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  1. #include <boost/fusion/adapted/std_pair.hpp>
  2. #include <boost/spirit/include/qi.hpp>
  3. #include <boost/spirit/include/phoenix.hpp>
  4. #include <boost/spirit/include/phoenix_fusion.hpp>
  5.  
  6. namespace qi    = boost::spirit::qi;
  7. namespace phx   = boost::phoenix;
  8.  
  9. typedef std::string column_name_t;
  10.  
  11. enum sql_faggregate
  12. {
  13.     AVG,
  14.     // ....
  15.     SUM,
  16. };
  17.  
  18. typedef std::pair<column_name_t, int/*sql_faggregate*/> column_and_aggregate;
  19. typedef std::vector<column_and_aggregate> column_and_aggregate_container;
  20.  
  21. namespace parsers
  22. {
  23.     typedef std::string::const_iterator iterator;
  24.  
  25.     qi::rule< iterator, column_name_t() > quoted_string = 
  26.         qi::lexeme["\"" >> +~qi::char_("\"") >> "\""];
  27.     qi::rule< iterator, column_and_aggregate(), qi::space_type > agg_pair =
  28.         quoted_string  [ phx::at_c<0>(qi::_val) = qi::_1 ]
  29.         > ':'
  30.         // A rule validation technic is used below.
  31.         > qi::int_[qi::_pass = (qi::_1 >=AVG && qi::_1<=SUM), phx::at_c<1>(qi::_val) = qi::_1];//::boost::bind( &apply_col_and_aggr_visitor, qi::_val, qi::_1 )];
  32.     qi::rule< iterator, column_and_aggregate_container(), qi::space_type > aggregates_parser =
  33.         '{'
  34.         > agg_pair/*[phoenix::push_back(qi::_val, qi::_1)]*/ % ',' // N.B.!!! list-redux technic
  35.         > '}';
  36. }
  37.  
  38. bool doParse(const std::string& input)
  39. {
  40.     using namespace parsers;
  41.  
  42.     auto f(begin(input)), l(end(input));
  43.  
  44.     //parser<iterator, qi::space_type> p;
  45.     column_and_aggregate_container data;
  46.     try
  47.     {
  48.         bool ok = qi::phrase_parse(f,l,aggregates_parser,qi::space,data);
  49.         if (ok)   
  50.         {
  51.             std::cout << "parse success\n";
  52.             for (auto& pair : data)
  53.                 std::cout << "result: '" << pair.first << "' : " << (int) pair.second << "\n";
  54.         }
  55.         else      std::cerr << "parse failed: '" << std::string(f,l) << "'\n";
  56.  
  57.         if (f!=l) std::cerr << "trailing unparsed: '" << std::string(f,l) << "'\n";
  58.         return ok;
  59.     }
  60.     catch(const qi::expectation_failure<iterator>& e)
  61.     {
  62.         std::string frag(e.first, e.last);
  63.         std::cerr << e.what() << "'" << frag << "'\n";
  64.     }
  65.  
  66.     return false;
  67. }
  68.  
  69. int main()
  70. {
  71.     //bool ok = doParse("{ 'column 1' : 1, 'column 2' : 0, 'column 3' : 1 }");
  72.     doParse("{ \"column 1\" : 1, \"column 2\" : 0, \"column 3\" : 1 }");
  73.     //return ok? 0 : 255;
  74. }
  75.  
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https://ideone.com/0vjeKE
language:
C++14 (gcc 8.3)
created:
10 years ago
visibility:
secret

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