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1 | // Boost.Bimap |
2 | // | |
3 | // Copyright (c) 2006-2007 Matias Capeletto | |
4 | // | |
5 | // Distributed under the Boost Software License, Version 1.0. | |
6 | // (See accompanying file LICENSE_1_0.txt or copy at | |
7 | // http://www.boost.org/LICENSE_1_0.txt) | |
8 | ||
9 | /// \file tags/support/tag_of.hpp | |
10 | /// \brief Safe way to acces the tag of a type | |
11 | ||
12 | #ifndef BOOST_BIMAP_TAGS_SUPPORT_TAG_OF_HPP | |
13 | #define BOOST_BIMAP_TAGS_SUPPORT_TAG_OF_HPP | |
14 | ||
15 | #if defined(_MSC_VER) | |
16 | #pragma once | |
17 | #endif | |
18 | ||
19 | #include <boost/config.hpp> | |
20 | ||
21 | #include <boost/bimap/tags/tagged.hpp> | |
22 | #include <boost/bimap/detail/debug/static_error.hpp> | |
23 | ||
24 | /** \struct boost::bimaps::tags::support::tag_of | |
25 | \brief Metafunction to obtain the tag of a type. | |
26 | ||
27 | \code | |
28 | template< class TaggedType > | |
29 | struct tag_of | |
30 | { | |
31 | typedef {Tag} type; | |
32 | }; | |
33 | \endcode | |
34 | ||
35 | If the type is not tagged you will get a compile timer error with the following message: | |
36 | ||
37 | \verbatim | |
38 | USING_TAG_OF_WITH_AN_UNTAGGED_TYPE, TaggedType | |
39 | \endverbatim | |
40 | ||
41 | See also tagged, value_type_of. | |
42 | **/ | |
43 | ||
44 | #ifndef BOOST_BIMAP_DOXYGEN_WILL_NOT_PROCESS_THE_FOLLOWING_LINES | |
45 | ||
46 | namespace boost { | |
47 | namespace bimaps { | |
48 | namespace tags { | |
49 | namespace support { | |
50 | ||
51 | ||
52 | // tag_of metafunction | |
53 | ||
54 | template< class Type > | |
55 | struct tag_of | |
56 | { | |
57 | BOOST_BIMAP_STATIC_ERROR( USING_TAG_OF_WITH_AN_UNTAGGED_TYPE, (Type) ); | |
58 | }; | |
59 | ||
60 | template< class Type, class Tag > | |
61 | struct tag_of< tagged< Type, Tag > > | |
62 | { | |
63 | typedef Tag type; | |
64 | }; | |
65 | ||
66 | ||
67 | } // namespace support | |
68 | } // namespace tags | |
69 | } // namespace bimaps | |
70 | } // namespace boost | |
71 | ||
72 | #endif // BOOST_BIMAP_DOXYGEN_WILL_NOT_PROCESS_THE_FOLLOWING_LINES | |
73 | ||
74 | #endif // BOOST_BIMAP_TAGS_SUPPORT_TAG_OF_HPP | |
75 |