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1 | |
2 | #ifndef BOOST_MPL_IF_HPP_INCLUDED | |
3 | #define BOOST_MPL_IF_HPP_INCLUDED | |
4 | ||
5 | // Copyright Aleksey Gurtovoy 2000-2004 | |
6 | // | |
7 | // Distributed under the Boost Software License, Version 1.0. | |
8 | // (See accompanying file LICENSE_1_0.txt or copy at | |
9 | // http://www.boost.org/LICENSE_1_0.txt) | |
10 | // | |
11 | // See http://www.boost.org/libs/mpl for documentation. | |
12 | ||
13 | // $Id$ | |
14 | // $Date$ | |
15 | // $Revision$ | |
16 | ||
17 | #include <boost/mpl/aux_/value_wknd.hpp> | |
18 | #include <boost/mpl/aux_/static_cast.hpp> | |
19 | #include <boost/mpl/aux_/na_spec.hpp> | |
20 | #include <boost/mpl/aux_/lambda_support.hpp> | |
21 | #include <boost/mpl/aux_/config/integral.hpp> | |
22 | #include <boost/mpl/aux_/config/ctps.hpp> | |
23 | #include <boost/mpl/aux_/config/workaround.hpp> | |
24 | ||
25 | namespace boost { namespace mpl { | |
26 | ||
27 | #if !defined(BOOST_NO_TEMPLATE_PARTIAL_SPECIALIZATION) | |
28 | ||
29 | template< | |
30 | bool C | |
31 | , typename T1 | |
32 | , typename T2 | |
33 | > | |
34 | struct if_c | |
35 | { | |
36 | typedef T1 type; | |
37 | }; | |
38 | ||
39 | template< | |
40 | typename T1 | |
41 | , typename T2 | |
42 | > | |
43 | struct if_c<false,T1,T2> | |
44 | { | |
45 | typedef T2 type; | |
46 | }; | |
47 | ||
48 | // agurt, 05/sep/04: nondescriptive parameter names for the sake of DigitalMars | |
92f5a8d4 | 49 | // (and possibly MWCW < 8.0); see https://lists.boost.org/Archives/boost/2004/09/71383.php |
7c673cae FG |
50 | template< |
51 | typename BOOST_MPL_AUX_NA_PARAM(T1) | |
52 | , typename BOOST_MPL_AUX_NA_PARAM(T2) | |
53 | , typename BOOST_MPL_AUX_NA_PARAM(T3) | |
54 | > | |
55 | struct if_ | |
56 | { | |
57 | private: | |
58 | // agurt, 02/jan/03: two-step 'type' definition for the sake of aCC | |
59 | typedef if_c< | |
60 | #if defined(BOOST_MPL_CFG_BCC_INTEGRAL_CONSTANTS) | |
61 | BOOST_MPL_AUX_VALUE_WKND(T1)::value | |
62 | #else | |
63 | BOOST_MPL_AUX_STATIC_CAST(bool, BOOST_MPL_AUX_VALUE_WKND(T1)::value) | |
64 | #endif | |
65 | , T2 | |
66 | , T3 | |
67 | > almost_type_; | |
68 | ||
69 | public: | |
70 | typedef typename almost_type_::type type; | |
71 | ||
72 | BOOST_MPL_AUX_LAMBDA_SUPPORT(3,if_,(T1,T2,T3)) | |
73 | }; | |
74 | ||
75 | #else | |
76 | ||
77 | // no partial class template specialization | |
78 | ||
79 | namespace aux { | |
80 | ||
81 | template< bool C > | |
82 | struct if_impl | |
83 | { | |
84 | template< typename T1, typename T2 > struct result_ | |
85 | { | |
86 | typedef T1 type; | |
87 | }; | |
88 | }; | |
89 | ||
90 | template<> | |
91 | struct if_impl<false> | |
92 | { | |
93 | template< typename T1, typename T2 > struct result_ | |
94 | { | |
95 | typedef T2 type; | |
96 | }; | |
97 | }; | |
98 | ||
99 | } // namespace aux | |
100 | ||
101 | template< | |
102 | bool C_ | |
103 | , typename T1 | |
104 | , typename T2 | |
105 | > | |
106 | struct if_c | |
107 | { | |
108 | typedef typename aux::if_impl< C_ > | |
109 | ::template result_<T1,T2>::type type; | |
110 | }; | |
111 | ||
112 | // (almost) copy & paste in order to save one more | |
113 | // recursively nested template instantiation to user | |
114 | template< | |
115 | typename BOOST_MPL_AUX_NA_PARAM(C_) | |
116 | , typename BOOST_MPL_AUX_NA_PARAM(T1) | |
117 | , typename BOOST_MPL_AUX_NA_PARAM(T2) | |
118 | > | |
119 | struct if_ | |
120 | { | |
121 | enum { msvc_wknd_ = BOOST_MPL_AUX_MSVC_VALUE_WKND(C_)::value }; | |
122 | ||
123 | typedef typename aux::if_impl< BOOST_MPL_AUX_STATIC_CAST(bool, msvc_wknd_) > | |
124 | ::template result_<T1,T2>::type type; | |
125 | ||
126 | BOOST_MPL_AUX_LAMBDA_SUPPORT(3,if_,(C_,T1,T2)) | |
127 | }; | |
128 | ||
129 | #endif // BOOST_NO_TEMPLATE_PARTIAL_SPECIALIZATION | |
130 | ||
131 | BOOST_MPL_AUX_NA_SPEC(3, if_) | |
132 | ||
133 | }} | |
134 | ||
135 | #endif // BOOST_MPL_IF_HPP_INCLUDED |