1 // Boost.Units - A C++ library for zero-overhead dimensional analysis and
2 // unit/quantity manipulation and conversion
3 //
4 // Copyright (C) 2003-2008 Matthias Christian Schabel
5 // Copyright (C) 2008 Steven Watanabe
6 //
7 // Distributed under the Boost Software License, Version 1.0. (See
8 // accompanying file LICENSE_1_0.txt or copy at
9 // http://www.boost.org/LICENSE_1_0.txt)
10 
11 #ifndef BOOST_UNITS_ABSOLUTE_IMPL_HPP
12 #define BOOST_UNITS_ABSOLUTE_IMPL_HPP
13 
14 #include <iosfwd>
15 
16 #include <boost/units/config.hpp>
17 #include <boost/units/conversion.hpp>
18 #include <boost/units/heterogeneous_system.hpp>
19 #include <boost/units/units_fwd.hpp>
20 
21 namespace boost {
22 
23 namespace units {
24 
25 /// INTERNAL ONLY
26 template<class D, class S>
27 struct reduce_unit<absolute<unit<D, S> > >
28 {
29     typedef absolute<typename reduce_unit<unit<D, S> >::type> type;
30 };
31 
32 namespace detail {
33 
34 struct undefined_affine_conversion_base {
35     static const bool is_defined = false;
36 };
37 
38 } // namespace detail
39 
40 /// INTERNAL ONLY
41 template<class From, class To>
42 struct affine_conversion_helper : detail::undefined_affine_conversion_base { };
43 
44 namespace detail {
45 
46 template<bool IsDefined, bool ReverseIsDefined>
47 struct affine_conversion_impl;
48 
49 template<bool ReverseIsDefined>
50 struct affine_conversion_impl<true, ReverseIsDefined>
51 {
52     template<class Unit1, class Unit2, class T0, class T1>
53     struct apply {
valueboost::units::detail::affine_conversion_impl::apply54         static T1 value(const T0& t0)
55         {
56             return(
57                 t0 *
58                 conversion_factor(Unit1(), Unit2()) +
59                 affine_conversion_helper<typename reduce_unit<Unit1>::type, typename reduce_unit<Unit2>::type>::value());
60         }
61     };
62 };
63 
64 template<>
65 struct affine_conversion_impl<false, true>
66 {
67     template<class Unit1, class Unit2, class T0, class T1>
68     struct apply
69     {
valueboost::units::detail::affine_conversion_impl::apply70         static T1 value(const T0& t0)
71         {
72             return(
73                 (t0 - affine_conversion_helper<typename reduce_unit<Unit2>::type, typename reduce_unit<Unit1>::type>::value()) *
74                 conversion_factor(Unit1(), Unit2()));
75         }
76     };
77 };
78 
79 } // namespace detail
80 
81 /// INTERNAL ONLY
82 template<class Unit1, class T1, class Unit2, class T2>
83 struct conversion_helper<quantity<absolute<Unit1>, T1>, quantity<absolute<Unit2>, T2> >
84 {
85     typedef quantity<absolute<Unit1>, T1> from_quantity_type;
86     typedef quantity<absolute<Unit2>, T2> to_quantity_type;
convertboost::units::conversion_helper87     static to_quantity_type convert(const from_quantity_type& source)
88     {
89         return(
90             to_quantity_type::from_value(
91                 detail::affine_conversion_impl<
92                     affine_conversion_helper<typename reduce_unit<Unit1>::type, typename reduce_unit<Unit2>::type>::is_defined,
93                     affine_conversion_helper<typename reduce_unit<Unit2>::type, typename reduce_unit<Unit1>::type>::is_defined
94                 >::template apply<Unit1, Unit2, T1, T2>::value(source.value())
95             )
96         );
97     }
98 };
99 
100 } // namespace units
101 
102 } // namespace boost
103 
104 #endif // BOOST_UNITS_ABSOLUTE_IMPL_HPP
105