boost/boost/xpressive/detail/static/productions/Attic/alt_compilers.hpp

   1 ///////////////////////////////////////////////////////////////////////////////
   2 // alt_compilers.hpp
   3 //
   4 //  Copyright 2004 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_PRODUCTIONS_ALT_COMPILERS_HPP_EAN_10_04_2005
   9 #define BOOST_XPRESSIVE_DETAIL_STATIC_PRODUCTIONS_ALT_COMPILERS_HPP_EAN_10_04_2005
  10
  11 #include <boost/version.hpp>
  12 #include <boost/xpressive/detail/detail_fwd.hpp>
  13 #include <boost/xpressive/proto/proto.hpp>
  14 #include <boost/xpressive/proto/compiler/fold.hpp>
  15 #include <boost/xpressive/proto/compiler/branch.hpp>
  16 #include <boost/xpressive/detail/utility/cons.hpp>
  17 #include <boost/xpressive/detail/utility/dont_care.hpp>
  18 #include <boost/xpressive/detail/static/productions/domain_tags.hpp>
  19
  20 namespace boost { namespace xpressive { namespace detail
  21 {
  22
  23     ///////////////////////////////////////////////////////////////////////////////
  24     // alt_branch
  25     //   Describes how to construct an alternate xpression
  26     struct alt_branch
  27     {
  28         typedef boost::fusion::nil state_type;
  29
  30         template<typename Op, typename State, typename Visitor>
  31         struct apply
  32         {
  33             typedef static_xpression
  34             <
  35                 alternate_matcher<alternates_list<Op>, typename Visitor::traits_type>
  36               , State
  37             > type;
  38         };
  39
  40         template<typename Op, typename State, typename Visitor>
  41         static typename apply<Op, State, Visitor>::type
  42         call(Op const &op, State const &state, Visitor &)
  43         {
  44             typedef alternate_matcher<alternates_list<Op>, typename Visitor::traits_type> alt_matcher;
  45             return make_static_xpression(alt_matcher(op), state);
  46         }
  47     };
  48
  49     ///////////////////////////////////////////////////////////////////////////////
  50     // alt_list_branch
  51     struct alt_list_branch
  52     {
  53         typedef alternate_end_xpression state_type;
  54
  55         template<typename Op, typename State, typename>
  56         struct apply
  57         {
  58             typedef boost::fusion::cons<Op, State> type;
  59         };
  60
  61         template<typename Op, typename State>
  62         static boost::fusion::cons<Op, State>
  63         call(Op const &op, State const &state, dont_care)
  64         {
  65             return boost::fusion::make_cons(op, state);
  66         }
  67     };
  68
  69 }}}
  70
  71 namespace boost { namespace proto
  72 {
  73     // production for alternates in sequence
  74     template<>
  75     struct compiler<bitor_tag, xpressive::detail::seq_tag, void>
  76       : branch_compiler<xpressive::detail::alt_branch, xpressive::detail::alt_tag>
  77     {
  78     };
  79
  80     // handle alternates with the alt branch compiler
  81     template<typename OpTag>
  82     struct compiler<OpTag, xpressive::detail::alt_tag, void>
  83       : branch_compiler<xpressive::detail::alt_list_branch, xpressive::detail::seq_tag>
  84     {
  85     };
  86
  87     // production for alternates in alternate
  88     template<>
  89     struct compiler<bitor_tag, xpressive::detail::alt_tag, void>
  90       : fold_compiler<bitor_tag, xpressive::detail::alt_tag>
  91     {
  92     };
  93
  94 }}
  95
  96 #endif