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_HETEROGENEOUS_SYSTEM_HPP |
12 | #define BOOST_UNITS_HETEROGENEOUS_SYSTEM_HPP |
13 | |
14 | /// \file |
15 | /// \brief A heterogeneous system is a sorted list of base unit/exponent pairs. |
16 | |
17 | #include <boost/mpl/bool.hpp> |
18 | #include <boost/mpl/plus.hpp> |
19 | #include <boost/mpl/times.hpp> |
20 | #include <boost/mpl/divides.hpp> |
21 | #include <boost/mpl/negate.hpp> |
22 | #include <boost/mpl/less.hpp> |
23 | #include <boost/mpl/size.hpp> |
24 | #include <boost/mpl/begin.hpp> |
25 | #include <boost/mpl/next.hpp> |
26 | #include <boost/mpl/deref.hpp> |
27 | #include <boost/mpl/front.hpp> |
28 | #include <boost/mpl/push_front.hpp> |
29 | #include <boost/mpl/pop_front.hpp> |
30 | #include <boost/mpl/assert.hpp> |
31 | #include <boost/type_traits/is_same.hpp> |
32 | |
33 | #include <boost/units/config.hpp> |
34 | #include <boost/units/static_rational.hpp> |
35 | #include <boost/units/dimension.hpp> |
36 | #include <boost/units/units_fwd.hpp> |
37 | #include <boost/units/detail/push_front_if.hpp> |
38 | #include <boost/units/detail/push_front_or_add.hpp> |
39 | #include <boost/units/detail/linear_algebra.hpp> |
40 | #include <boost/units/detail/unscale.hpp> |
41 | |
42 | namespace boost { |
43 | |
44 | namespace units { |
45 | |
46 | namespace detail { |
47 | |
48 | // A normal system is a sorted list of base units. |
49 | // A heterogeneous system is a sorted list of base unit/exponent pairs. |
50 | // As long as we don't need to convert heterogeneous systems |
51 | // directly everything is cool. |
52 | |
53 | template<class T> |
54 | struct is_zero : mpl::false_ {}; |
55 | |
56 | template<> |
57 | struct is_zero<static_rational<0> > : mpl::true_ {}; |
58 | |
59 | } // namespace detail |
60 | |
61 | /// INTERNAL ONLY |
62 | template<class L, class Dimensions, class Scale> |
63 | struct heterogeneous_system_impl |
64 | { |
65 | typedef L type; |
66 | typedef Dimensions dimensions; |
67 | typedef Scale scale; |
68 | }; |
69 | |
70 | /// INTERNAL ONLY |
71 | typedef dimensionless_type no_scale; |
72 | |
73 | /// A system that can represent any possible combination |
74 | /// of units at the expense of not preserving information |
75 | /// about how it was created. Do not create specializations |
76 | /// of this template directly. Instead use @c reduce_unit and |
77 | /// @c base_unit<...>::unit_type. |
78 | template<class T> |
79 | struct heterogeneous_system : T {}; |
80 | |
81 | /// INTERNAL ONLY |
82 | struct heterogeneous_system_dim_tag {}; |
83 | |
84 | /// INTERNAL ONLY |
85 | template<class Unit, class Exponent> |
86 | struct heterogeneous_system_dim |
87 | { |
88 | typedef heterogeneous_system_dim_tag tag; |
89 | typedef heterogeneous_system_dim type; |
90 | typedef Unit tag_type; |
91 | typedef Exponent value_type; |
92 | }; |
93 | |
94 | /// INTERNAL ONLY |
95 | #define BOOST_UNITS_MAKE_HETEROGENEOUS_UNIT(BaseUnit, Dimensions) \ |
96 | boost::units::unit< \ |
97 | Dimensions, \ |
98 | boost::units::heterogeneous_system< \ |
99 | boost::units::heterogeneous_system_impl< \ |
100 | boost::units::list< \ |
101 | boost::units::heterogeneous_system_dim< \ |
102 | BaseUnit, \ |
103 | boost::units::static_rational<1> \ |
104 | >, \ |
105 | boost::units::dimensionless_type \ |
106 | >, \ |
107 | Dimensions, \ |
108 | boost::units::no_scale \ |
109 | > \ |
110 | > \ |
111 | > |
112 | |
113 | } // namespace units |
114 | |
115 | } // namespace boost |
116 | |
117 | |
118 | #if BOOST_UNITS_HAS_BOOST_TYPEOF |
119 | |
120 | #include BOOST_TYPEOF_INCREMENT_REGISTRATION_GROUP() |
121 | |
122 | BOOST_TYPEOF_REGISTER_TEMPLATE(boost::units::heterogeneous_system_impl, (class)(class)(class)) |
123 | BOOST_TYPEOF_REGISTER_TEMPLATE(boost::units::heterogeneous_system, (class)) |
124 | BOOST_TYPEOF_REGISTER_TEMPLATE(boost::units::heterogeneous_system_dim, (class)(class)) |
125 | |
126 | #endif |
127 | |
128 | namespace boost { |
129 | |
130 | namespace mpl { |
131 | |
132 | /// INTERNAL ONLY |
133 | template<> |
134 | struct less_impl<boost::units::heterogeneous_system_dim_tag, boost::units::heterogeneous_system_dim_tag> |
135 | { |
136 | template<class T0, class T1> |
137 | struct apply : mpl::less<typename T0::tag_type, typename T1::tag_type> {}; |
138 | }; |
139 | |
140 | } |
141 | |
142 | namespace units { |
143 | |
144 | namespace detail { |
145 | |
146 | template<class Unit1, class Exponent1> |
147 | struct is_empty_dim<heterogeneous_system_dim<Unit1,Exponent1> > : detail::is_zero<Exponent1> {}; |
148 | |
149 | } // namespace detail |
150 | |
151 | } // namespace units |
152 | |
153 | namespace mpl { |
154 | |
155 | /// INTERNAL ONLY |
156 | template<> |
157 | struct plus_impl<boost::units::heterogeneous_system_dim_tag, boost::units::heterogeneous_system_dim_tag> |
158 | { |
159 | template<class T0, class T1> |
160 | struct apply |
161 | { |
162 | typedef boost::units::heterogeneous_system_dim< |
163 | typename T0::tag_type, |
164 | typename mpl::plus<typename T0::value_type,typename T1::value_type>::type |
165 | > type; |
166 | }; |
167 | }; |
168 | |
169 | /// INTERNAL ONLY |
170 | template<> |
171 | struct times_impl<boost::units::heterogeneous_system_dim_tag, boost::units::detail::static_rational_tag> |
172 | { |
173 | template<class T0, class T1> |
174 | struct apply |
175 | { |
176 | typedef boost::units::heterogeneous_system_dim< |
177 | typename T0::tag_type, |
178 | typename mpl::times<typename T0::value_type,T1>::type |
179 | > type; |
180 | }; |
181 | }; |
182 | |
183 | /// INTERNAL ONLY |
184 | template<> |
185 | struct divides_impl<boost::units::heterogeneous_system_dim_tag, boost::units::detail::static_rational_tag> |
186 | { |
187 | template<class T0, class T1> |
188 | struct apply |
189 | { |
190 | typedef boost::units::heterogeneous_system_dim< |
191 | typename T0::tag_type, |
192 | typename mpl::divides<typename T0::value_type,T1>::type |
193 | > type; |
194 | }; |
195 | }; |
196 | |
197 | /// INTERNAL ONLY |
198 | template<> |
199 | struct negate_impl<boost::units::heterogeneous_system_dim_tag> |
200 | { |
201 | template<class T> |
202 | struct apply |
203 | { |
204 | typedef boost::units::heterogeneous_system_dim<typename T::tag_type, typename mpl::negate<typename T::value_type>::type> type; |
205 | }; |
206 | }; |
207 | |
208 | } // namespace mpl |
209 | |
210 | namespace units { |
211 | |
212 | namespace detail { |
213 | |
214 | template<int N> |
215 | struct make_heterogeneous_system_impl |
216 | { |
217 | template<class UnitsBegin, class ExponentsBegin> |
218 | struct apply |
219 | { |
220 | typedef typename push_front_if<!(is_zero<typename ExponentsBegin::item>::value)>::template apply< |
221 | typename make_heterogeneous_system_impl<N-1>::template apply< |
222 | typename UnitsBegin::next, |
223 | typename ExponentsBegin::next |
224 | >::type, |
225 | heterogeneous_system_dim<typename UnitsBegin::item, typename ExponentsBegin::item> |
226 | >::type type; |
227 | }; |
228 | }; |
229 | |
230 | template<> |
231 | struct make_heterogeneous_system_impl<0> |
232 | { |
233 | template<class UnitsBegin, class ExponentsBegin> |
234 | struct apply |
235 | { |
236 | typedef dimensionless_type type; |
237 | }; |
238 | }; |
239 | |
240 | template<class Dimensions, class System> |
241 | struct make_heterogeneous_system |
242 | { |
243 | typedef typename calculate_base_unit_exponents<typename System::type, Dimensions>::type exponents; |
244 | BOOST_MPL_ASSERT_MSG((!boost::is_same<exponents, inconsistent>::value), the_specified_dimension_is_not_representible_in_the_given_system, (types<Dimensions, System>)); |
245 | typedef typename make_heterogeneous_system_impl<System::type::size::value>::template apply< |
246 | typename System::type, |
247 | exponents |
248 | >::type unit_list; |
249 | typedef heterogeneous_system<heterogeneous_system_impl<unit_list, Dimensions, no_scale> > type; |
250 | }; |
251 | |
252 | template<class Dimensions, class T> |
253 | struct make_heterogeneous_system<Dimensions, heterogeneous_system<T> > |
254 | { |
255 | typedef heterogeneous_system<T> type; |
256 | }; |
257 | |
258 | template<class T0, class T1> |
259 | struct multiply_systems |
260 | { |
261 | typedef heterogeneous_system< |
262 | heterogeneous_system_impl< |
263 | typename mpl::times<typename T0::type, typename T1::type>::type, |
264 | typename mpl::times<typename T0::dimensions, typename T1::dimensions>::type, |
265 | typename mpl::times<typename T0::scale, typename T1::scale>::type |
266 | > |
267 | > type; |
268 | }; |
269 | |
270 | template<class T0, class T1> |
271 | struct divide_systems |
272 | { |
273 | typedef heterogeneous_system< |
274 | heterogeneous_system_impl< |
275 | typename mpl::divides<typename T0::type, typename T1::type>::type, |
276 | typename mpl::divides<typename T0::dimensions, typename T1::dimensions>::type, |
277 | typename mpl::divides<typename T0::scale, typename T1::scale>::type |
278 | > |
279 | > type; |
280 | }; |
281 | |
282 | } // namespace detail |
283 | |
284 | /// INTERNAL ONLY |
285 | template<class S, long N, long D> |
286 | struct static_power<heterogeneous_system<S>, static_rational<N,D> > |
287 | { |
288 | typedef heterogeneous_system< |
289 | heterogeneous_system_impl< |
290 | typename static_power<typename S::type, static_rational<N,D> >::type, |
291 | typename static_power<typename S::dimensions, static_rational<N,D> >::type, |
292 | typename static_power<typename S::scale, static_rational<N,D> >::type |
293 | > |
294 | > type; |
295 | }; |
296 | |
297 | /// INTERNAL ONLY |
298 | template<class S, long N, long D> |
299 | struct static_root<heterogeneous_system<S>, static_rational<N,D> > |
300 | { |
301 | typedef heterogeneous_system< |
302 | heterogeneous_system_impl< |
303 | typename static_root<typename S::type, static_rational<N,D> >::type, |
304 | typename static_root<typename S::dimensions, static_rational<N,D> >::type, |
305 | typename static_root<typename S::scale, static_rational<N,D> >::type |
306 | > |
307 | > type; |
308 | }; |
309 | |
310 | namespace detail { |
311 | |
312 | template<int N> |
313 | struct unscale_heterogeneous_system_impl |
314 | { |
315 | template<class Begin> |
316 | struct apply |
317 | { |
318 | typedef typename push_front_or_add< |
319 | typename unscale_heterogeneous_system_impl<N-1>::template apply< |
320 | typename Begin::next |
321 | >::type, |
322 | typename unscale<typename Begin::item>::type |
323 | >::type type; |
324 | }; |
325 | }; |
326 | |
327 | template<> |
328 | struct unscale_heterogeneous_system_impl<0> |
329 | { |
330 | template<class Begin> |
331 | struct apply |
332 | { |
333 | typedef dimensionless_type type; |
334 | }; |
335 | }; |
336 | |
337 | } // namespace detail |
338 | |
339 | /// Unscale all the base units. e.g |
340 | /// km s -> m s |
341 | /// cm km -> m^2 |
342 | /// INTERNAL ONLY |
343 | template<class T> |
344 | struct unscale<heterogeneous_system<T> > |
345 | { |
346 | typedef heterogeneous_system< |
347 | heterogeneous_system_impl< |
348 | typename detail::unscale_heterogeneous_system_impl< |
349 | T::type::size::value |
350 | >::template apply< |
351 | typename T::type |
352 | >::type, |
353 | typename T::dimensions, |
354 | no_scale |
355 | > |
356 | > type; |
357 | }; |
358 | |
359 | /// INTERNAL ONLY |
360 | template<class Unit, class Exponent> |
361 | struct unscale<heterogeneous_system_dim<Unit, Exponent> > |
362 | { |
363 | typedef heterogeneous_system_dim<typename unscale<Unit>::type, Exponent> type; |
364 | }; |
365 | |
366 | namespace detail { |
367 | |
368 | template<int N> |
369 | struct get_scale_list_of_heterogeneous_system_impl |
370 | { |
371 | template<class Begin> |
372 | struct apply |
373 | { |
374 | typedef typename mpl::times< |
375 | typename get_scale_list_of_heterogeneous_system_impl<N-1>::template apply< |
376 | typename Begin::next |
377 | >::type, |
378 | typename get_scale_list<typename Begin::item>::type |
379 | >::type type; |
380 | }; |
381 | }; |
382 | |
383 | template<> |
384 | struct get_scale_list_of_heterogeneous_system_impl<0> |
385 | { |
386 | template<class Begin> |
387 | struct apply |
388 | { |
389 | typedef dimensionless_type type; |
390 | }; |
391 | }; |
392 | |
393 | } // namespace detail |
394 | |
395 | /// INTERNAL ONLY |
396 | template<class T> |
397 | struct get_scale_list<heterogeneous_system<T> > |
398 | { |
399 | typedef typename mpl::times< |
400 | typename detail::get_scale_list_of_heterogeneous_system_impl< |
401 | T::type::size::value |
402 | >::template apply<typename T::type>::type, |
403 | typename T::scale |
404 | >::type type; |
405 | }; |
406 | |
407 | /// INTERNAL ONLY |
408 | template<class Unit, class Exponent> |
409 | struct get_scale_list<heterogeneous_system_dim<Unit, Exponent> > |
410 | { |
411 | typedef typename static_power<typename get_scale_list<Unit>::type, Exponent>::type type; |
412 | }; |
413 | |
414 | namespace detail { |
415 | |
416 | template<class System, class Dimension> |
417 | struct check_system : mpl::false_ {}; |
418 | |
419 | template<class System, class Dimension, class Scale> |
420 | struct check_system<heterogeneous_system<heterogeneous_system_impl<System, Dimension, Scale> >, Dimension> : mpl::true_ {}; |
421 | |
422 | } // namespace detail |
423 | |
424 | } // namespace units |
425 | |
426 | } // namespace boost |
427 | |
428 | #endif |
429 | |