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1 | /*============================================================================= | |
2 | Copyright (c) 2007 Tobias Schwinger | |
3 | ||
4 | Use modification and distribution are subject to the Boost Software | |
5 | License, Version 1.0. (See accompanying file LICENSE_1_0.txt or copy at | |
6 | http://www.boost.org/LICENSE_1_0.txt). | |
7 | ==============================================================================*/ | |
8 | ||
9 | #if !defined(BOOST_FUSION_SUPPORT_DEDUCE_HPP_INCLUDED) | |
10 | #define BOOST_FUSION_SUPPORT_DEDUCE_HPP_INCLUDED | |
11 | ||
12 | #include <boost/fusion/support/config.hpp> | |
13 | #include <boost/ref.hpp> | |
14 | ||
15 | #ifndef BOOST_NO_CXX11_HDR_FUNCTIONAL | |
16 | #include <functional> | |
17 | #endif | |
18 | ||
19 | namespace boost { namespace fusion { namespace traits | |
20 | { | |
21 | template <typename T> struct deduce; | |
22 | ||
23 | //----- ---- --- -- - - - - | |
24 | ||
25 | // Non-references pass unchanged | |
26 | ||
27 | template <typename T> | |
28 | struct deduce | |
29 | { | |
30 | typedef T type; | |
31 | }; | |
32 | ||
33 | template <typename T> | |
34 | struct deduce<T const> | |
35 | { | |
36 | typedef T type; | |
37 | }; | |
38 | ||
39 | template <typename T> | |
40 | struct deduce<T volatile> | |
41 | { | |
42 | typedef T type; | |
43 | }; | |
44 | ||
45 | template <typename T> | |
46 | struct deduce<T const volatile> | |
47 | { | |
48 | typedef T type; | |
49 | }; | |
50 | ||
51 | // Keep references on mutable LValues | |
52 | ||
53 | template <typename T> | |
54 | struct deduce<T &> | |
55 | { | |
56 | typedef T & type; | |
57 | }; | |
58 | ||
59 | template <typename T> | |
60 | struct deduce<T volatile&> | |
61 | { | |
62 | typedef T volatile& type; | |
63 | }; | |
64 | ||
65 | // Store away potential RValues | |
66 | ||
67 | template <typename T> | |
68 | struct deduce<T const&> | |
69 | { | |
70 | typedef T type; | |
71 | }; | |
72 | ||
73 | template <typename T> | |
74 | struct deduce<T const volatile&> | |
75 | { | |
76 | typedef T type; | |
77 | }; | |
78 | ||
79 | // Unwrap Boost.RefS (referencee cv is deduced) | |
80 | ||
81 | template <typename T> | |
82 | struct deduce<reference_wrapper<T> & > | |
83 | { | |
84 | typedef T& type; | |
85 | }; | |
86 | ||
87 | template <typename T> | |
88 | struct deduce<reference_wrapper<T> const & > | |
89 | { | |
90 | typedef T& type; | |
91 | }; | |
92 | ||
93 | // Also unwrap C++11 std::ref if available (referencee cv is deduced) | |
94 | #ifndef BOOST_NO_CXX11_HDR_FUNCTIONAL | |
95 | template <typename T> | |
96 | struct deduce<std::reference_wrapper<T> &> | |
97 | { | |
98 | typedef T& type; | |
99 | }; | |
100 | ||
101 | template <typename T> | |
102 | struct deduce<std::reference_wrapper<T> const &> | |
103 | { | |
104 | typedef T& type; | |
105 | }; | |
106 | #endif | |
107 | ||
108 | // Keep references on arrays, even if const | |
109 | ||
110 | template <typename T, int N> | |
111 | struct deduce<T(&)[N]> | |
112 | { | |
113 | typedef T(&type)[N]; | |
114 | }; | |
115 | ||
116 | template <typename T, int N> | |
117 | struct deduce<volatile T(&)[N]> | |
118 | { | |
119 | typedef volatile T(&type)[N]; | |
120 | }; | |
121 | ||
122 | template <typename T, int N> | |
123 | struct deduce<const T(&)[N]> | |
124 | { | |
125 | typedef const T(&type)[N]; | |
126 | }; | |
127 | ||
128 | template <typename T, int N> | |
129 | struct deduce<const volatile T(&)[N]> | |
130 | { | |
131 | typedef const volatile T(&type)[N]; | |
132 | }; | |
133 | ||
134 | }}} | |
135 | ||
136 | #endif | |
137 |