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| 2 | #ifndef BOOST_MPL_IS_PLACEHOLDER_HPP_INCLUDED |
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| 3 | #define BOOST_MPL_IS_PLACEHOLDER_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 | // $Source: /cvsroot/boost/boost/boost/mpl/is_placeholder.hpp,v $ |
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| 14 | // $Date: 2004/09/07 08:51:31 $ |
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| 15 | // $Revision: 1.6 $ |
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| 16 | |
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| 17 | #include <boost/mpl/arg_fwd.hpp> |
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| 18 | #include <boost/mpl/bool.hpp> |
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| 19 | #include <boost/mpl/aux_/yes_no.hpp> |
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| 20 | #include <boost/mpl/aux_/type_wrapper.hpp> |
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| 21 | #include <boost/mpl/aux_/nttp_decl.hpp> |
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| 22 | #include <boost/mpl/aux_/config/ctps.hpp> |
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| 23 | #include <boost/mpl/aux_/config/static_constant.hpp> |
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| 24 | |
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| 25 | namespace boost { namespace mpl { |
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| 26 | |
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| 27 | #if !defined(BOOST_NO_TEMPLATE_PARTIAL_SPECIALIZATION) |
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| 28 | |
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| 29 | template< typename T > |
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| 30 | struct is_placeholder |
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| 31 | : bool_<false> |
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| 32 | { |
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| 33 | }; |
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| 34 | |
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| 35 | template< BOOST_MPL_AUX_NTTP_DECL(int, N) > |
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| 36 | struct is_placeholder< arg<N> > |
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| 37 | : bool_<true> |
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| 38 | { |
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| 39 | }; |
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| 40 | |
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| 41 | #else |
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| 42 | |
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| 43 | namespace aux { |
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| 44 | |
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| 45 | aux::no_tag is_placeholder_helper(...); |
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| 46 | |
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| 47 | template< BOOST_MPL_AUX_NTTP_DECL(int, N) > |
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| 48 | aux::yes_tag is_placeholder_helper(aux::type_wrapper< arg<N> >*); |
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| 49 | |
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| 50 | } // namespace aux |
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| 51 | |
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| 52 | template< typename T > |
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| 53 | struct is_placeholder |
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| 54 | { |
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| 55 | static aux::type_wrapper<T>* get(); |
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| 56 | BOOST_STATIC_CONSTANT(bool, value = |
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| 57 | sizeof(aux::is_placeholder_helper(get())) == sizeof(aux::yes_tag) |
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| 58 | ); |
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| 59 | |
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| 60 | typedef bool_<value> type; |
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| 61 | }; |
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| 62 | |
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| 63 | #endif // BOOST_NO_TEMPLATE_PARTIAL_SPECIALIZATION |
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| 64 | |
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| 65 | }} |
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| 66 | |
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| 67 | #endif // BOOST_MPL_IS_PLACEHOLDER_HPP_INCLUDED |
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