68 lines
1.5 KiB
C++
68 lines
1.5 KiB
C++
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#ifndef BOOST_MPL_IS_PLACEHOLDER_HPP_INCLUDED
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#define BOOST_MPL_IS_PLACEHOLDER_HPP_INCLUDED
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// Copyright Aleksey Gurtovoy 2001-2004
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//
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// Distributed under the Boost Software License, Version 1.0.
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// (See accompanying file LICENSE_1_0.txt or copy at
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// http://www.boost.org/LICENSE_1_0.txt)
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//
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// See http://www.boost.org/libs/mpl for documentation.
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// $Id$
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// $Date$
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// $Revision$
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#include <boost/mpl/arg_fwd.hpp>
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#include <boost/mpl/bool.hpp>
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#include <boost/mpl/aux_/yes_no.hpp>
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#include <boost/mpl/aux_/type_wrapper.hpp>
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#include <boost/mpl/aux_/nttp_decl.hpp>
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#include <boost/mpl/aux_/config/ctps.hpp>
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#include <boost/mpl/aux_/config/static_constant.hpp>
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namespace boost { namespace mpl {
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#if !defined(BOOST_NO_TEMPLATE_PARTIAL_SPECIALIZATION)
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template< typename T >
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struct is_placeholder
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: bool_<false>
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{
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};
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template< BOOST_MPL_AUX_NTTP_DECL(int, N) >
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struct is_placeholder< arg<N> >
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: bool_<true>
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{
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};
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#else
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namespace aux {
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aux::no_tag is_placeholder_helper(...);
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template< BOOST_MPL_AUX_NTTP_DECL(int, N) >
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aux::yes_tag is_placeholder_helper(aux::type_wrapper< arg<N> >*);
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} // namespace aux
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template< typename T >
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struct is_placeholder
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{
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static aux::type_wrapper<T>* get();
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BOOST_STATIC_CONSTANT(bool, value =
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sizeof(aux::is_placeholder_helper(get())) == sizeof(aux::yes_tag)
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);
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typedef bool_<value> type;
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};
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#endif // BOOST_NO_TEMPLATE_PARTIAL_SPECIALIZATION
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}}
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#endif // BOOST_MPL_IS_PLACEHOLDER_HPP_INCLUDED
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