units/detail/sort.hpp

0001 // Boost.Units - A C++ library for zero-overhead dimensional analysis and
0002 // unit/quantity manipulation and conversion
0003 //
0004 // Copyright (C) 2003-2008 Matthias Christian Schabel
0005 // Copyright (C) 2008 Steven Watanabe
0006 //
0007 // Distributed under the Boost Software License, Version 1.0. (See
0008 // accompanying file LICENSE_1_0.txt or copy at
0009 // http://www.boost.org/LICENSE_1_0.txt)
0010
0011 #ifndef BOOST_UNITS_DETAIL_SORT_HPP
0012 #define BOOST_UNITS_DETAIL_SORT_HPP
0013
0014 #include <boost/mpl/size.hpp>
0015 #include <boost/mpl/begin.hpp>
0016 #include <boost/mpl/next.hpp>
0017 #include <boost/mpl/deref.hpp>
0018 #include <boost/mpl/push_front.hpp>
0019 #include <boost/mpl/less.hpp>
0020
0021 #include <boost/units/dimensionless_type.hpp>
0022 #include <boost/units/detail/dimension_list.hpp>
0023
0024 namespace boost {
0025
0026 namespace units {
0027
0028 namespace detail {
0029
0030 template<int N>
0031 struct insertion_sort_insert;
0032
0033 template<bool is_greater>
0034 struct insertion_sort_comparison_impl;
0035
0036 // have to recursively add the element to the next sequence.
0037 template<>
0038 struct insertion_sort_comparison_impl<true> {
0039     template<class Begin, int N, class T>
0040     struct apply {
0041         typedef list<
0042             typename Begin::item,
0043             typename insertion_sort_insert<N - 1>::template apply<
0044                 typename Begin::next,
0045                 T
0046             >::type
0047         > type;
0048     };
0049 };
0050
0051 // prepend the current element
0052 template<>
0053 struct insertion_sort_comparison_impl<false> {
0054     template<class Begin, int N, class T>
0055     struct apply {
0056         typedef list<T, Begin> type;
0057     };
0058 };
0059
0060 template<int N>
0061 struct insertion_sort_insert {
0062     template<class Begin, class T>
0063     struct apply {
0064         typedef typename insertion_sort_comparison_impl<mpl::less<typename Begin::item, T>::value>::template apply<
0065             Begin,
0066             N,
0067             T
0068         >::type type;
0069     };
0070 };
0071
0072 template<>
0073 struct insertion_sort_insert<0> {
0074     template<class Begin, class T>
0075     struct apply {
0076         typedef list<T, dimensionless_type> type;
0077     };
0078 };
0079
0080 template<int N>
0081 struct insertion_sort_impl {
0082     template<class Begin>
0083     struct apply {
0084         typedef typename insertion_sort_impl<N - 1>::template apply<typename Begin::next>::type next;
0085         typedef typename insertion_sort_insert<(next::size::value)>::template apply<next, typename Begin::item>::type type;
0086     };
0087 };
0088
0089 template<>
0090 struct insertion_sort_impl<0> {
0091     template<class Begin>
0092     struct apply {
0093         typedef dimensionless_type type;
0094     };
0095 };
0096
0097 template<class T>
0098 struct insertion_sort
0099 {
0100     typedef typename insertion_sort_impl<T::size::value>::template apply<T>::type type;
0101 };
0102
0103 } // namespace detail
0104
0105 } // namespace units
0106
0107 } // namespace boost
0108
0109 #endif