boost spirit, boost any and quoted string - compile-time error - c++

Question

I have the following code:
#include <boost/any.hpp>
#include <boost/spirit/include/qi.hpp>
#include <iostream>
#include <string>
template <typename Iterator>
struct parser : boost::spirit::qi::grammar<Iterator, boost::any(), boost::spirit::qi::ascii::space_type>
{
parser() : parser::base_type(start)
{
start %= boost::spirit::qi::int_ | boost::spirit::qi::lexeme['"' >> +(boost::spirit::qi::char_ - '"') >> '"']; // example: 0 or "str"
}
boost::spirit::qi::rule<Iterator, boost::any(), boost::spirit::qi::ascii::space_type> start;
};
int main()
{
const std::string input_data("\"str\"");
boost::any var = 0;
auto itr = input_data.begin();
auto end = input_data.end();
parser<decltype(itr)> g;
bool res = boost::spirit::qi::phrase_parse(itr, end, g, boost::spirit::ascii::space, var);
if (res && itr == end)
{
std::cout << "Parsing succeeded \n";
try
{
std::cout << boost::any_cast<std::string>(var) << '\n';
}
catch (const boost::bad_any_cast& ex)
{
std::cerr << ex.what() << '\n';
}
}
else
{
std::cout << "Parsing failed \n";
}
}
It compiles fine until I add
boost::spirit::qi::lexeme['"' >> +(boost::spirit::qi::char_ - '"') >> '"']
I can't post the errors here and on pastie.org because of the characters amount limitations.
What am I doing wrong? How can I fix it?

Answer 1

Again, why would you want to complicate matters and make it slow by using boost::any?
Anyways, +char_ exposes std::vector<char> and apparently the attribute compatibility rules don't want to decide what to transform this to.
Make it explicit with as_string: Live On Coliru
#include <boost/any.hpp>
#include <boost/spirit/include/qi.hpp>
#include <iostream>
#include <string>
template <typename Iterator>
struct parser : boost::spirit::qi::grammar<Iterator, boost::any(), boost::spirit::qi::ascii::space_type>
{
parser() : parser::base_type(start)
{
using namespace boost::spirit::qi;
start %= int_ | as_string [ lexeme['"' >> +(char_ - '"') >> '"'] ]; // example: 0 or "str"
}
boost::spirit::qi::rule<Iterator, boost::any(), boost::spirit::qi::ascii::space_type> start;
};
int main()
{
// const std::string input_data("\"str\"");
const std::string input_data("123");
for (std::string const& input_data : { "\"str\"", "123" })
{
boost::any var = boost::none;
auto itr = input_data.begin();
auto end = input_data.end();
parser<decltype(itr)> g;
bool res = boost::spirit::qi::phrase_parse(itr, end, g, boost::spirit::ascii::space, var);
if (res && itr == end)
{
std::cout << "Parsing succeeded \n";
try { std::cout << boost::any_cast<int> (var) << '\n'; } catch (const boost::bad_any_cast& ex) { std::cerr << ex.what() << '\n'; }
try { std::cout << boost::any_cast<std::string>(var) << '\n'; } catch (const boost::bad_any_cast& ex) { std::cerr << ex.what() << '\n'; }
}
else
{
std::cout << "Parsing failed \n";
}
}
}