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> iterator_range_size(Iterator first,Iterator last)27inline 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 45