ceph/src/boost/libs/spirit/example/x3/calc/calc2.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 //  A Calculator example demonstrating the grammar and semantic actions
  10 //  using lambda functions. The parser prints code suitable for a stack
  11 //  based virtual machine.
  12 //
  13 //  [ JDG May 10, 2002 ]        spirit 1
  14 //  [ JDG March 4, 2007 ]       spirit 2
  15 //  [ JDG February 21, 2011 ]   spirit 2.5
  16 //  [ JDG June 6, 2014 ]        spirit x3 (from qi calc2, but using lambda functions)
  17 //
  18 ///////////////////////////////////////////////////////////////////////////////
  19
  20 #include <boost/spirit/home/x3.hpp>
  21 #include <boost/spirit/home/x3/support/ast/variant.hpp>
  22 #include <boost/fusion/include/adapt_struct.hpp>
  23
  24 #include <iostream>
  25 #include <string>
  26 #include <list>
  27 #include <numeric>
  28
  29 namespace x3 = boost::spirit::x3;
  30
  31 namespace client
  32 {
  33     ///////////////////////////////////////////////////////////////////////////////
  34     //  Semantic actions
  35     ////////////////////////////////////////////////////////1///////////////////////
  36     namespace
  37     {
  38         using x3::_attr;
  39
  40         auto do_int     = [](auto& ctx) { std::cout << "push " << _attr(ctx) << std::endl; };
  41         auto do_add     = []{ std::cout << "add\n"; };
  42         auto do_subt    = []{ std::cout << "subtract\n"; };
  43         auto do_mult    = []{ std::cout << "mult\n"; };
  44         auto do_div     = []{ std::cout << "divide\n"; };
  45         auto do_neg     = []{ std::cout << "negate\n"; };
  46     }
  47
  48     ///////////////////////////////////////////////////////////////////////////////
  49     //  The calculator grammar
  50     ///////////////////////////////////////////////////////////////////////////////
  51     namespace calculator_grammar
  52     {
  53         using x3::uint_;
  54         using x3::char_;
  55
  56         x3::rule<class expression> const expression("expression");
  57         x3::rule<class term> const term("term");
  58         x3::rule<class factor> const factor("factor");
  59
  60         auto const expression_def =
  61             term
  62             >> *(   ('+' >> term            [do_add])
  63                 |   ('-' >> term            [do_subt])
  64                 )
  65             ;
  66
  67         auto const term_def =
  68             factor
  69             >> *(   ('*' >> factor          [do_mult])
  70                 |   ('/' >> factor          [do_div])
  71                 )
  72             ;
  73
  74         auto const factor_def =
  75                 uint_                       [do_int]
  76             |   '(' >> expression >> ')'
  77             |   ('-' >> factor              [do_neg])
  78             |   ('+' >> factor)
  79             ;
  80
  81         BOOST_SPIRIT_DEFINE(
  82             expression
  83           , term
  84           , factor
  85         );
  86
  87         auto calculator = expression;
  88     }
  89
  90     using calculator_grammar::calculator;
  91
  92 }
  93
  94 ///////////////////////////////////////////////////////////////////////////////
  95 //  Main program
  96 ///////////////////////////////////////////////////////////////////////////////
  97 int
  98 main()
  99 {
 100     std::cout << "/////////////////////////////////////////////////////////\n\n";
 101     std::cout << "Expression parser...\n\n";
 102     std::cout << "/////////////////////////////////////////////////////////\n\n";
 103     std::cout << "Type an expression...or [q or Q] to quit\n\n";
 104
 105     typedef std::string::const_iterator iterator_type;
 106
 107     std::string str;
 108     while (std::getline(std::cin, str))
 109     {
 110         if (str.empty() || str[0] == 'q' || str[0] == 'Q')
 111             break;
 112
 113         auto& calc = client::calculator;    // Our grammar
 114
 115         iterator_type iter = str.begin();
 116         iterator_type end = str.end();
 117         boost::spirit::x3::ascii::space_type space;
 118         bool r = phrase_parse(iter, end, calc, space);
 119
 120         if (r && iter == end)
 121         {
 122             std::cout << "-------------------------\n";
 123             std::cout << "Parsing succeeded\n";
 124             std::cout << "-------------------------\n";
 125         }
 126         else
 127         {
 128             std::string rest(iter, end);
 129             std::cout << "-------------------------\n";
 130             std::cout << "Parsing failed\n";
 131             std::cout << "stopped at: \"" << rest << "\"\n";
 132             std::cout << "-------------------------\n";
 133         }
 134     }
 135
 136     std::cout << "Bye... :-) \n\n";
 137     return 0;
 138 }