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1 | /* Copyright 2006-2009 Joaquin M Lopez Munoz. |
2 | * Distributed under the Boost Software License, Version 1.0. | |
3 | * (See accompanying file LICENSE_1_0.txt or copy at | |
4 | * http://www.boost.org/LICENSE_1_0.txt) | |
5 | * | |
6 | * See http://www.boost.org/libs/flyweight for library home page. | |
7 | */ | |
8 | ||
9 | #ifndef BOOST_FLYWEIGHT_DETAIL_IS_PLACEHOLDER_EXPR_HPP | |
10 | #define BOOST_FLYWEIGHT_DETAIL_IS_PLACEHOLDER_EXPR_HPP | |
11 | ||
12 | #if defined(_MSC_VER) | |
13 | #pragma once | |
14 | #endif | |
15 | ||
16 | #include <boost/type_traits/is_same.hpp> | |
17 | #include <boost/mpl/apply.hpp> | |
18 | #include <boost/mpl/aux_/lambda_support.hpp> | |
19 | #include <boost/mpl/not.hpp> | |
20 | #include <boost/preprocessor/facilities/intercept.hpp> | |
21 | #include <boost/preprocessor/repetition/enum_params.hpp> | |
22 | ||
23 | namespace boost{ | |
24 | ||
25 | namespace flyweights{ | |
26 | ||
27 | namespace detail{ | |
28 | ||
29 | /* is_placeholder_expression<T> indicates whether T is an | |
30 | * MPL placeholder expression. | |
31 | */ | |
32 | ||
33 | template<typename T> | |
34 | struct is_placeholder_expression_helper | |
35 | { | |
36 | template< | |
37 | BOOST_PP_ENUM_PARAMS( | |
38 | BOOST_MPL_LIMIT_METAFUNCTION_ARITY,typename BOOST_PP_INTERCEPT) | |
39 | > | |
40 | struct apply{ | |
41 | typedef int type; | |
42 | }; | |
43 | ||
44 | BOOST_MPL_AUX_LAMBDA_SUPPORT(1,is_placeholder_expression_helper,(T)) | |
45 | }; | |
46 | ||
47 | template<typename T> | |
48 | struct is_placeholder_expression: | |
49 | mpl::not_<is_same< | |
50 | typename mpl::apply< | |
51 | is_placeholder_expression_helper<T>, | |
52 | BOOST_PP_ENUM_PARAMS( | |
53 | BOOST_MPL_LIMIT_METAFUNCTION_ARITY,int BOOST_PP_INTERCEPT) | |
54 | >::type, | |
55 | int | |
56 | > > | |
57 | {}; | |
58 | ||
59 | } /* namespace flyweights::detail */ | |
60 | ||
61 | } /* namespace flyweights */ | |
62 | ||
63 | } /* namespace boost */ | |
64 | ||
65 | #endif |