libstdc++-v3/include/parallel/find_selectors.h

   1 // -*- C++ -*-
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  30
  31 /** @file parallel/find_selectors.h
  32  *  @brief Function objects representing different tasks to be plugged
  33  *  into the parallel find algorithm.
  34  *  This file is a GNU parallel extension to the Standard C++ Library.
  35  */
  36
  37 // Written by Felix Putze.
  38
  39 #ifndef _GLIBCXX_PARALLEL_FIND_FUNCTIONS_H
  40 #define _GLIBCXX_PARALLEL_FIND_FUNCTIONS_H 1
  41
  42 #include <parallel/tags.h>
  43 #include <parallel/basic_iterator.h>
  44 #include <bits/stl_pair.h>
  45
  46 namespace __gnu_parallel
  47 {
  48   /** @brief Base class of all __gnu_parallel::find_template selectors. */
  49   struct generic_find_selector
  50   { };
  51
  52   /**
  53    *  @brief Test predicate on a single element, used for std::find()
  54    *  and std::find_if ().
  55    */
  56   struct find_if_selector : public generic_find_selector
  57   {
  58     /** @brief Test on one position.
  59      * @param i1 Iterator on first sequence.
  60      * @param i2 Iterator on second sequence (unused).
  61      * @param pred Find predicate.
  62      */
  63     template<typename RandomAccessIterator1, typename RandomAccessIterator2, typename Pred>
  64     inline bool
  65     operator()(RandomAccessIterator1 i1, RandomAccessIterator2 i2, Pred pred)
  66     { return pred(*i1); }
  67
  68     /** @brief Corresponding sequential algorithm on a sequence.
  69      *  @param begin1 Begin iterator of first sequence.
  70      *  @param end1 End iterator of first sequence.
  71      *  @param begin2 Begin iterator of second sequence.
  72      *  @param pred Find predicate.
  73      */
  74     template<typename RandomAccessIterator1, typename RandomAccessIterator2, typename Pred>
  75     inline std::pair<RandomAccessIterator1, RandomAccessIterator2>
  76     sequential_algorithm(RandomAccessIterator1 begin1, RandomAccessIterator1 end1, RandomAccessIterator2 begin2, Pred pred)
  77     {
  78       return std::make_pair(find_if(begin1, end1, pred, sequential_tag()), begin2);
  79     }
  80   };
  81
  82   /** @brief Test predicate on two adjacent elements. */
  83   struct adjacent_find_selector : public generic_find_selector
  84   {
  85     /** @brief Test on one position.
  86      *  @param i1 Iterator on first sequence.
  87      *  @param i2 Iterator on second sequence (unused).
  88      *  @param pred Find predicate.
  89      */
  90     template<typename RandomAccessIterator1, typename RandomAccessIterator2, typename Pred>
  91     inline bool
  92     operator()(RandomAccessIterator1 i1, RandomAccessIterator2 i2, Pred pred)
  93     {
  94       // Passed end iterator is one short.
  95       return pred(*i1, *(i1 + 1));
  96     }
  97
  98     /** @brief Corresponding sequential algorithm on a sequence.
  99      *  @param begin1 Begin iterator of first sequence.
 100      *  @param end1 End iterator of first sequence.
 101      *  @param begin2 Begin iterator of second sequence.
 102      *  @param pred Find predicate.
 103      */
 104     template<typename RandomAccessIterator1, typename RandomAccessIterator2, typename Pred>
 105     inline std::pair<RandomAccessIterator1, RandomAccessIterator2>
 106     sequential_algorithm(RandomAccessIterator1 begin1, RandomAccessIterator1 end1, RandomAccessIterator2 begin2, Pred pred)
 107     {
 108       // Passed end iterator is one short.
 109       RandomAccessIterator1 spot = adjacent_find(begin1, end1 + 1, pred, sequential_tag());
 110       if (spot == (end1 + 1))
 111         spot = end1;
 112       return std::make_pair(spot, begin2);
 113     }
 114   };
 115
 116   /** @brief Test inverted predicate on a single element. */
 117   struct mismatch_selector : public generic_find_selector
 118   {
 119     /**
 120      *  @brief Test on one position.
 121      *  @param i1 Iterator on first sequence.
 122      *  @param i2 Iterator on second sequence (unused).
 123      *  @param pred Find predicate.
 124      */
 125     template<typename RandomAccessIterator1, typename RandomAccessIterator2, typename Pred>
 126     inline bool
 127     operator()(RandomAccessIterator1 i1, RandomAccessIterator2 i2, Pred pred)
 128     { return !pred(*i1, *i2); }
 129
 130     /**
 131      *  @brief Corresponding sequential algorithm on a sequence.
 132      *  @param begin1 Begin iterator of first sequence.
 133      *  @param end1 End iterator of first sequence.
 134      *  @param begin2 Begin iterator of second sequence.
 135      *  @param pred Find predicate.
 136      */
 137     template<typename RandomAccessIterator1, typename RandomAccessIterator2, typename Pred>
 138     inline std::pair<RandomAccessIterator1, RandomAccessIterator2>
 139     sequential_algorithm(RandomAccessIterator1 begin1, RandomAccessIterator1 end1, RandomAccessIterator2 begin2, Pred pred)
 140     {
 141       return mismatch(begin1, end1, begin2, pred, sequential_tag());
 142     }
 143   };
 144
 145
 146   /** @brief Test predicate on several elements. */
 147   template<typename ForwardIterator>
 148   struct find_first_of_selector : public generic_find_selector
 149   {
 150     ForwardIterator begin;
 151     ForwardIterator end;
 152
 153     explicit find_first_of_selector(ForwardIterator begin, ForwardIterator end)
 154     : begin(begin), end(end) { }
 155
 156     /** @brief Test on one position.
 157      *  @param i1 Iterator on first sequence.
 158      *  @param i2 Iterator on second sequence (unused).
 159      *  @param pred Find predicate. */
 160     template<typename RandomAccessIterator1, typename RandomAccessIterator2, typename Pred>
 161     inline bool
 162     operator()(RandomAccessIterator1 i1, RandomAccessIterator2 i2, Pred pred)
 163     {
 164       for (ForwardIterator pos_in_candidates = begin; pos_in_candidates != end; pos_in_candidates++)
 165         if (pred(*i1, *pos_in_candidates))
 166           return true;
 167       return false;
 168     }
 169
 170     /** @brief Corresponding sequential algorithm on a sequence.
 171      *  @param begin1 Begin iterator of first sequence.
 172      *  @param end1 End iterator of first sequence.
 173      *  @param begin2 Begin iterator of second sequence.
 174      *  @param pred Find predicate. */
 175     template<typename RandomAccessIterator1, typename RandomAccessIterator2, typename Pred>
 176     inline std::pair<RandomAccessIterator1, RandomAccessIterator2>
 177     sequential_algorithm(RandomAccessIterator1 begin1, RandomAccessIterator1 end1, RandomAccessIterator2 begin2, Pred pred)
 178     {
 179       return std::make_pair(find_first_of(begin1, end1, begin, end, pred, sequential_tag()), begin2);
 180     }
 181   };
 182 }
 183
 184 #endif