--- /dev/null
+// -*- C++ -*-
+
+// Copyright (C) 2007, 2008, 2009 Free Software Foundation, Inc.
+//
+// This file is part of the GNU ISO C++ Library. This library is free
+// software; you can redistribute it and/or modify it under the terms
+// of the GNU General Public License as published by the Free Software
+// Foundation; either version 3, or (at your option) any later
+// version.
+
+// This library is distributed in the hope that it will be useful, but
+// WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+// General Public License for more details.
+
+// Under Section 7 of GPL version 3, you are granted additional
+// permissions described in the GCC Runtime Library Exception, version
+// 3.1, as published by the Free Software Foundation.
+
+// You should have received a copy of the GNU General Public License and
+// a copy of the GCC Runtime Library Exception along with this program;
+// see the files COPYING3 and COPYING.RUNTIME respectively. If not, see
+// <http://www.gnu.org/licenses/>.
+
+/** @file parallel/search.h
+ * @brief Parallel implementation base for std::search() and
+ * std::search_n().
+ * This file is a GNU parallel extension to the Standard C++ Library.
+ */
+
+// Written by Felix Putze.
+
+#ifndef _GLIBCXX_PARALLEL_SEARCH_H
+#define _GLIBCXX_PARALLEL_SEARCH_H 1
+
+#include <bits/stl_algobase.h>
+
+#include <parallel/parallel.h>
+#include <parallel/equally_split.h>
+
+
+namespace __gnu_parallel
+{
+ /**
+ * @brief Precalculate advances for Knuth-Morris-Pratt algorithm.
+ * @param elements Begin iterator of sequence to search for.
+ * @param length Length of sequence to search for.
+ * @param advances Returned offsets.
+ */
+template<typename RandomAccessIterator, typename _DifferenceTp>
+ void
+ calc_borders(RandomAccessIterator elements, _DifferenceTp length,
+ _DifferenceTp* off)
+ {
+ typedef _DifferenceTp difference_type;
+
+ off[0] = -1;
+ if (length > 1)
+ off[1] = 0;
+ difference_type k = 0;
+ for (difference_type j = 2; j <= length; j++)
+ {
+ while ((k >= 0) && !(elements[k] == elements[j-1]))
+ k = off[k];
+ off[j] = ++k;
+ }
+ }
+
+ // Generic parallel find algorithm (requires random access iterator).
+
+ /** @brief Parallel std::search.
+ * @param begin1 Begin iterator of first sequence.
+ * @param end1 End iterator of first sequence.
+ * @param begin2 Begin iterator of second sequence.
+ * @param end2 End iterator of second sequence.
+ * @param pred Find predicate.
+ * @return Place of finding in first sequences. */
+template<typename _RandomAccessIterator1,
+ typename _RandomAccessIterator2,
+ typename Pred>
+ _RandomAccessIterator1
+ search_template(_RandomAccessIterator1 begin1, _RandomAccessIterator1 end1,
+ _RandomAccessIterator2 begin2, _RandomAccessIterator2 end2,
+ Pred pred)
+ {
+ typedef std::iterator_traits<_RandomAccessIterator1> traits_type;
+ typedef typename traits_type::difference_type difference_type;
+
+ _GLIBCXX_CALL((end1 - begin1) + (end2 - begin2));
+
+ difference_type pattern_length = end2 - begin2;
+
+ // Pattern too short.
+ if(pattern_length <= 0)
+ return end1;
+
+ // Last point to start search.
+ difference_type input_length = (end1 - begin1) - pattern_length;
+
+ // Where is first occurrence of pattern? defaults to end.
+ difference_type result = (end1 - begin1);
+ difference_type *splitters;
+
+ // Pattern too long.
+ if (input_length < 0)
+ return end1;
+
+ omp_lock_t result_lock;
+ omp_init_lock(&result_lock);
+
+ thread_index_t num_threads =
+ std::max<difference_type>(1,
+ std::min<difference_type>(input_length, get_max_threads()));
+
+ difference_type advances[pattern_length];
+ calc_borders(begin2, pattern_length, advances);
+
+# pragma omp parallel num_threads(num_threads)
+ {
+# pragma omp single
+ {
+ num_threads = omp_get_num_threads();
+ splitters = new difference_type[num_threads + 1];
+ equally_split(input_length, num_threads, splitters);
+ }
+
+ thread_index_t iam = omp_get_thread_num();
+
+ difference_type start = splitters[iam], stop = splitters[iam + 1];
+
+ difference_type pos_in_pattern = 0;
+ bool found_pattern = false;
+
+ while (start <= stop && !found_pattern)
+ {
+ // Get new value of result.
+ #pragma omp flush(result)
+ // No chance for this thread to find first occurrence.
+ if (result < start)
+ break;
+ while (pred(begin1[start + pos_in_pattern],
+ begin2[pos_in_pattern]))
+ {
+ ++pos_in_pattern;
+ if (pos_in_pattern == pattern_length)
+ {
+ // Found new candidate for result.
+ omp_set_lock(&result_lock);
+ result = std::min(result, start);
+ omp_unset_lock(&result_lock);
+
+ found_pattern = true;
+ break;
+ }
+ }
+ // Make safe jump.
+ start += (pos_in_pattern - advances[pos_in_pattern]);
+ pos_in_pattern =
+ (advances[pos_in_pattern] < 0) ? 0 : advances[pos_in_pattern];
+ }
+ } //parallel
+
+ omp_destroy_lock(&result_lock);
+
+ delete[] splitters;
+
+ // Return iterator on found element.
+ return (begin1 + result);
+ }
+} // end namespace
+
+#endif /* _GLIBCXX_PARALLEL_SEARCH_H */
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