boost/xpressive/detail/static/transforms/as_independent.hpp

   1 ///////////////////////////////////////////////////////////////////////////////
   2 // as_independent.hpp
   3 //
   4 //  Copyright 2008 Eric Niebler. Distributed under the Boost
   5 //  Software License, Version 1.0. (See accompanying file
   6 //  LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
   7
   8 #ifndef BOOST_XPRESSIVE_DETAIL_STATIC_TRANSFORMS_AS_INDEPENDENT_HPP_EAN_04_05_2007
   9 #define BOOST_XPRESSIVE_DETAIL_STATIC_TRANSFORMS_AS_INDEPENDENT_HPP_EAN_04_05_2007
  10
  11 // MS compatible compilers support #pragma once
  12 #if defined(_MSC_VER)
  13 # pragma once
  14 #endif
  15
  16 #include <boost/mpl/sizeof.hpp>
  17 #include <boost/xpressive/detail/detail_fwd.hpp>
  18 #include <boost/xpressive/detail/static/static.hpp>
  19 #include <boost/proto/core.hpp>
  20 #include <boost/proto/transform/arg.hpp>
  21 #include <boost/proto/transform/when.hpp>
  22 #include <boost/proto/transform/fold.hpp>
  23 #include <boost/proto/transform/fold_tree.hpp>
  24
  25 namespace boost { namespace xpressive { namespace detail
  26 {
  27     struct keeper_tag
  28     {};
  29
  30     struct lookahead_tag
  31     {};
  32
  33     struct lookbehind_tag
  34     {};
  35 }}}
  36
  37 namespace boost { namespace xpressive { namespace grammar_detail
  38 {
  39     // A grammar that only accepts static regexes that
  40     // don't have semantic actions.
  41     struct NotHasAction
  42       : proto::switch_<struct NotHasActionCases>
  43     {};
  44
  45     struct NotHasActionCases
  46     {
  47         template<typename Tag, int Dummy = 0>
  48         struct case_
  49           : proto::nary_expr<Tag, proto::vararg<NotHasAction> >
  50         {};
  51
  52         template<int Dummy>
  53         struct case_<proto::tag::terminal, Dummy>
  54           : not_< or_<
  55                 proto::terminal<detail::tracking_ptr<detail::regex_impl<_> > >,
  56                 proto::terminal<reference_wrapper<_> >
  57             > >
  58         {};
  59
  60         template<int Dummy>
  61         struct case_<proto::tag::comma, Dummy>
  62           : proto::_    // because (set='a','b') can't contain an action
  63         {};
  64
  65         template<int Dummy>
  66         struct case_<proto::tag::complement, Dummy>
  67           : proto::_    // because in ~X, X can't contain an unscoped action
  68         {};
  69
  70         template<int Dummy>
  71         struct case_<detail::lookahead_tag, Dummy>
  72           : proto::_    // because actions in lookaheads are scoped
  73         {};
  74
  75         template<int Dummy>
  76         struct case_<detail::lookbehind_tag, Dummy>
  77           : proto::_    // because actions in lookbehinds are scoped
  78         {};
  79
  80         template<int Dummy>
  81         struct case_<detail::keeper_tag, Dummy>
  82           : proto::_    // because actions in keepers are scoped
  83         {};
  84
  85         template<int Dummy>
  86         struct case_<proto::tag::subscript, Dummy>
  87           : proto::subscript<detail::set_initializer_type, _>
  88         {}; // only accept set[...], not actions!
  89     };
  90
  91     struct IndependentEndXpression
  92       : or_<
  93             when<NotHasAction, detail::true_xpression()>
  94           , otherwise<detail::independent_end_xpression()>
  95         >
  96     {};
  97
  98     template<typename Grammar, typename Callable = proto::callable>
  99     struct as_lookahead : proto::transform<as_lookahead<Grammar, Callable> >
 100     {
 101         template<typename Expr, typename State, typename Data>
 102         struct impl : proto::transform_impl<Expr, State, Data>
 103         {
 104             typedef typename proto::result_of::child<Expr>::type arg_type;
 105
 106             typedef
 107                 typename IndependentEndXpression::impl<arg_type, int, int>::result_type
 108             end_xpr_type;
 109
 110             typedef
 111                 typename Grammar::template impl<arg_type, end_xpr_type, Data>::result_type
 112             xpr_type;
 113
 114             typedef
 115                 detail::lookahead_matcher<xpr_type>
 116             result_type;
 117
 118             result_type operator ()(
 119                 typename impl::expr_param expr
 120               , typename impl::state_param
 121               , typename impl::data_param data
 122             ) const
 123             {
 124                 int i = 0;
 125                 return result_type(
 126                     typename Grammar::template impl<arg_type, end_xpr_type, Data>()(
 127                         proto::child(expr)
 128                       , IndependentEndXpression::impl<arg_type, int, int>()(proto::child(expr), i, i)
 129                       , data
 130                     )
 131                   , false
 132                 );
 133             }
 134         };
 135     };
 136
 137     template<typename Grammar, typename Callable = proto::callable>
 138     struct as_lookbehind : proto::transform<as_lookbehind<Grammar, Callable> >
 139     {
 140         template<typename Expr, typename State, typename Data>
 141         struct impl : proto::transform_impl<Expr, State, Data>
 142         {
 143             typedef typename proto::result_of::child<Expr>::type arg_type;
 144
 145             typedef
 146                 typename IndependentEndXpression::impl<arg_type, int, int>::result_type
 147             end_xpr_type;
 148
 149             typedef
 150                 typename Grammar::template impl<arg_type, end_xpr_type, Data>::result_type
 151             xpr_type;
 152
 153             typedef
 154                 detail::lookbehind_matcher<xpr_type>
 155             result_type;
 156
 157             result_type operator ()(
 158                 typename impl::expr_param expr
 159               , typename impl::state_param
 160               , typename impl::data_param data
 161             ) const
 162             {
 163                 int i = 0;
 164                 xpr_type expr2 = typename Grammar::template impl<arg_type, end_xpr_type, Data>()(
 165                     proto::child(expr)
 166                   , IndependentEndXpression::impl<arg_type, int, int>()(proto::child(expr), i, i)
 167                   , data
 168                 );
 169                 std::size_t width = expr2.get_width().value();
 170                 return result_type(expr2, width, false);
 171             }
 172         };
 173     };
 174
 175     template<typename Grammar, typename Callable = proto::callable>
 176     struct as_keeper : proto::transform<as_keeper<Grammar, Callable> >
 177     {
 178         template<typename Expr, typename State, typename Data>
 179         struct impl : proto::transform_impl<Expr, State, Data>
 180         {
 181             typedef typename proto::result_of::child<Expr>::type arg_type;
 182
 183             typedef
 184                 typename IndependentEndXpression::impl<arg_type, int, int>::result_type
 185             end_xpr_type;
 186
 187             typedef
 188                 typename Grammar::template impl<arg_type, end_xpr_type, Data>::result_type
 189             xpr_type;
 190
 191             typedef
 192                 detail::keeper_matcher<xpr_type>
 193             result_type;
 194
 195             result_type operator ()(
 196                 typename impl::expr_param expr
 197               , typename impl::state_param
 198               , typename impl::data_param data
 199             ) const
 200             {
 201                 int i = 0;
 202                 return result_type(
 203                     typename Grammar::template impl<arg_type, end_xpr_type, Data>()(
 204                         proto::child(expr)
 205                       , IndependentEndXpression::impl<arg_type, int, int>()(proto::child(expr), i, i)
 206                       , data
 207                     )
 208                 );
 209             }
 210         };
 211     };
 212
 213 }}}
 214
 215 #endif