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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) 2007-2008 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_DETAIL_DIMENSIONLESS_UNIT_HPP | |
12 | #define BOOST_UNITS_DETAIL_DIMENSIONLESS_UNIT_HPP | |
13 | ||
14 | #include <boost/mpl/bool.hpp> | |
15 | #include <boost/units/units_fwd.hpp> | |
16 | ||
17 | namespace boost { | |
18 | namespace units { | |
19 | ||
20 | template<class T> | |
21 | struct heterogeneous_system; | |
22 | ||
23 | template<class T> | |
24 | struct homogeneous_system; | |
25 | ||
26 | template<class T1, class T2, class Scale> | |
27 | struct heterogeneous_system_impl; | |
28 | ||
29 | typedef boost::units::heterogeneous_system< | |
30 | boost::units::heterogeneous_system_impl< | |
31 | boost::units::dimensionless_type, | |
32 | boost::units::dimensionless_type, | |
33 | boost::units::dimensionless_type | |
34 | > | |
35 | > heterogeneous_dimensionless_system; | |
36 | ||
37 | namespace detail { | |
38 | ||
39 | template<class System> | |
40 | struct void_if_dimensionless { | |
41 | typedef int type; | |
42 | }; | |
43 | ||
44 | template<class T> | |
45 | struct void_if_dimensionless<boost::units::homogeneous_system<T> > { | |
46 | typedef void type; | |
47 | }; | |
48 | ||
49 | template<> | |
50 | struct void_if_dimensionless<heterogeneous_dimensionless_system> { | |
51 | typedef void type; | |
52 | }; | |
53 | ||
54 | template<class System, class Test = void> | |
55 | struct void_if_heterogeneous { | |
56 | typedef void type; | |
57 | }; | |
58 | ||
59 | template<class System> | |
60 | struct void_if_heterogeneous<System, typename void_if_dimensionless<System>::type> { | |
61 | typedef int type; | |
62 | }; | |
63 | ||
64 | template<class System, class Enable=void> | |
65 | struct is_dimensionless_system : mpl::false_ {}; | |
66 | ||
67 | template<class System> | |
68 | struct is_dimensionless_system<System, typename void_if_dimensionless<System>::type> : mpl::true_ {}; | |
69 | ||
70 | #define BOOST_UNITS_DIMENSIONLESS_UNIT(T)\ | |
71 | boost::units::unit<\ | |
72 | boost::units::dimensionless_type,\ | |
73 | T,\ | |
74 | typename ::boost::units::detail::void_if_dimensionless<T>::type\ | |
75 | > | |
76 | ||
77 | #define BOOST_UNITS_HETEROGENEOUS_DIMENSIONLESS_UNIT(T)\ | |
78 | boost::units::unit<\ | |
79 | boost::units::dimensionless_type,\ | |
80 | T,\ | |
81 | typename ::boost::units::detail::void_if_heterogeneous<T>::type\ | |
82 | > | |
83 | ||
84 | } | |
85 | } | |
86 | } | |
87 | ||
88 | #endif |