ceph/src/boost/libs/compute/include/boost/compute/detail/iterator_range_size.hpp

   1 //---------------------------------------------------------------------------//
   2 // Copyright (c) 2013 Kyle Lutz <kyle.r.lutz@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_DETAIL_ITERATOR_RANGE_SIZE_H
  12 #define BOOST_COMPUTE_DETAIL_ITERATOR_RANGE_SIZE_H
  13
  14 #include <cstddef>
  15 #include <algorithm>
  16 #include <iterator>
  17
  18 namespace boost {
  19 namespace compute {
  20 namespace detail {
  21
  22 // This is a convenience function which returns the size of a range
  23 // bounded by two iterators. This function has two differences from
  24 // the std::distance() function: 1) the return type (size_t) is
  25 // unsigned, and 2) the return value is always positive.
  26 template<class Iterator>
  27 inline size_t iterator_range_size(Iterator first, Iterator last)
  28 {
  29     typedef typename
  30         std::iterator_traits<Iterator>::difference_type
  31         difference_type;
  32
  33     difference_type difference = std::distance(first, last);
  34
  35     return static_cast<size_t>(
  36         (std::max)(difference, static_cast<difference_type>(0))
  37     );
  38 }
  39
  40 } // end detail namespace
  41 } // end compute namespace
  42 } // end boost namespace
  43
  44 #endif // BOOST_COMPUTE_DETAIL_ITERATOR_RANGE_SIZE_H