// 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) 2007-2008 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_DIMENSION_HPP | |
#define BOOST_UNITS_DIMENSION_HPP | |
#include <boost/static_assert.hpp> | |
#include <boost/type_traits/is_same.hpp> | |
#include <boost/mpl/arithmetic.hpp> | |
#include <boost/units/static_rational.hpp> | |
#include <boost/units/detail/dimension_list.hpp> | |
#include <boost/units/detail/dimension_impl.hpp> | |
/// \file | |
/// \brief Core metaprogramming utilities for compile-time dimensional analysis. | |
namespace boost { | |
namespace units { | |
/// Reduce dimension list to cardinal form. This algorithm collapses duplicate | |
/// base dimension tags and sorts the resulting list by the tag ordinal value. | |
/// Dimension lists that resolve to the same dimension are guaranteed to be | |
/// represented by an identical type. | |
/// | |
/// The argument should be an MPL forward sequence containing instances | |
/// of the @c dim template. | |
/// | |
/// The result is also an MPL forward sequence. It also supports the | |
/// following metafunctions to allow use as a dimension. | |
/// | |
/// - @c mpl::plus is defined only on two equal dimensions and returns the argument unchanged. | |
/// - @c mpl::minus is defined only for two equal dimensions and returns the argument unchanged. | |
/// - @c mpl::negate will return its argument unchanged. | |
/// - @c mpl::times is defined for any dimensions and adds corresponding exponents. | |
/// - @c mpl::divides is defined for any dimensions and subtracts the exponents of the | |
/// right had argument from the corresponding exponents of the left had argument. | |
/// Missing base dimension tags are assumed to have an exponent of zero. | |
/// - @c static_power takes a dimension and a static_rational and multiplies all | |
/// the exponents of the dimension by the static_rational. | |
/// - @c static_root takes a dimension and a static_rational and divides all | |
/// the exponents of the dimension by the static_rational. | |
template<typename Seq> | |
struct make_dimension_list | |
{ | |
typedef typename detail::sort_dims<Seq>::type type; | |
}; | |
/// Raise a dimension list to a scalar power. | |
template<typename DL,typename Ex> | |
struct static_power | |
{ | |
typedef typename detail::static_power_impl<DL::size::value>::template apply< | |
DL, | |
Ex | |
>::type type; | |
}; | |
/// Take a scalar root of a dimension list. | |
template<typename DL,typename Rt> | |
struct static_root | |
{ | |
typedef typename detail::static_root_impl<DL::size::value>::template apply< | |
DL, | |
Rt | |
>::type type; | |
}; | |
} // namespace units | |
#ifndef BOOST_UNITS_DOXYGEN | |
namespace mpl { | |
template<> | |
struct plus_impl<boost::units::detail::dimension_list_tag,boost::units::detail::dimension_list_tag> | |
{ | |
template<class T0, class T1> | |
struct apply | |
{ | |
BOOST_STATIC_ASSERT((boost::is_same<T0,T1>::value == true)); | |
typedef T0 type; | |
}; | |
}; | |
template<> | |
struct minus_impl<boost::units::detail::dimension_list_tag,boost::units::detail::dimension_list_tag> | |
{ | |
template<class T0, class T1> | |
struct apply | |
{ | |
BOOST_STATIC_ASSERT((boost::is_same<T0,T1>::value == true)); | |
typedef T0 type; | |
}; | |
}; | |
template<> | |
struct times_impl<boost::units::detail::dimension_list_tag,boost::units::detail::dimension_list_tag> | |
{ | |
template<class T0, class T1> | |
struct apply | |
{ | |
typedef typename boost::units::detail::merge_dimensions<T0,T1>::type type; | |
}; | |
}; | |
template<> | |
struct divides_impl<boost::units::detail::dimension_list_tag,boost::units::detail::dimension_list_tag> | |
{ | |
template<class T0, class T1> | |
struct apply | |
{ | |
typedef typename boost::units::detail::merge_dimensions< | |
T0, | |
typename boost::units::detail::static_inverse_impl< | |
T1::size::value | |
>::template apply< | |
T1 | |
>::type | |
>::type type; | |
}; | |
}; | |
template<> | |
struct negate_impl<boost::units::detail::dimension_list_tag> | |
{ | |
template<class T0> | |
struct apply | |
{ | |
typedef T0 type; | |
}; | |
}; | |
} // namespace mpl | |
#endif | |
} // namespace boost | |
#endif // BOOST_UNITS_DIMENSION_HPP |