boost/spirit/home/x3/directive/lexeme.hpp

   1 /*=============================================================================
   2     Copyright (c) 2001-2014 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_LEXEME_MARCH_24_2007_0802AM)
   8 #define SPIRIT_LEXEME_MARCH_24_2007_0802AM
   9
  10 #if defined(_MSC_VER)
  11 #pragma once
  12 #endif
  13
  14 #include <boost/spirit/home/x3/support/context.hpp>
  15 #include <boost/spirit/home/x3/support/unused.hpp>
  16 #include <boost/spirit/home/x3/core/skip_over.hpp>
  17 #include <boost/spirit/home/x3/core/parser.hpp>
  18 #include <boost/type_traits/remove_reference.hpp>
  19 #include <boost/utility/enable_if.hpp>
  20
  21 namespace boost { namespace spirit { namespace x3
  22 {
  23     template <typename Subject>
  24     struct lexeme_directive : unary_parser<Subject, lexeme_directive<Subject>>
  25     {
  26         typedef unary_parser<Subject, lexeme_directive<Subject> > base_type;
  27         static bool const is_pass_through_unary = true;
  28         static bool const handles_container = Subject::handles_container;
  29
  30         lexeme_directive(Subject const& subject)
  31           : base_type(subject) {}
  32
  33         template <typename Iterator, typename Context
  34           , typename RContext, typename Attribute>
  35         typename enable_if<has_skipper<Context>, bool>::type
  36         parse(Iterator& first, Iterator const& last
  37           , Context const& context, RContext& rcontext, Attribute& attr) const
  38         {
  39             x3::skip_over(first, last, context);
  40             auto const& skipper = x3::get<skipper_tag>(context);
  41
  42             typedef unused_skipper<
  43                 typename remove_reference<decltype(skipper)>::type>
  44             unused_skipper_type;
  45             unused_skipper_type unused_skipper(skipper);
  46
  47             return this->subject.parse(
  48                 first, last
  49               , make_context<skipper_tag>(unused_skipper, context)
  50               , rcontext
  51               , attr);
  52         }
  53
  54         template <typename Iterator, typename Context
  55           , typename RContext, typename Attribute>
  56         typename disable_if<has_skipper<Context>, bool>::type
  57         parse(Iterator& first, Iterator const& last
  58           , Context const& context, RContext& rcontext, Attribute& attr) const
  59         {
  60             //  no need to pre-skip if skipper is unused
  61             //- x3::skip_over(first, last, context);
  62
  63             return this->subject.parse(
  64                 first, last
  65               , context
  66               , rcontext
  67               , attr);
  68         }
  69     };
  70
  71     struct lexeme_gen
  72     {
  73         template <typename Subject>
  74         lexeme_directive<typename extension::as_parser<Subject>::value_type>
  75         operator[](Subject const& subject) const
  76         {
  77             return {as_parser(subject)};
  78         }
  79     };
  80
  81     lexeme_gen const lexeme = lexeme_gen();
  82 }}}
  83
  84 #endif