ceph/src/boost/libs/spirit/include/boost/spirit/home/x3/auxiliary/eps.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(BOOST_SPIRIT_X3_EPS_MARCH_23_2007_0454PM)
   8 #define BOOST_SPIRIT_X3_EPS_MARCH_23_2007_0454PM
   9
  10 #include <boost/spirit/home/x3/core/skip_over.hpp>
  11 #include <boost/spirit/home/x3/core/parser.hpp>
  12 #include <boost/spirit/home/x3/support/unused.hpp>
  13
  14 namespace boost { namespace spirit { namespace x3
  15 {
  16     struct rule_context_tag;
  17
  18     struct semantic_predicate : parser<semantic_predicate>
  19     {
  20         typedef unused_type attribute_type;
  21         static bool const has_attribute = false;
  22
  23         semantic_predicate(bool predicate)
  24           : predicate(predicate) {}
  25
  26         template <typename Iterator, typename Context, typename Attribute>
  27         bool parse(Iterator& first, Iterator const& last
  28           , Context const& context, unused_type, Attribute&) const
  29         {
  30             x3::skip_over(first, last, context);
  31             return predicate;
  32         }
  33
  34         bool predicate;
  35     };
  36
  37     template <typename F>
  38     struct lazy_semantic_predicate : parser<lazy_semantic_predicate<F>>
  39     {
  40         typedef unused_type attribute_type;
  41         static bool const has_attribute = false;
  42
  43         lazy_semantic_predicate(F f)
  44           : f(f) {}
  45
  46         template <typename Iterator, typename Context, typename Attribute>
  47         bool parse(Iterator& first, Iterator const& last
  48           , Context const& context, unused_type, Attribute& attr) const
  49         {
  50             x3::skip_over(first, last, context);
  51             return f(x3::get<rule_context_tag>(context));
  52         }
  53
  54         F f;
  55     };
  56
  57     struct eps_parser : parser<eps_parser>
  58     {
  59         typedef unused_type attribute_type;
  60         static bool const has_attribute = false;
  61
  62         template <typename Iterator, typename Context
  63           , typename RuleContext, typename Attribute>
  64         bool parse(Iterator& first, Iterator const& last
  65           , Context const& context, RuleContext&, Attribute&) const
  66         {
  67             x3::skip_over(first, last, context);
  68             return true;
  69         }
  70
  71         inline semantic_predicate operator()(bool predicate) const
  72         {
  73             return { predicate };
  74         }
  75
  76         template <typename F>
  77         lazy_semantic_predicate<F> operator()(F f) const
  78         {
  79             return { f };
  80         }
  81     };
  82
  83     auto const eps = eps_parser{};
  84 }}}
  85
  86 #endif