forked from boostorg/mpl
66 lines
1.8 KiB
C++
66 lines
1.8 KiB
C++
//-----------------------------------------------------------------------------
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// boost mpl/is_placeholder.hpp header file
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// See http://www.boost.org for updates, documentation, and revision history.
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//-----------------------------------------------------------------------------
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//
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// Copyright (c) 2001-02
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// Aleksey Gurtovoy
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//
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// Permission to use, copy, modify, distribute and sell this software
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// and its documentation for any purpose is hereby granted without fee,
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// provided that the above copyright notice appears in all copies and
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// that both the copyright notice and this permission notice appear in
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// supporting documentation. No representations are made about the
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// suitability of this software for any purpose. It is provided "as is"
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// without express or implied warranty.
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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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#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_/config/ctps.hpp"
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#include "boost/mpl/aux_/config/nttp.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(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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BOOST_STATIC_CONSTANT(bool, value =
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sizeof(aux::is_placeholder_helper(static_cast<T*>(0))) == sizeof(aux::yes_tag)
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);
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};
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#endif // BOOST_NO_TEMPLATE_PARTIAL_SPECIALIZATION
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}} // namespace boost::mpl
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#endif // BOOST_MPL_IS_PLACEHOLDER_HPP_INCLUDED
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