deps/boost_1_63_0/boost/fusion/iterator/detail/segmented_next_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_ITERATOR_NEXT_IMPL_HPP_INCLUDED)
   8 #define BOOST_FUSION_SEGMENTED_ITERATOR_NEXT_IMPL_HPP_INCLUDED
   9
  10 #include <boost/fusion/support/config.hpp>
  11 #include <boost/type_traits/add_const.hpp>
  12 #include <boost/type_traits/remove_reference.hpp>
  13 #include <boost/fusion/iterator/equal_to.hpp>
  14 #include <boost/fusion/container/list/cons_fwd.hpp>
  15 #include <boost/fusion/iterator/next.hpp>
  16 #include <boost/fusion/iterator/deref.hpp>
  17
  18 namespace boost { namespace fusion
  19 {
  20     template <typename First, typename Second>
  21     struct iterator_range;
  22
  23     template <typename Context>
  24     struct segmented_iterator;
  25
  26     namespace detail
  27     {
  28         template <typename Sequence, typename Stack>
  29         struct segmented_begin_impl;
  30
  31         //bool is_invalid(stack)
  32         //{
  33         //  return empty(car(stack));
  34         //}
  35
  36         template <typename Stack>
  37         struct is_invalid
  38           : result_of::equal_to<
  39                 typename Stack::car_type::begin_type,
  40                 typename Stack::car_type::end_type
  41             >
  42         {};
  43
  44         ////Advance the first iterator in the seq at the
  45         ////top of a stack of iterator ranges. Return the
  46         ////new stack.
  47         //auto pop_front_car(stack)
  48         //{
  49         //  return cons(iterator_range(next(begin(car(stack))), end(car(stack))), cdr(stack));
  50         //}
  51
  52         template <typename Stack>
  53         struct pop_front_car
  54         {
  55             typedef
  56                 iterator_range<
  57                     typename result_of::next<
  58                         typename Stack::car_type::begin_type
  59                     >::type
  60                   , typename Stack::car_type::end_type
  61                 >
  62             car_type;
  63
  64             typedef
  65                 cons<car_type, typename Stack::cdr_type>
  66             type;
  67
  68             BOOST_CONSTEXPR BOOST_FUSION_GPU_ENABLED
  69             static type call(Stack const & stack)
  70             {
  71                 return type(
  72                     car_type(fusion::next(stack.car.first), stack.car.last),
  73                     stack.cdr);
  74             }
  75         };
  76
  77         template <
  78             typename Stack,
  79             typename Next   = typename pop_front_car<Stack>::type,
  80             bool IsInvalid  = is_invalid<Next>::value,
  81             int StackSize   = Stack::size::value>
  82         struct segmented_next_impl_recurse;
  83
  84         // Handle the case where the top of the stack has no usable
  85         //auto segmented_next_impl_recurse3(stack)
  86         //{
  87         //  if (size(stack) == 1)
  88         //    return cons(iterator_range(end(car(stack)), end(car(stack))), nil_);
  89         //  else
  90         //    return segmented_next_impl_recurse(stack.cdr);
  91         //}
  92
  93         template <
  94             typename Stack,
  95             int StackSize = Stack::size::value>
  96         struct segmented_next_impl_recurse3
  97         {
  98             typedef segmented_next_impl_recurse<typename Stack::cdr_type> impl;
  99             typedef typename impl::type type;
 100
 101             BOOST_CONSTEXPR BOOST_FUSION_GPU_ENABLED
 102             static type call(Stack const & stack)
 103             {
 104                 return impl::call(stack.cdr);
 105             }
 106         };
 107
 108         template <typename Stack>
 109         struct segmented_next_impl_recurse3<Stack, 1>
 110         {
 111             typedef typename Stack::car_type::end_type end_type;
 112             typedef iterator_range<end_type, end_type> range_type;
 113             typedef cons<range_type> type;
 114
 115             BOOST_CONSTEXPR BOOST_FUSION_GPU_ENABLED
 116             static type call(Stack const & stack)
 117             {
 118                 return type(range_type(stack.car.last, stack.car.last));
 119             }
 120         };
 121
 122         //auto segmented_next_impl_recurse2(stack)
 123         //{
 124         //  auto res = segmented_begin_impl(front(car(stack)), stack);
 125         //  if (is_invalid(res))
 126         //    return segmented_next_impl_recurse3(stack);
 127         //  else
 128         //    return res;
 129         //}
 130
 131         template <
 132             typename Stack,
 133             typename Sequence  =
 134                 typename remove_reference<
 135                     typename add_const<
 136                         typename result_of::deref<
 137                             typename Stack::car_type::begin_type
 138                         >::type
 139                     >::type
 140                 >::type,
 141             typename Result =
 142                 typename segmented_begin_impl<Sequence, Stack>::type,
 143             bool IsInvalid  =
 144                 is_invalid<Result>::value>
 145         struct segmented_next_impl_recurse2
 146         {
 147             typedef segmented_next_impl_recurse3<Stack> impl;
 148             typedef typename impl::type type;
 149
 150             BOOST_CONSTEXPR BOOST_FUSION_GPU_ENABLED
 151             static type call(Stack const & stack)
 152             {
 153                 return impl::call(stack);
 154             }
 155         };
 156
 157         template <typename Stack, typename Sequence, typename Result>
 158         struct segmented_next_impl_recurse2<Stack, Sequence, Result, false>
 159         {
 160             typedef Result type;
 161
 162             BOOST_CONSTEXPR BOOST_FUSION_GPU_ENABLED
 163             static type call(Stack const & stack)
 164             {
 165                 return segmented_begin_impl<Sequence, Stack>::call(*stack.car.first, stack);
 166             }
 167         };
 168
 169         //auto segmented_next_impl_recurse(stack)
 170         //{
 171         //  auto next = pop_front_car(stack);
 172         //  if (is_invalid(next))
 173         //    if (1 == size(stack))
 174         //      return next;
 175         //    else
 176         //      return segmented_next_impl_recurse(cdr(stack));
 177         //  else
 178         //    return segmented_next_impl_recurse2(next)
 179         //}
 180
 181         template <typename Stack, typename Next, bool IsInvalid, int StackSize>
 182         struct segmented_next_impl_recurse
 183         {
 184             typedef
 185                 typename segmented_next_impl_recurse<typename Stack::cdr_type>::type
 186             type;
 187
 188             BOOST_CONSTEXPR BOOST_FUSION_GPU_ENABLED
 189             static type call(Stack const& stack)
 190             {
 191                 return segmented_next_impl_recurse<typename Stack::cdr_type>::call(stack.cdr);
 192             }
 193         };
 194
 195         template <typename Stack, typename Next>
 196         struct segmented_next_impl_recurse<Stack, Next, true, 1>
 197         {
 198             typedef Next type;
 199
 200             BOOST_CONSTEXPR BOOST_FUSION_GPU_ENABLED
 201             static type call(Stack const & stack)
 202             {
 203                 return pop_front_car<Stack>::call(stack);
 204             }
 205         };
 206
 207         template <typename Stack, typename Next, int StackSize>
 208         struct segmented_next_impl_recurse<Stack, Next, false, StackSize>
 209         {
 210             typedef segmented_next_impl_recurse2<Next> impl;
 211             typedef typename impl::type type;
 212
 213             BOOST_CONSTEXPR BOOST_FUSION_GPU_ENABLED
 214             static type call(Stack const & stack)
 215             {
 216                 return impl::call(pop_front_car<Stack>::call(stack));
 217             }
 218         };
 219
 220         //auto segmented_next_impl(stack)
 221         //{
 222         //  // car(stack) is a seq of values, not a seq of segments
 223         //  auto next = pop_front_car(stack);
 224         //  if (is_invalid(next))
 225         //    return segmented_next_impl_recurse(cdr(next));
 226         //  else
 227         //    return next;
 228         //}
 229
 230         template <
 231             typename Stack,
 232             typename Next   = typename pop_front_car<Stack>::type,
 233             bool IsInvalid  = is_invalid<Next>::value>
 234         struct segmented_next_impl_aux
 235         {
 236             typedef segmented_next_impl_recurse<typename Stack::cdr_type> impl;
 237             typedef typename impl::type type;
 238
 239             BOOST_CONSTEXPR BOOST_FUSION_GPU_ENABLED
 240             static type call(Stack const & stack)
 241             {
 242                 return impl::call(stack.cdr);
 243             }
 244         };
 245
 246         template <typename Stack, typename Next>
 247         struct segmented_next_impl_aux<Stack, Next, false>
 248         {
 249             typedef Next type;
 250
 251             BOOST_CONSTEXPR BOOST_FUSION_GPU_ENABLED
 252             static type call(Stack const & stack)
 253             {
 254                 return pop_front_car<Stack>::call(stack);
 255             }
 256         };
 257
 258         template <typename Stack>
 259         struct segmented_next_impl
 260           : segmented_next_impl_aux<Stack>
 261         {};
 262     }
 263 }}
 264
 265 #endif