ceph/src/boost/libs/spirit/example/x3/actions.cpp

   1 /*=============================================================================
   2     Copyright (c) 2001-2015 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 #include <boost/config/warning_disable.hpp>
   8 #include <boost/spirit/home/x3.hpp>
   9
  10 #include <iostream>
  11
  12 // Presented are various ways to attach semantic actions
  13 //  * Using plain function pointer
  14 //  * Using simple function object
  15
  16 namespace client
  17 {
  18     namespace x3 = boost::spirit::x3;
  19     using x3::_attr;
  20
  21     struct print_action
  22     {
  23         template <typename Context>
  24         void operator()(Context const& ctx) const
  25         {
  26             std::cout << _attr(ctx) << std::endl;
  27         }
  28     };
  29 }
  30
  31 int main()
  32 {
  33     using boost::spirit::x3::int_;
  34     using boost::spirit::x3::parse;
  35     using client::print_action;
  36
  37     { // example using function object
  38
  39         char const *first = "{43}", *last = first + std::strlen(first);
  40         parse(first, last, '{' >> int_[print_action()] >> '}');
  41     }
  42
  43     { // example using C++14 lambda
  44
  45         using boost::spirit::x3::_attr;
  46         char const *first = "{44}", *last = first + std::strlen(first);
  47         auto f = [](auto& ctx){ std::cout << _attr(ctx) << std::endl; };
  48         parse(first, last, '{' >> int_[f] >> '}');
  49     }
  50
  51     return 0;
  52 }