2 #ifndef BOOST_MPL_IS_PLACEHOLDER_HPP_INCLUDED
3 #define BOOST_MPL_IS_PLACEHOLDER_HPP_INCLUDED
5 // Copyright Aleksey Gurtovoy 2001-2004
7 // Distributed under the Boost Software License, Version 1.0.
8 // (See accompanying file LICENSE_1_0.txt or copy at
9 // http://www.boost.org/LICENSE_1_0.txt)
11 // See http://www.boost.org/libs/mpl for documentation.
14 // $Date: 2004-09-07 04:53:22 -0400 (Tue, 07 Sep 2004) $
17 #include <boost/mpl/arg_fwd.hpp>
18 #include <boost/mpl/bool.hpp>
19 #include <boost/mpl/aux_/yes_no.hpp>
20 #include <boost/mpl/aux_/type_wrapper.hpp>
21 #include <boost/mpl/aux_/nttp_decl.hpp>
22 #include <boost/mpl/aux_/config/ctps.hpp>
23 #include <boost/mpl/aux_/config/static_constant.hpp>
25 namespace boost { namespace mpl {
27 #if !defined(BOOST_NO_TEMPLATE_PARTIAL_SPECIALIZATION)
29 template< typename T >
35 template< BOOST_MPL_AUX_NTTP_DECL(int, N) >
36 struct is_placeholder< arg<N> >
45 aux::no_tag is_placeholder_helper(...);
47 template< BOOST_MPL_AUX_NTTP_DECL(int, N) >
48 aux::yes_tag is_placeholder_helper(aux::type_wrapper< arg<N> >*);
52 template< typename T >
55 static aux::type_wrapper<T>* get();
56 BOOST_STATIC_CONSTANT(bool, value =
57 sizeof(aux::is_placeholder_helper(get())) == sizeof(aux::yes_tag)
60 typedef bool_<value> type;
63 #endif // BOOST_NO_TEMPLATE_PARTIAL_SPECIALIZATION
67 #endif // BOOST_MPL_IS_PLACEHOLDER_HPP_INCLUDED