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107 lines
3.6 KiB
107 lines
3.6 KiB
// Boost.Units - A C++ library for zero-overhead dimensional analysis and |
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// unit/quantity manipulation and conversion |
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// |
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// Copyright (C) 2003-2008 Matthias Christian Schabel |
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// Copyright (C) 2007-2008 Steven Watanabe |
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// |
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// Distributed under the Boost Software License, Version 1.0. (See |
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// accompanying file LICENSE_1_0.txt or copy at |
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// http://www.boost.org/LICENSE_1_0.txt) |
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/// \file |
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/// \brief base dimensions (mass, length, time...). |
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/// \details base dimension definition registration. |
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#ifndef BOOST_UNITS_BASE_DIMENSION_HPP |
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#define BOOST_UNITS_BASE_DIMENSION_HPP |
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#include <boost/units/config.hpp> |
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#include <boost/units/dim.hpp> |
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#include <boost/units/static_rational.hpp> |
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#include <boost/units/units_fwd.hpp> |
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#include <boost/units/detail/dimension_list.hpp> |
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#include <boost/units/detail/ordinal.hpp> |
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#include <boost/units/detail/prevent_redefinition.hpp> |
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namespace boost { |
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namespace units { |
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/// This must be in namespace boost::units so that ADL |
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/// will work with friend functions defined inline. |
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/// INTERNAL ONLY |
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template<long N> struct base_dimension_ordinal { }; |
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/// INTERNAL ONLY |
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template<class T, long N> struct base_dimension_pair { }; |
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/// INTERNAL ONLY |
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template<class T, long N> |
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struct check_base_dimension { |
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enum { |
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value = |
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sizeof(boost_units_is_registered(units::base_dimension_ordinal<N>())) == sizeof(detail::yes) && |
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sizeof(boost_units_is_registered(units::base_dimension_pair<T, N>())) != sizeof(detail::yes) |
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}; |
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}; |
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/// Defines a base dimension. To define a dimension you need to provide |
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/// the derived class (CRTP) and a unique integer. |
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/// @code |
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/// struct my_dimension : boost::units::base_dimension<my_dimension, 1> {}; |
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/// @endcode |
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/// It is designed so that you will get an error message if you try |
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/// to use the same value in multiple definitions. |
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template<class Derived, |
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long N |
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#if !defined(BOOST_UNITS_DOXYGEN) && !defined(__BORLANDC__) |
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, |
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class = typename detail::ordinal_has_already_been_defined< |
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check_base_dimension<Derived, N>::value |
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>::type |
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#endif |
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> |
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class base_dimension : |
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public ordinal<N> |
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{ |
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public: |
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/// INTERNAL ONLY |
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typedef base_dimension this_type; |
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/// A convenience typedef. Equivalent to boost::units::derived_dimension<Derived,1>::type. |
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#ifndef BOOST_UNITS_DOXYGEN |
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typedef list<dim<Derived,static_rational<1> >, dimensionless_type> dimension_type; |
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#else |
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typedef detail::unspecified dimension_type; |
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#endif |
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/// Provided for mpl compatability. |
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typedef Derived type; |
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private: |
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/// Check for C++0x. In C++0x, we have to have identical |
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/// arguments but a different return type to trigger an |
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/// error. Note that this is only needed for clang as |
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/// check_base_dimension will trigger an error earlier |
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/// for compilers with less strict name lookup. |
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/// INTERNAL ONLY |
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friend BOOST_CONSTEXPR Derived* |
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check_double_register(const units::base_dimension_ordinal<N>&) |
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{ return(0); } |
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/// Register this ordinal |
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/// INTERNAL ONLY |
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friend BOOST_CONSTEXPR detail::yes |
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boost_units_is_registered(const units::base_dimension_ordinal<N>&) |
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{ return(detail::yes()); } |
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/// But make sure we can identify the current instantiation! |
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/// INTERNAL ONLY |
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friend BOOST_CONSTEXPR detail::yes |
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boost_units_is_registered(const units::base_dimension_pair<Derived, N>&) |
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{ return(detail::yes()); } |
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}; |
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} // namespace units |
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} // namespace boost |
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#endif // BOOST_UNITS_BASE_DIMENSION_HPP
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