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