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1 | |
2 | #ifndef BOOST_MPL_VOID_HPP_INCLUDED | |
3 | #define BOOST_MPL_VOID_HPP_INCLUDED | |
4 | ||
5 | // Copyright Aleksey Gurtovoy 2001-2004 | |
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/void_fwd.hpp> | |
18 | #include <boost/mpl/bool.hpp> | |
19 | #include <boost/mpl/aux_/na_spec.hpp> | |
20 | #include <boost/mpl/aux_/config/msvc.hpp> | |
21 | #include <boost/mpl/aux_/config/workaround.hpp> | |
22 | ||
23 | BOOST_MPL_AUX_ADL_BARRIER_NAMESPACE_OPEN | |
24 | ||
25 | // [JDG Feb-4-2003] made void_ a complete type to allow it to be | |
26 | // instantiated so that it can be passed in as an object that can be | |
27 | // used to select an overloaded function. Possible use includes signaling | |
28 | // a zero arity functor evaluation call. | |
29 | struct void_ { typedef void_ type; }; | |
30 | ||
31 | BOOST_MPL_AUX_ADL_BARRIER_NAMESPACE_CLOSE | |
32 | ||
33 | namespace boost { namespace mpl { | |
34 | ||
35 | template< typename T > | |
36 | struct is_void_ | |
37 | : false_ | |
38 | { | |
39 | #if BOOST_WORKAROUND(BOOST_MSVC, < 1300) | |
40 | using false_::value; | |
41 | #endif | |
42 | }; | |
43 | ||
44 | template<> | |
45 | struct is_void_<void_> | |
46 | : true_ | |
47 | { | |
48 | #if BOOST_WORKAROUND(BOOST_MSVC, < 1300) | |
49 | using true_::value; | |
50 | #endif | |
51 | }; | |
52 | ||
53 | template< typename T > | |
54 | struct is_not_void_ | |
55 | : true_ | |
56 | { | |
57 | #if BOOST_WORKAROUND(BOOST_MSVC, < 1300) | |
58 | using true_::value; | |
59 | #endif | |
60 | }; | |
61 | ||
62 | template<> | |
63 | struct is_not_void_<void_> | |
64 | : false_ | |
65 | { | |
66 | #if BOOST_WORKAROUND(BOOST_MSVC, < 1300) | |
67 | using false_::value; | |
68 | #endif | |
69 | }; | |
70 | ||
71 | BOOST_MPL_AUX_NA_SPEC(1, is_void_) | |
72 | BOOST_MPL_AUX_NA_SPEC(1, is_not_void_) | |
73 | ||
74 | }} | |
75 | ||
76 | #endif // BOOST_MPL_VOID_HPP_INCLUDED |