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  1. #include <boost/spirit/include/qi.hpp>
  2. #include <boost/spirit/include/phoenix.hpp>
  3.  
  4. namespace qi    = boost::spirit::qi;
  5. namespace phx   = boost::phoenix;
  6.  
  7. typedef boost::function<double()> Value;
  8.  
  9. #define BINARY_FUNCTOR(name, op)                        \
  10.     struct name                                         \
  11.     {                                                   \
  12.         name(Value x, Value y): x_(x), y_(y) {}         \
  13.         double operator()() { return x_() op y_(); }    \
  14.         Value x_, y_;                                   \
  15.     };
  16.  
  17. BINARY_FUNCTOR(ADD, +)
  18. BINARY_FUNCTOR(SUB, -)
  19. BINARY_FUNCTOR(MUL, *)
  20. BINARY_FUNCTOR(DIV, /)
  21.  
  22. struct LIT
  23. {
  24.     LIT(double x): x_(x) {}
  25.     double operator()()
  26.     {
  27.         return x_;
  28.     }
  29.     double x_;
  30. };
  31.  
  32. struct NEG
  33. {
  34.     NEG(Value x): x_(x) {}
  35.     double operator()()
  36.     {
  37.         return -x_();
  38.     }
  39.     Value x_;
  40. };
  41.  
  42. struct SQRT
  43. {
  44.     SQRT(Value x): x_(x) {}
  45.     double operator()()
  46.     {
  47.         return sqrt(x_());
  48.     }
  49.     Value x_;
  50. };
  51.  
  52. // expression grammar definition
  53. template <typename It, typename Skipper=qi::space_type>
  54. struct parser : qi::grammar<It, Value(),  Skipper>
  55. {
  56.     parser() : parser::base_type(expression)
  57.     {
  58.         using namespace qi;
  59.         expression =
  60.             term                    [_val = _1]
  61.             >> *(('+' >> term       [_val = phx::construct<ADD>(_val, _1)])
  62.                     | ('-' >> term  [_val = phx::construct<SUB>(_val, _1)])
  63.                 );
  64.         term =
  65.             factor                  [_val = _1]
  66.             >> *(('*' >> factor     [_val = phx::construct<MUL>(_val, _1)])
  67.                  | ('/' >> factor   [_val = phx::construct<DIV>(_val, _1)])
  68.                 );
  69.         factor =
  70.             double_                 [_val = phx::construct<LIT>(_1)]
  71.             | '(' >> expression [_val = _1] >> ')'
  72.             | ('-' >> factor        [_val = phx::construct<NEG>(_1)])
  73.             | ('+' >> factor        [_val = _1])
  74.             | (string("SQRT") >> '(' >> expression [_val = phx::construct<SQRT>(_1)] >> ')');
  75.  
  76.         BOOST_SPIRIT_DEBUG_NODE(expression);
  77.         BOOST_SPIRIT_DEBUG_NODE(term);
  78.         BOOST_SPIRIT_DEBUG_NODE(factor);
  79.     }
  80.  
  81.     private:
  82.     qi::rule<It, std::wstring(), Skipper> scientificNumber;
  83.     qi::rule<It, Value(), Skipper> expression, term, factor;
  84.  
  85. };
  86.  
  87.  
  88.  
  89. int main()
  90. {
  91.     const std::wstring testExp = L"3E-10*(12-3)";
  92.  
  93.     typedef std::wstring::const_iterator It;
  94.     It f(testExp.begin()), e(testExp.end());
  95.     parser<It, qi::space_type> expressionParser;
  96.  
  97.     Value logicExpression;
  98.     bool ok = phrase_parse(f,e,expressionParser,qi::space,logicExpression);
  99.  
  100.     std::cout << "Success: " << std::boolalpha << ok << "\tValue: " << logicExpression() << '\n';
  101. }
  102.  
Compilation error #stdin compilation error #stdout 0s 0KB
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stdin
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Standard input is empty
compilation info 
prog.cpp:1:39: fatal error: boost/spirit/include/qi.hpp: No such file or directory
compilation terminated.
stdout
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Standard output is empty
https://ideone.com/mI1ESI
language:
C++ (gcc 8.3)
created:
12 years ago
visibility:
public

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