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_FACTORY_TAG_HPP |
10 | #define BOOST_FLYWEIGHT_FACTORY_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 | /* Three ways to indicate that a given class T is a factory specifier: |
25 | * 1. Make it derived from factory_marker. |
26 | * 2. Specialize is_factory to evaluate to boost::mpl::true_. |
27 | * 3. Pass it as factory<T> when defining a flyweight type. |
28 | */ |
29 | |
30 | struct factory_marker{}; |
31 | |
32 | template<typename T> |
33 | struct is_factory:is_base_and_derived<factory_marker,T> |
34 | {}; |
35 | |
36 | template<typename T=parameter::void_> |
37 | struct factory:parameter::template_keyword<factory<>,T> |
38 | {}; |
39 | |
40 | } /* namespace flyweights */ |
41 | |
42 | } /* namespace boost */ |
43 | |
44 | #endif |
45 | |