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39
40#ifndef QTCONCURRENT_FILTERKERNEL_H
41#define QTCONCURRENT_FILTERKERNEL_H
42
43#include <QtConcurrent/qtconcurrent_global.h>
44
45#if !defined(QT_NO_CONCURRENT) || defined (Q_CLANG_QDOC)
46
47#include <QtConcurrent/qtconcurrentiteratekernel.h>
48#include <QtConcurrent/qtconcurrentmapkernel.h>
49#include <QtConcurrent/qtconcurrentreducekernel.h>
50
51QT_BEGIN_NAMESPACE
52
53
54
55namespace QtConcurrent {
56
57template <typename T>
58struct qValueType
59{
60 typedef typename T::value_type value_type;
61};
62
63template <typename T>
64struct qValueType<const T*>
65{
66 typedef T value_type;
67};
68
69template <typename T>
70struct qValueType<T*>
71{
72 typedef T value_type;
73};
74
75// Implementation of filter
76template <typename Sequence, typename KeepFunctor, typename ReduceFunctor>
77class FilterKernel : public IterateKernel<typename Sequence::const_iterator, void>
78{
79 typedef ReduceKernel<ReduceFunctor, Sequence, typename Sequence::value_type> Reducer;
80 typedef IterateKernel<typename Sequence::const_iterator, void> IterateKernelType;
81 typedef typename ReduceFunctor::result_type T;
82
83 Sequence reducedResult;
84 Sequence &sequence;
85 KeepFunctor keep;
86 ReduceFunctor reduce;
87 Reducer reducer;
88
89public:
90 FilterKernel(Sequence &_sequence, KeepFunctor _keep, ReduceFunctor _reduce)
91 : IterateKernelType(const_cast<const Sequence &>(_sequence).begin(), const_cast<const Sequence &>(_sequence).end()), reducedResult(),
92 sequence(_sequence),
93 keep(_keep),
94 reduce(_reduce),
95 reducer(OrderedReduce)
96 { }
97
98 bool runIteration(typename Sequence::const_iterator it, int index, T *) override
99 {
100 IntermediateResults<typename Sequence::value_type> results;
101 results.begin = index;
102 results.end = index + 1;
103
104 if (keep(*it))
105 results.vector.append(*it);
106
107 reducer.runReduce(reduce, reducedResult, results);
108 return false;
109 }
110
111 bool runIterations(typename Sequence::const_iterator sequenceBeginIterator, int begin, int end, T *) override
112 {
113 IntermediateResults<typename Sequence::value_type> results;
114 results.begin = begin;
115 results.end = end;
116 results.vector.reserve(end - begin);
117
118
119 typename Sequence::const_iterator it = sequenceBeginIterator;
120 std::advance(it, begin);
121 for (int i = begin; i < end; ++i) {
122 if (keep(*it))
123 results.vector.append(*it);
124 std::advance(it, 1);
125 }
126
127 reducer.runReduce(reduce, reducedResult, results);
128 return false;
129 }
130
131 void finish() override
132 {
133 reducer.finish(reduce, reducedResult);
134 sequence = reducedResult;
135 }
136
137 inline bool shouldThrottleThread() override
138 {
139 return IterateKernelType::shouldThrottleThread() || reducer.shouldThrottle();
140 }
141
142 inline bool shouldStartThread() override
143 {
144 return IterateKernelType::shouldStartThread() && reducer.shouldStartThread();
145 }
146
147 typedef void ReturnType;
148 typedef void ResultType;
149};
150
151// Implementation of filter-reduce
152template <typename ReducedResultType,
153 typename Iterator,
154 typename KeepFunctor,
155 typename ReduceFunctor,
156 typename Reducer = ReduceKernel<ReduceFunctor,
157 ReducedResultType,
158 typename qValueType<Iterator>::value_type> >
159class FilteredReducedKernel : public IterateKernel<Iterator, ReducedResultType>
160{
161 ReducedResultType reducedResult;
162 KeepFunctor keep;
163 ReduceFunctor reduce;
164 Reducer reducer;
165 typedef IterateKernel<Iterator, ReducedResultType> IterateKernelType;
166
167public:
168 FilteredReducedKernel(Iterator begin,
169 Iterator end,
170 KeepFunctor _keep,
171 ReduceFunctor _reduce,
172 ReduceOptions reduceOption)
173 : IterateKernelType(begin, end), reducedResult(), keep(_keep), reduce(_reduce), reducer(reduceOption)
174 { }
175
176#if 0
177 FilteredReducedKernel(ReducedResultType initialValue,
178 KeepFunctor keep,
179 ReduceFunctor reduce,
180 ReduceOption reduceOption)
181 : reducedResult(initialValue), keep(keep), reduce(reduce), reducer(reduceOption)
182 { }
183#endif
184
185 bool runIteration(Iterator it, int index, ReducedResultType *) override
186 {
187 IntermediateResults<typename qValueType<Iterator>::value_type> results;
188 results.begin = index;
189 results.end = index + 1;
190
191 if (keep(*it))
192 results.vector.append(*it);
193
194 reducer.runReduce(reduce, reducedResult, results);
195 return false;
196 }
197
198 bool runIterations(Iterator sequenceBeginIterator, int begin, int end, ReducedResultType *) override
199 {
200 IntermediateResults<typename qValueType<Iterator>::value_type> results;
201 results.begin = begin;
202 results.end = end;
203 results.vector.reserve(end - begin);
204
205 Iterator it = sequenceBeginIterator;
206 std::advance(it, begin);
207 for (int i = begin; i < end; ++i) {
208 if (keep(*it))
209 results.vector.append(*it);
210 std::advance(it, 1);
211 }
212
213 reducer.runReduce(reduce, reducedResult, results);
214 return false;
215 }
216
217 void finish() override
218 {
219 reducer.finish(reduce, reducedResult);
220 }
221
222 inline bool shouldThrottleThread() override
223 {
224 return IterateKernelType::shouldThrottleThread() || reducer.shouldThrottle();
225 }
226
227 inline bool shouldStartThread() override
228 {
229 return IterateKernelType::shouldStartThread() && reducer.shouldStartThread();
230 }
231
232 typedef ReducedResultType ReturnType;
233 typedef ReducedResultType ResultType;
234 ReducedResultType *result() override
235 {
236 return &reducedResult;
237 }
238};
239
240// Implementation of filter that reports individual results via QFutureInterface
241template <typename Iterator, typename KeepFunctor>
242class FilteredEachKernel : public IterateKernel<Iterator, typename qValueType<Iterator>::value_type>
243{
244 typedef typename qValueType<Iterator>::value_type T;
245 typedef IterateKernel<Iterator, T> IterateKernelType;
246
247 KeepFunctor keep;
248
249public:
250 typedef T ReturnType;
251 typedef T ResultType;
252
253 FilteredEachKernel(Iterator begin, Iterator end, KeepFunctor _keep)
254 : IterateKernelType(begin, end), keep(_keep)
255 { }
256
257 void start() override
258 {
259 if (this->futureInterface)
260 this->futureInterface->setFilterMode(true);
261 IterateKernelType::start();
262 }
263
264 bool runIteration(Iterator it, int index, T *) override
265 {
266 if (keep(*it))
267 this->reportResult(&(*it), index);
268 else
269 this->reportResult(nullptr, index);
270 return false;
271 }
272
273 bool runIterations(Iterator sequenceBeginIterator, int begin, int end, T *) override
274 {
275 const int count = end - begin;
276 IntermediateResults<typename qValueType<Iterator>::value_type> results;
277 results.begin = begin;
278 results.end = end;
279 results.vector.reserve(count);
280
281 Iterator it = sequenceBeginIterator;
282 std::advance(it, begin);
283 for (int i = begin; i < end; ++i) {
284 if (keep(*it))
285 results.vector.append(*it);
286 std::advance(it, 1);
287 }
288
289 this->reportResults(results.vector, begin, count);
290 return false;
291 }
292};
293
294//! [QtConcurrent-2]
295template <typename Iterator, typename KeepFunctor>
296inline
297ThreadEngineStarter<typename qValueType<Iterator>::value_type>
298startFiltered(Iterator begin, Iterator end, KeepFunctor functor)
299{
300 return startThreadEngine(new FilteredEachKernel<Iterator, KeepFunctor>(begin, end, functor));
301}
302
303//! [QtConcurrent-3]
304template <typename Sequence, typename KeepFunctor>
305inline ThreadEngineStarter<typename Sequence::value_type>
306startFiltered(const Sequence &sequence, KeepFunctor functor)
307{
308 typedef SequenceHolder1<Sequence,
309 FilteredEachKernel<typename Sequence::const_iterator, KeepFunctor>,
310 KeepFunctor>
311 SequenceHolderType;
312 return startThreadEngine(new SequenceHolderType(sequence, functor));
313}
314
315//! [QtConcurrent-4]
316template <typename ResultType, typename Sequence, typename MapFunctor, typename ReduceFunctor>
317inline ThreadEngineStarter<ResultType> startFilteredReduced(const Sequence & sequence,
318 MapFunctor mapFunctor, ReduceFunctor reduceFunctor,
319 ReduceOptions options)
320{
321 typedef typename Sequence::const_iterator Iterator;
322 typedef ReduceKernel<ReduceFunctor, ResultType, typename qValueType<Iterator>::value_type > Reducer;
323 typedef FilteredReducedKernel<ResultType, Iterator, MapFunctor, ReduceFunctor, Reducer> FilteredReduceType;
324 typedef SequenceHolder2<Sequence, FilteredReduceType, MapFunctor, ReduceFunctor> SequenceHolderType;
325 return startThreadEngine(new SequenceHolderType(sequence, mapFunctor, reduceFunctor, options));
326}
327
328
329//! [QtConcurrent-5]
330template <typename ResultType, typename Iterator, typename MapFunctor, typename ReduceFunctor>
331inline ThreadEngineStarter<ResultType> startFilteredReduced(Iterator begin, Iterator end,
332 MapFunctor mapFunctor, ReduceFunctor reduceFunctor,
333 ReduceOptions options)
334{
335 typedef ReduceKernel<ReduceFunctor, ResultType, typename qValueType<Iterator>::value_type> Reducer;
336 typedef FilteredReducedKernel<ResultType, Iterator, MapFunctor, ReduceFunctor, Reducer> FilteredReduceType;
337 return startThreadEngine(new FilteredReduceType(begin, end, mapFunctor, reduceFunctor, options));
338}
339
340
341} // namespace QtConcurrent
342
343
344QT_END_NAMESPACE
345
346#endif // QT_NO_CONCURRENT
347
348#endif
349

source code of qtbase/src/concurrent/qtconcurrentfilterkernel.h