| /* Copyright 2006-2008 Joaquin M Lopez Munoz. | |
| * Distributed under the Boost Software License, Version 1.0. | |
| * (See accompanying file LICENSE_1_0.txt or copy at | |
| * http://www.boost.org/LICENSE_1_0.txt) | |
| * | |
| * See http://www.boost.org/libs/flyweight for library home page. | |
| */ | |
| #ifndef BOOST_FLYWEIGHT_DETAIL_VALUE_TAG_HPP | |
| #define BOOST_FLYWEIGHT_DETAIL_VALUE_TAG_HPP | |
| #if defined(_MSC_VER)&&(_MSC_VER>=1200) | |
| #pragma once | |
| #endif | |
| #include <boost/config.hpp> /* keep it first to prevent nasty warns in MSVC */ | |
| #include <boost/parameter/parameters.hpp> | |
| #include <boost/type_traits/is_base_and_derived.hpp> | |
| namespace boost{ | |
| namespace flyweights{ | |
| namespace detail{ | |
| /* Three ways to indicate that a given class T is a value policy: | |
| * 1. Make it derived from value_marker. | |
| * 2. Specialize is_value to evaluate to boost::mpl::true_. | |
| * 3. Pass it as value<T> when defining a flyweight type. | |
| * | |
| * For the time being the interface of value policies is not public. | |
| */ | |
| struct value_marker{}; | |
| template<typename T> | |
| struct is_value:is_base_and_derived<value_marker,T> | |
| {}; | |
| template<typename T=parameter::void_> | |
| struct value:parameter::template_keyword<value<>,T> | |
| {}; | |
| } /* namespace flyweights::detail */ | |
| } /* namespace flyweights */ | |
| } /* namespace boost */ | |
| #endif |