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 ///
12 /// \file
13 /// \brief Absolute units (points rather than vectors).
14 /// \details Operations between absolute units, and relative units like temperature differences.
15 ///
16
17 #ifndef BOOST_UNITS_ABSOLUTE_HPP
18 #define BOOST_UNITS_ABSOLUTE_HPP
19
20 #include <iosfwd>
21
22 #include <boost/units/detail/absolute_impl.hpp>
23
24 namespace boost {
25
26 namespace units {
27
28 /// A wrapper to represent absolute units (points rather than vectors). Intended
29 /// originally for temperatures, this class implements operators for absolute units
30 /// so that addition of a relative unit to an absolute unit results in another
31 /// absolute unit : absolute<T> +/- T -> absolute<T> and subtraction of one absolute
32 /// unit from another results in a relative unit : absolute<T> - absolute<T> -> T.
33 template<class Y>
34 class absolute
35 {
36 public:
37 typedef absolute<Y> this_type;
38 typedef Y value_type;
39
absolute()40 BOOST_CONSTEXPR absolute() : val_() { }
absolute(const value_type & val)41 BOOST_CONSTEXPR absolute(const value_type& val) : val_(val) { }
absolute(const this_type & source)42 BOOST_CONSTEXPR absolute(const this_type& source) : val_(source.val_) { }
43
operator =(const this_type & source)44 BOOST_CXX14_CONSTEXPR this_type& operator=(const this_type& source) { val_ = source.val_; return *this; }
45
value() const46 BOOST_CONSTEXPR const value_type& value() const { return val_; }
47
operator +=(const value_type & val)48 BOOST_CXX14_CONSTEXPR const this_type& operator+=(const value_type& val) { val_ += val; return *this; }
operator -=(const value_type & val)49 BOOST_CXX14_CONSTEXPR const this_type& operator-=(const value_type& val) { val_ -= val; return *this; }
50
51 private:
52 value_type val_;
53 };
54
55 /// add a relative value to an absolute one
56 template<class Y>
operator +(const absolute<Y> & aval,const Y & rval)57 BOOST_CONSTEXPR absolute<Y> operator+(const absolute<Y>& aval,const Y& rval)
58 {
59 return absolute<Y>(aval.value()+rval);
60 }
61
62 /// add a relative value to an absolute one
63 template<class Y>
operator +(const Y & rval,const absolute<Y> & aval)64 BOOST_CONSTEXPR absolute<Y> operator+(const Y& rval,const absolute<Y>& aval)
65 {
66 return absolute<Y>(aval.value()+rval);
67 }
68
69 /// subtract a relative value from an absolute one
70 template<class Y>
operator -(const absolute<Y> & aval,const Y & rval)71 BOOST_CONSTEXPR absolute<Y> operator-(const absolute<Y>& aval,const Y& rval)
72 {
73 return absolute<Y>(aval.value()-rval);
74 }
75
76 /// subtracting two absolutes gives a difference
77 template<class Y>
operator -(const absolute<Y> & aval1,const absolute<Y> & aval2)78 BOOST_CONSTEXPR Y operator-(const absolute<Y>& aval1,const absolute<Y>& aval2)
79 {
80 return Y(aval1.value()-aval2.value());
81 }
82
83 /// creates a quantity from an absolute unit and a raw value
84 template<class D, class S, class T>
operator *(const T & t,const absolute<unit<D,S>> &)85 BOOST_CONSTEXPR quantity<absolute<unit<D, S> >, T> operator*(const T& t, const absolute<unit<D, S> >&)
86 {
87 return(quantity<absolute<unit<D, S> >, T>::from_value(t));
88 }
89
90 /// creates a quantity from an absolute unit and a raw value
91 template<class D, class S, class T>
operator *(const absolute<unit<D,S>> &,const T & t)92 BOOST_CONSTEXPR quantity<absolute<unit<D, S> >, T> operator*(const absolute<unit<D, S> >&, const T& t)
93 {
94 return(quantity<absolute<unit<D, S> >, T>::from_value(t));
95 }
96
97 /// Print an absolute unit
98 template<class Char, class Traits, class Y>
operator <<(std::basic_ostream<Char,Traits> & os,const absolute<Y> & aval)99 std::basic_ostream<Char, Traits>& operator<<(std::basic_ostream<Char, Traits>& os,const absolute<Y>& aval)
100 {
101
102 os << "absolute " << aval.value();
103
104 return os;
105 }
106
107 } // namespace units
108
109 } // namespace boost
110
111 #if BOOST_UNITS_HAS_BOOST_TYPEOF
112
113 #include BOOST_TYPEOF_INCREMENT_REGISTRATION_GROUP()
114
115 BOOST_TYPEOF_REGISTER_TEMPLATE(boost::units::absolute, (class))
116
117 #endif
118
119 namespace boost {
120
121 namespace units {
122
123 /// Macro to define the offset between two absolute units.
124 /// Requires the value to be in the destination units e.g
125 /// @code
126 /// BOOST_UNITS_DEFINE_CONVERSION_OFFSET(celsius_base_unit, fahrenheit_base_unit, double, 32.0);
127 /// @endcode
128 /// @c BOOST_UNITS_DEFINE_CONVERSION_FACTOR is also necessary to
129 /// specify the conversion factor. Like @c BOOST_UNITS_DEFINE_CONVERSION_FACTOR
130 /// this macro defines both forward and reverse conversions so
131 /// defining, e.g., the conversion from celsius to fahrenheit as above will also
132 /// define the inverse conversion from fahrenheit to celsius.
133 #define BOOST_UNITS_DEFINE_CONVERSION_OFFSET(From, To, type_, value_) \
134 namespace boost { \
135 namespace units { \
136 template<> \
137 struct affine_conversion_helper< \
138 reduce_unit<From::unit_type>::type, \
139 reduce_unit<To::unit_type>::type> \
140 { \
141 BOOST_STATIC_CONSTEXPR bool is_defined = true; \
142 typedef type_ type; \
143 static BOOST_CONSTEXPR type value() { return(value_); } \
144 }; \
145 } \
146 } \
147 void boost_units_require_semicolon()
148
149 } // namespace units
150
151 } // namespace boost
152
153 #endif // BOOST_UNITS_ABSOLUTE_HPP
154