// Boost.Units - A C++ library for zero-overhead dimensional analysis and | |
// unit/quantity manipulation and conversion | |
// | |
// Copyright (C) 2003-2008 Matthias Christian Schabel | |
// Copyright (C) 2008 Steven Watanabe | |
// | |
// 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) | |
#ifndef BOOST_UNITS_DETAIL_PUSH_FRONT_OR_ADD_HPP | |
#define BOOST_UNITS_DETAIL_PUSH_FRONT_OR_ADD_HPP | |
#include <boost/mpl/plus.hpp> | |
#include <boost/mpl/front.hpp> | |
#include <boost/mpl/push_front.hpp> | |
#include <boost/mpl/pop_front.hpp> | |
#include <boost/type_traits/is_same.hpp> | |
#include <boost/units/units_fwd.hpp> | |
#include <boost/units/detail/push_front_if.hpp> | |
namespace boost { | |
namespace units { | |
template<class Item, class Next> | |
struct list; | |
namespace detail { | |
template<class T> | |
struct is_empty_dim; | |
/// add an instantiation of dim to Sequence. | |
template<bool> | |
struct push_front_or_add_impl; | |
template<> | |
struct push_front_or_add_impl<true> | |
{ | |
template<typename Sequence, typename T> | |
struct apply | |
{ | |
typedef typename mpl::plus<T, typename Sequence::item>::type item; | |
typedef typename push_front_if<!is_empty_dim<item>::value>::template apply< | |
typename Sequence::next, | |
item | |
> type; | |
}; | |
}; | |
template<> | |
struct push_front_or_add_impl<false> | |
{ | |
template<typename Sequence, typename T> | |
struct apply | |
{ | |
typedef list<T, Sequence> type; | |
}; | |
}; | |
template<typename Sequence, typename T> | |
struct push_front_or_add | |
{ | |
typedef typename push_front_or_add_impl<boost::is_same<typename T::tag_type, typename Sequence::item::tag_type>::value>::template apply< | |
Sequence, | |
T | |
>::type type; | |
}; | |
template<typename T> | |
struct push_front_or_add<dimensionless_type, T> | |
{ | |
typedef list<T, dimensionless_type> type; | |
}; | |
} // namespace detail | |
} // namespace units | |
} // namespace boost | |
#endif |