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- // 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
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