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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_DIM_HPP
- #define BOOST_UNITS_DIM_HPP
- #include <boost/static_assert.hpp>
- #include <boost/type_traits/is_same.hpp>
- #include <boost/mpl/arithmetic.hpp>
- #include <boost/units/config.hpp>
- #include <boost/units/static_rational.hpp>
- #include <boost/units/detail/dim_impl.hpp>
- /// \file dim.hpp
- /// \brief Handling of fundamental dimension/exponent pairs.
- namespace boost {
- namespace units {
- namespace detail {
- struct dim_tag { };
- }
- /// \brief Dimension tag/exponent pair for a single fundamental dimension.
- ///
- /// \details
- /// The dim class represents a single dimension tag/dimension exponent pair.
- /// That is, @c dim<tag_type,value_type> is a pair where @c tag_type represents the
- /// fundamental dimension being represented and @c value_type represents the
- /// exponent of that fundamental dimension as a @c static_rational. @c tag_type must
- /// be a derived from a specialization of @c base_dimension.
- /// Specialization of the following Boost.MPL metafunctions are provided
- ///
- /// - @c mpl::plus for two @c dims
- /// - @c mpl::minus for two @c dims
- /// - @c mpl::negate for a @c dim
- ///
- /// These metafunctions all operate on the exponent, and require
- /// that the @c dim operands have the same base dimension tag.
- /// In addition, multiplication and division by @c static_rational
- /// is supported.
- ///
- /// - @c mpl::times for a @c static_rational and a @c dim in either order
- /// - @c mpl::divides for a @c static_rational and a @c dim in either order
- ///
- /// These metafunctions likewise operate on the exponent only.
- template<typename T,typename V>
- struct dim
- {
- typedef dim type;
- typedef detail::dim_tag tag;
- typedef T tag_type;
- typedef V value_type;
- };
- } // namespace units
- } // namespace boost
- #if BOOST_UNITS_HAS_BOOST_TYPEOF
- #include BOOST_TYPEOF_INCREMENT_REGISTRATION_GROUP()
- BOOST_TYPEOF_REGISTER_TEMPLATE(boost::units::dim, 2)
- #endif
- #ifndef BOOST_UNITS_DOXYGEN
- namespace boost {
- namespace mpl {
- // define MPL operators acting on dim<T,V>
- template<>
- struct plus_impl<boost::units::detail::dim_tag,boost::units::detail::dim_tag>
- {
- template<class T0, class T1>
- struct apply
- {
- BOOST_STATIC_ASSERT((boost::is_same<typename T0::tag_type,typename T1::tag_type>::value == true));
- typedef boost::units::dim<typename T0::tag_type, typename mpl::plus<typename T0::value_type, typename T1::value_type>::type> type;
- };
- };
- template<>
- struct minus_impl<boost::units::detail::dim_tag,boost::units::detail::dim_tag>
- {
- template<class T0, class T1>
- struct apply
- {
- BOOST_STATIC_ASSERT((boost::is_same<typename T0::tag_type,typename T1::tag_type>::value == true));
- typedef boost::units::dim<typename T0::tag_type, typename mpl::minus<typename T0::value_type, typename T1::value_type>::type> type;
- };
- };
- template<>
- struct times_impl<boost::units::detail::dim_tag,boost::units::detail::static_rational_tag>
- {
- template<class T0, class T1>
- struct apply
- {
- typedef boost::units::dim<typename T0::tag_type, typename mpl::times<typename T0::value_type, T1>::type> type;
- };
- };
- template<>
- struct times_impl<boost::units::detail::static_rational_tag,boost::units::detail::dim_tag>
- {
- template<class T0, class T1>
- struct apply
- {
- typedef boost::units::dim<typename T1::tag_type, typename mpl::times<T0, typename T1::value_type>::type> type;
- };
- };
- template<>
- struct divides_impl<boost::units::detail::dim_tag,boost::units::detail::static_rational_tag>
- {
- template<class T0, class T1>
- struct apply
- {
- typedef boost::units::dim<typename T0::tag_type, typename mpl::divides<typename T0::value_type, T1>::type> type;
- };
- };
- template<>
- struct divides_impl<boost::units::detail::static_rational_tag,boost::units::detail::dim_tag>
- {
- template<class T0, class T1>
- struct apply
- {
- typedef boost::units::dim<typename T1::tag_type, typename mpl::divides<T0, typename T1::value_type>::type> type;
- };
- };
- template<>
- struct negate_impl<boost::units::detail::dim_tag>
- {
- template<class T0>
- struct apply
- {
- typedef boost::units::dim<typename T0::tag_type,typename mpl::negate<typename T0::value_type>::type> type;
- };
- };
- } // namespace mpl
- } // namespace boost
- #endif
- #endif // BOOST_UNITS_DIM_HPP
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