ceph/src/boost/boost/compute/algorithm/search.hpp

   1 //---------------------------------------------------------------------------//
   2 // Copyright (c) 2014 Roshan <thisisroshansmail@gmail.com>
   3 //
   4 // Distributed under the Boost Software License, Version 1.0
   5 // See accompanying file LICENSE_1_0.txt or copy at
   6 // http://www.boost.org/LICENSE_1_0.txt
   7 //
   8 // See http://boostorg.github.com/compute for more information.
   9 //---------------------------------------------------------------------------//
  10
  11 #ifndef BOOST_COMPUTE_ALGORITHM_SEARCH_HPP
  12 #define BOOST_COMPUTE_ALGORITHM_SEARCH_HPP
  13
  14 #include <boost/compute/algorithm/detail/search_all.hpp>
  15 #include <boost/compute/algorithm/find.hpp>
  16 #include <boost/compute/container/vector.hpp>
  17 #include <boost/compute/detail/iterator_range_size.hpp>
  18 #include <boost/compute/detail/meta_kernel.hpp>
  19 #include <boost/compute/system.hpp>
  20
  21 namespace boost {
  22 namespace compute {
  23
  24 ///
  25 /// \brief Substring matching algorithm
  26 ///
  27 /// Searches for the first match of the pattern [p_first, p_last)
  28 /// in text [t_first, t_last).
  29 /// \return Iterator pointing to beginning of first occurrence
  30 ///
  31 /// \param t_first Iterator pointing to start of text
  32 /// \param t_last Iterator pointing to end of text
  33 /// \param p_first Iterator pointing to start of pattern
  34 /// \param p_last Iterator pointing to end of pattern
  35 /// \param queue Queue on which to execute
  36 ///
  37 /// Space complexity: \Omega(distance(\p t_first, \p t_last))
  38 template<class TextIterator, class PatternIterator>
  39 inline TextIterator search(TextIterator t_first,
  40                            TextIterator t_last,
  41                            PatternIterator p_first,
  42                            PatternIterator p_last,
  43                            command_queue &queue = system::default_queue())
  44 {
  45     // there is no need to check if pattern starts at last n - 1 indices
  46     vector<uint_> matching_indices(
  47         detail::iterator_range_size(t_first, t_last)
  48             - detail::iterator_range_size(p_first, p_last) + 1,
  49         queue.get_context()
  50     );
  51
  52     // search_kernel puts value 1 at every index in vector where pattern starts at
  53     detail::search_kernel<PatternIterator,
  54                           TextIterator,
  55                           vector<uint_>::iterator> kernel;
  56
  57     kernel.set_range(p_first, p_last, t_first, t_last, matching_indices.begin());
  58     kernel.exec(queue);
  59
  60     vector<uint_>::iterator index = ::boost::compute::find(
  61         matching_indices.begin(), matching_indices.end(), uint_(1), queue
  62     );
  63
  64     // pattern was not found
  65     if(index == matching_indices.end())
  66         return t_last;
  67
  68     return t_first + detail::iterator_range_size(matching_indices.begin(), index);
  69 }
  70
  71 } //end compute namespace
  72 } //end boost namespace
  73
  74 #endif // BOOST_COMPUTE_ALGORITHM_SEARCH_HPP