1/* Copyright 2006-2009 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_NESTED_XXX_IF_NOT_PH_HPP
10#define BOOST_FLYWEIGHT_DETAIL_NESTED_XXX_IF_NOT_PH_HPP
11
12#if defined(_MSC_VER)
13#pragma once
14#endif
15
16#include <boost/flyweight/detail/is_placeholder_expr.hpp>
17#include <boost/mpl/if.hpp>
18
19/* nested_##name##_if_not_placeholder_expression<T>::type is T::name unless
20 * T is an MPL placeholder expression, in which case it defaults to int.
21 */
22
23#define BOOST_FLYWEIGHT_NESTED_XXX_IF_NOT_PLACEHOLDER_EXPRESSION_DEF(name) \
24struct nested_##name##_if_not_placeholder_expression_helper \
25{ \
26 typedef int name; \
27}; \
28 \
29template<typename T> \
30struct nested_##name##_if_not_placeholder_expression \
31{ \
32 typedef typename boost::mpl::if_< \
33 boost::flyweights::detail::is_placeholder_expression<T>, \
34 nested_##name##_if_not_placeholder_expression_helper, \
35 T \
36 >::type::name type; \
37};
38
39#endif
40

source code of boost/libs/flyweight/include/boost/flyweight/detail/nested_xxx_if_not_ph.hpp