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1 | // Boost.TypeErasure library |
2 | // | |
3 | // Copyright 2011 Steven Watanabe | |
4 | // | |
5 | // Distributed under the Boost Software License Version 1.0. (See | |
6 | // accompanying file LICENSE_1_0.txt or copy at | |
7 | // http://www.boost.org/LICENSE_1_0.txt) | |
8 | // | |
9 | // $Id$ | |
10 | ||
11 | #ifndef BOOST_TYPE_ERASURE_REBIND_ANY_HPP_INCLUDED | |
12 | #define BOOST_TYPE_ERASURE_REBIND_ANY_HPP_INCLUDED | |
13 | ||
14 | #include <boost/mpl/if.hpp> | |
15 | #include <boost/type_traits/remove_cv.hpp> | |
16 | #include <boost/type_traits/remove_reference.hpp> | |
17 | #include <boost/type_erasure/is_placeholder.hpp> | |
18 | #include <boost/type_erasure/concept_of.hpp> | |
19 | ||
20 | namespace boost { | |
21 | namespace type_erasure { | |
22 | ||
23 | template<class Concept, class T> | |
24 | class any; | |
25 | ||
26 | /** | |
27 | * A metafunction that changes the @ref placeholder of | |
28 | * an @ref any. If @c T is not a placeholder, | |
29 | * returns @c T unchanged. This class is intended | |
30 | * to be used in @ref concept_interface to deduce | |
31 | * the argument types from the arguments of the concept. | |
32 | * | |
33 | * @pre Any must be a specialization of @ref any or a base | |
34 | * class of such a specialization. | |
35 | * | |
36 | * \code | |
37 | * rebind_any<any<Concept>, _a>::type -> any<Concept, _a> | |
38 | * rebind_any<any<Concept>, _b&>::type -> any<Concept, _b&> | |
39 | * rebind_any<any<Concept>, int>::type -> int | |
40 | * \endcode | |
41 | * | |
42 | * @see derived, as_param | |
43 | */ | |
44 | template<class Any, class T> | |
45 | struct rebind_any | |
46 | { | |
47 | #ifdef BOOST_TYPE_ERASURE_DOXYGEN | |
48 | typedef detail::unspecified type; | |
49 | #else | |
50 | typedef typename ::boost::mpl::if_< | |
51 | ::boost::type_erasure::is_placeholder< | |
52 | typename ::boost::remove_cv< | |
53 | typename ::boost::remove_reference<T>::type | |
54 | >::type | |
55 | >, | |
56 | ::boost::type_erasure::any< | |
57 | typename ::boost::type_erasure::concept_of<Any>::type, | |
58 | T | |
59 | >, | |
60 | T | |
61 | >::type type; | |
62 | #endif | |
63 | }; | |
64 | ||
65 | } | |
66 | } | |
67 | ||
68 | #endif |