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

   1 /*=============================================================================
   2     Copyright (c) 2001-2011 Hartmut Kaiser
   3     http://spirit.sourceforge.net/
   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 //[porting_guide_qi_includes
   9 #include <boost/spirit/include/qi.hpp>
  10 #include <boost/spirit/include/phoenix_operator.hpp>
  11 #include <iostream>
  12 #include <string>
  13 #include <algorithm>
  14 //]
  15
  16 //[porting_guide_qi_namespace
  17 using namespace boost::spirit;
  18 //]
  19
  20 //[porting_guide_qi_grammar
  21 template <typename Iterator>
  22 struct roman : qi::grammar<Iterator, unsigned()>
  23 {
  24     roman() : roman::base_type(first)
  25     {
  26         hundreds.add
  27             ("C"  , 100)("CC"  , 200)("CCC"  , 300)("CD" , 400)("D" , 500)
  28             ("DC" , 600)("DCC" , 700)("DCCC" , 800)("CM" , 900) ;
  29
  30         tens.add
  31             ("X"  , 10)("XX"  , 20)("XXX"  , 30)("XL" , 40)("L" , 50)
  32             ("LX" , 60)("LXX" , 70)("LXXX" , 80)("XC" , 90) ;
  33
  34         ones.add
  35             ("I"  , 1)("II"  , 2)("III"  , 3)("IV" , 4)("V" , 5)
  36             ("VI" , 6)("VII" , 7)("VIII" , 8)("IX" , 9) ;
  37
  38         // qi::_val refers to the attribute of the rule on the left hand side
  39         first = eps          [qi::_val = 0]
  40             >>  (  +lit('M') [qi::_val += 1000]
  41                 ||  hundreds [qi::_val += qi::_1]
  42                 ||  tens     [qi::_val += qi::_1]
  43                 ||  ones     [qi::_val += qi::_1]
  44                 ) ;
  45     }
  46
  47     qi::rule<Iterator, unsigned()> first;
  48     qi::symbols<char, unsigned> hundreds;
  49     qi::symbols<char, unsigned> tens;
  50     qi::symbols<char, unsigned> ones;
  51 };
  52 //]
  53
  54 int main()
  55 {
  56     {
  57         //[porting_guide_qi_parse
  58         std::string input("1,1");
  59         std::string::iterator it = input.begin();
  60         bool result = qi::parse(it, input.end(), qi::int_);
  61
  62         if (result)
  63             std::cout << "successful match!\n";
  64
  65         if (it == input.end())
  66             std::cout << "full match!\n";
  67         else
  68             std::cout << "stopped at: " << std::string(it, input.end()) << "\n";
  69
  70         // seldomly needed: use std::distance to calculate the length of the match
  71         std::cout << "matched length: " << std::distance(input.begin(), it) << "\n";
  72         //]
  73     }
  74
  75     {
  76         //[porting_guide_qi_phrase_parse
  77         std::string input(" 1, 1");
  78         std::string::iterator it = input.begin();
  79         bool result = qi::phrase_parse(it, input.end(), qi::int_, ascii::space);
  80
  81         if (result)
  82             std::cout << "successful match!\n";
  83
  84         if (it == input.end())
  85             std::cout << "full match!\n";
  86         else
  87             std::cout << "stopped at: " << std::string(it, input.end()) << "\n";
  88
  89         // seldomly needed: use std::distance to calculate the length of the match
  90         std::cout << "matched length: " << std::distance(input.begin(), it) << "\n";
  91         //]
  92     }
  93
  94     {
  95         //[porting_guide_qi_use_grammar
  96         std::string input("MMIX");        // MMIX == 2009
  97         std::string::iterator it = input.begin();
  98         unsigned value = 0;
  99         roman<std::string::iterator> r;
 100         if (qi::parse(it, input.end(), r, value))
 101             std::cout << "successfully matched: " << value << "\n";
 102         //]
 103     }
 104     return 0;
 105 }
 106