Chris@16: // Boost.Units - A C++ library for zero-overhead dimensional analysis and 
Chris@16: // unit/quantity manipulation and conversion
Chris@16: //
Chris@16: // Copyright (C) 2003-2008 Matthias Christian Schabel
Chris@16: // Copyright (C) 2007-2008 Steven Watanabe
Chris@16: //
Chris@16: // Distributed under the Boost Software License, Version 1.0. (See
Chris@16: // accompanying file LICENSE_1_0.txt or copy at
Chris@16: // http://www.boost.org/LICENSE_1_0.txt)
Chris@16: 
Chris@16: #ifndef BOOST_UNITS_DIMENSION_HPP
Chris@16: #define BOOST_UNITS_DIMENSION_HPP
Chris@16: 
Chris@16: #include <boost/static_assert.hpp>
Chris@16: 
Chris@16: #include <boost/type_traits/is_same.hpp>
Chris@16: 
Chris@16: #include <boost/mpl/arithmetic.hpp>
Chris@16: 
Chris@16: #include <boost/units/static_rational.hpp>
Chris@16: #include <boost/units/detail/dimension_list.hpp>
Chris@16: #include <boost/units/detail/dimension_impl.hpp>
Chris@16: 
Chris@16: /// \file 
Chris@16: /// \brief Core metaprogramming utilities for compile-time dimensional analysis.
Chris@16: 
Chris@16: namespace boost {
Chris@16: 
Chris@16: namespace units {
Chris@16: 
Chris@16: /// Reduce dimension list to cardinal form. This algorithm collapses duplicate
Chris@16: /// base dimension tags and sorts the resulting list by the tag ordinal value.
Chris@16: /// Dimension lists that resolve to the same dimension are guaranteed to be  
Chris@16: /// represented by an identical type.
Chris@16: ///
Chris@16: /// The argument should be an MPL forward sequence containing instances
Chris@16: /// of the @c dim template.
Chris@16: ///
Chris@16: /// The result is also an MPL forward sequence.  It also supports the
Chris@16: /// following metafunctions to allow use as a dimension.
Chris@16: ///
Chris@16: ///    - @c mpl::plus is defined only on two equal dimensions and returns the argument unchanged.
Chris@16: ///    - @c mpl::minus is defined only for two equal dimensions and returns the argument unchanged.
Chris@16: ///    - @c mpl::negate will return its argument unchanged.
Chris@16: ///    - @c mpl::times is defined for any dimensions and adds corresponding exponents.
Chris@16: ///    - @c mpl::divides is defined for any dimensions and subtracts the exponents of the
Chris@16: ///         right had argument from the corresponding exponents of the left had argument.
Chris@16: ///         Missing base dimension tags are assumed to have an exponent of zero.
Chris@16: ///    - @c static_power takes a dimension and a static_rational and multiplies all
Chris@16: ///         the exponents of the dimension by the static_rational.
Chris@16: ///    - @c static_root takes a dimension and a static_rational and divides all
Chris@16: ///         the exponents of the dimension by the static_rational.
Chris@16: template<typename Seq>
Chris@16: struct make_dimension_list
Chris@16: {
Chris@16:     typedef typename detail::sort_dims<Seq>::type type;
Chris@16: };
Chris@16: 
Chris@16: /// Raise a dimension list to a scalar power.
Chris@16: template<typename DL,typename Ex> 
Chris@16: struct static_power
Chris@16: {
Chris@16:     typedef typename detail::static_power_impl<DL::size::value>::template apply<
Chris@16:         DL,
Chris@16:         Ex
Chris@16:     >::type type;    
Chris@16: };
Chris@16: 
Chris@16: /// Take a scalar root of a dimension list.
Chris@16: template<typename DL,typename Rt> 
Chris@16: struct static_root
Chris@16: {
Chris@16:     typedef typename detail::static_root_impl<DL::size::value>::template apply<
Chris@16:         DL,
Chris@16:         Rt
Chris@16:     >::type type;    
Chris@16: };
Chris@16: 
Chris@16: } // namespace units
Chris@16: 
Chris@16: #ifndef BOOST_UNITS_DOXYGEN
Chris@16: 
Chris@16: namespace mpl {
Chris@16: 
Chris@16: template<>
Chris@16: struct plus_impl<boost::units::detail::dimension_list_tag,boost::units::detail::dimension_list_tag>
Chris@16: {
Chris@16:     template<class T0, class T1>
Chris@16:     struct apply
Chris@16:     {
Chris@16:         BOOST_STATIC_ASSERT((boost::is_same<T0,T1>::value == true));
Chris@16:         typedef T0 type;
Chris@16:     };
Chris@16: };
Chris@16: 
Chris@16: template<>
Chris@16: struct minus_impl<boost::units::detail::dimension_list_tag,boost::units::detail::dimension_list_tag>
Chris@16: {
Chris@16:     template<class T0, class T1>
Chris@16:     struct apply
Chris@16:     {
Chris@16:         BOOST_STATIC_ASSERT((boost::is_same<T0,T1>::value == true));
Chris@16:         typedef T0 type;
Chris@16:     };
Chris@16: };
Chris@16: 
Chris@16: template<>
Chris@16: struct times_impl<boost::units::detail::dimension_list_tag,boost::units::detail::dimension_list_tag>
Chris@16: {
Chris@16:     template<class T0, class T1>
Chris@16:     struct apply
Chris@16:     {
Chris@16:         typedef typename boost::units::detail::merge_dimensions<T0,T1>::type type;
Chris@16:     };
Chris@16: };
Chris@16: 
Chris@16: template<>
Chris@16: struct divides_impl<boost::units::detail::dimension_list_tag,boost::units::detail::dimension_list_tag>
Chris@16: {
Chris@16:     template<class T0, class T1>
Chris@16:     struct apply
Chris@16:     {
Chris@16:         typedef typename boost::units::detail::merge_dimensions<
Chris@16:             T0,
Chris@16:             typename boost::units::detail::static_inverse_impl<
Chris@16:                 T1::size::value
Chris@16:             >::template apply<
Chris@16:                 T1
Chris@16:             >::type
Chris@16:         >::type type;
Chris@16:     };
Chris@16: };
Chris@16: 
Chris@16: template<>
Chris@16: struct negate_impl<boost::units::detail::dimension_list_tag>
Chris@16: {
Chris@16:     template<class T0>
Chris@16:     struct apply
Chris@16:     {
Chris@16:         typedef T0 type;
Chris@16:     };
Chris@16: };
Chris@16: 
Chris@16: } // namespace mpl
Chris@16: 
Chris@16: #endif
Chris@16: 
Chris@16: } // namespace boost
Chris@16: 
Chris@16: #endif // BOOST_UNITS_DIMENSION_HPP