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1 | //---------------------------------------------------------------------------// |
2 | // Copyright (c) 2013-2014 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_IDENTITY_HPP | |
12 | #define BOOST_COMPUTE_FUNCTIONAL_IDENTITY_HPP | |
13 | ||
14 | namespace boost { | |
15 | namespace compute { | |
16 | namespace detail { | |
17 | ||
18 | template<class T, class Arg> | |
19 | struct invoked_identity | |
20 | { | |
21 | typedef T result_type; | |
22 | ||
23 | invoked_identity(const Arg &arg) | |
24 | : m_arg(arg) | |
25 | { | |
26 | } | |
27 | ||
28 | Arg m_arg; | |
29 | }; | |
30 | ||
31 | } // end detail namespace | |
32 | ||
33 | /// Identity function which simply returns its input. | |
34 | /// | |
35 | /// For example, to directly copy values using the transform() algorithm: | |
36 | /// \code | |
37 | /// transform(input.begin(), input.end(), output.begin(), identity<int>(), queue); | |
38 | /// \endcode | |
39 | /// | |
40 | /// \see \ref as "as<T>", \ref convert "convert<T>" | |
41 | template<class T> | |
42 | class identity | |
43 | { | |
44 | public: | |
45 | /// Identity function result type. | |
46 | typedef T result_type; | |
47 | ||
48 | /// Creates a new identity function. | |
49 | identity() | |
50 | { | |
51 | } | |
52 | ||
53 | /// \internal_ | |
54 | template<class Arg> | |
55 | detail::invoked_identity<T, Arg> operator()(const Arg &arg) const | |
56 | { | |
57 | return detail::invoked_identity<T, Arg>(arg); | |
58 | } | |
59 | }; | |
60 | ||
61 | } // end compute namespace | |
62 | } // end boost namespace | |
63 | ||
64 | #endif // BOOST_COMPUTE_FUNCTIONAL_IDENTITY_HPP |