ceph/src/boost/libs/spirit/example/x3/calc/calc1.cpp

   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 ///////////////////////////////////////////////////////////////////////////////
   8 //
   9 //  Plain calculator example demonstrating the grammar. The parser is a
  10 //  syntax checker only and does not do any semantic evaluation.
  11 //
  12 //  [ JDG May 10, 2002 ]        spirit 1
  13 //  [ JDG March 4, 2007 ]       spirit 2
  14 //  [ JDG February 21, 2011 ]   spirit 2.5
  15 //  [ JDG June 6, 2014 ]        spirit x3
  16 //
  17 ///////////////////////////////////////////////////////////////////////////////
  18
  19 #include <boost/spirit/home/x3.hpp>
  20 #include <boost/spirit/home/x3/support/ast/variant.hpp>
  21 #include <boost/fusion/include/adapt_struct.hpp>
  22
  23 #include <iostream>
  24 #include <string>
  25 #include <list>
  26 #include <numeric>
  27
  28 namespace x3 = boost::spirit::x3;
  29
  30 namespace client
  31 {
  32     ///////////////////////////////////////////////////////////////////////////////
  33     //  The calculator grammar
  34     ///////////////////////////////////////////////////////////////////////////////
  35     namespace calculator_grammar
  36     {
  37         using x3::uint_;
  38         using x3::char_;
  39
  40         x3::rule<class expression> const expression("expression");
  41         x3::rule<class term> const term("term");
  42         x3::rule<class factor> const factor("factor");
  43
  44         auto const expression_def =
  45             term
  46             >> *(   ('+' >> term)
  47                 |   ('-' >> term)
  48                 )
  49             ;
  50
  51         auto const term_def =
  52             factor
  53             >> *(   ('*' >> factor)
  54                 |   ('/' >> factor)
  55                 )
  56             ;
  57
  58         auto const factor_def =
  59                 uint_
  60             |   '(' >> expression >> ')'
  61             |   ('-' >> factor)
  62             |   ('+' >> factor)
  63             ;
  64
  65         BOOST_SPIRIT_DEFINE(
  66             expression
  67           , term
  68           , factor
  69         );
  70
  71         auto calculator = expression;
  72     }
  73
  74     using calculator_grammar::calculator;
  75
  76 }
  77
  78 ///////////////////////////////////////////////////////////////////////////////
  79 //  Main program
  80 ///////////////////////////////////////////////////////////////////////////////
  81 int
  82 main()
  83 {
  84     std::cout << "/////////////////////////////////////////////////////////\n\n";
  85     std::cout << "Expression parser...\n\n";
  86     std::cout << "/////////////////////////////////////////////////////////\n\n";
  87     std::cout << "Type an expression...or [q or Q] to quit\n\n";
  88
  89     typedef std::string::const_iterator iterator_type;
  90
  91     std::string str;
  92     while (std::getline(std::cin, str))
  93     {
  94         if (str.empty() || str[0] == 'q' || str[0] == 'Q')
  95             break;
  96
  97         auto& calc = client::calculator;    // Our grammar
  98
  99         iterator_type iter = str.begin();
 100         iterator_type end = str.end();
 101         boost::spirit::x3::ascii::space_type space;
 102         bool r = phrase_parse(iter, end, calc, space);
 103
 104         if (r && iter == end)
 105         {
 106             std::cout << "-------------------------\n";
 107             std::cout << "Parsing succeeded\n";
 108             std::cout << "-------------------------\n";
 109         }
 110         else
 111         {
 112             std::string rest(iter, end);
 113             std::cout << "-------------------------\n";
 114             std::cout << "Parsing failed\n";
 115             std::cout << "stopped at: \"" << rest << "\"\n";
 116             std::cout << "-------------------------\n";
 117         }
 118     }
 119
 120     std::cout << "Bye... :-) \n\n";
 121     return 0;
 122 }