#include <string>
#include <sstream>
#include <iostream>
#include <climits>
#include <boost/spirit/core.hpp>
#include <boost/spirit/attribute.hpp>
#include <boost/spirit/phoenix.hpp>
#include <boost/spirit/utility/chset.hpp>

struct ExtractDouble
{
   ExtractDouble(void)
   {}

   template<typename T1, typename T2>
   struct result
   {
      typedef double type;
   };

   template<class IteratorType>
   double operator() (IteratorType a, IteratorType b) const
   {
      std::string tmp;
      tmp.reserve(std::distance(a, b));
      // We have to replace 'd' and 'D' by 'e'
      
      for (IteratorType i = a; i != b; ++i)
      {
         switch(*i)
         {
         case 'd':
         case 'D': tmp.append(1, 'e'); break;
         default:  tmp.append(1, *i);
         }
      }

      std::stringstream s(tmp);
      double value;
      s >> value;
      return (value);
   }
};


struct __declspec(dllexport) ExtRealParserClosure : boost::spirit::closure<ExtRealParserClosure, double>
{
   boost::spirit::closure<ExtRealParserClosure, double>::member1 val;
};

struct __declspec(dllexport) ExtRealParser : public boost::spirit::grammar<ExtRealParser, ExtRealParserClosure::context_t>
{
   template<class Scanner>
   struct definition
   {
      boost::spirit::rule<Scanner> top;

      definition(const ExtRealParser& self)
      {
         using namespace boost::spirit;
         using namespace phoenix;

         chset<> sign("+-");
         chset<> exponentMarker("eEdD");
         function<ExtractDouble> extractDouble;

         top = (!sign >> ((+digit_p >> !(ch_p<>('.') >> *digit_p) >> !(exponentMarker >> !sign >> +digit_p)) |
                                        (ch_p<>('.') >> +digit_p  >> !(exponentMarker >> !sign >> +digit_p))))
                [ self.val =  extractDouble(arg1, arg2) ];
      }

      // Tell Spirit to start parsing with "top"
      boost::spirit::rule<Scanner> const& start() const { return top; }
   };
};

const ExtRealParser ext_real_p;

int main(void)
{
    double result;
    boost::spirit::parse("3.1415", ext_real_p [phoenix::var(result) = phoenix::arg1], 
                                     boost::spirit::space_p);
    std::cout << "Result is " << result << "\n";
}