Chris@16: // Boost.Units - A C++ library for zero-overhead dimensional analysis and 
Chris@16: // unit/quantity manipulation and conversion
Chris@16: //
Chris@16: // Copyright (C) 2003-2008 Matthias Christian Schabel
Chris@16: // Copyright (C) 2008 Steven Watanabe
Chris@16: //
Chris@16: // Distributed under the Boost Software License, Version 1.0. (See
Chris@16: // accompanying file LICENSE_1_0.txt or copy at
Chris@16: // http://www.boost.org/LICENSE_1_0.txt)
Chris@16: 
Chris@16: #ifndef BOOST_UNITS_DIM_IMPL_HPP
Chris@16: #define BOOST_UNITS_DIM_IMPL_HPP
Chris@16: 
Chris@16: #include <boost/mpl/bool.hpp>
Chris@16: #include <boost/mpl/less.hpp>
Chris@16: 
Chris@16: #include <boost/units/units_fwd.hpp>
Chris@16: 
Chris@16: /// \file 
Chris@16: /// \brief Class encapsulating a dimension tag/value pair
Chris@16: 
Chris@16: namespace boost {
Chris@16: 
Chris@16: namespace units {
Chris@16: 
Chris@16: namespace detail {
Chris@16: 
Chris@16: struct dim_tag;
Chris@16: 
Chris@16: }
Chris@16: 
Chris@16: }
Chris@16: 
Chris@16: namespace mpl {
Chris@16: 
Chris@16: /// Less than comparison for sorting @c dim.
Chris@16: template<>
Chris@16: struct less_impl<boost::units::detail::dim_tag, boost::units::detail::dim_tag>
Chris@16: {
Chris@16:     template<class T0, class T1>
Chris@16:     struct apply : mpl::less<typename T0::tag_type, typename T1::tag_type> {};
Chris@16: };
Chris@16: 
Chris@16: }
Chris@16: 
Chris@16: namespace units {
Chris@16: 
Chris@16: template<class Tag, class Exponent>
Chris@16: struct dim;
Chris@16: 
Chris@16: template<long N, long D>
Chris@16: class static_rational;
Chris@16: 
Chris@16: namespace detail {
Chris@16: 
Chris@16: /// Extract @c tag_type from a @c dim.
Chris@16: template<typename T>
Chris@16: struct get_tag
Chris@16: {
Chris@16:     typedef typename T::tag_type    type;
Chris@16: };
Chris@16: 
Chris@16: /// Extract @c value_type from a @c dim.
Chris@16: template<typename T>
Chris@16: struct get_value
Chris@16: {
Chris@16:     typedef typename T::value_type    type;
Chris@16: };
Chris@16: 
Chris@16: /// Determine if a @c dim is empty (has a zero exponent).
Chris@16: template<class T>
Chris@16: struct is_empty_dim;
Chris@16: 
Chris@16: template<typename T>
Chris@16: struct is_empty_dim< dim<T, static_rational<0, 1> > > :
Chris@16:     mpl::true_ 
Chris@16: { };
Chris@16: 
Chris@16: template<typename T, typename V>
Chris@16: struct is_empty_dim< dim<T, V> > :
Chris@16:     mpl::false_ 
Chris@16: { };
Chris@16: 
Chris@16: } // namespace detail
Chris@16: 
Chris@16: } // namespace units
Chris@16: 
Chris@16: } // namespace boost
Chris@16: 
Chris@16: #endif // BOOST_UNITS_DIM_IMPL_HPP