ceph/src/boost/boost/spirit/home/qi/auxiliary/eps.hpp

   1 /*=============================================================================
   2     Copyright (c) 2001-2011 Joel de Guzman
   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_SPIRIT_EPS_MARCH_23_2007_0454PM)
   8 #define BOOST_SPIRIT_EPS_MARCH_23_2007_0454PM
   9
  10 #if defined(_MSC_VER)
  11 #pragma once
  12 #endif
  13
  14 #include <boost/spirit/home/qi/domain.hpp>
  15 #include <boost/spirit/home/qi/skip_over.hpp>
  16 #include <boost/spirit/home/qi/meta_compiler.hpp>
  17 #include <boost/spirit/home/support/unused.hpp>
  18 #include <boost/spirit/home/support/info.hpp>
  19 #include <boost/spirit/home/support/common_terminals.hpp>
  20 #include <boost/fusion/include/at.hpp>
  21 #include <boost/type_traits/is_convertible.hpp>
  22
  23 namespace boost { namespace spirit
  24 {
  25     ///////////////////////////////////////////////////////////////////////////
  26     // Enablers
  27     ///////////////////////////////////////////////////////////////////////////
  28     template <>
  29     struct use_terminal<qi::domain, tag::eps>       // enables eps
  30       : mpl::true_ {};
  31
  32     template <typename A0>
  33     struct use_terminal<qi::domain
  34       , terminal_ex<tag::eps, fusion::vector1<A0> > // enables eps(bool-condition)
  35     > : is_convertible<A0, bool> {};
  36
  37     template <>                                     // enables eps(f)
  38     struct use_lazy_terminal<
  39         qi::domain, tag::eps, 1 /*arity*/
  40     > : mpl::true_ {};
  41 }}
  42
  43 namespace boost { namespace spirit { namespace qi
  44 {
  45 #ifndef BOOST_SPIRIT_NO_PREDEFINED_TERMINALS
  46     using spirit::eps;
  47 #endif
  48     using spirit::eps_type;
  49
  50     struct eps_parser : primitive_parser<eps_parser>
  51     {
  52         template <typename Context, typename Iterator>
  53         struct attribute
  54         {
  55             typedef unused_type type;
  56         };
  57
  58         template <typename Iterator, typename Context
  59           , typename Skipper, typename Attribute>
  60         bool parse(Iterator& first, Iterator const& last
  61           , Context& /*context*/, Skipper const& skipper
  62           , Attribute& /*attr*/) const
  63         {
  64             qi::skip_over(first, last, skipper);
  65             return true;
  66         }
  67
  68         template <typename Context>
  69         info what(Context& /*context*/) const
  70         {
  71             return info("eps");
  72         }
  73     };
  74
  75     struct semantic_predicate : primitive_parser<semantic_predicate>
  76     {
  77         template <typename Context, typename Iterator>
  78         struct attribute
  79         {
  80             typedef unused_type type;
  81         };
  82
  83         semantic_predicate(bool predicate_)
  84           : predicate(predicate_) {}
  85
  86         template <typename Iterator, typename Context
  87           , typename Skipper, typename Attribute>
  88         bool parse(Iterator& first, Iterator const& last
  89           , Context& /*context*/, Skipper const& skipper
  90           , Attribute& /*attr*/) const
  91         {
  92             qi::skip_over(first, last, skipper);
  93             return predicate;
  94         }
  95
  96         template <typename Context>
  97         info what(Context& /*context*/) const
  98         {
  99             return info("semantic-predicate");
 100         }
 101
 102         bool predicate;
 103     };
 104
 105     ///////////////////////////////////////////////////////////////////////////
 106     // Parser generators: make_xxx function (objects)
 107     ///////////////////////////////////////////////////////////////////////////
 108     template <typename Modifiers>
 109     struct make_primitive<tag::eps, Modifiers>
 110     {
 111         typedef eps_parser result_type;
 112         result_type operator()(unused_type, unused_type) const
 113         {
 114             return result_type();
 115         }
 116     };
 117
 118     template <typename Modifiers, typename A0>
 119     struct make_primitive<
 120         terminal_ex<tag::eps, fusion::vector1<A0> >
 121       , Modifiers>
 122     {
 123         typedef semantic_predicate result_type;
 124         template <typename Terminal>
 125         result_type operator()(Terminal const& term, unused_type) const
 126         {
 127             return result_type(fusion::at_c<0>(term.args) ? true : false);
 128         }
 129     };
 130 }}}
 131
 132 #endif