boost/units/detail/heterogeneous_conversion.hpp
// Boost.Units - A C++ library for zero-overhead dimensional analysis and
// unit/quantity manipulation and conversion
//
// Copyright (C) 2003-2008 Matthias Christian Schabel
// Copyright (C) 2008 Steven Watanabe
//
// Distributed under the Boost Software License, Version 1.0. (See
// accompanying file LICENSE_1_0.txt or copy at
// http://www.boost.org/LICENSE_1_0.txt)
#ifndef BOOST_UNITS_DETAIL_HETEROGENEOUS_CONVERSION_HPP
#define BOOST_UNITS_DETAIL_HETEROGENEOUS_CONVERSION_HPP
#include <boost/mpl/minus.hpp>
#include <boost/mpl/times.hpp>
#include <boost/units/static_rational.hpp>
#include <boost/units/homogeneous_system.hpp>
#include <boost/units/detail/linear_algebra.hpp>
namespace boost {
namespace units {
namespace detail {
struct solve_end {
template<class Begin, class Y>
struct apply {
typedef dimensionless_type type;
};
};
struct no_solution {};
template<class X1, class X2, class Next>
struct solve_normal {
template<class Begin, class Y>
struct apply {
typedef typename Begin::next next;
typedef list<
typename mpl::minus<
typename mpl::times<X1, Y>::type,
typename mpl::times<X2, typename Begin::item>::type
>::type,
typename Next::template apply<next, Y>::type
> type;
};
};
template<class Next>
struct solve_leading_zeroes {
template<class Begin>
struct apply {
typedef list<
typename Begin::item,
typename Next::template apply<typename Begin::next>::type
> type;
};
typedef solve_leading_zeroes type;
};
template<>
struct solve_leading_zeroes<no_solution> {
typedef no_solution type;
};
template<class Next>
struct solve_first_non_zero {
template<class Begin>
struct apply {
typedef typename Next::template apply<
typename Begin::next,
typename Begin::item
>::type type;
};
};
template<class Next>
struct solve_internal_zero {
template<class Begin, class Y>
struct apply {
typedef list<
typename Begin::item,
typename Next::template apply<typename Begin::next, Y>::type
> type;
};
};
template<class T>
struct make_solve_list_internal_zero {
template<class Next, class X>
struct apply {
typedef solve_normal<T, X, Next> type;
};
};
template<>
struct make_solve_list_internal_zero<static_rational<0> > {
template<class Next, class X>
struct apply {
typedef solve_internal_zero<Next> type;
};
};
template<int N>
struct make_solve_list_normal {
template<class Begin, class X>
struct apply {
typedef typename make_solve_list_internal_zero<
typename Begin::item
>::template apply<
typename make_solve_list_normal<N-1>::template apply<typename Begin::next, X>::type,
X
>::type type;
};
};
template<>
struct make_solve_list_normal<0> {
template<class Begin, class X>
struct apply {
typedef solve_end type;
};
};
template<int N>
struct make_solve_list_leading_zeroes;
template<class T>
struct make_solve_list_first_non_zero {
template<class Begin, int N>
struct apply {
typedef solve_first_non_zero<
typename make_solve_list_normal<N-1>::template apply<
typename Begin::next,
typename Begin::item
>::type
> type;
};
};
template<>
struct make_solve_list_first_non_zero<static_rational<0> > {
template<class Begin, int N>
struct apply {
typedef typename solve_leading_zeroes<
typename make_solve_list_leading_zeroes<N-1>::template apply<
typename Begin::next
>::type
>::type type;
};
};
template<int N>
struct make_solve_list_leading_zeroes {
template<class Begin>
struct apply {
typedef typename make_solve_list_first_non_zero<typename Begin::item>::template apply<Begin, N>::type type;
};
};
template<>
struct make_solve_list_leading_zeroes<0> {
template<class Begin>
struct apply {
typedef no_solution type;
};
};
template<int N>
struct try_add_unit_impl {
template<class Begin, class L>
struct apply {
typedef typename try_add_unit_impl<N-1>::template apply<typename Begin::next, L>::type next;
typedef typename Begin::item::template apply<next>::type type;
BOOST_STATIC_ASSERT((next::size::value - 1 == type::size::value));
};
};
template<>
struct try_add_unit_impl<0> {
template<class Begin, class L>
struct apply {
typedef L type;
};
};
template<int N>
struct make_homogeneous_system_impl;
template<class T, bool is_done>
struct make_homogeneous_system_func;
template<class T>
struct make_homogeneous_system_func<T, false> {
template<class Begin, class Current, class Units, class Dimensions, int N>
struct apply {
typedef typename make_homogeneous_system_impl<N-1>::template apply<
typename Begin::next,
list<T, Current>,
list<typename Begin::item, Units>,
Dimensions
>::type type;
};
};
template<class T>
struct make_homogeneous_system_func<T, true> {
template<class Begin, class Current, class Units, class Dimensions, int N>
struct apply {
typedef list<typename Begin::item, Units> type;
};
};
template<>
struct make_homogeneous_system_func<no_solution, false> {
template<class Begin, class Current, class Units, class Dimensions, int N>
struct apply {
typedef typename make_homogeneous_system_impl<N-1>::template apply<
typename Begin::next,
Current,
Units,
Dimensions
>::type type;
};
};
template<>
struct make_homogeneous_system_func<no_solution, true> {
template<class Begin, class Current, class Units, class Dimensions, int N>
struct apply {
typedef typename make_homogeneous_system_impl<N-1>::template apply<
typename Begin::next,
Current,
Units,
Dimensions
>::type type;
};
};
template<int N>
struct make_homogeneous_system_impl {
template<class Begin, class Current, class Units, class Dimensions>
struct apply {
typedef typename expand_dimensions<Dimensions::size::value>::template apply<
Dimensions,
typename Begin::item::dimension_type
>::type dimensions;
typedef typename try_add_unit_impl<Current::size::value>::template apply<Current, dimensions>::type new_element;
typedef typename make_solve_list_leading_zeroes<new_element::size::value>::template apply<new_element>::type new_func;
typedef typename make_homogeneous_system_func<
new_func,
((Current::size::value)+1) == (Dimensions::size::value)
>::template apply<Begin, Current, Units, Dimensions, N>::type type;
};
};
template<>
struct make_homogeneous_system_impl<0> {
template<class Begin, class Current, class Units, class Dimensions>
struct apply {
typedef Units type;
};
};
template<class Units>
struct make_homogeneous_system {
typedef typename find_base_dimensions<Units>::type base_dimensions;
typedef homogeneous_system<
typename insertion_sort<
typename make_homogeneous_system_impl<
Units::size::value
>::template apply<
Units,
dimensionless_type,
dimensionless_type,
base_dimensions
>::type
>::type
> type;
};
template<int N>
struct extract_base_units {
template<class Begin, class T>
struct apply {
typedef list<
typename Begin::item::tag_type,
typename extract_base_units<N-1>::template apply<typename Begin::next, T>::type
> type;
};
};
template<>
struct extract_base_units<0> {
template<class Begin, class T>
struct apply {
typedef T type;
};
};
}
}
}
#endif