1 | |
---|
2 | #ifndef BOOST_MPL_IS_PLACEHOLDER_HPP_INCLUDED |
---|
3 | #define BOOST_MPL_IS_PLACEHOLDER_HPP_INCLUDED |
---|
4 | |
---|
5 | // Copyright Aleksey Gurtovoy 2001-2004 |
---|
6 | // |
---|
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) |
---|
10 | // |
---|
11 | // See http://www.boost.org/libs/mpl for documentation. |
---|
12 | |
---|
13 | // $Id: is_placeholder.hpp 49267 2008-10-11 06:19:02Z agurtovoy $ |
---|
14 | // $Date: 2008-10-11 02:19:02 -0400 (Sat, 11 Oct 2008) $ |
---|
15 | // $Revision: 49267 $ |
---|
16 | |
---|
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> |
---|
24 | |
---|
25 | namespace boost { namespace mpl { |
---|
26 | |
---|
27 | #if !defined(BOOST_NO_TEMPLATE_PARTIAL_SPECIALIZATION) |
---|
28 | |
---|
29 | template< typename T > |
---|
30 | struct is_placeholder |
---|
31 | : bool_<false> |
---|
32 | { |
---|
33 | }; |
---|
34 | |
---|
35 | template< BOOST_MPL_AUX_NTTP_DECL(int, N) > |
---|
36 | struct is_placeholder< arg<N> > |
---|
37 | : bool_<true> |
---|
38 | { |
---|
39 | }; |
---|
40 | |
---|
41 | #else |
---|
42 | |
---|
43 | namespace aux { |
---|
44 | |
---|
45 | aux::no_tag is_placeholder_helper(...); |
---|
46 | |
---|
47 | template< BOOST_MPL_AUX_NTTP_DECL(int, N) > |
---|
48 | aux::yes_tag is_placeholder_helper(aux::type_wrapper< arg<N> >*); |
---|
49 | |
---|
50 | } // namespace aux |
---|
51 | |
---|
52 | template< typename T > |
---|
53 | struct is_placeholder |
---|
54 | { |
---|
55 | static aux::type_wrapper<T>* get(); |
---|
56 | BOOST_STATIC_CONSTANT(bool, value = |
---|
57 | sizeof(aux::is_placeholder_helper(get())) == sizeof(aux::yes_tag) |
---|
58 | ); |
---|
59 | |
---|
60 | typedef bool_<value> type; |
---|
61 | }; |
---|
62 | |
---|
63 | #endif // BOOST_NO_TEMPLATE_PARTIAL_SPECIALIZATION |
---|
64 | |
---|
65 | }} |
---|
66 | |
---|
67 | #endif // BOOST_MPL_IS_PLACEHOLDER_HPP_INCLUDED |
---|