]>
Commit | Line | Data |
---|---|---|
7c673cae FG |
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_DETAIL_VALUE_TAG_HPP | |
10 | #define BOOST_FLYWEIGHT_DETAIL_VALUE_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 | namespace boost{ | |
21 | ||
22 | namespace flyweights{ | |
23 | ||
24 | namespace detail{ | |
25 | ||
26 | /* Three ways to indicate that a given class T is a value policy: | |
27 | * 1. Make it derived from value_marker. | |
28 | * 2. Specialize is_value to evaluate to boost::mpl::true_. | |
29 | * 3. Pass it as value<T> when defining a flyweight type. | |
30 | * | |
31 | * For the time being the interface of value policies is not public. | |
32 | */ | |
33 | ||
34 | struct value_marker{}; | |
35 | ||
36 | template<typename T> | |
37 | struct is_value:is_base_and_derived<value_marker,T> | |
38 | {}; | |
39 | ||
40 | template<typename T=parameter::void_> | |
41 | struct value:parameter::template_keyword<value<>,T> | |
42 | {}; | |
43 | ||
44 | } /* namespace flyweights::detail */ | |
45 | ||
46 | } /* namespace flyweights */ | |
47 | ||
48 | } /* namespace boost */ | |
49 | ||
50 | #endif |