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_HOMOGENEOUS_SYSTEM_HPP_INCLUDED
12 #define BOOST_UNITS_HOMOGENEOUS_SYSTEM_HPP_INCLUDED
13 
14 #include <boost/mpl/bool.hpp>
15 
16 #include <boost/units/config.hpp>
17 #include <boost/units/static_rational.hpp>
18 
19 #ifdef BOOST_UNITS_CHECK_HOMOGENEOUS_UNITS
20 
21 #include <boost/type_traits/is_same.hpp>
22 #include <boost/mpl/not.hpp>
23 
24 #include <boost/units/detail/linear_algebra.hpp>
25 
26 #endif
27 
28 namespace boost {
29 
30 namespace units {
31 
32 /// A system that can uniquely represent any unit
33 /// which can be composed from a linearly independent set
34 /// of base units.  It is safe to rebind a unit with
35 /// such a system to different dimensions.
36 ///
37 /// Do not construct this template directly.  Use
38 /// make_system instead.
39 template<class L>
40 struct homogeneous_system {
41     /// INTERNAL ONLY
42     typedef L type;
43 };
44 
45 template<class T, class E>
46 struct static_power;
47 
48 template<class T, class R>
49 struct static_root;
50 
51 /// INTERNAL ONLY
52 template<class L, long N, long D>
53 struct static_power<homogeneous_system<L>, static_rational<N,D> >
54 {
55     typedef homogeneous_system<L> type;
56 };
57 
58 /// INTERNAL ONLY
59 template<class L, long N, long D>
60 struct static_root<homogeneous_system<L>, static_rational<N,D> >
61 {
62     typedef homogeneous_system<L> type;
63 };
64 
65 namespace detail {
66 
67 template<class System, class Dimensions>
68 struct check_system;
69 
70 #ifdef BOOST_UNITS_CHECK_HOMOGENEOUS_UNITS
71 
72 template<class L, class Dimensions>
73 struct check_system<homogeneous_system<L>, Dimensions> :
74     boost::mpl::not_<
75         boost::is_same<
76             typename calculate_base_unit_exponents<
77                 L,
78                 Dimensions
79             >::type,
80             inconsistent
81         >
82     > {};
83 
84 #else
85 
86 template<class L, class Dimensions>
87 struct check_system<homogeneous_system<L>, Dimensions> : mpl::true_ {};
88 
89 #endif
90 
91 } // namespace detail
92 
93 } // namespace units
94 
95 } // namespace boost
96 
97 #if BOOST_UNITS_HAS_BOOST_TYPEOF
98 
99 #include BOOST_TYPEOF_INCREMENT_REGISTRATION_GROUP()
100 
101 BOOST_TYPEOF_REGISTER_TEMPLATE(boost::units::homogeneous_system, (class))
102 
103 #endif
104 
105 #endif
106