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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_FUNCTIONAL_GET_HPP | |
12 | #define BOOST_COMPUTE_FUNCTIONAL_GET_HPP | |
13 | ||
14 | #include <cstddef> | |
15 | ||
16 | #include <boost/compute/types/fundamental.hpp> | |
17 | #include <boost/compute/type_traits/scalar_type.hpp> | |
18 | ||
19 | namespace boost { | |
20 | namespace compute { | |
21 | namespace detail { | |
22 | ||
23 | // meta-function returning the result type for get<N>() | |
24 | template<size_t N, class Arg> | |
25 | struct get_result_type | |
26 | { | |
27 | typedef typename scalar_type<Arg>::type type; | |
28 | }; | |
29 | ||
30 | template<size_t N, class Arg, class T> | |
31 | struct invoked_get | |
32 | { | |
33 | typedef typename get_result_type<N, T>::type result_type; | |
34 | ||
35 | invoked_get(const Arg &arg) | |
36 | : m_arg(arg) | |
37 | { | |
38 | } | |
39 | ||
40 | Arg m_arg; | |
41 | }; | |
42 | ||
43 | } // end detail namespace | |
44 | ||
45 | /// Returns the \c N'th element of an aggregate type (e.g. scalarN, | |
46 | /// pair, tuple, etc.). | |
47 | /// | |
48 | /// \see \ref field "field<T>" | |
49 | template<size_t N> | |
50 | struct get | |
51 | { | |
52 | /// \internal_ | |
53 | template<class> struct result; | |
54 | ||
55 | /// \internal_ | |
56 | template<class F, class Arg> | |
57 | struct result<F(Arg)> | |
58 | { | |
59 | typedef typename detail::get_result_type<N, Arg>::type type; | |
60 | }; | |
61 | ||
62 | template<class Arg> | |
63 | detail::invoked_get< | |
64 | N, Arg, typename boost::remove_cv<typename Arg::result_type>::type | |
65 | > operator()(const Arg &arg) const | |
66 | { | |
67 | typedef typename boost::remove_cv<typename Arg::result_type>::type T; | |
68 | ||
69 | return detail::invoked_get<N, Arg, T>(arg); | |
70 | } | |
71 | }; | |
72 | ||
73 | } // end compute namespace | |
74 | } // end boost namespace | |
75 | ||
76 | #endif // BOOST_COMPUTE_FUNCTIONAL_GET_HPP |