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| 2 | #ifndef BOOST_MPL_VOID_HPP_INCLUDED |
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| 3 | #define BOOST_MPL_VOID_HPP_INCLUDED |
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| 4 | |
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| 5 | // Copyright Aleksey Gurtovoy 2001-2004 |
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| 6 | // |
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| 7 | // Distributed under the Boost Software License, Version 1.0. |
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| 8 | // (See accompanying file LICENSE_1_0.txt or copy at |
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| 9 | // http://www.boost.org/LICENSE_1_0.txt) |
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| 10 | // |
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| 11 | // See http://www.boost.org/libs/mpl for documentation. |
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| 12 | |
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| 13 | // $Id: void.hpp 49267 2008-10-11 06:19:02Z agurtovoy $ |
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| 14 | // $Date: 2008-10-11 02:19:02 -0400 (Sat, 11 Oct 2008) $ |
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| 15 | // $Revision: 49267 $ |
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| 16 | |
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| 17 | #include <boost/mpl/void_fwd.hpp> |
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| 18 | #include <boost/mpl/bool.hpp> |
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| 19 | #include <boost/mpl/aux_/na_spec.hpp> |
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| 20 | #include <boost/mpl/aux_/config/msvc.hpp> |
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| 21 | #include <boost/mpl/aux_/config/workaround.hpp> |
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| 22 | |
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| 23 | BOOST_MPL_AUX_ADL_BARRIER_NAMESPACE_OPEN |
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| 24 | |
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| 25 | // [JDG Feb-4-2003] made void_ a complete type to allow it to be |
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| 26 | // instantiated so that it can be passed in as an object that can be |
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| 27 | // used to select an overloaded function. Possible use includes signaling |
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| 28 | // a zero arity functor evaluation call. |
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| 29 | struct void_ { typedef void_ type; }; |
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| 30 | |
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| 31 | BOOST_MPL_AUX_ADL_BARRIER_NAMESPACE_CLOSE |
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| 32 | |
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| 33 | namespace boost { namespace mpl { |
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| 34 | |
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| 35 | template< typename T > |
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| 36 | struct is_void_ |
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| 37 | : false_ |
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| 38 | { |
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| 39 | #if BOOST_WORKAROUND(BOOST_MSVC, < 1300) |
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| 40 | using false_::value; |
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| 41 | #endif |
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| 42 | }; |
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| 43 | |
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| 44 | template<> |
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| 45 | struct is_void_<void_> |
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| 46 | : true_ |
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| 47 | { |
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| 48 | #if BOOST_WORKAROUND(BOOST_MSVC, < 1300) |
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| 49 | using true_::value; |
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| 50 | #endif |
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| 51 | }; |
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| 52 | |
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| 53 | template< typename T > |
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| 54 | struct is_not_void_ |
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| 55 | : true_ |
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| 56 | { |
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| 57 | #if BOOST_WORKAROUND(BOOST_MSVC, < 1300) |
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| 58 | using true_::value; |
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| 59 | #endif |
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| 60 | }; |
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| 61 | |
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| 62 | template<> |
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| 63 | struct is_not_void_<void_> |
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| 64 | : false_ |
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| 65 | { |
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| 66 | #if BOOST_WORKAROUND(BOOST_MSVC, < 1300) |
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| 67 | using false_::value; |
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| 68 | #endif |
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| 69 | }; |
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| 70 | |
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| 71 | BOOST_MPL_AUX_NA_SPEC(1, is_void_) |
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| 72 | BOOST_MPL_AUX_NA_SPEC(1, is_not_void_) |
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| 73 | |
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| 74 | }} |
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| 75 | |
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| 76 | #endif // BOOST_MPL_VOID_HPP_INCLUDED |
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