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

   1 /*=============================================================================
   2     Copyright (c) 2002-2010 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 parser for summing a comma-separated list of numbers using phoenix.
  10 //
  11 //  [ JDG June 28, 2002 ]   spirit1
  12 //  [ JDG March 24, 2007 ]  spirit2
  13 //
  14 ///////////////////////////////////////////////////////////////////////////////
  15
  16 #include <boost/config/warning_disable.hpp>
  17 //[tutorial_adder_includes
  18 #include <boost/spirit/include/qi.hpp>
  19 #include <boost/spirit/include/phoenix_core.hpp>
  20 #include <boost/spirit/include/phoenix_operator.hpp>
  21 #include <iostream>
  22 #include <string>
  23 //]
  24
  25 namespace client
  26 {
  27     //[tutorial_adder_using
  28     namespace qi = boost::spirit::qi;
  29     namespace ascii = boost::spirit::ascii;
  30     namespace phoenix = boost::phoenix;
  31
  32     using qi::double_;
  33     using qi::_1;
  34     using ascii::space;
  35     using phoenix::ref;
  36     //]
  37
  38     ///////////////////////////////////////////////////////////////////////////
  39     //  Our adder
  40     ///////////////////////////////////////////////////////////////////////////
  41
  42     //[tutorial_adder
  43     template <typename Iterator>
  44     bool adder(Iterator first, Iterator last, double& n)
  45     {
  46         bool r = qi::phrase_parse(first, last,
  47
  48             //  Begin grammar
  49             (
  50                 double_[ref(n) = _1] >> *(',' >> double_[ref(n) += _1])
  51             )
  52             ,
  53             //  End grammar
  54
  55             space);
  56
  57         if (first != last) // fail if we did not get a full match
  58             return false;
  59         return r;
  60     }
  61     //]
  62 }
  63
  64 ////////////////////////////////////////////////////////////////////////////
  65 //  Main program
  66 ////////////////////////////////////////////////////////////////////////////
  67 int
  68 main()
  69 {
  70     std::cout << "/////////////////////////////////////////////////////////\n\n";
  71     std::cout << "\t\tA parser for summing a list of numbers...\n\n";
  72     std::cout << "/////////////////////////////////////////////////////////\n\n";
  73
  74     std::cout << "Give me a comma separated list of numbers.\n";
  75     std::cout << "The numbers are added using Phoenix.\n";
  76     std::cout << "Type [q or Q] to quit\n\n";
  77
  78     std::string str;
  79     while (getline(std::cin, str))
  80     {
  81         if (str.empty() || str[0] == 'q' || str[0] == 'Q')
  82             break;
  83
  84         double n;
  85         if (client::adder(str.begin(), str.end(), n))
  86         {
  87             std::cout << "-------------------------\n";
  88             std::cout << "Parsing succeeded\n";
  89             std::cout << str << " Parses OK: " << std::endl;
  90
  91             std::cout << "sum = " << n;
  92             std::cout << "\n-------------------------\n";
  93         }
  94         else
  95         {
  96             std::cout << "-------------------------\n";
  97             std::cout << "Parsing failed\n";
  98             std::cout << "-------------------------\n";
  99         }
 100     }
 101
 102     std::cout << "Bye... :-) \n\n";
 103     return 0;
 104 }
 105
 106