boost/spirit/home/qi/directive/skip.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(SPIRIT_SKIP_JANUARY_26_2008_0422PM)
   8 #define SPIRIT_SKIP_JANUARY_26_2008_0422PM
   9
  10 #if defined(_MSC_VER)
  11 #pragma once
  12 #endif
  13
  14 #include <boost/spirit/home/qi/meta_compiler.hpp>
  15 #include <boost/spirit/home/qi/parser.hpp>
  16 #include <boost/spirit/home/qi/auxiliary/lazy.hpp>
  17 #include <boost/spirit/home/qi/operator/kleene.hpp>
  18 #include <boost/spirit/home/qi/directive/lexeme.hpp>
  19 #include <boost/spirit/home/qi/skip_over.hpp>
  20 #include <boost/spirit/home/qi/detail/unused_skipper.hpp>
  21 #include <boost/spirit/home/support/container.hpp>
  22 #include <boost/spirit/home/support/common_terminals.hpp>
  23 #include <boost/spirit/home/qi/detail/attributes.hpp>
  24 #include <boost/spirit/home/support/info.hpp>
  25 #include <boost/spirit/home/support/has_semantic_action.hpp>
  26 #include <boost/spirit/home/support/handles_container.hpp>
  27 #include <boost/fusion/include/at.hpp>
  28 #include <boost/fusion/include/vector.hpp>
  29 #include <boost/utility/enable_if.hpp>
  30
  31 namespace boost { namespace spirit
  32 {
  33     ///////////////////////////////////////////////////////////////////////////
  34     // Enablers
  35     ///////////////////////////////////////////////////////////////////////////
  36     template <>
  37     struct use_directive<qi::domain, tag::skip>     // enables skip[p]
  38       : mpl::true_ {};
  39
  40     template <typename T>
  41     struct use_directive<qi::domain
  42       , terminal_ex<tag::skip                       // enables skip(s)[p]
  43         , fusion::vector1<T> >
  44     > : boost::spirit::traits::matches<qi::domain, T> {};
  45
  46     template <>                                     // enables *lazy* skip(s)[p]
  47     struct use_lazy_directive<
  48         qi::domain
  49       , tag::skip
  50       , 1 // arity
  51     > : mpl::true_ {};
  52 }}
  53
  54 namespace boost { namespace spirit { namespace qi
  55 {
  56 #ifndef BOOST_SPIRIT_NO_PREDEFINED_TERMINALS
  57     using spirit::skip;
  58 #endif
  59     using spirit::skip_type;
  60
  61     template <typename Subject>
  62     struct reskip_parser : unary_parser<reskip_parser<Subject> >
  63     {
  64         typedef Subject subject_type;
  65
  66         template <typename Context, typename Iterator>
  67         struct attribute
  68         {
  69             typedef typename
  70                 traits::attribute_of<Subject, Context, Iterator>::type
  71             type;
  72         };
  73
  74         reskip_parser(Subject const& subject_)
  75           : subject(subject_) {}
  76
  77         template <typename Iterator, typename Context
  78           , typename Skipper, typename Attribute>
  79         typename enable_if<detail::is_unused_skipper<Skipper>, bool>::type
  80         parse(Iterator& first, Iterator const& last
  81           , Context& context, Skipper const& u // --> The skipper is reintroduced
  82           , Attribute& attr_) const
  83         {
  84             return subject.parse(first, last, context
  85               , detail::get_skipper(u), attr_);
  86         }
  87         template <typename Iterator, typename Context
  88           , typename Skipper, typename Attribute>
  89         typename disable_if<detail::is_unused_skipper<Skipper>, bool>::type
  90         parse(Iterator& first, Iterator const& last
  91           , Context& context, Skipper const& skipper
  92           , Attribute& attr_) const
  93         {
  94             return subject.parse(first, last, context
  95               , skipper, attr_);
  96         }
  97
  98         template <typename Context>
  99         info what(Context& context) const
 100         {
 101             return info("skip", subject.what(context));
 102         }
 103
 104         Subject subject;
 105     };
 106
 107     template <typename Subject, typename Skipper>
 108     struct skip_parser : unary_parser<skip_parser<Subject, Skipper> >
 109     {
 110         typedef Subject subject_type;
 111         typedef Skipper skipper_type;
 112
 113         template <typename Context, typename Iterator>
 114         struct attribute
 115         {
 116             typedef typename
 117                 traits::attribute_of<Subject, Context, Iterator>::type
 118             type;
 119         };
 120
 121         skip_parser(Subject const& subject_, Skipper const& skipper_)
 122           : subject(subject_), skipper(skipper_) {}
 123
 124         template <typename Iterator, typename Context
 125           , typename Skipper_, typename Attribute>
 126         bool parse(Iterator& first, Iterator const& last
 127           , Context& context, Skipper_ const& //skipper --> bypass the supplied skipper
 128           , Attribute& attr_) const
 129         {
 130             return subject.parse(first, last, context, skipper, attr_);
 131         }
 132
 133         template <typename Context>
 134         info what(Context& context) const
 135         {
 136             return info("skip", subject.what(context));
 137         }
 138
 139         Subject subject;
 140         Skipper skipper;
 141     };
 142
 143     ///////////////////////////////////////////////////////////////////////////
 144     // Parser generators: make_xxx function (objects)
 145     ///////////////////////////////////////////////////////////////////////////
 146     template <typename Subject, typename Modifiers>
 147     struct make_directive<tag::skip, Subject, Modifiers>
 148     {
 149         typedef reskip_parser<Subject> result_type;
 150         result_type operator()(unused_type, Subject const& subject, unused_type) const
 151         {
 152             return result_type(subject);
 153         }
 154     };
 155
 156     template <typename Skipper, typename Subject, typename Modifiers>
 157     struct make_directive<
 158         terminal_ex<tag::skip, fusion::vector1<Skipper> >, Subject, Modifiers>
 159     {
 160         typedef typename
 161             result_of::compile<qi::domain, Skipper, Modifiers>::type
 162         skipper_type;
 163
 164         typedef skip_parser<Subject, skipper_type> result_type;
 165
 166         template <typename Terminal>
 167         result_type operator()(Terminal const& term, Subject const& subject
 168           , Modifiers const& modifiers) const
 169         {
 170             return result_type(subject
 171               , compile<qi::domain>(fusion::at_c<0>(term.args), modifiers));
 172         }
 173     };
 174
 175 }}}
 176
 177 namespace boost { namespace spirit { namespace traits
 178 {
 179     ///////////////////////////////////////////////////////////////////////////
 180     template <typename Subject>
 181     struct has_semantic_action<qi::reskip_parser<Subject> >
 182       : unary_has_semantic_action<Subject> {};
 183
 184     template <typename Subject, typename Skipper>
 185     struct has_semantic_action<qi::skip_parser<Subject, Skipper> >
 186       : unary_has_semantic_action<Subject> {};
 187
 188     ///////////////////////////////////////////////////////////////////////////
 189     template <typename Subject, typename Attribute, typename Context
 190         , typename Iterator>
 191     struct handles_container<qi::reskip_parser<Subject>, Attribute
 192         , Context, Iterator>
 193       : unary_handles_container<Subject, Attribute, Context, Iterator> {};
 194
 195     template <typename Subject, typename Skipper, typename Attribute
 196         , typename Context, typename Iterator>
 197     struct handles_container<qi::skip_parser<Subject, Skipper>, Attribute
 198         , Context, Iterator>
 199       : unary_handles_container<Subject, Attribute, Context, Iterator> {};
 200 }}}
 201
 202 #endif