ceph/src/boost/boost/units/dimension.hpp

   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_DIMENSION_HPP
  12 #define BOOST_UNITS_DIMENSION_HPP
  13
  14 #include <boost/static_assert.hpp>
  15
  16 #include <boost/type_traits/is_same.hpp>
  17
  18 #include <boost/mpl/arithmetic.hpp>
  19
  20 #include <boost/units/static_rational.hpp>
  21 #include <boost/units/detail/dimension_list.hpp>
  22 #include <boost/units/detail/dimension_impl.hpp>
  23
  24 /// \file
  25 /// \brief Core metaprogramming utilities for compile-time dimensional analysis.
  26
  27 namespace boost {
  28
  29 namespace units {
  30
  31 /// Reduce dimension list to cardinal form. This algorithm collapses duplicate
  32 /// base dimension tags and sorts the resulting list by the tag ordinal value.
  33 /// Dimension lists that resolve to the same dimension are guaranteed to be
  34 /// represented by an identical type.
  35 ///
  36 /// The argument should be an MPL forward sequence containing instances
  37 /// of the @c dim template.
  38 ///
  39 /// The result is also an MPL forward sequence.  It also supports the
  40 /// following metafunctions to allow use as a dimension.
  41 ///
  42 ///    - @c mpl::plus is defined only on two equal dimensions and returns the argument unchanged.
  43 ///    - @c mpl::minus is defined only for two equal dimensions and returns the argument unchanged.
  44 ///    - @c mpl::negate will return its argument unchanged.
  45 ///    - @c mpl::times is defined for any dimensions and adds corresponding exponents.
  46 ///    - @c mpl::divides is defined for any dimensions and subtracts the exponents of the
  47 ///         right had argument from the corresponding exponents of the left had argument.
  48 ///         Missing base dimension tags are assumed to have an exponent of zero.
  49 ///    - @c static_power takes a dimension and a static_rational and multiplies all
  50 ///         the exponents of the dimension by the static_rational.
  51 ///    - @c static_root takes a dimension and a static_rational and divides all
  52 ///         the exponents of the dimension by the static_rational.
  53 template<typename Seq>
  54 struct make_dimension_list
  55 {
  56     typedef typename detail::sort_dims<Seq>::type type;
  57 };
  58
  59 /// Raise a dimension list to a scalar power.
  60 template<typename DL,typename Ex>
  61 struct static_power
  62 {
  63     typedef typename detail::static_power_impl<DL::size::value>::template apply<
  64         DL,
  65         Ex
  66     >::type type;
  67 };
  68
  69 /// Take a scalar root of a dimension list.
  70 template<typename DL,typename Rt>
  71 struct static_root
  72 {
  73     typedef typename detail::static_root_impl<DL::size::value>::template apply<
  74         DL,
  75         Rt
  76     >::type type;
  77 };
  78
  79 } // namespace units
  80
  81 #ifndef BOOST_UNITS_DOXYGEN
  82
  83 namespace mpl {
  84
  85 template<>
  86 struct plus_impl<boost::units::detail::dimension_list_tag,boost::units::detail::dimension_list_tag>
  87 {
  88     template<class T0, class T1>
  89     struct apply
  90     {
  91         BOOST_STATIC_ASSERT((boost::is_same<T0,T1>::value == true));
  92         typedef T0 type;
  93     };
  94 };
  95
  96 template<>
  97 struct minus_impl<boost::units::detail::dimension_list_tag,boost::units::detail::dimension_list_tag>
  98 {
  99     template<class T0, class T1>
 100     struct apply
 101     {
 102         BOOST_STATIC_ASSERT((boost::is_same<T0,T1>::value == true));
 103         typedef T0 type;
 104     };
 105 };
 106
 107 template<>
 108 struct times_impl<boost::units::detail::dimension_list_tag,boost::units::detail::dimension_list_tag>
 109 {
 110     template<class T0, class T1>
 111     struct apply
 112     {
 113         typedef typename boost::units::detail::merge_dimensions<T0,T1>::type type;
 114     };
 115 };
 116
 117 template<>
 118 struct divides_impl<boost::units::detail::dimension_list_tag,boost::units::detail::dimension_list_tag>
 119 {
 120     template<class T0, class T1>
 121     struct apply
 122     {
 123         typedef typename boost::units::detail::merge_dimensions<
 124             T0,
 125             typename boost::units::detail::static_inverse_impl<
 126                 T1::size::value
 127             >::template apply<
 128                 T1
 129             >::type
 130         >::type type;
 131     };
 132 };
 133
 134 template<>
 135 struct negate_impl<boost::units::detail::dimension_list_tag>
 136 {
 137     template<class T0>
 138     struct apply
 139     {
 140         typedef T0 type;
 141     };
 142 };
 143
 144 } // namespace mpl
 145
 146 #endif
 147
 148 } // namespace boost
 149
 150 #endif // BOOST_UNITS_DIMENSION_HPP