1 // -*- C++ -*- 2 3 // Copyright (C) 2007-2018 Free Software Foundation, Inc. 4 // 5 // This file is part of the GNU ISO C++ Library. This library is free 6 // software; you can redistribute it and/or modify it under the terms 7 // of the GNU General Public License as published by the Free Software 8 // Foundation; either version 3, or (at your option) any later 9 // version. 10 11 // This library is distributed in the hope that it will be useful, but 12 // WITHOUT ANY WARRANTY; without even the implied warranty of 13 // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU 14 // General Public License for more details. 15 16 // Under Section 7 of GPL version 3, you are granted additional 17 // permissions described in the GCC Runtime Library Exception, version 18 // 3.1, as published by the Free Software Foundation. 19 20 // You should have received a copy of the GNU General Public License and 21 // a copy of the GCC Runtime Library Exception along with this program; 22 // see the files COPYING3 and COPYING.RUNTIME respectively. If not, see 23 // <http://www.gnu.org/licenses/>. 24 25 /** @file parallel/unique_copy.h 26 * @brief Parallel implementations of std::unique_copy(). 27 * This file is a GNU parallel extension to the Standard C++ Library. 28 */ 29 30 // Written by Robert Geisberger and Robin Dapp. 31 32 #ifndef _GLIBCXX_PARALLEL_UNIQUE_COPY_H 33 #define _GLIBCXX_PARALLEL_UNIQUE_COPY_H 1 34 35 #include <parallel/parallel.h> 36 #include <parallel/multiseq_selection.h> 37 38 namespace __gnu_parallel 39 { 40 /** @brief Parallel std::unique_copy(), w/__o explicit equality predicate. 41 * @param __first Begin iterator of input sequence. 42 * @param __last End iterator of input sequence. 43 * @param __result Begin iterator of result __sequence. 44 * @param __binary_pred Equality predicate. 45 * @return End iterator of result __sequence. */ 46 template<typename _IIter, 47 class _OutputIterator, 48 class _BinaryPredicate> 49 _OutputIterator 50 __parallel_unique_copy(_IIter __first, _IIter __last, 51 _OutputIterator __result, 52 _BinaryPredicate __binary_pred) 53 { 54 _GLIBCXX_CALL(__last - __first) 55 56 typedef std::iterator_traits<_IIter> _TraitsType; 57 typedef typename _TraitsType::value_type _ValueType; 58 typedef typename _TraitsType::difference_type _DifferenceType; 59 60 _DifferenceType __size = __last - __first; 61 62 if (__size == 0) 63 return __result; 64 65 // Let the first thread process two parts. 66 _DifferenceType *__counter; 67 _DifferenceType *__borders; 68 69 _ThreadIndex __num_threads = __get_max_threads(); 70 // First part contains at least one element. 71 # pragma omp parallel num_threads(__num_threads) 72 { 73 # pragma omp single 74 { 75 __num_threads = omp_get_num_threads(); 76 __borders = new _DifferenceType[__num_threads + 2]; 77 __equally_split(__size, __num_threads + 1, __borders); 78 __counter = new _DifferenceType[__num_threads + 1]; 79 } 80 81 _ThreadIndex __iam = omp_get_thread_num(); 82 83 _DifferenceType __begin, __end; 84 85 // Check for length without duplicates 86 // Needed for position in output 87 _DifferenceType __i = 0; 88 _OutputIterator __out = __result; 89 90 if (__iam == 0) 91 { 92 __begin = __borders[0] + 1; // == 1 93 __end = __borders[__iam + 1]; 94 95 ++__i; 96 *__out++ = *__first; 97 98 for (_IIter __iter = __first + __begin; __iter < __first + __end; 99 ++__iter) 100 { 101 if (!__binary_pred(*__iter, *(__iter - 1))) 102 { 103 ++__i; 104 *__out++ = *__iter; 105 } 106 } 107 } 108 else 109 { 110 __begin = __borders[__iam]; //one part 111 __end = __borders[__iam + 1]; 112 113 for (_IIter __iter = __first + __begin; __iter < __first + __end; 114 ++__iter) 115 { 116 if (!__binary_pred(*__iter, *(__iter - 1))) 117 ++__i; 118 } 119 } 120 __counter[__iam] = __i; 121 122 // Last part still untouched. 123 _DifferenceType __begin_output; 124 125 # pragma omp barrier 126 127 // Store result in output on calculated positions. 128 __begin_output = 0; 129 130 if (__iam == 0) 131 { 132 for (_ThreadIndex __t = 0; __t < __num_threads; ++__t) 133 __begin_output += __counter[__t]; 134 135 __i = 0; 136 137 _OutputIterator __iter_out = __result + __begin_output; 138 139 __begin = __borders[__num_threads]; 140 __end = __size; 141 142 for (_IIter __iter = __first + __begin; __iter < __first + __end; 143 ++__iter) 144 { 145 if (__iter == __first 146 || !__binary_pred(*__iter, *(__iter - 1))) 147 { 148 ++__i; 149 *__iter_out++ = *__iter; 150 } 151 } 152 153 __counter[__num_threads] = __i; 154 } 155 else 156 { 157 for (_ThreadIndex __t = 0; __t < __iam; __t++) 158 __begin_output += __counter[__t]; 159 160 _OutputIterator __iter_out = __result + __begin_output; 161 for (_IIter __iter = __first + __begin; __iter < __first + __end; 162 ++__iter) 163 { 164 if (!__binary_pred(*__iter, *(__iter - 1))) 165 *__iter_out++ = *__iter; 166 } 167 } 168 } 169 170 _DifferenceType __end_output = 0; 171 for (_ThreadIndex __t = 0; __t < __num_threads + 1; __t++) 172 __end_output += __counter[__t]; 173 174 delete[] __borders; 175 176 return __result + __end_output; 177 } 178 179 /** @brief Parallel std::unique_copy(), without explicit equality predicate 180 * @param __first Begin iterator of input sequence. 181 * @param __last End iterator of input sequence. 182 * @param __result Begin iterator of result __sequence. 183 * @return End iterator of result __sequence. */ 184 template<typename _IIter, class _OutputIterator> 185 inline _OutputIterator 186 __parallel_unique_copy(_IIter __first, _IIter __last, 187 _OutputIterator __result) 188 { 189 typedef typename std::iterator_traits<_IIter>::value_type 190 _ValueType; 191 return __parallel_unique_copy(__first, __last, __result, 192 std::equal_to<_ValueType>()); 193 } 194 195 }//namespace __gnu_parallel 196 197 #endif /* _GLIBCXX_PARALLEL_UNIQUE_COPY_H */ 198