ceph/src/boost/libs/spirit/example/qi/complex_number.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 complex number micro parser.
  10 //
  11 //  [ JDG May 10, 2002 ]    spirit1
  12 //  [ JDG May 9, 2007 ]     spirit2
  13 //
  14 ///////////////////////////////////////////////////////////////////////////////
  15
  16 #include <boost/config/warning_disable.hpp>
  17 #include <boost/spirit/include/qi.hpp>
  18 #include <boost/spirit/include/phoenix_core.hpp>
  19 #include <boost/spirit/include/phoenix_operator.hpp>
  20
  21 #include <iostream>
  22 #include <string>
  23 #include <complex>
  24
  25 ///////////////////////////////////////////////////////////////////////////////
  26 //  Our complex number parser/compiler
  27 ///////////////////////////////////////////////////////////////////////////////
  28 //[tutorial_complex_number
  29 namespace client
  30 {
  31     template <typename Iterator>
  32     bool parse_complex(Iterator first, Iterator last, std::complex<double>& c)
  33     {
  34         using boost::spirit::qi::double_;
  35         using boost::spirit::qi::_1;
  36         using boost::spirit::qi::phrase_parse;
  37         using boost::spirit::ascii::space;
  38         using boost::phoenix::ref;
  39
  40         double rN = 0.0;
  41         double iN = 0.0;
  42         bool r = phrase_parse(first, last,
  43
  44             //  Begin grammar
  45             (
  46                     '(' >> double_[ref(rN) = _1]
  47                         >> -(',' >> double_[ref(iN) = _1]) >> ')'
  48                 |   double_[ref(rN) = _1]
  49             ),
  50             //  End grammar
  51
  52             space);
  53
  54         if (!r || first != last) // fail if we did not get a full match
  55             return false;
  56         c = std::complex<double>(rN, iN);
  57         return r;
  58     }
  59 }
  60 //]
  61
  62 ////////////////////////////////////////////////////////////////////////////
  63 //  Main program
  64 ////////////////////////////////////////////////////////////////////////////
  65 int
  66 main()
  67 {
  68     std::cout << "/////////////////////////////////////////////////////////\n\n";
  69     std::cout << "\t\tA complex number micro parser for Spirit...\n\n";
  70     std::cout << "/////////////////////////////////////////////////////////\n\n";
  71
  72     std::cout << "Give me a complex number of the form r or (r) or (r,i) \n";
  73     std::cout << "Type [q or Q] to quit\n\n";
  74
  75     std::string str;
  76     while (getline(std::cin, str))
  77     {
  78         if (str.empty() || str[0] == 'q' || str[0] == 'Q')
  79             break;
  80
  81         std::complex<double> c;
  82         if (client::parse_complex(str.begin(), str.end(), c))
  83         {
  84             std::cout << "-------------------------\n";
  85             std::cout << "Parsing succeeded\n";
  86             std::cout << "got: " << c << std::endl;
  87             std::cout << "\n-------------------------\n";
  88         }
  89         else
  90         {
  91             std::cout << "-------------------------\n";
  92             std::cout << "Parsing failed\n";
  93             std::cout << "-------------------------\n";
  94         }
  95     }
  96
  97     std::cout << "Bye... :-) \n\n";
  98     return 0;
  99 }
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