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1 | /* Copyright 2006-2008 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_TAG_HPP | |
10 | #define BOOST_FLYWEIGHT_TAG_HPP | |
11 | ||
12 | #if defined(_MSC_VER) | |
13 | #pragma once | |
14 | #endif | |
15 | ||
16 | #include <boost/config.hpp> /* keep it first to prevent nasty warns in MSVC */ | |
17 | #include <boost/parameter/parameters.hpp> | |
18 | #include <boost/type_traits/is_base_and_derived.hpp> | |
19 | ||
20 | /* A type T can be used as a tag in the specification of a flyweight | |
21 | * by passing it wrapped in the form tag<T>. | |
22 | */ | |
23 | ||
24 | namespace boost{ | |
25 | ||
26 | namespace flyweights{ | |
27 | ||
28 | namespace detail{ | |
29 | ||
30 | struct tag_marker{}; | |
31 | ||
32 | template<typename T> | |
33 | struct is_tag:is_base_and_derived<tag_marker,T> | |
34 | {}; | |
35 | ||
36 | } /* namespace flyweights::detail */ | |
37 | ||
38 | template<typename T=parameter::void_> | |
39 | struct tag:parameter::template_keyword<tag<>,T>,detail::tag_marker | |
40 | {}; | |
41 | ||
42 | } /* namespace flyweights */ | |
43 | ||
44 | } /* namespace boost */ | |
45 | ||
46 | #endif |