ceph/src/boost/libs/spirit/include/boost/spirit/home/x3/auxiliary/guard.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_GUARD_FERBRUARY_02_2013_0649PM)
   8 #define BOOST_SPIRIT_X3_GUARD_FERBRUARY_02_2013_0649PM
   9
  10 #include <boost/spirit/home/x3/support/context.hpp>
  11 #include <boost/spirit/home/x3/directive/expect.hpp>
  12
  13 namespace boost { namespace spirit { namespace x3
  14 {
  15     enum class error_handler_result
  16     {
  17         fail
  18       , retry
  19       , accept
  20       , rethrow
  21     };
  22
  23     template <typename Subject, typename Handler>
  24     struct guard : unary_parser<Subject, guard<Subject, Handler>>
  25     {
  26         typedef unary_parser<Subject, guard<Subject, Handler>> base_type;
  27         static bool const is_pass_through_unary = true;
  28
  29         guard(Subject const& subject, Handler handler)
  30           : base_type(subject), handler(handler) {}
  31
  32         template <typename Iterator, typename Context
  33           , typename RuleContext, typename Attribute>
  34         bool parse(Iterator& first, Iterator const& last
  35           , Context const& context, RuleContext& rcontext, Attribute& attr) const
  36         {
  37             for (;;)
  38             {
  39                 try
  40                 {
  41                     Iterator i = first;
  42                     bool r = this->subject.parse(i, last, context, rcontext, attr);
  43                     if (r)
  44                         first = i;
  45                     return r;
  46                 }
  47                 catch (expectation_failure<Iterator> const& x)
  48                 {
  49                     switch (handler(first, last, x, context))
  50                     {
  51                         case error_handler_result::fail:
  52                             return false;
  53                         case error_handler_result::retry:
  54                             continue;
  55                         case error_handler_result::accept:
  56                             return true;
  57                         case error_handler_result::rethrow:
  58                             throw;
  59                     }
  60                 }
  61             }
  62             return false;
  63         }
  64
  65         Handler handler;
  66     };
  67 }}}
  68
  69 #endif