mpl/aux_/iter_fold_if_impl.hpp

0001
0002 #ifndef BOOST_MPL_AUX_ITER_FOLD_IF_IMPL_HPP_INCLUDED
0003 #define BOOST_MPL_AUX_ITER_FOLD_IF_IMPL_HPP_INCLUDED
0004
0005 // Copyright Aleksey Gurtovoy 2001-2004
0006 // Copyright David Abrahams 2001-2002
0007 //
0008 // Distributed under the Boost Software License, Version 1.0.
0009 // (See accompanying file LICENSE_1_0.txt or copy at
0010 // http://www.boost.org/LICENSE_1_0.txt)
0011 //
0012 // See http://www.boost.org/libs/mpl for documentation.
0013
0014 // $Id$
0015 // $Date$
0016 // $Revision$
0017
0018 #if !defined(BOOST_MPL_PREPROCESSING_MODE)
0019 #   include <boost/mpl/identity.hpp>
0020 #   include <boost/mpl/next.hpp>
0021 #   include <boost/mpl/if.hpp>
0022 #   include <boost/mpl/apply.hpp>
0023 #   include <boost/mpl/aux_/value_wknd.hpp>
0024 #endif
0025
0026 #include <boost/mpl/aux_/config/use_preprocessed.hpp>
0027
0028 #if !defined(BOOST_MPL_CFG_NO_PREPROCESSED_HEADERS) \
0029     && !defined(BOOST_MPL_PREPROCESSING_MODE)
0030
0031 #   define BOOST_MPL_PREPROCESSED_HEADER iter_fold_if_impl.hpp
0032 #   include <boost/mpl/aux_/include_preprocessed.hpp>
0033
0034 #else
0035
0036 #   include <boost/mpl/limits/unrolling.hpp>
0037 #   include <boost/preprocessor/arithmetic/sub.hpp>
0038 #   include <boost/preprocessor/repeat.hpp>
0039 #   include <boost/preprocessor/inc.hpp>
0040 #   include <boost/preprocessor/dec.hpp>
0041 #   include <boost/preprocessor/cat.hpp>
0042
0043 namespace boost { namespace mpl { namespace aux {
0044
0045 template< typename Iterator, typename State >
0046 struct iter_fold_if_null_step
0047 {
0048     typedef State state;
0049     typedef Iterator iterator;
0050 };
0051
0052 template< bool >
0053 struct iter_fold_if_step_impl
0054 {
0055     template<
0056           typename Iterator
0057         , typename State
0058         , typename StateOp
0059         , typename IteratorOp
0060         >
0061     struct result_
0062     {
0063         typedef typename apply2<StateOp,State,Iterator>::type state;
0064         typedef typename IteratorOp::type iterator;
0065     };
0066 };
0067
0068 template<>
0069 struct iter_fold_if_step_impl<false>
0070 {
0071     template<
0072           typename Iterator
0073         , typename State
0074         , typename StateOp
0075         , typename IteratorOp
0076         >
0077     struct result_
0078     {
0079         typedef State state;
0080         typedef Iterator iterator;
0081     };
0082 };
0083
0084 // agurt, 25/jun/02: MSVC 6.5 workaround, had to get rid of inheritance
0085 // here and in 'iter_fold_if_backward_step', because sometimes it interfered
0086 // with the "early template instantiation bug" in _really_ ugly ways
0087 template<
0088       typename Iterator
0089     , typename State
0090     , typename ForwardOp
0091     , typename Predicate
0092     >
0093 struct iter_fold_if_forward_step
0094 {
0095     typedef typename apply2<Predicate,State,Iterator>::type not_last;
0096     typedef typename iter_fold_if_step_impl<
0097           BOOST_MPL_AUX_MSVC_VALUE_WKND(not_last)::value
0098         >::template result_< Iterator,State,ForwardOp,mpl::next<Iterator> > impl_;
0099
0100     typedef typename impl_::state state;
0101     typedef typename impl_::iterator iterator;
0102 };
0103
0104 template<
0105       typename Iterator
0106     , typename State
0107     , typename BackwardOp
0108     , typename Predicate
0109     >
0110 struct iter_fold_if_backward_step
0111 {
0112     typedef typename apply2<Predicate,State,Iterator>::type not_last;
0113     typedef typename iter_fold_if_step_impl<
0114           BOOST_MPL_AUX_MSVC_VALUE_WKND(not_last)::value
0115         >::template result_< Iterator,State,BackwardOp,identity<Iterator> > impl_;
0116
0117     typedef typename impl_::state state;
0118     typedef typename impl_::iterator iterator;
0119 };
0120
0121
0122 // local macros, #undef-ined at the end of the header
0123
0124 #   define AUX_ITER_FOLD_FORWARD_STEP(unused, i, unused2) \
0125     typedef iter_fold_if_forward_step< \
0126           typename BOOST_PP_CAT(forward_step,i)::iterator \
0127         , typename BOOST_PP_CAT(forward_step,i)::state \
0128         , ForwardOp \
0129         , ForwardPredicate \
0130         > BOOST_PP_CAT(forward_step, BOOST_PP_INC(i)); \
0131     /**/
0132
0133 #   define AUX_ITER_FOLD_BACKWARD_STEP_FUNC(i) \
0134     typedef iter_fold_if_backward_step< \
0135           typename BOOST_PP_CAT(forward_step,BOOST_PP_DEC(i))::iterator \
0136         , typename BOOST_PP_CAT(backward_step,i)::state \
0137         , BackwardOp \
0138         , BackwardPredicate \
0139         > BOOST_PP_CAT(backward_step,BOOST_PP_DEC(i)); \
0140     /**/
0141
0142 #   define AUX_ITER_FOLD_BACKWARD_STEP(unused, i, unused2) \
0143     AUX_ITER_FOLD_BACKWARD_STEP_FUNC( \
0144         BOOST_PP_SUB_D(1,BOOST_MPL_LIMIT_UNROLLING,i) \
0145         ) \
0146     /**/
0147
0148 #   define AUX_LAST_FORWARD_STEP \
0149     BOOST_PP_CAT(forward_step, BOOST_MPL_LIMIT_UNROLLING) \
0150     /**/
0151
0152 #   define AUX_LAST_BACKWARD_STEP \
0153     BOOST_PP_CAT(backward_step, BOOST_MPL_LIMIT_UNROLLING) \
0154     /**/
0155
0156 template<
0157       typename Iterator
0158     , typename State
0159     , typename ForwardOp
0160     , typename ForwardPredicate
0161     , typename BackwardOp
0162     , typename BackwardPredicate
0163     >
0164 struct iter_fold_if_impl
0165 {
0166  private:
0167     typedef iter_fold_if_null_step<Iterator,State> forward_step0;
0168     BOOST_PP_REPEAT(
0169           BOOST_MPL_LIMIT_UNROLLING
0170         , AUX_ITER_FOLD_FORWARD_STEP
0171         , unused
0172         )
0173
0174     typedef typename if_<
0175           typename AUX_LAST_FORWARD_STEP::not_last
0176         , iter_fold_if_impl<
0177               typename AUX_LAST_FORWARD_STEP::iterator
0178             , typename AUX_LAST_FORWARD_STEP::state
0179             , ForwardOp
0180             , ForwardPredicate
0181             , BackwardOp
0182             , BackwardPredicate
0183             >
0184         , iter_fold_if_null_step<
0185               typename AUX_LAST_FORWARD_STEP::iterator
0186             , typename AUX_LAST_FORWARD_STEP::state
0187             >
0188         >::type AUX_LAST_BACKWARD_STEP;
0189
0190     BOOST_PP_REPEAT(
0191           BOOST_MPL_LIMIT_UNROLLING
0192         , AUX_ITER_FOLD_BACKWARD_STEP
0193         , unused
0194         )
0195
0196  public:
0197     typedef typename backward_step0::state state;
0198     typedef typename AUX_LAST_BACKWARD_STEP::iterator iterator;
0199 };
0200
0201 #   undef AUX_LAST_BACKWARD_STEP
0202 #   undef AUX_LAST_FORWARD_STEP
0203 #   undef AUX_ITER_FOLD_BACKWARD_STEP
0204 #   undef AUX_ITER_FOLD_BACKWARD_STEP_FUNC
0205 #   undef AUX_ITER_FOLD_FORWARD_STEP
0206
0207 }}}
0208
0209 #endif // BOOST_MPL_CFG_NO_PREPROCESSED_HEADERS
0210 #endif // BOOST_MPL_AUX_ITER_FOLD_IF_IMPL_HPP_INCLUDED