __first1 != __last1; ++__result) {
78cb14a3feSDimitry Andric     if (__first2 == __last2) {
7961cfbce3SDimitry Andric       std::__move<_AlgPolicy>(__first1, __last1, __result);
80fe6060f1SDimitry Andric       return;
81fe6060f1SDimitry Andric     }
82fe6060f1SDimitry Andric 
83cb14a3feSDimitry Andric     if (__comp(*__first2, *__first1)) {
84fcaf7f86SDimitry Andric       *__result = _IterOps<_AlgPolicy>::__iter_move(__first2);
85fe6060f1SDimitry Andric       ++__first2;
86cb14a3feSDimitry Andric     } else {
87fcaf7f86SDimitry Andric       *__result = _IterOps<_AlgPolicy>::__iter_move(__first1);
88fe6060f1SDimitry Andric       ++__first1;
89fe6060f1SDimitry Andric     }
90fe6060f1SDimitry Andric   }
91fe6060f1SDimitry Andric   // __first2 through __last2 are already in the right spot.
92fe6060f1SDimitry Andric }
93fe6060f1SDimitry Andric 
94fcaf7f86SDimitry Andric template <class _AlgPolicy, class _Compare, class _BidirectionalIterator>
95cb14a3feSDimitry Andric _LIBCPP_HIDE_FROM_ABI void __buffered_inplace_merge(
9661cfbce3SDimitry Andric     _BidirectionalIterator __first,
9761cfbce3SDimitry Andric     _BidirectionalIterator __middle,
9861cfbce3SDimitry Andric     _BidirectionalIterator __last,
9961cfbce3SDimitry Andric     _Compare&& __comp,
10061cfbce3SDimitry Andric     typename iterator_traits<_BidirectionalIterator>::difference_type __len1,
101fe6060f1SDimitry Andric     typename iterator_traits<_BidirectionalIterator>::difference_type __len2,
10261cfbce3SDimitry Andric     typename iterator_traits<_BidirectionalIterator>::value_type* __buff) {
103fe6060f1SDimitry Andric   typedef typename iterator_traits<_BidirectionalIterator>::value_type value_type;
104fe6060f1SDimitry Andric   __destruct_n __d(0);
105fe6060f1SDimitry Andric   unique_ptr<value_type, __destruct_n&> __h2(__buff, __d);
106cb14a3feSDimitry Andric   if (__len1 <= __len2) {
107fe6060f1SDimitry Andric     value_type* __p = __buff;
108cb14a3feSDimitry Andric     for (_BidirectionalIterator __i = __first; __i != __middle;
109cb14a3feSDimitry Andric          __d.template __incr<value_type>(), (void)++__i, (void)++__p)
110fcaf7f86SDimitry Andric       ::new ((void*)__p) value_type(_IterOps<_AlgPolicy>::__iter_move(__i));
11161cfbce3SDimitry Andric     std::__half_inplace_merge<_AlgPolicy>(__buff, __p, __middle, __last, __first, __comp);
112cb14a3feSDimitry Andric   } else {
113fe6060f1SDimitry Andric     value_type* __p = __buff;
114cb14a3feSDimitry Andric     for (_BidirectionalIterator __i = __middle; __i != __last;
115cb14a3feSDimitry Andric          __d.template __incr<value_type>(), (void)++__i, (void)++__p)
116fcaf7f86SDimitry Andric       ::new ((void*)__p) value_type(_IterOps<_AlgPolicy>::__iter_move(__i));
117*0fca6ea1SDimitry Andric     typedef reverse_iterator<_BidirectionalIterator> _RBi;
118*0fca6ea1SDimitry Andric     typedef reverse_iterator<value_type*> _Rv;
119fe6060f1SDimitry Andric     typedef __invert<_Compare> _Inverted;
120cb14a3feSDimitry Andric     std::__half_inplace_merge<_AlgPolicy>(
121cb14a3feSDimitry Andric         _Rv(__p), _Rv(__buff), _RBi(__middle), _RBi(__first), _RBi(__last), _Inverted(__comp));
122fe6060f1SDimitry Andric   }
123fe6060f1SDimitry Andric }
124fe6060f1SDimitry Andric 
125fcaf7f86SDimitry Andric template <class _AlgPolicy, class _Compare, class _BidirectionalIterator>
12661cfbce3SDimitry Andric void __inplace_merge(
12761cfbce3SDimitry Andric     _BidirectionalIterator __first,
12861cfbce3SDimitry Andric     _BidirectionalIterator __middle,
12961cfbce3SDimitry Andric     _BidirectionalIterator __last,
13061cfbce3SDimitry Andric     _Compare&& __comp,
13161cfbce3SDimitry Andric     typename iterator_traits<_BidirectionalIterator>::difference_type __len1,
132fe6060f1SDimitry Andric     typename iterator_traits<_BidirectionalIterator>::difference_type __len2,
13361cfbce3SDimitry Andric     typename iterator_traits<_BidirectionalIterator>::value_type* __buff,
13461cfbce3SDimitry Andric     ptrdiff_t __buff_size) {
135fcaf7f86SDimitry Andric   using _Ops = _IterOps<_AlgPolicy>;
136fcaf7f86SDimitry Andric 
137fe6060f1SDimitry Andric   typedef typename iterator_traits<_BidirectionalIterator>::difference_type difference_type;
138cb14a3feSDimitry Andric   while (true) {
139fe6060f1SDimitry Andric     // if __middle == __last, we're done
140fe6060f1SDimitry Andric     if (__len2 == 0)
141fe6060f1SDimitry Andric       return;
142fe6060f1SDimitry Andric     if (__len1 <= __buff_size || __len2 <= __buff_size)
143cb14a3feSDimitry Andric       return std::__buffered_inplace_merge<_AlgPolicy>(__first, __middle, __last, __comp, __len1, __len2, __buff);
144fe6060f1SDimitry Andric     // shrink [__first, __middle) as much as possible (with no moves), returning if it shrinks to 0
145cb14a3feSDimitry Andric     for (; true; ++__first, (void)--__len1) {
146fe6060f1SDimitry Andric       if (__len1 == 0)
147fe6060f1SDimitry Andric         return;
148fe6060f1SDimitry Andric       if (__comp(*__middle, *__first))
149fe6060f1SDimitry Andric         break;
150fe6060f1SDimitry Andric     }
151fe6060f1SDimitry Andric     // __first < __middle < __last
152fe6060f1SDimitry Andric     // *__first > *__middle
153fe6060f1SDimitry Andric     // partition [__first, __m1) [__m1, __middle) [__middle, __m2) [__m2, __last) such that
154fe6060f1SDimitry Andric     //     all elements in:
155fe6060f1SDimitry Andric     //         [__first, __m1)  <= [__middle, __m2)
156fe6060f1SDimitry Andric     //         [__middle, __m2) <  [__m1, __middle)
157fe6060f1SDimitry Andric     //         [__m1, __middle) <= [__m2, __last)
158fe6060f1SDimitry Andric     //     and __m1 or __m2 is in the middle of its range
159fe6060f1SDimitry Andric     _BidirectionalIterator __m1; // "median" of [__first, __middle)
160fe6060f1SDimitry Andric     _BidirectionalIterator __m2; // "median" of [__middle, __last)
161fe6060f1SDimitry Andric     difference_type __len11;     // distance(__first, __m1)
162fe6060f1SDimitry Andric     difference_type __len21;     // distance(__middle, __m2)
163fe6060f1SDimitry Andric     // binary search smaller range
164cb14a3feSDimitry Andric     if (__len1 < __len2) { // __len >= 1, __len2 >= 2
165fe6060f1SDimitry Andric       __len21 = __len2 / 2;
166fe6060f1SDimitry Andric       __m2    = __middle;
167fcaf7f86SDimitry Andric       _Ops::advance(__m2, __len21);
16861cfbce3SDimitry Andric       __m1    = std::__upper_bound<_AlgPolicy>(__first, __middle, *__m2, __comp, std::__identity());
169fcaf7f86SDimitry Andric       __len11 = _Ops::distance(__first, __m1);
170cb14a3feSDimitry Andric     } else {
171cb14a3feSDimitry Andric       if (__len1 == 1) { // __len1 >= __len2 && __len2 > 0, therefore __len2 == 1
172fe6060f1SDimitry Andric                          // It is known *__first > *__middle
173fcaf7f86SDimitry Andric         _Ops::iter_swap(__first, __middle);
174fe6060f1SDimitry Andric         return;
175fe6060f1SDimitry Andric       }
176fe6060f1SDimitry Andric       // __len1 >= 2, __len2 >= 1
177fe6060f1SDimitry Andric       __len11 = __len1 / 2;
178fe6060f1SDimitry Andric       __m1    = __first;
179fcaf7f86SDimitry Andric       _Ops::advance(__m1, __len11);
18081ad6265SDimitry Andric       __m2    = std::lower_bound(__middle, __last, *__m1, __comp);
181fcaf7f86SDimitry Andric       __len21 = _Ops::distance(__middle, __m2);
182fe6060f1SDimitry Andric     }
183fe6060f1SDimitry Andric     difference_type __len12 = __len1 - __len11; // distance(__m1, __middle)
184fe6060f1SDimitry Andric     difference_type __len22 = __len2 - __len21; // distance(__m2, __last)
185fe6060f1SDimitry Andric     // [__first, __m1) [__m1, __middle) [__middle, __m2) [__m2, __last)
186fe6060f1SDimitry Andric     // swap middle two partitions
18761cfbce3SDimitry Andric     __middle = std::__rotate<_AlgPolicy>(__m1, __middle, __m2).first;
188fe6060f1SDimitry Andric     // __len12 and __len21 now have swapped meanings
189fe6060f1SDimitry Andric     // merge smaller range with recursive call and larger with tail recursion elimination
190cb14a3feSDimitry Andric     if (__len11 + __len21 < __len12 + __len22) {
191cb14a3feSDimitry Andric       std::__inplace_merge<_AlgPolicy>(__first, __m1, __middle, __comp, __len11, __len21, __buff, __buff_size);
192fe6060f1SDimitry Andric       __first  = __middle;
193fe6060f1SDimitry Andric       __middle = __m2;
194fe6060f1SDimitry Andric       __len1   = __len12;
195fe6060f1SDimitry Andric       __len2   = __len22;
196cb14a3feSDimitry Andric     } else {
197cb14a3feSDimitry Andric       std::__inplace_merge<_AlgPolicy>(__middle, __m2, __last, __comp, __len12, __len22, __buff, __buff_size);
198fe6060f1SDimitry Andric       __last   = __middle;
199fe6060f1SDimitry Andric       __middle = __m1;
200fe6060f1SDimitry Andric       __len1   = __len11;
201fe6060f1SDimitry Andric       __len2   = __len21;
202fe6060f1SDimitry Andric     }
203fe6060f1SDimitry Andric   }
204fe6060f1SDimitry Andric }
205fe6060f1SDimitry Andric 
20661cfbce3SDimitry Andric template <class _AlgPolicy, class _BidirectionalIterator, class _Compare>
207cb14a3feSDimitry Andric _LIBCPP_HIDE_FROM_ABI void __inplace_merge(
208cb14a3feSDimitry Andric     _BidirectionalIterator __first, _BidirectionalIterator __middle, _BidirectionalIterator __last, _Compare&& __comp) {
209fe6060f1SDimitry Andric   typedef typename iterator_traits<_BidirectionalIterator>::value_type value_type;
210fe6060f1SDimitry Andric   typedef typename iterator_traits<_BidirectionalIterator>::difference_type difference_type;
21161cfbce3SDimitry Andric   difference_type __len1     = _IterOps<_AlgPolicy>::distance(__first, __middle);
21261cfbce3SDimitry Andric   difference_type __len2     = _IterOps<_AlgPolicy>::distance(__middle, __last);
2135f757f3fSDimitry Andric   difference_type __buf_size = std::min(__len1, __len2);
21481ad6265SDimitry Andric   // TODO: Remove the use of std::get_temporary_buffer
21581ad6265SDimitry Andric   _LIBCPP_SUPPRESS_DEPRECATED_PUSH
2165f757f3fSDimitry Andric   pair<value_type*, ptrdiff_t> __buf = std::get_temporary_buffer<value_type>(__buf_size);
21781ad6265SDimitry Andric   _LIBCPP_SUPPRESS_DEPRECATED_POP
218fe6060f1SDimitry Andric   unique_ptr<value_type, __return_temporary_buffer> __h(__buf.first);
21961cfbce3SDimitry Andric   return std::__inplace_merge<_AlgPolicy>(
22061cfbce3SDimitry Andric       std::move(__first), std::move(__middle), std::move(__last), __comp, __len1, __len2, __buf.first, __buf.second);
22161cfbce3SDimitry Andric }
22261cfbce3SDimitry Andric 
22361cfbce3SDimitry Andric template <class _BidirectionalIterator, class _Compare>
22461cfbce3SDimitry Andric inline _LIBCPP_HIDE_FROM_ABI void inplace_merge(
22561cfbce3SDimitry Andric     _BidirectionalIterator __first, _BidirectionalIterator __middle, _BidirectionalIterator __last, _Compare __comp) {
22661cfbce3SDimitry Andric   std::__inplace_merge<_ClassicAlgPolicy>(
227bdd1243dSDimitry Andric       std::move(__first), std::move(__middle), std::move(__last), static_cast<__comp_ref_type<_Compare> >(__comp));
228fe6060f1SDimitry Andric }
229fe6060f1SDimitry Andric 
230fe6060f1SDimitry Andric template <class _BidirectionalIterator>
231cb14a3feSDimitry Andric inline _LIBCPP_HIDE_FROM_ABI void
232cb14a3feSDimitry Andric inplace_merge(_BidirectionalIterator __first, _BidirectionalIterator __middle, _BidirectionalIterator __last) {
23306c3fb27SDimitry Andric   std::inplace_merge(std::move(__first), std::move(__middle), std::move(__last), __less<>());
234fe6060f1SDimitry Andric }
235fe6060f1SDimitry Andric 
236fe6060f1SDimitry Andric _LIBCPP_END_NAMESPACE_STD
237fe6060f1SDimitry Andric 
238fe6060f1SDimitry Andric _LIBCPP_POP_MACROS
239fe6060f1SDimitry Andric 
240fe6060f1SDimitry Andric #endif // _LIBCPP___ALGORITHM_INPLACE_MERGE_H
241