3rdparty/boost/boost/fusion/support/detail/segmented_fold_until_impl.hpp

   1 /*=============================================================================
   2     Copyright (c) 2011 Eric Niebler
   3
   4     Distributed under the Boost Software License, Version 1.0. (See accompanying
   5     file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
   6 ==============================================================================*/
   7 #if !defined(BOOST_FUSION_SEGMENTED_FOLD_UNTIL_IMPL_HPP_INCLUDED)
   8 #define BOOST_FUSION_SEGMENTED_FOLD_UNTIL_IMPL_HPP_INCLUDED
   9
  10 #include <boost/fusion/support/config.hpp>
  11 #include <boost/mpl/bool.hpp>
  12 #include <boost/mpl/eval_if.hpp>
  13 #include <boost/mpl/identity.hpp>
  14 #include <boost/utility/result_of.hpp>
  15 #include <boost/type_traits/add_const.hpp>
  16 #include <boost/type_traits/remove_reference.hpp>
  17
  18 #include <boost/fusion/support/void.hpp>
  19 #include <boost/fusion/container/list/cons_fwd.hpp>
  20 #include <boost/fusion/sequence/intrinsic_fwd.hpp>
  21 #include <boost/fusion/iterator/equal_to.hpp>
  22 #include <boost/fusion/iterator/deref.hpp>
  23 #include <boost/fusion/iterator/next.hpp>
  24 #include <boost/fusion/support/is_segmented.hpp>
  25 #include <boost/fusion/sequence/intrinsic/segments.hpp>
  26
  27 // fun(seq, state, context)
  28 //  seq: a non-segmented range
  29 //  state: the state of the fold so far
  30 //  context: the path to the current range
  31 //
  32 // returns: (state', fcontinue)
  33
  34 namespace boost { namespace fusion
  35 {
  36     template <typename First, typename Last>
  37     struct iterator_range;
  38
  39     template <typename Context>
  40     struct segmented_iterator;
  41
  42     namespace result_of
  43     {
  44         template <typename Cur, typename Context>
  45         struct make_segmented_iterator
  46         {
  47             typedef
  48                 iterator_range<
  49                     Cur
  50                   , typename result_of::end<
  51                         typename remove_reference<
  52                             typename add_const<
  53                                 typename result_of::deref<
  54                                     typename Context::car_type::begin_type
  55                                 >::type
  56                             >::type
  57                         >::type
  58                     >::type
  59                 >
  60             range_type;
  61
  62             typedef
  63                 segmented_iterator<cons<range_type, Context> >
  64             type;
  65         };
  66     }
  67
  68     template <typename Cur, typename Context>
  69     BOOST_CONSTEXPR BOOST_FUSION_GPU_ENABLED
  70     inline typename result_of::make_segmented_iterator<Cur, Context>::type
  71     make_segmented_iterator(Cur const& cur, Context const& context)
  72     {
  73         typedef result_of::make_segmented_iterator<Cur, Context> impl_type;
  74         typedef typename impl_type::type type;
  75         typedef typename impl_type::range_type range_type;
  76         return type(cons<range_type, Context>(range_type(cur, fusion::end(*context.car.first)), context));
  77     }
  78
  79     namespace detail
  80     {
  81         template <
  82             typename Begin
  83           , typename End
  84           , typename State
  85           , typename Context
  86           , typename Fun
  87           , bool IsEmpty
  88         >
  89         struct segmented_fold_until_iterate_skip_empty;
  90
  91         template <
  92             typename Begin
  93           , typename End
  94           , typename State
  95           , typename Context
  96           , typename Fun
  97           , bool IsDone = result_of::equal_to<Begin, End>::type::value
  98         >
  99         struct segmented_fold_until_iterate;
 100
 101         template <
 102             typename Sequence
 103           , typename State
 104           , typename Context
 105           , typename Fun
 106           , bool IsSegmented = traits::is_segmented<Sequence>::type::value
 107         >
 108         struct segmented_fold_until_impl;
 109
 110         template <typename Segments, typename State, typename Context, typename Fun>
 111         struct segmented_fold_until_on_segments;
 112
 113         //auto push_context(cur, end, context)
 114         //{
 115         //  return push_back(context, segment_sequence(iterator_range(cur, end)));
 116         //}
 117
 118         template <typename Cur, typename End, typename Context>
 119         struct push_context
 120         {
 121             typedef iterator_range<Cur, End>    range_type;
 122             typedef cons<range_type, Context>   type;
 123
 124             BOOST_CONSTEXPR BOOST_FUSION_GPU_ENABLED
 125             static type call(Cur const& cur, End const& end, Context const& context)
 126             {
 127                 return cons<range_type, Context>(range_type(cur, end), context);
 128             }
 129         };
 130
 131         //auto make_segmented_iterator(cur, end, context)
 132         //{
 133         //  return segmented_iterator(push_context(cur, end, context));
 134         //}
 135         //
 136         //auto segmented_fold_until_impl(seq, state, context, fun)
 137         //{
 138         //  if (is_segmented(seq))
 139         //  {
 140         //    segmented_fold_until_on_segments(segments(seq), state, context, fun);
 141         //  }
 142         //  else
 143         //  {
 144         //    return fun(seq, state, context);
 145         //  }
 146         //}
 147
 148         template <
 149             typename Sequence
 150           , typename State
 151           , typename Context
 152           , typename Fun
 153           , bool IsSegmented
 154         >
 155         struct segmented_fold_until_impl
 156         {
 157             typedef
 158                 segmented_fold_until_on_segments<
 159                     typename remove_reference<
 160                         typename add_const<
 161                             typename result_of::segments<Sequence>::type
 162                         >::type
 163                     >::type
 164                   , State
 165                   , Context
 166                   , Fun
 167                 >
 168             impl;
 169
 170             typedef typename impl::type type;
 171             typedef typename impl::continue_type continue_type;
 172
 173             BOOST_CONSTEXPR BOOST_FUSION_GPU_ENABLED
 174             static type call(Sequence& seq, State const& state, Context const& context, Fun const& fun)
 175             {
 176                 return impl::call(fusion::segments(seq), state, context, fun);
 177             }
 178         };
 179
 180         template <
 181             typename Sequence
 182           , typename State
 183           , typename Context
 184           , typename Fun
 185         >
 186         struct segmented_fold_until_impl<Sequence, State, Context, Fun, false>
 187         {
 188             typedef
 189                 typename Fun::template apply<Sequence, State, Context>
 190             apply_type;
 191
 192             typedef typename apply_type::type type;
 193             typedef typename apply_type::continue_type continue_type;
 194
 195             BOOST_CONSTEXPR BOOST_FUSION_GPU_ENABLED
 196             static type call(Sequence& seq, State const& state, Context const& context, Fun const& fun)
 197             {
 198                 return apply_type::call(seq, state, context, fun);
 199             }
 200         };
 201
 202         //auto segmented_fold_until_on_segments(segs, state, context, fun)
 203         //{
 204         //  auto cur = begin(segs), end = end(segs);
 205         //  for (; cur != end; ++cur)
 206         //  {
 207         //    if (empty(*cur))
 208         //      continue;
 209         //    auto context` = push_context(cur, end, context);
 210         //    state = segmented_fold_until_impl(*cur, state, context`, fun);
 211         //    if (!second(state))
 212         //      return state;
 213         //  }
 214         //}
 215
 216         template <typename Apply>
 217         struct continue_wrap
 218         {
 219             typedef typename Apply::continue_type type;
 220         };
 221
 222         template <typename Begin, typename End, typename State, typename Context, typename Fun, bool IsEmpty>
 223         struct segmented_fold_until_iterate_skip_empty
 224         {
 225             // begin != end and !empty(*begin)
 226             typedef
 227                 push_context<Begin, End, Context>
 228             push_context_impl;
 229
 230             typedef
 231                 typename push_context_impl::type
 232             next_context_type;
 233
 234             typedef
 235                 segmented_fold_until_impl<
 236                     typename remove_reference<
 237                         typename add_const<
 238                             typename result_of::deref<Begin>::type
 239                         >::type
 240                     >::type
 241                   , State
 242                   , next_context_type
 243                   , Fun
 244                 >
 245             fold_recurse_impl;
 246
 247             typedef
 248                 typename fold_recurse_impl::type
 249             next_state_type;
 250
 251             typedef
 252                 segmented_fold_until_iterate<
 253                     typename result_of::next<Begin>::type
 254                   , End
 255                   , next_state_type
 256                   , Context
 257                   , Fun
 258                 >
 259             next_iteration_impl;
 260
 261             typedef
 262                 typename mpl::eval_if<
 263                     typename fold_recurse_impl::continue_type
 264                   , next_iteration_impl
 265                   , mpl::identity<next_state_type>
 266                 >::type
 267             type;
 268
 269             typedef
 270                 typename mpl::eval_if<
 271                     typename fold_recurse_impl::continue_type
 272                   , continue_wrap<next_iteration_impl>
 273                   , mpl::identity<mpl::false_>
 274                 >::type
 275             continue_type;
 276
 277             BOOST_CONSTEXPR BOOST_FUSION_GPU_ENABLED
 278             static type call(Begin const& beg, End const& end, State const& state
 279                            , Context const& context, Fun const& fun)
 280             {
 281                 return call(beg, end, state, context, fun, typename fold_recurse_impl::continue_type());
 282             }
 283
 284             BOOST_CONSTEXPR BOOST_FUSION_GPU_ENABLED
 285             static type call(Begin const& beg, End const& end, State const& state
 286                            , Context const& context, Fun const& fun, mpl::true_) // continue
 287             {
 288                 return next_iteration_impl::call(
 289                     fusion::next(beg)
 290                   , end
 291                   , fold_recurse_impl::call(
 292                         *beg
 293                       , state
 294                       , push_context_impl::call(beg, end, context)
 295                       , fun)
 296                   , context
 297                   , fun);
 298             }
 299
 300             BOOST_CONSTEXPR BOOST_FUSION_GPU_ENABLED
 301             static type call(Begin const& beg, End const& end, State const& state
 302                            , Context const& context, Fun const& fun, mpl::false_) // break
 303             {
 304                 return fold_recurse_impl::call(
 305                     *beg
 306                   , state
 307                   , push_context_impl::call(beg, end, context)
 308                   , fun);
 309             }
 310         };
 311
 312         template <typename Begin, typename End, typename State, typename Context, typename Fun>
 313         struct segmented_fold_until_iterate_skip_empty<Begin, End, State, Context, Fun, true>
 314         {
 315             typedef
 316                 segmented_fold_until_iterate<
 317                     typename result_of::next<Begin>::type
 318                   , End
 319                   , State
 320                   , Context
 321                   , Fun
 322                 >
 323             impl;
 324
 325             typedef typename impl::type type;
 326             typedef typename impl::continue_type continue_type;
 327
 328             BOOST_CONSTEXPR BOOST_FUSION_GPU_ENABLED
 329             static type call(Begin const& beg, End const& end, State const& state
 330                            , Context const& context, Fun const& fun)
 331             {
 332                 return impl::call(fusion::next(beg), end, state, context, fun);
 333             }
 334         };
 335
 336         template <typename Begin, typename End, typename State, typename Context, typename Fun, bool IsDone>
 337         struct segmented_fold_until_iterate
 338         {
 339             typedef
 340                 typename result_of::empty<
 341                     typename remove_reference<
 342                         typename result_of::deref<Begin>::type
 343                     >::type
 344                 >::type
 345             empty_type;
 346
 347             typedef
 348                 segmented_fold_until_iterate_skip_empty<Begin, End, State, Context, Fun, empty_type::value>
 349             impl;
 350
 351             typedef typename impl::type type;
 352             typedef typename impl::continue_type continue_type;
 353
 354             BOOST_CONSTEXPR BOOST_FUSION_GPU_ENABLED
 355             static type call(Begin const& beg, End const& end, State const& state
 356                            , Context const& context, Fun const& fun)
 357             {
 358                 return impl::call(beg, end, state, context, fun);
 359             }
 360         };
 361
 362         template <typename Begin, typename End, typename State, typename Context, typename Fun>
 363         struct segmented_fold_until_iterate<Begin, End, State, Context, Fun, true>
 364         {
 365             typedef State type;
 366             typedef mpl::true_ continue_type;
 367
 368             BOOST_CONSTEXPR BOOST_FUSION_GPU_ENABLED
 369             static type call(Begin const&, End const&, State const& state
 370                            , Context const&, Fun const&)
 371             {
 372                 return state;
 373             }
 374         };
 375
 376         template <typename Segments, typename State, typename Context, typename Fun>
 377         struct segmented_fold_until_on_segments
 378         {
 379             typedef
 380                 segmented_fold_until_iterate<
 381                     typename result_of::begin<Segments>::type
 382                   , typename result_of::end<Segments>::type
 383                   , State
 384                   , Context
 385                   , Fun
 386                 >
 387             impl;
 388
 389             typedef typename impl::type type;
 390             typedef typename impl::continue_type continue_type;
 391
 392             BOOST_CONSTEXPR BOOST_FUSION_GPU_ENABLED
 393             static type call(Segments& segs, State const& state, Context const& context, Fun const& fun)
 394             {
 395                 return impl::call(fusion::begin(segs), fusion::end(segs), state, context, fun);
 396             }
 397         };
 398     }
 399 }}
 400
 401 #endif