boost/mpl/aux_/iter_fold_if_impl.hpp

   1
   2 #ifndef BOOST_MPL_AUX_ITER_FOLD_IF_IMPL_HPP_INCLUDED
   3 #define BOOST_MPL_AUX_ITER_FOLD_IF_IMPL_HPP_INCLUDED
   4
   5 // Copyright Aleksey Gurtovoy 2001-2004
   6 // Copyright David Abrahams 2001-2002
   7 //
   8 // Distributed under the Boost Software License, Version 1.0.
   9 // (See accompanying file LICENSE_1_0.txt or copy at
  10 // http://www.boost.org/LICENSE_1_0.txt)
  11 //
  12 // See http://www.boost.org/libs/mpl for documentation.
  13
  14 // $Id: iter_fold_if_impl.hpp 49267 2008-10-11 06:19:02Z agurtovoy $
  15 // $Date: 2008-10-10 23:19:02 -0700 (Fri, 10 Oct 2008) $
  16 // $Revision: 49267 $
  17
  18 #if !defined(BOOST_MPL_PREPROCESSING_MODE)
  19 #   include <boost/mpl/identity.hpp>
  20 #   include <boost/mpl/next.hpp>
  21 #   include <boost/mpl/if.hpp>
  22 #   include <boost/mpl/apply.hpp>
  23 #   include <boost/mpl/aux_/value_wknd.hpp>
  24 #endif
  25
  26 #include <boost/mpl/aux_/config/use_preprocessed.hpp>
  27
  28 #if !defined(BOOST_MPL_CFG_NO_PREPROCESSED_HEADERS) \
  29     && !defined(BOOST_MPL_PREPROCESSING_MODE)
  30
  31 #   define BOOST_MPL_PREPROCESSED_HEADER iter_fold_if_impl.hpp
  32 #   include <boost/mpl/aux_/include_preprocessed.hpp>
  33
  34 #else
  35
  36 #   include <boost/mpl/limits/unrolling.hpp>
  37 #   include <boost/preprocessor/arithmetic/sub.hpp>
  38 #   include <boost/preprocessor/repeat.hpp>
  39 #   include <boost/preprocessor/inc.hpp>
  40 #   include <boost/preprocessor/dec.hpp>
  41 #   include <boost/preprocessor/cat.hpp>
  42
  43 namespace boost { namespace mpl { namespace aux {
  44
  45 template< typename Iterator, typename State >
  46 struct iter_fold_if_null_step
  47 {
  48     typedef State state;
  49     typedef Iterator iterator;
  50 };
  51
  52 template< bool >
  53 struct iter_fold_if_step_impl
  54 {
  55     template<
  56           typename Iterator
  57         , typename State
  58         , typename StateOp
  59         , typename IteratorOp
  60         >
  61     struct result_
  62     {
  63         typedef typename apply2<StateOp,State,Iterator>::type state;
  64         typedef typename IteratorOp::type iterator;
  65     };
  66 };
  67
  68 template<>
  69 struct iter_fold_if_step_impl<false>
  70 {
  71     template<
  72           typename Iterator
  73         , typename State
  74         , typename StateOp
  75         , typename IteratorOp
  76         >
  77     struct result_
  78     {
  79         typedef State state;
  80         typedef Iterator iterator;
  81     };
  82 };
  83
  84 // agurt, 25/jun/02: MSVC 6.5 workaround, had to get rid of inheritance
  85 // here and in 'iter_fold_if_backward_step', because sometimes it interfered
  86 // with the "early template instantiation bug" in _really_ ugly ways
  87 template<
  88       typename Iterator
  89     , typename State
  90     , typename ForwardOp
  91     , typename Predicate
  92     >
  93 struct iter_fold_if_forward_step
  94 {
  95     typedef typename apply2<Predicate,State,Iterator>::type not_last;
  96     typedef typename iter_fold_if_step_impl<
  97           BOOST_MPL_AUX_MSVC_VALUE_WKND(not_last)::value
  98         >::template result_< Iterator,State,ForwardOp,mpl::next<Iterator> > impl_;
  99
 100     typedef typename impl_::state state;
 101     typedef typename impl_::iterator iterator;
 102 };
 103
 104 template<
 105       typename Iterator
 106     , typename State
 107     , typename BackwardOp
 108     , typename Predicate
 109     >
 110 struct iter_fold_if_backward_step
 111 {
 112     typedef typename apply2<Predicate,State,Iterator>::type not_last;
 113     typedef typename iter_fold_if_step_impl<
 114           BOOST_MPL_AUX_MSVC_VALUE_WKND(not_last)::value
 115         >::template result_< Iterator,State,BackwardOp,identity<Iterator> > impl_;
 116
 117     typedef typename impl_::state state;
 118     typedef typename impl_::iterator iterator;
 119 };
 120
 121
 122 // local macros, #undef-ined at the end of the header
 123
 124 #   define AUX_ITER_FOLD_FORWARD_STEP(unused, i, unused2) \
 125     typedef iter_fold_if_forward_step< \
 126           typename BOOST_PP_CAT(forward_step,i)::iterator \
 127         , typename BOOST_PP_CAT(forward_step,i)::state \
 128         , ForwardOp \
 129         , ForwardPredicate \
 130         > BOOST_PP_CAT(forward_step, BOOST_PP_INC(i)); \
 131     /**/
 132
 133 #   define AUX_ITER_FOLD_BACKWARD_STEP_FUNC(i) \
 134     typedef iter_fold_if_backward_step< \
 135           typename BOOST_PP_CAT(forward_step,BOOST_PP_DEC(i))::iterator \
 136         , typename BOOST_PP_CAT(backward_step,i)::state \
 137         , BackwardOp \
 138         , BackwardPredicate \
 139         > BOOST_PP_CAT(backward_step,BOOST_PP_DEC(i)); \
 140     /**/
 141
 142 #   define AUX_ITER_FOLD_BACKWARD_STEP(unused, i, unused2) \
 143     AUX_ITER_FOLD_BACKWARD_STEP_FUNC( \
 144         BOOST_PP_SUB_D(1,BOOST_MPL_LIMIT_UNROLLING,i) \
 145         ) \
 146     /**/
 147
 148 #   define AUX_LAST_FORWARD_STEP \
 149     BOOST_PP_CAT(forward_step, BOOST_MPL_LIMIT_UNROLLING) \
 150     /**/
 151
 152 #   define AUX_LAST_BACKWARD_STEP \
 153     BOOST_PP_CAT(backward_step, BOOST_MPL_LIMIT_UNROLLING) \
 154     /**/
 155
 156 template<
 157       typename Iterator
 158     , typename State
 159     , typename ForwardOp
 160     , typename ForwardPredicate
 161     , typename BackwardOp
 162     , typename BackwardPredicate
 163     >
 164 struct iter_fold_if_impl
 165 {
 166  private:
 167     typedef iter_fold_if_null_step<Iterator,State> forward_step0;
 168     BOOST_PP_REPEAT(
 169           BOOST_MPL_LIMIT_UNROLLING
 170         , AUX_ITER_FOLD_FORWARD_STEP
 171         , unused
 172         )
 173
 174     typedef typename if_<
 175           typename AUX_LAST_FORWARD_STEP::not_last
 176         , iter_fold_if_impl<
 177               typename AUX_LAST_FORWARD_STEP::iterator
 178             , typename AUX_LAST_FORWARD_STEP::state
 179             , ForwardOp
 180             , ForwardPredicate
 181             , BackwardOp
 182             , BackwardPredicate
 183             >
 184         , iter_fold_if_null_step<
 185               typename AUX_LAST_FORWARD_STEP::iterator
 186             , typename AUX_LAST_FORWARD_STEP::state
 187             >
 188         >::type AUX_LAST_BACKWARD_STEP;
 189
 190     BOOST_PP_REPEAT(
 191           BOOST_MPL_LIMIT_UNROLLING
 192         , AUX_ITER_FOLD_BACKWARD_STEP
 193         , unused
 194         )
 195
 196  public:
 197     typedef typename backward_step0::state state;
 198     typedef typename AUX_LAST_BACKWARD_STEP::iterator iterator;
 199 };
 200
 201 #   undef AUX_LAST_BACKWARD_STEP
 202 #   undef AUX_LAST_FORWARD_STEP
 203 #   undef AUX_ITER_FOLD_BACKWARD_STEP
 204 #   undef AUX_ITER_FOLD_BACKWARD_STEP_FUNC
 205 #   undef AUX_ITER_FOLD_FORWARD_STEP
 206
 207 }}}
 208
 209 #endif // BOOST_MPL_CFG_NO_PREPROCESSED_HEADERS
 210 #endif // BOOST_MPL_AUX_ITER_FOLD_IF_IMPL_HPP_INCLUDED