Using semantic actions with synthesized attributes. Do the attributes only get matched with the part of the rule that lacks actions? Or the whole thing?

gistfile1.cpp

// a test case for combining semantic actions with synthesized attributes in the same rule

#include <iostream>
#include <vector>
#include <string>
#include <iterator>

#include <boost/spirit/include/qi.hpp>
#include <boost/spirit/include/phoenix.hpp>

void action_func(std::string const& a, std::string const& b)
{
   std::cout << "a=" << a << ", b=" << b << std::endl;
}

int main()
{
   typedef std::string::iterator Iterator;

   namespace qi = boost::spirit::qi;
   using boost::spirit::_1;
   using boost::spirit::_2;
   using boost::phoenix::bind;

   typedef std::vector<std::string> result_t;
   boost::spirit::qi::rule<Iterator, result_t()> testrule;
   // things that compile successfully:
   // testrule %= qi::string("A") >> qi::string("B") >> qi::string("C") ; // does not call action
   // testrule %= qi::string("A") >> (qi::string("B") >> qi::string("C")) ; // does not call action
   // these do not store the synthesized attribute:
   // testrule = (qi::string("A") >> qi::string("B") >> qi::string("C"))[bind(action_func, _1, _2)] ;
   // testrule = qi::string("A") >> (qi::string("B") >> qi::string("C"))[bind(action_func, _1, _2)] ;

   // things that fail to compile entirely
//   testrule %= (qi::string("A") >> qi::string("B") >> qi::string("C"))[bind(action_func, _1, _2)] ;
//   testrule %= qi::string("A") >> (qi::string("B") >> qi::string("C"))[bind(action_func, _1, _2)];

   std::string testdata("ABC");
   result_t result;
   Iterator beg = testdata.begin();
   if (!qi::parse(beg, testdata.end(), testrule, result))
   {
      std::cerr << "parse failed" << std::endl;
      return 1;
   }
   if (beg != testdata.end())
   {
      std::cerr << "not all input consumed! Remaining: ";
      std::copy(beg, testdata.end(), std::ostream_iterator<char>(std::cerr, ""));
      std::cerr << std::endl;
      return 2;
   }

   std::cout << "parsed vector result:" << std::endl;
   std::copy(result.begin(), result.end(), std::ostream_iterator<std::string>(std::cout, "\n"));

   return 0;
}