ceph/src/boost/libs/spirit/example/qi/calc_utree.cpp

   1 /*=============================================================================
   2     Copyright (c) 2001-2011 Hartmut Kaiser
   3     Copyright (c) 2001-2011 Joel de Guzman
   4
   5     Distributed under the Boost Software License, Version 1.0. (See accompanying
   6     file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
   7 =============================================================================*/
   8 ///////////////////////////////////////////////////////////////////////////////
   9 //
  10 //  Plain calculator example demonstrating the grammar. The parser is a
  11 //  syntax checker only and does not do any semantic evaluation.
  12 //
  13 //  [ JDG May 10, 2002 ]        spirit1
  14 //  [ JDG March 4, 2007 ]       spirit2
  15 //  [ HK November 30, 2010 ]    spirit2/utree
  16 //
  17 ///////////////////////////////////////////////////////////////////////////////
  18
  19 // #define BOOST_SPIRIT_DEBUG
  20
  21 #include <boost/config/warning_disable.hpp>
  22 #include <boost/spirit/include/qi.hpp>
  23 #include <boost/spirit/include/support_utree.hpp>
  24 #include <boost/spirit/include/phoenix_operator.hpp>
  25 #include <boost/spirit/include/phoenix_function.hpp>
  26
  27 #include <iostream>
  28 #include <string>
  29
  30 #if BOOST_PHOENIX_VERSION == 0x2000
  31 namespace boost { namespace phoenix
  32 {
  33     // There's a bug in the Phoenix V2 type deduction mechanism that prevents
  34     // correct return type deduction for the math operations below. Newer
  35     // versions of Phoenix will be switching to BOOST_TYPEOF. In the meantime,
  36     // we will use the specializations helping with return type deduction
  37     // below:
  38     template <>
  39     struct result_of_plus<spirit::utree&, spirit::utree&>
  40     {
  41         typedef spirit::utree type;
  42     };
  43
  44     template <>
  45     struct result_of_minus<spirit::utree&, spirit::utree&>
  46     {
  47         typedef spirit::utree type;
  48     };
  49
  50     template <>
  51     struct result_of_multiplies<spirit::utree&, spirit::utree&>
  52     {
  53         typedef spirit::utree type;
  54     };
  55
  56     template <>
  57     struct result_of_divides<spirit::utree&, spirit::utree&>
  58     {
  59         typedef spirit::utree type;
  60     };
  61
  62     template <>
  63     struct result_of_negate<spirit::utree&>
  64     {
  65         typedef spirit::utree type;
  66     };
  67 }}
  68 #endif
  69
  70 namespace client
  71 {
  72     namespace qi = boost::spirit::qi;
  73     namespace ascii = boost::spirit::ascii;
  74     namespace spirit = boost::spirit;
  75
  76     ///////////////////////////////////////////////////////////////////////////////
  77     //  Our calculator grammar
  78     ///////////////////////////////////////////////////////////////////////////////
  79     template <typename Iterator>
  80     struct calculator : qi::grammar<Iterator, ascii::space_type, spirit::utree()>
  81     {
  82         calculator() : calculator::base_type(expression)
  83         {
  84             using qi::uint_;
  85             using qi::_val;
  86             using qi::_1;
  87
  88             expression =
  89                 term                            [_val = _1]
  90                 >> *(   ('+' >> term            [_val = _val + _1])
  91                     |   ('-' >> term            [_val = _val - _1])
  92                     )
  93                 ;
  94
  95             term =
  96                 factor                          [_val = _1]
  97                 >> *(   ('*' >> factor          [_val = _val * _1])
  98                     |   ('/' >> factor          [_val = _val / _1])
  99                     )
 100                 ;
 101
 102             factor =
 103                 uint_                           [_val = _1]
 104                 |   '(' >> expression           [_val = _1] >> ')'
 105                 |   ('-' >> factor              [_val = -_1])
 106                 |   ('+' >> factor              [_val = _1])
 107                 ;
 108
 109             BOOST_SPIRIT_DEBUG_NODE(expression);
 110             BOOST_SPIRIT_DEBUG_NODE(term);
 111             BOOST_SPIRIT_DEBUG_NODE(factor);
 112         }
 113
 114         qi::rule<Iterator, ascii::space_type, spirit::utree()> expression, term, factor;
 115     };
 116 }
 117
 118 ///////////////////////////////////////////////////////////////////////////////
 119 //  Main program
 120 ///////////////////////////////////////////////////////////////////////////////
 121 int main()
 122 {
 123     std::cout << "/////////////////////////////////////////////////////////\n\n";
 124     std::cout << "Expression parser...\n\n";
 125     std::cout << "/////////////////////////////////////////////////////////\n\n";
 126     std::cout << "Type an expression...or [q or Q] to quit\n\n";
 127
 128     using boost::spirit::ascii::space;
 129     using boost::spirit::utree;
 130     typedef std::string::const_iterator iterator_type;
 131     typedef client::calculator<iterator_type> calculator;
 132
 133     calculator calc; // Our grammar
 134
 135     std::string str;
 136     while (std::getline(std::cin, str))
 137     {
 138         if (str.empty() || str[0] == 'q' || str[0] == 'Q')
 139             break;
 140
 141         std::string::const_iterator iter = str.begin();
 142         std::string::const_iterator end = str.end();
 143         utree ut;
 144         bool r = phrase_parse(iter, end, calc, space, ut);
 145
 146         if (r && iter == end)
 147         {
 148             std::cout << "-------------------------\n";
 149             std::cout << "Parsing succeeded: " << ut << "\n";
 150             std::cout << "-------------------------\n";
 151         }
 152         else
 153         {
 154             std::string rest(iter, end);
 155             std::cout << "-------------------------\n";
 156             std::cout << "Parsing failed\n";
 157             std::cout << "stopped at: \": " << rest << "\"\n";
 158             std::cout << "-------------------------\n";
 159         }
 160     }
 161
 162     std::cout << "Bye... :-) \n\n";
 163     return 0;
 164 }
 165
 166