1 //===----------------------------------------------------------------------===// 2 // 3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions. 4 // See https://llvm.org/LICENSE.txt for license information. 5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception 6 // 7 //===----------------------------------------------------------------------===// 8 9 #ifndef _LIBCPP___ALGORITHM_INPLACE_MERGE_H 10 #define _LIBCPP___ALGORITHM_INPLACE_MERGE_H 11 12 #include <__algorithm/comp.h> 13 #include <__algorithm/comp_ref_type.h> 14 #include <__algorithm/iterator_operations.h> 15 #include <__algorithm/lower_bound.h> 16 #include <__algorithm/min.h> 17 #include <__algorithm/move.h> 18 #include <__algorithm/rotate.h> 19 #include <__algorithm/upper_bound.h> 20 #include <__config> 21 #include <__cstddef/ptrdiff_t.h> 22 #include <__functional/identity.h> 23 #include <__iterator/iterator_traits.h> 24 #include <__iterator/reverse_iterator.h> 25 #include <__memory/destruct_n.h> 26 #include <__memory/unique_ptr.h> 27 #include <__memory/unique_temporary_buffer.h> 28 #include <__utility/move.h> 29 #include <__utility/pair.h> 30 31 #if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER) 32 # pragma GCC system_header 33 #endif 34 35 _LIBCPP_PUSH_MACROS 36 #include <__undef_macros> 37 38 _LIBCPP_BEGIN_NAMESPACE_STD 39 40 template <class _Predicate> 41 class __invert // invert the sense of a comparison 42 { 43 private: 44 _Predicate __p_; 45 46 public: 47 _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX26 __invert() {} 48 49 _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX26 explicit __invert(_Predicate __p) : __p_(__p) {} 50 51 template <class _T1> 52 _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX26 bool operator()(const _T1& __x) { 53 return !__p_(__x); 54 } 55 56 template <class _T1, class _T2> 57 _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX26 bool operator()(const _T1& __x, const _T2& __y) { 58 return __p_(__y, __x); 59 } 60 }; 61 62 template <class _AlgPolicy, 63 class _Compare, 64 class _InputIterator1, 65 class _Sent1, 66 class _InputIterator2, 67 class _Sent2, 68 class _OutputIterator> 69 _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX26 void __half_inplace_merge( 70 _InputIterator1 __first1, 71 _Sent1 __last1, 72 _InputIterator2 __first2, 73 _Sent2 __last2, 74 _OutputIterator __result, 75 _Compare&& __comp) { 76 for (; __first1 != __last1; ++__result) { 77 if (__first2 == __last2) { 78 std::__move<_AlgPolicy>(__first1, __last1, __result); 79 return; 80 } 81 82 if (__comp(*__first2, *__first1)) { 83 *__result = _IterOps<_AlgPolicy>::__iter_move(__first2); 84 ++__first2; 85 } else { 86 *__result = _IterOps<_AlgPolicy>::__iter_move(__first1); 87 ++__first1; 88 } 89 } 90 // __first2 through __last2 are already in the right spot. 91 } 92 93 template <class _AlgPolicy, class _Compare, class _BidirectionalIterator> 94 _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX26 void __buffered_inplace_merge( 95 _BidirectionalIterator __first, 96 _BidirectionalIterator __middle, 97 _BidirectionalIterator __last, 98 _Compare&& __comp, 99 typename iterator_traits<_BidirectionalIterator>::difference_type __len1, 100 typename iterator_traits<_BidirectionalIterator>::difference_type __len2, 101 typename iterator_traits<_BidirectionalIterator>::value_type* __buff) { 102 typedef typename iterator_traits<_BidirectionalIterator>::value_type value_type; 103 __destruct_n __d(0); 104 unique_ptr<value_type, __destruct_n&> __h2(__buff, __d); 105 if (__len1 <= __len2) { 106 value_type* __p = __buff; 107 for (_BidirectionalIterator __i = __first; __i != __middle; 108 __d.template __incr<value_type>(), (void)++__i, (void)++__p) 109 ::new ((void*)__p) value_type(_IterOps<_AlgPolicy>::__iter_move(__i)); 110 std::__half_inplace_merge<_AlgPolicy>(__buff, __p, __middle, __last, __first, __comp); 111 } else { 112 value_type* __p = __buff; 113 for (_BidirectionalIterator __i = __middle; __i != __last; 114 __d.template __incr<value_type>(), (void)++__i, (void)++__p) 115 ::new ((void*)__p) value_type(_IterOps<_AlgPolicy>::__iter_move(__i)); 116 typedef reverse_iterator<_BidirectionalIterator> _RBi; 117 typedef reverse_iterator<value_type*> _Rv; 118 typedef __invert<_Compare> _Inverted; 119 std::__half_inplace_merge<_AlgPolicy>( 120 _Rv(__p), _Rv(__buff), _RBi(__middle), _RBi(__first), _RBi(__last), _Inverted(__comp)); 121 } 122 } 123 124 template <class _AlgPolicy, class _Compare, class _BidirectionalIterator> 125 _LIBCPP_CONSTEXPR_SINCE_CXX26 void __inplace_merge( 126 _BidirectionalIterator __first, 127 _BidirectionalIterator __middle, 128 _BidirectionalIterator __last, 129 _Compare&& __comp, 130 typename iterator_traits<_BidirectionalIterator>::difference_type __len1, 131 typename iterator_traits<_BidirectionalIterator>::difference_type __len2, 132 typename iterator_traits<_BidirectionalIterator>::value_type* __buff, 133 ptrdiff_t __buff_size) { 134 using _Ops = _IterOps<_AlgPolicy>; 135 136 typedef typename iterator_traits<_BidirectionalIterator>::difference_type difference_type; 137 while (true) { 138 // if __middle == __last, we're done 139 if (__len2 == 0) 140 return; 141 if (__len1 <= __buff_size || __len2 <= __buff_size) 142 return std::__buffered_inplace_merge<_AlgPolicy>(__first, __middle, __last, __comp, __len1, __len2, __buff); 143 // shrink [__first, __middle) as much as possible (with no moves), returning if it shrinks to 0 144 for (; true; ++__first, (void)--__len1) { 145 if (__len1 == 0) 146 return; 147 if (__comp(*__middle, *__first)) 148 break; 149 } 150 // __first < __middle < __last 151 // *__first > *__middle 152 // partition [__first, __m1) [__m1, __middle) [__middle, __m2) [__m2, __last) such that 153 // all elements in: 154 // [__first, __m1) <= [__middle, __m2) 155 // [__middle, __m2) < [__m1, __middle) 156 // [__m1, __middle) <= [__m2, __last) 157 // and __m1 or __m2 is in the middle of its range 158 _BidirectionalIterator __m1; // "median" of [__first, __middle) 159 _BidirectionalIterator __m2; // "median" of [__middle, __last) 160 difference_type __len11; // distance(__first, __m1) 161 difference_type __len21; // distance(__middle, __m2) 162 // binary search smaller range 163 if (__len1 < __len2) { // __len >= 1, __len2 >= 2 164 __len21 = __len2 / 2; 165 __m2 = __middle; 166 _Ops::advance(__m2, __len21); 167 __m1 = std::__upper_bound<_AlgPolicy>(__first, __middle, *__m2, __comp, std::__identity()); 168 __len11 = _Ops::distance(__first, __m1); 169 } else { 170 if (__len1 == 1) { // __len1 >= __len2 && __len2 > 0, therefore __len2 == 1 171 // It is known *__first > *__middle 172 _Ops::iter_swap(__first, __middle); 173 return; 174 } 175 // __len1 >= 2, __len2 >= 1 176 __len11 = __len1 / 2; 177 __m1 = __first; 178 _Ops::advance(__m1, __len11); 179 __m2 = std::lower_bound(__middle, __last, *__m1, __comp); 180 __len21 = _Ops::distance(__middle, __m2); 181 } 182 difference_type __len12 = __len1 - __len11; // distance(__m1, __middle) 183 difference_type __len22 = __len2 - __len21; // distance(__m2, __last) 184 // [__first, __m1) [__m1, __middle) [__middle, __m2) [__m2, __last) 185 // swap middle two partitions 186 __middle = std::__rotate<_AlgPolicy>(__m1, __middle, __m2).first; 187 // __len12 and __len21 now have swapped meanings 188 // merge smaller range with recursive call and larger with tail recursion elimination 189 if (__len11 + __len21 < __len12 + __len22) { 190 std::__inplace_merge<_AlgPolicy>(__first, __m1, __middle, __comp, __len11, __len21, __buff, __buff_size); 191 __first = __middle; 192 __middle = __m2; 193 __len1 = __len12; 194 __len2 = __len22; 195 } else { 196 std::__inplace_merge<_AlgPolicy>(__middle, __m2, __last, __comp, __len12, __len22, __buff, __buff_size); 197 __last = __middle; 198 __middle = __m1; 199 __len1 = __len11; 200 __len2 = __len21; 201 } 202 } 203 } 204 205 template <class _AlgPolicy, class _BidirectionalIterator, class _Compare> 206 _LIBCPP_HIDE_FROM_ABI void __inplace_merge( 207 _BidirectionalIterator __first, _BidirectionalIterator __middle, _BidirectionalIterator __last, _Compare&& __comp) { 208 typedef typename iterator_traits<_BidirectionalIterator>::value_type value_type; 209 typedef typename iterator_traits<_BidirectionalIterator>::difference_type difference_type; 210 difference_type __len1 = _IterOps<_AlgPolicy>::distance(__first, __middle); 211 difference_type __len2 = _IterOps<_AlgPolicy>::distance(__middle, __last); 212 difference_type __buf_size = std::min(__len1, __len2); 213 __unique_temporary_buffer<value_type> __unique_buf = std::__allocate_unique_temporary_buffer<value_type>(__buf_size); 214 return std::__inplace_merge<_AlgPolicy>( 215 std::move(__first), 216 std::move(__middle), 217 std::move(__last), 218 __comp, 219 __len1, 220 __len2, 221 __unique_buf.get(), 222 __unique_buf.get_deleter().__count_); 223 } 224 225 template <class _BidirectionalIterator, class _Compare> 226 inline _LIBCPP_HIDE_FROM_ABI void inplace_merge( 227 _BidirectionalIterator __first, _BidirectionalIterator __middle, _BidirectionalIterator __last, _Compare __comp) { 228 std::__inplace_merge<_ClassicAlgPolicy>( 229 std::move(__first), std::move(__middle), std::move(__last), static_cast<__comp_ref_type<_Compare> >(__comp)); 230 } 231 232 template <class _BidirectionalIterator> 233 inline _LIBCPP_HIDE_FROM_ABI void 234 inplace_merge(_BidirectionalIterator __first, _BidirectionalIterator __middle, _BidirectionalIterator __last) { 235 std::inplace_merge(std::move(__first), std::move(__middle), std::move(__last), __less<>()); 236 } 237 238 _LIBCPP_END_NAMESPACE_STD 239 240 _LIBCPP_POP_MACROS 241 242 #endif // _LIBCPP___ALGORITHM_INPLACE_MERGE_H 243