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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 |