ceph/src/boost/libs/spirit/include/boost/spirit/home/x3/operator/difference.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_DIFFERENCE_FEBRUARY_11_2007_1250PM)
   8 #define SPIRIT_DIFFERENCE_FEBRUARY_11_2007_1250PM
   9
  10 #include <boost/spirit/home/x3/support/traits/attribute_of.hpp>
  11 #include <boost/spirit/home/x3/support/traits/has_attribute.hpp>
  12 #include <boost/spirit/home/x3/core/parser.hpp>
  13
  14 namespace boost { namespace spirit { namespace x3
  15 {
  16     template <typename Left, typename Right>
  17     struct difference : binary_parser<Left, Right, difference<Left, Right>>
  18     {
  19         typedef binary_parser<Left, Right, difference<Left, Right>> base_type;
  20         static bool const handles_container = Left::handles_container;
  21
  22         difference(Left const& left, Right const& right)
  23           : base_type(left, right) {}
  24
  25         template <typename Iterator, typename Context
  26           , typename RContext, typename Attribute>
  27         bool parse(Iterator& first, Iterator const& last
  28           , Context const& context, RContext& rcontext, Attribute& attr) const
  29         {
  30             // Try Right first
  31             Iterator start = first;
  32             if (this->right.parse(first, last, context, rcontext, unused))
  33             {
  34                 // Right succeeds, we fail.
  35                 first = start;
  36                 return false;
  37             }
  38             // Right fails, now try Left
  39             return this->left.parse(first, last, context, rcontext, attr);
  40         }
  41
  42         template <typename Left_, typename Right_>
  43         difference<Left_, Right_>
  44         make(Left_ const& left, Right_ const& right) const
  45         {
  46             return { left, right };
  47         }
  48     };
  49
  50     template <typename Left, typename Right>
  51     inline difference<
  52         typename extension::as_parser<Left>::value_type
  53       , typename extension::as_parser<Right>::value_type>
  54     operator-(Left const& left, Right const& right)
  55     {
  56         return { as_parser(left), as_parser(right) };
  57     }
  58 }}}
  59
  60 namespace boost { namespace spirit { namespace x3 { namespace traits
  61 {
  62     template <typename Left, typename Right, typename Context>
  63     struct attribute_of<x3::difference<Left, Right>, Context>
  64         : attribute_of<Left, Context> {};
  65
  66     template <typename Left, typename Right, typename Context>
  67     struct has_attribute<x3::difference<Left, Right>, Context>
  68         : has_attribute<Left, Context> {};
  69 }}}}
  70
  71 #endif