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#include <boost/core/lightweight_test.hpp>
12
13#include <boost/units/base_dimension.hpp>
14#include <boost/units/base_unit.hpp>
15#include <boost/units/make_system.hpp>
16#include <boost/units/scaled_base_unit.hpp>
17#include <boost/units/conversion.hpp>
18#include <boost/units/unit.hpp>
19
20struct dimension1_tag : boost::units::base_dimension<dimension1_tag, 1> {};
21struct dimension2_tag : boost::units::base_dimension<dimension2_tag, 2> {};
22
23typedef dimension1_tag::dimension_type dimension1;
24typedef dimension2_tag::dimension_type dimension2;
25typedef boost::mpl::times<dimension1, dimension2>::type dimension12;
26
27struct unit1_tag : boost::units::base_unit<unit1_tag, dimension1, 1> {};
28struct unit2_tag : boost::units::base_unit<unit2_tag, dimension1, 2> {};
29struct unit3_tag : boost::units::base_unit<unit3_tag, dimension1, 3> {};
30struct unit4_tag : boost::units::base_unit<unit4_tag, dimension2, 4> {};
31struct unit5_tag : boost::units::base_unit<unit5_tag, dimension12, 5> {};
32struct unit6_tag : boost::units::base_unit<unit6_tag, dimension1, 6> {};
33struct unit7_tag : boost::units::base_unit<unit7_tag, dimension1, 7> {};
34
35BOOST_UNITS_DEFINE_CONVERSION_FACTOR(unit1_tag, unit2_tag, double, 2.0);
36BOOST_UNITS_DEFINE_CONVERSION_FACTOR(unit2_tag, unit3_tag, double, 3.0);
37BOOST_UNITS_DEFINE_CONVERSION_FACTOR(unit6_tag, unit3_tag, double, 5.0);
38BOOST_UNITS_DEFINE_CONVERSION_FACTOR(unit7_tag, unit1_tag, double, 7.0);
39
40typedef boost::units::multiply_typeof_helper<unit3_tag::unit_type, unit4_tag::unit_type>::type unit34_type;
41BOOST_UNITS_DEFINE_CONVERSION_FACTOR(unit5_tag, unit34_type , double, 5.0);
42
43template<class BaseUnit>
44struct make_unit {
45 typedef boost::units::unit<
46 typename BaseUnit::dimension_type,
47 typename boost::units::make_system<BaseUnit>::type> type;
48};
49
50BOOST_UNITS_DEFAULT_CONVERSION(unit1_tag, unit2_tag);
51BOOST_UNITS_DEFAULT_CONVERSION(unit3_tag, unit2_tag);
52BOOST_UNITS_DEFAULT_CONVERSION(unit5_tag, unit34_type);
53BOOST_UNITS_DEFAULT_CONVERSION(unit6_tag, make_unit<unit3_tag>::type);
54BOOST_UNITS_DEFAULT_CONVERSION(unit7_tag, make_unit<unit1_tag>::type);
55
56int main() {
57 BOOST_CONSTEXPR_OR_CONST double value1 = boost::units::conversion_factor(unit3_tag::unit_type(), unit1_tag::unit_type());
58 BOOST_TEST(std::abs(value1 - 1.0/6.0) < .0000000001);
59 BOOST_CONSTEXPR_OR_CONST double value2 = boost::units::conversion_factor(unit5_tag::unit_type() / unit4_tag::unit_type(), unit1_tag::unit_type());
60 BOOST_TEST(std::abs(value2 - 5.0/6.0) < .0000000001);
61 typedef boost::units::scaled_base_unit<unit5_tag, boost::units::scale<2, boost::units::static_rational<1> > > scaled_unit5_tag;
62 BOOST_CONSTEXPR_OR_CONST double value3 = boost::units::conversion_factor(scaled_unit5_tag::unit_type() / unit4_tag::unit_type(), unit1_tag::unit_type());
63 BOOST_TEST(std::abs(value3 - 10.0/6.0) < .0000000001);
64
65 // check homogeneous unit conversions
66 BOOST_CONSTEXPR_OR_CONST double value4 = boost::units::conversion_factor(make_unit<unit3_tag>::type(), make_unit<unit1_tag>::type());
67 BOOST_TEST(std::abs(value4 - 1.0/6.0) < .0000000001);
68 BOOST_CONSTEXPR_OR_CONST double value5 = boost::units::conversion_factor(unit3_tag::unit_type(), make_unit<unit1_tag>::type());
69 BOOST_TEST(std::abs(value5 - 1.0/6.0) < .0000000001);
70 BOOST_CONSTEXPR_OR_CONST double value6 = boost::units::conversion_factor(make_unit<unit3_tag>::type(), unit1_tag::unit_type());
71 BOOST_TEST(std::abs(value6 - 1.0/6.0) < .0000000001);
72
73 // check chained homogeneous conversions
74 BOOST_CONSTEXPR_OR_CONST double value7 = boost::units::conversion_factor(unit6_tag::unit_type(), unit7_tag::unit_type());
75 BOOST_TEST(std::abs(value7 - 5.0/42.0) < .0000000001);
76
77 return boost::report_errors();
78}
79

source code of boost/libs/units/test/test_default_conversion.cpp