2 #ifndef BOOST_MPL_VOID_HPP_INCLUDED
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3 #define BOOST_MPL_VOID_HPP_INCLUDED
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5 // Copyright Aleksey Gurtovoy 2001-2004
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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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11 // See http://www.boost.org/libs/mpl for documentation.
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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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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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23 BOOST_MPL_AUX_ADL_BARRIER_NAMESPACE_OPEN
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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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31 BOOST_MPL_AUX_ADL_BARRIER_NAMESPACE_CLOSE
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33 namespace boost { namespace mpl {
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35 template< typename T >
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39 #if BOOST_WORKAROUND(BOOST_MSVC, < 1300)
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40 using false_::value;
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45 struct is_void_<void_>
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48 #if BOOST_WORKAROUND(BOOST_MSVC, < 1300)
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53 template< typename T >
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57 #if BOOST_WORKAROUND(BOOST_MSVC, < 1300)
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63 struct is_not_void_<void_>
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66 #if BOOST_WORKAROUND(BOOST_MSVC, < 1300)
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67 using false_::value;
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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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76 #endif // BOOST_MPL_VOID_HPP_INCLUDED
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