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[official-gcc.git] / libstdc++-v3 / include / parallel / for_each_selectors.h
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4 //
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25 /** @file parallel/for_each_selectors.h
26 * @brief Functors representing different tasks to be plugged into the
27 * generic parallelization methods for embarrassingly parallel functions.
28 * This file is a GNU parallel extension to the Standard C++ Library.
31 // Written by Felix Putze.
33 #ifndef _GLIBCXX_PARALLEL_FOR_EACH_SELECTORS_H
34 #define _GLIBCXX_PARALLEL_FOR_EACH_SELECTORS_H 1
36 #include <parallel/basic_iterator.h>
38 namespace __gnu_parallel
40 /** @brief Generic __selector for embarrassingly parallel functions. */
41 template<typename _It>
42 struct __generic_for_each_selector
44 /** @brief _Iterator on last element processed; needed for some
45 * algorithms (e. g. std::transform()).
47 _It _M_finish_iterator;
50 /** @brief std::for_each() selector. */
51 template<typename _It>
52 struct __for_each_selector : public __generic_for_each_selector<_It>
54 /** @brief Functor execution.
55 * @param __o Operator.
56 * @param __i iterator referencing object. */
57 template<typename _Op>
58 bool
59 operator()(_Op& __o, _It __i)
61 __o(*__i);
62 return true;
66 /** @brief std::generate() selector. */
67 template<typename _It>
68 struct __generate_selector : public __generic_for_each_selector<_It>
70 /** @brief Functor execution.
71 * @param __o Operator.
72 * @param __i iterator referencing object. */
73 template<typename _Op>
74 bool
75 operator()(_Op& __o, _It __i)
77 *__i = __o();
78 return true;
82 /** @brief std::fill() selector. */
83 template<typename _It>
84 struct __fill_selector : public __generic_for_each_selector<_It>
86 /** @brief Functor execution.
87 * @param __v Current value.
88 * @param __i iterator referencing object. */
89 template<typename _ValueType>
90 bool
91 operator()(_ValueType& __v, _It __i)
93 *__i = __v;
94 return true;
98 /** @brief std::transform() __selector, one input sequence variant. */
99 template<typename _It>
100 struct __transform1_selector : public __generic_for_each_selector<_It>
102 /** @brief Functor execution.
103 * @param __o Operator.
104 * @param __i iterator referencing object. */
105 template<typename _Op>
106 bool
107 operator()(_Op& __o, _It __i)
109 *__i.second = __o(*__i.first);
110 return true;
114 /** @brief std::transform() __selector, two input sequences variant. */
115 template<typename _It>
116 struct __transform2_selector : public __generic_for_each_selector<_It>
118 /** @brief Functor execution.
119 * @param __o Operator.
120 * @param __i iterator referencing object. */
121 template<typename _Op>
122 bool
123 operator()(_Op& __o, _It __i)
125 *__i._M_third = __o(*__i._M_first, *__i._M_second);
126 return true;
130 /** @brief std::replace() selector. */
131 template<typename _It, typename _Tp>
132 struct __replace_selector : public __generic_for_each_selector<_It>
134 /** @brief Value to replace with. */
135 const _Tp& __new_val;
137 /** @brief Constructor
138 * @param __new_val Value to replace with. */
139 explicit
140 __replace_selector(const _Tp &__new_val) : __new_val(__new_val) {}
142 /** @brief Functor execution.
143 * @param __v Current value.
144 * @param __i iterator referencing object. */
145 bool
146 operator()(_Tp& __v, _It __i)
148 if (*__i == __v)
149 *__i = __new_val;
150 return true;
154 /** @brief std::replace() selector. */
155 template<typename _It, typename _Op, typename _Tp>
156 struct __replace_if_selector : public __generic_for_each_selector<_It>
158 /** @brief Value to replace with. */
159 const _Tp& __new_val;
161 /** @brief Constructor.
162 * @param __new_val Value to replace with. */
163 explicit
164 __replace_if_selector(const _Tp &__new_val) : __new_val(__new_val) { }
166 /** @brief Functor execution.
167 * @param __o Operator.
168 * @param __i iterator referencing object. */
169 bool
170 operator()(_Op& __o, _It __i)
172 if (__o(*__i))
173 *__i = __new_val;
174 return true;
178 /** @brief std::count() selector. */
179 template<typename _It, typename _Diff>
180 struct __count_selector : public __generic_for_each_selector<_It>
182 /** @brief Functor execution.
183 * @param __v Current value.
184 * @param __i iterator referencing object.
185 * @return 1 if count, 0 if does not count. */
186 template<typename _ValueType>
187 _Diff
188 operator()(_ValueType& __v, _It __i)
189 { return (__v == *__i) ? 1 : 0; }
192 /** @brief std::count_if () selector. */
193 template<typename _It, typename _Diff>
194 struct __count_if_selector : public __generic_for_each_selector<_It>
196 /** @brief Functor execution.
197 * @param __o Operator.
198 * @param __i iterator referencing object.
199 * @return 1 if count, 0 if does not count. */
200 template<typename _Op>
201 _Diff
202 operator()(_Op& __o, _It __i)
203 { return (__o(*__i)) ? 1 : 0; }
206 /** @brief std::accumulate() selector. */
207 template<typename _It>
208 struct __accumulate_selector : public __generic_for_each_selector<_It>
210 /** @brief Functor execution.
211 * @param __o Operator (unused).
212 * @param __i iterator referencing object.
213 * @return The current value. */
214 template<typename _Op>
215 typename std::iterator_traits<_It>::value_type
216 operator()(_Op __o, _It __i)
217 { return *__i; }
220 /** @brief std::inner_product() selector. */
221 template<typename _It, typename _It2, typename _Tp>
222 struct __inner_product_selector : public __generic_for_each_selector<_It>
224 /** @brief Begin iterator of first sequence. */
225 _It __begin1_iterator;
227 /** @brief Begin iterator of second sequence. */
228 _It2 __begin2_iterator;
230 /** @brief Constructor.
231 * @param __b1 Begin iterator of first sequence.
232 * @param __b2 Begin iterator of second sequence. */
233 explicit
234 __inner_product_selector(_It __b1, _It2 __b2)
235 : __begin1_iterator(__b1), __begin2_iterator(__b2) { }
237 /** @brief Functor execution.
238 * @param __mult Multiplication functor.
239 * @param __current iterator referencing object.
240 * @return Inner product elemental __result. */
241 template<typename _Op>
243 operator()(_Op __mult, _It __current)
245 typename std::iterator_traits<_It>::difference_type __position
246 = __current - __begin1_iterator;
247 return __mult(*__current, *(__begin2_iterator + __position));
251 /** @brief Selector that just returns the passed iterator. */
252 template<typename _It>
253 struct __identity_selector : public __generic_for_each_selector<_It>
255 /** @brief Functor execution.
256 * @param __o Operator (unused).
257 * @param __i iterator referencing object.
258 * @return Passed iterator. */
259 template<typename _Op>
261 operator()(_Op __o, _It __i)
262 { return __i; }
265 /** @brief Selector that returns the difference between two adjacent
266 * __elements.
268 template<typename _It>
269 struct __adjacent_difference_selector
270 : public __generic_for_each_selector<_It>
272 template<typename _Op>
273 bool
274 operator()(_Op& __o, _It __i)
276 typename _It::first_type __go_back_one = __i.first;
277 --__go_back_one;
278 *__i.second = __o(*__i.first, *__go_back_one);
279 return true;
283 /** @brief Functor doing nothing
285 * For some __reduction tasks (this is not a function object, but is
286 * passed as __selector __dummy parameter.
288 struct _Nothing
290 /** @brief Functor execution.
291 * @param __i iterator referencing object. */
292 template<typename _It>
293 void
294 operator()(_It __i) { }
297 /** @brief Reduction function doing nothing. */
298 struct _DummyReduct
300 bool
301 operator()(bool, bool) const
302 { return true; }
305 /** @brief Reduction for finding the maximum element, using a comparator. */
306 template<typename _Compare, typename _It>
307 struct __min_element_reduct
309 _Compare& __comp;
311 explicit
312 __min_element_reduct(_Compare &__c) : __comp(__c) { }
315 operator()(_It __x, _It __y)
316 { return (__comp(*__x, *__y)) ? __x : __y; }
319 /** @brief Reduction for finding the maximum element, using a comparator. */
320 template<typename _Compare, typename _It>
321 struct __max_element_reduct
323 _Compare& __comp;
325 explicit
326 __max_element_reduct(_Compare& __c) : __comp(__c) { }
329 operator()(_It __x, _It __y)
330 { return (__comp(*__x, *__y)) ? __y : __x; }
333 /** @brief General reduction, using a binary operator. */
334 template<typename _BinOp>
335 struct __accumulate_binop_reduct
337 _BinOp& __binop;
339 explicit
340 __accumulate_binop_reduct(_BinOp& __b) : __binop(__b) { }
342 template<typename _Result, typename _Addend>
343 _Result
344 operator()(const _Result& __x, const _Addend& __y)
345 { return __binop(__x, __y); }
349 #endif /* _GLIBCXX_PARALLEL_FOR_EACH_SELECTORS_H */