boost spirit qi rules' attribute question - c++

Question

I have the following code can not compile, however I do not know where is the problem:
#include <boost/config/warning_disable.hpp>
#include <boost/spirit/include/qi.hpp>
#include <boost/spirit/include/phoenix_core.hpp>
#include <boost/spirit/include/phoenix_operator.hpp>
#include <boost/spirit/include/phoenix_fusion.hpp>
#include <boost/spirit/include/phoenix_stl.hpp>
#include <boost/fusion/include/adapt_struct.hpp>
#include <boost/variant/recursive_variant.hpp>
#include <boost/foreach.hpp>
#include <iostream>
#include <fstream>
#include <string>
#include <vector>
void print (std::string& s)
{
std::cout << "Get string [" << s << ']' << std::endl;
}
namespace client
{
namespace fusion = boost::fusion;
namespace phoenix = boost::phoenix;
namespace qi = boost::spirit::qi;
namespace ascii = boost::spirit::ascii;
template <typename Iterator>
struct my_grammar
: qi::grammar<Iterator, std::string(), ascii::space_type>
{
my_grammar()
: my_grammar::base_type(start)
{
using qi::lit;
using qi::int_;
using qi::lexeme;
using ascii::char_;
using ascii::string;
using ascii::space_type;
using namespace qi::labels;
// Here you can see the rule oct_char with attribute type as char
// +(char) would be vector<char> which is compactable with string type
// Why the compiler still told me the type of the attribute is not right?
start %= lexeme[+(oct_char)] [&print]
;
oct_char =
lexeme["//"
>> char_('0','3') [ _a = ( _1 - '0' ) ]
|| char_('0','7') [ _a = _a << 3 + ( _1 - '0' ) ]
|| char_('0','7') [ _a = _a << 3 + ( _1 - '0' ) ]]
[ _val = _a ]
;
}
qi::rule<Iterator, std::string(), ascii::space_type> start;
qi::rule<Iterator, char(), qi::locals<char>, ascii::space_type> oct_char;
};
}
int main(int argc, char **argv)
{
typedef client::my_grammar<std::string::const_iterator> Grammer;
Grammer grm;
std::string str;
using boost::spirit::ascii::space;
while (getline(std::cin, str))
{
if (str.empty() || str[0] == 'q' || str[0] == 'Q')
break;
if (phrase_parse(str.begin(), str.end(), grm, space))
{
std::cout << "-------------------------\n";
std::cout << "Parsing succeeded\n";
std::cout << "got: " << str << std::endl;
std::cout << "\n-------------------------\n";
}
else
{
std::cout << "-------------------------\n";
std::cout << "Parsing failed\n";
std::cout << "-------------------------\n";
}
}
std::cout << "Bye... :-) \n\n";
return 0;
}
Here are the error messages:
Error 2 error C2664: 'void (std::basic_string<_Elem,_Traits,_Ax> )' : cannot convert parameter 1 from 'std::vector<_Ty>' to 'std::basic_string<_Elem,_Traits,_Ax> ' d:\code\boost_1_46_1\boost\spirit\home\support\action_dispatch.hpp 70
Is there anyone can give some suggestions?
Thanks

Answer 1

This has been discussed at length elsewhere (for instance here). If you change your print function to take a vector<char> it will work:
void print (std::vector<char> const& s)
{
std::cout << "Get string ["
<< std::string(s.begin(), s.end()) << ']'
<< std::endl;
}
There is one more error in your code, though. The rule oct_char does not need to have a skipper as it is used inside lexeme[]:
qi::rule<Iterator, char(), qi::locals<char> > oct_char;