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_DETAIL_CONVERSION_IMPL_HPP
Chris@16: #define BOOST_UNITS_DETAIL_CONVERSION_IMPL_HPP
Chris@16: 
Chris@16: #include <boost/mpl/bool.hpp>
Chris@16: #include <boost/mpl/and.hpp>
Chris@16: #include <boost/mpl/divides.hpp>
Chris@16: #include <boost/preprocessor/seq/enum.hpp>
Chris@16: #include <boost/type_traits/is_same.hpp>
Chris@16: 
Chris@16: #include <boost/units/heterogeneous_system.hpp>
Chris@16: #include <boost/units/homogeneous_system.hpp>
Chris@16: #include <boost/units/reduce_unit.hpp>
Chris@16: #include <boost/units/static_rational.hpp>
Chris@16: #include <boost/units/units_fwd.hpp>
Chris@16: #include <boost/units/detail/dimension_list.hpp>
Chris@16: #include <boost/units/detail/heterogeneous_conversion.hpp>
Chris@16: #include <boost/units/detail/one.hpp>
Chris@16: #include <boost/units/detail/static_rational_power.hpp>
Chris@16: #include <boost/units/detail/unscale.hpp>
Chris@16: 
Chris@16: #include <boost/units/units_fwd.hpp>
Chris@16: 
Chris@16: namespace boost {
Chris@16: 
Chris@16: namespace units {
Chris@16: 
Chris@16: namespace detail {
Chris@16: 
Chris@16: template<class Source, class Dest>
Chris@16: struct conversion_factor_helper;
Chris@16: 
Chris@16: template<class Source, class Dest>
Chris@16: struct call_base_unit_converter;
Chris@16: 
Chris@16: }
Chris@16: 
Chris@16: /// INTERNAL ONLY
Chris@16: struct undefined_base_unit_converter_base {
Chris@16:     static const bool is_defined = false;
Chris@16: };
Chris@16: 
Chris@16: /// INTERNAL ONLY
Chris@16: struct no_default_conversion {
Chris@16:     static const bool is_defined = false;
Chris@16: };
Chris@16: 
Chris@16: /// INTERNAL ONLY
Chris@16: template<class BaseUnit>
Chris@16: struct unscaled_get_default_conversion : no_default_conversion { };
Chris@16: 
Chris@16: /// INTERNAL ONLY
Chris@16: template<bool is_defined>
Chris@16: struct unscaled_get_default_conversion_impl;
Chris@16: 
Chris@16: /// INTERNAL ONLY
Chris@16: template<>
Chris@16: struct unscaled_get_default_conversion_impl<true>
Chris@16: {
Chris@16:     template<class T>
Chris@16:     struct apply
Chris@16:     {
Chris@16:         typedef typename unscaled_get_default_conversion<typename unscale<T>::type>::type type;
Chris@16:     };
Chris@16: };
Chris@16: 
Chris@16: /// INTERNAL ONLY
Chris@16: template<>
Chris@16: struct unscaled_get_default_conversion_impl<false>
Chris@16: {
Chris@16:     template<class T>
Chris@16:     struct apply
Chris@16:     {
Chris@16:         typedef typename T::unit_type type;
Chris@16:     };
Chris@16: };
Chris@16: 
Chris@16: /// INTERNAL ONLY
Chris@16: template<class BaseUnit>
Chris@16: struct get_default_conversion
Chris@16: {
Chris@16:     typedef typename unscaled_get_default_conversion_impl<
Chris@16:         unscaled_get_default_conversion<typename unscale<BaseUnit>::type>::is_defined
Chris@16:     >::template apply<BaseUnit>::type type;
Chris@16: };
Chris@16: 
Chris@16: /// INTERNAL ONLY
Chris@16: template<class Source, class Destination>
Chris@16: struct select_base_unit_converter
Chris@16: {
Chris@16:     typedef Source source_type;
Chris@16:     typedef Destination destination_type;
Chris@16: };
Chris@16: 
Chris@16: /// INTERNAL ONLY
Chris@16: template<class Source, class Dest>
Chris@16: struct base_unit_converter_base : undefined_base_unit_converter_base {
Chris@16: };
Chris@16: 
Chris@16: /// INTERNAL ONLY
Chris@16: template<class Source>
Chris@16: struct base_unit_converter_base<Source, BOOST_UNITS_MAKE_HETEROGENEOUS_UNIT(Source, typename Source::dimension_type)>
Chris@16: {
Chris@16:     static const bool is_defined = true;
Chris@16:     typedef one type;
Chris@16:     static type value() {
Chris@16:         one result;
Chris@16:         return(result);
Chris@16:     }
Chris@16: };
Chris@16: 
Chris@16: /// INTERNAL ONLY
Chris@16: template<class Source, class Dest>
Chris@16: struct base_unit_converter : base_unit_converter_base<Source, Dest> { };
Chris@16: 
Chris@16: namespace detail {
Chris@16: 
Chris@16: template<class Source, class Dest>
Chris@16: struct do_call_base_unit_converter {
Chris@16:     typedef select_base_unit_converter<typename unscale<Source>::type, typename unscale<Dest>::type> selector;
Chris@16:     typedef typename selector::source_type source_type;
Chris@16:     typedef typename selector::destination_type destination_type;
Chris@16:     typedef base_unit_converter<source_type, destination_type> converter;
Chris@16:     typedef typename mpl::divides<typename get_scale_list<Source>::type, typename get_scale_list<source_type>::type>::type source_factor;
Chris@16:     typedef typename mpl::divides<typename get_scale_list<Dest>::type, typename get_scale_list<destination_type>::type>::type destination_factor;
Chris@16:     typedef typename mpl::divides<source_factor, destination_factor>::type factor;
Chris@16:     typedef eval_scale_list<factor> eval_factor;
Chris@16:     typedef typename multiply_typeof_helper<typename converter::type, typename eval_factor::type>::type type;
Chris@16:     static type value()
Chris@16:     {
Chris@16:         return(converter::value() * eval_factor::value());
Chris@16:     }
Chris@16: };
Chris@16: 
Chris@16: template<bool forward_is_defined, bool reverse_is_defined>
Chris@16: struct call_base_unit_converter_base_unit_impl;
Chris@16: 
Chris@16: template<>
Chris@16: struct call_base_unit_converter_base_unit_impl<true, true>
Chris@16: {
Chris@16:     template<class Source, class Dest>
Chris@16:     struct apply
Chris@16:         : do_call_base_unit_converter<Source, typename Dest::unit_type> 
Chris@16:     {
Chris@16:     };
Chris@16: };
Chris@16: 
Chris@16: template<>
Chris@16: struct call_base_unit_converter_base_unit_impl<true, false>
Chris@16: {
Chris@16:     template<class Source, class Dest>
Chris@16:     struct apply
Chris@16:         : do_call_base_unit_converter<Source, typename Dest::unit_type> 
Chris@16:     {
Chris@16:     };
Chris@16: };
Chris@16: 
Chris@16: template<>
Chris@16: struct call_base_unit_converter_base_unit_impl<false, true>
Chris@16: {
Chris@16:     template<class Source, class Dest>
Chris@16:     struct apply
Chris@16:     {
Chris@16:         typedef do_call_base_unit_converter<Dest, typename Source::unit_type> converter;
Chris@16:         typedef typename divide_typeof_helper<one, typename converter::type>::type type;
Chris@16:         static type value() {
Chris@16:             one numerator;
Chris@16:             return(numerator / converter::value());
Chris@16:         }
Chris@16:     };
Chris@16: };
Chris@16: 
Chris@16: template<>
Chris@16: struct call_base_unit_converter_base_unit_impl<false, false>
Chris@16: {
Chris@16:     template<class Source, class Dest>
Chris@16:     struct apply
Chris@16:     {
Chris@16:         typedef typename reduce_unit<typename get_default_conversion<Source>::type>::type new_source;
Chris@16:         typedef typename reduce_unit<typename get_default_conversion<Dest>::type>::type new_dest;
Chris@16:         typedef call_base_unit_converter<Source, new_source> start;
Chris@16:         typedef detail::conversion_factor_helper<
Chris@16:             new_source,
Chris@16:             new_dest
Chris@16:         > conversion;
Chris@16:         typedef call_base_unit_converter<Dest, new_dest> end;
Chris@16:         typedef typename divide_typeof_helper<
Chris@16:             typename multiply_typeof_helper<
Chris@16:                 typename start::type,
Chris@16:                 typename conversion::type
Chris@16:             >::type,
Chris@16:             typename end::type
Chris@16:         >::type type;
Chris@16:         static type value() {
Chris@16:             return(start::value() * conversion::value() / end::value());
Chris@16:         }
Chris@16:     };
Chris@16: };
Chris@16: 
Chris@16: template<int N>
Chris@16: struct get_default_conversion_impl
Chris@16: {
Chris@16:     template<class Begin>
Chris@16:     struct apply
Chris@16:     {
Chris@16:         typedef typename Begin::item source_pair;
Chris@16:         typedef typename source_pair::value_type exponent;
Chris@16:         typedef typename source_pair::tag_type source;
Chris@16:         typedef typename reduce_unit<typename get_default_conversion<source>::type>::type new_source;
Chris@16:         typedef typename get_default_conversion_impl<N-1>::template apply<typename Begin::next> next_iteration;
Chris@16:         typedef typename multiply_typeof_helper<typename power_typeof_helper<new_source, exponent>::type, typename next_iteration::unit_type>::type unit_type;
Chris@16:         typedef call_base_unit_converter<source, new_source> conversion;
Chris@16:         typedef typename multiply_typeof_helper<typename conversion::type, typename next_iteration::type>::type type;
Chris@16:         static type value() {
Chris@16:             return(static_rational_power<exponent>(conversion::value()) * next_iteration::value());
Chris@16:         }
Chris@16:     };
Chris@16: };
Chris@16: 
Chris@16: template<>
Chris@16: struct get_default_conversion_impl<0>
Chris@16: {
Chris@16:     template<class Begin>
Chris@16:     struct apply
Chris@16:     {
Chris@16:         typedef unit<dimensionless_type, heterogeneous_system<heterogeneous_system_impl<dimensionless_type, dimensionless_type, no_scale> > > unit_type;
Chris@16:         typedef one type;
Chris@16:         static one value() {
Chris@16:             one result;
Chris@16:             return(result);
Chris@16:         }
Chris@16:     };
Chris@16: };
Chris@16: 
Chris@16: template<bool is_defined>
Chris@16: struct call_base_unit_converter_impl;
Chris@16: 
Chris@16: template<>
Chris@16: struct call_base_unit_converter_impl<true>
Chris@16: {
Chris@16:     template<class Source, class Dest>
Chris@16:     struct apply
Chris@16:         : do_call_base_unit_converter<Source, Dest> 
Chris@16:     {
Chris@16:     };
Chris@16: };
Chris@16: 
Chris@16: template<>
Chris@16: struct call_base_unit_converter_impl<false>
Chris@16: {
Chris@16:     template<class Source, class Dest>
Chris@16:     struct apply {
Chris@16:         typedef typename reduce_unit<typename get_default_conversion<Source>::type>::type new_source;
Chris@16:         typedef typename Dest::system_type::type system_list;
Chris@16:         typedef typename get_default_conversion_impl<system_list::size::value>::template apply<system_list> impl;
Chris@16:         typedef typename impl::unit_type new_dest;
Chris@16:         typedef call_base_unit_converter<Source, new_source> start;
Chris@16:         typedef conversion_factor_helper<new_source, new_dest> conversion;
Chris@16:         typedef typename divide_typeof_helper<
Chris@16:             typename multiply_typeof_helper<
Chris@16:                 typename start::type,
Chris@16:                 typename conversion::type
Chris@16:             >::type,
Chris@16:             typename impl::type
Chris@16:         >::type type;
Chris@16:         static type value() {
Chris@16:             return(start::value() * conversion::value() / impl::value());
Chris@16:         }
Chris@16:     };
Chris@16: };
Chris@16: 
Chris@16: #define BOOST_UNITS_DETAIL_BASE_UNIT_CONVERTER_IS_DEFINED(Source, Dest)\
Chris@16:     base_unit_converter<\
Chris@16:         typename select_base_unit_converter<typename unscale<Source>::type, typename unscale<Dest>::type>::source_type,\
Chris@16:         typename select_base_unit_converter<typename unscale<Source>::type, typename unscale<Dest>::type>::destination_type\
Chris@16:     >::is_defined
Chris@16: 
Chris@16: template<class Source, class Dest>
Chris@16: struct call_base_unit_converter : call_base_unit_converter_impl<BOOST_UNITS_DETAIL_BASE_UNIT_CONVERTER_IS_DEFINED(Source, Dest)>::template apply<Source, Dest>
Chris@16: {
Chris@16: };
Chris@16: 
Chris@16: template<class Source, class Dest>
Chris@16: struct call_base_unit_converter<Source, BOOST_UNITS_MAKE_HETEROGENEOUS_UNIT(Dest, typename Source::dimension_type)> :
Chris@16:     call_base_unit_converter_base_unit_impl<
Chris@16:         BOOST_UNITS_DETAIL_BASE_UNIT_CONVERTER_IS_DEFINED(Source, typename Dest::unit_type),
Chris@16:         BOOST_UNITS_DETAIL_BASE_UNIT_CONVERTER_IS_DEFINED(Dest, typename Source::unit_type)
Chris@16:     >::template apply<Source, Dest>
Chris@16: {
Chris@16: };
Chris@16: 
Chris@16: template<int N>
Chris@16: struct conversion_impl
Chris@16: {
Chris@16:     template<class Begin, class DestinationSystem>
Chris@16:     struct apply
Chris@16:     {
Chris@16:         typedef typename conversion_impl<N-1>::template apply<
Chris@16:             typename Begin::next,
Chris@16:             DestinationSystem
Chris@16:         > next_iteration;
Chris@16:         typedef typename Begin::item unit_pair;
Chris@16:         typedef typename unit_pair::tag_type unit;
Chris@16:         typedef typename unit::dimension_type dimensions;
Chris@16:         typedef typename reduce_unit<units::unit<dimensions, DestinationSystem> >::type reduced_unit;
Chris@16:         typedef detail::call_base_unit_converter<unit, reduced_unit> converter;
Chris@16:         typedef typename multiply_typeof_helper<typename converter::type, typename next_iteration::type>::type type;
Chris@16:         static type value() { return(static_rational_power<typename unit_pair::value_type>(converter::value()) * next_iteration::value()); }
Chris@16:     };
Chris@16: };
Chris@16: 
Chris@16: template<>
Chris@16: struct conversion_impl<0>
Chris@16: {
Chris@16:     template<class Begin, class DestinationSystem>
Chris@16:     struct apply
Chris@16:     {
Chris@16:         typedef one type;
Chris@16:         static type value() { one result; return(result); }
Chris@16:     };
Chris@16: };
Chris@16: 
Chris@16: } // namespace detail
Chris@16: 
Chris@16: /// forward to conversion_factor (intentionally allowing ADL)
Chris@16: /// INTERNAL ONLY
Chris@16: template<class Unit1, class T1, class Unit2, class T2>
Chris@16: struct conversion_helper<quantity<Unit1, T1>, quantity<Unit2, T2> >
Chris@16: {
Chris@16:     /// INTERNAL ONLY
Chris@16:     typedef quantity<Unit2, T2> destination_type;
Chris@16:     static destination_type convert(const quantity<Unit1, T1>& source)
Chris@16:     {
Chris@16:         Unit1 u1;
Chris@16:         Unit2 u2;
Chris@16:         return(destination_type::from_value(static_cast<T2>(source.value() * conversion_factor(u1, u2))));
Chris@16:     }
Chris@16: };
Chris@16: 
Chris@16: namespace detail {
Chris@16: 
Chris@16: template<class Source, class Dest>
Chris@16: struct conversion_factor_helper;
Chris@16: 
Chris@16: template<class D, class L1, class L2>
Chris@16: struct conversion_factor_helper<unit<D, homogeneous_system<L1> >, unit<D, homogeneous_system<L2> > >
Chris@16:   : conversion_factor_helper<
Chris@16:         typename reduce_unit<unit<D, homogeneous_system<L1> > >::type,
Chris@16:         typename reduce_unit<unit<D, homogeneous_system<L2> > >::type
Chris@16:     >
Chris@16: {
Chris@16:     //typedef typename reduce_unit<unit<D, homogeneous_system<L1> > >::type source_unit;
Chris@16:     //typedef typename source_unit::system_type::type unit_list;
Chris@16:     //typedef typename detail::conversion_impl<unit_list::size::value>::template apply<
Chris@16:     //    unit_list,
Chris@16:     //    homogeneous_system<L2>
Chris@16:     //> impl;
Chris@16:     //typedef typename impl::type type;
Chris@16:     //static type value()
Chris@16:     //{
Chris@16:     //    return(impl::value());
Chris@16:     //}
Chris@16: };
Chris@16: 
Chris@16: template<class D, class L1, class L2>
Chris@16: struct conversion_factor_helper<unit<D, heterogeneous_system<L1> >, unit<D, homogeneous_system<L2> > >
Chris@16:   : conversion_factor_helper<
Chris@16:         typename reduce_unit<unit<D, heterogeneous_system<L1> > >::type,
Chris@16:         typename reduce_unit<unit<D, homogeneous_system<L2> > >::type
Chris@16:     >
Chris@16: {
Chris@16:     //typedef typename detail::conversion_impl<L1::type::size::value>::template apply<
Chris@16:     //    typename L1::type,
Chris@16:     //    homogeneous_system<L2>
Chris@16:     //> impl;
Chris@16:     //typedef eval_scale_list<typename L1::scale> scale;
Chris@16:     //typedef typename multiply_typeof_helper<typename impl::type, typename scale::type>::type type;
Chris@16:     //static type value()
Chris@16:     //{
Chris@16:     //    return(impl::value() * scale::value());
Chris@16:     //}
Chris@16: };
Chris@16: 
Chris@16: // There is no simple algorithm for doing this conversion
Chris@16: // other than just defining it as the reverse of the
Chris@16: // heterogeneous->homogeneous case
Chris@16: template<class D, class L1, class L2>
Chris@16: struct conversion_factor_helper<unit<D, homogeneous_system<L1> >, unit<D, heterogeneous_system<L2> > >
Chris@16:   : conversion_factor_helper<
Chris@16:         typename reduce_unit<unit<D, homogeneous_system<L1> > >::type,
Chris@16:         typename reduce_unit<unit<D, heterogeneous_system<L2> > >::type
Chris@16:     >
Chris@16: {
Chris@16:     //typedef typename detail::conversion_impl<L2::type::size::value>::template apply<
Chris@16:     //    typename L2::type,
Chris@16:     //    homogeneous_system<L1>
Chris@16:     //> impl;
Chris@16:     //typedef eval_scale_list<typename L2::scale> scale;
Chris@16:     //typedef typename multiply_typeof_helper<typename impl::type, typename scale::type>::type type;
Chris@16:     //static type value()
Chris@16:     //{
Chris@16:     //    one numerator;
Chris@16:     //    return(numerator / (impl::value() * scale::value()));
Chris@16:     //}
Chris@16: };
Chris@16: 
Chris@16: /// Requires that all possible conversions
Chris@16: /// between base units are defined.
Chris@16: template<class D, class S1, class S2>
Chris@16: struct conversion_factor_helper<unit<D, heterogeneous_system<S1> >, unit<D, heterogeneous_system<S2> > >
Chris@16: {
Chris@16:     /// INTERNAL ONLY
Chris@16:     typedef typename detail::extract_base_units<S1::type::size::value>::template apply<
Chris@16:         typename S1::type,
Chris@16:         dimensionless_type
Chris@16:     >::type from_base_units;
Chris@16:     /// INTERNAL ONLY
Chris@16:     typedef typename detail::extract_base_units<S2::type::size::value>::template apply<
Chris@16:         typename S2::type,
Chris@16:         from_base_units
Chris@16:     >::type all_base_units;
Chris@16:     /// INTERNAL ONLY
Chris@16:     typedef typename detail::make_homogeneous_system<all_base_units>::type system;
Chris@16:     typedef typename detail::conversion_impl<S1::type::size::value>::template apply<
Chris@16:         typename S1::type,
Chris@16:         system
Chris@16:     > conversion1;
Chris@16:     typedef typename detail::conversion_impl<S2::type::size::value>::template apply<
Chris@16:         typename S2::type,
Chris@16:         system
Chris@16:     > conversion2;
Chris@16:     typedef eval_scale_list<typename mpl::divides<typename S1::scale, typename S2::scale>::type> scale;
Chris@16:     typedef typename multiply_typeof_helper<
Chris@16:         typename conversion1::type,
Chris@16:         typename divide_typeof_helper<typename scale::type, typename conversion2::type>::type
Chris@16:     >::type type;
Chris@16:     static type value()
Chris@16:     {
Chris@16:         return(conversion1::value() * (scale::value() / conversion2::value()));
Chris@16:     }
Chris@16: };
Chris@16: 
Chris@16: } // namespace detail
Chris@16: 
Chris@16: } // namespace units
Chris@16: 
Chris@16: } // namespace boost
Chris@16: 
Chris@16: #endif // BOOST_UNITS_CONVERSION_IMPL_HPP