#include <boost/config/warning_disable.hpp>
#include <boost/spirit/include/qi.hpp>

#include <iostream>
#include <string>

namespace qi = boost::spirit::qi;
namespace ascii = boost::spirit::ascii;

void onDouble(const double& d) {
    std::cout << "Found: " << d << std::endl;
}

template <typename Iterator>
bool parse_numbers(Iterator first, Iterator last) {
    using qi::double_;
    using qi::phrase_parse;
    using ascii::space;
    bool r = phrase_parse(
        first,
        last,
        double_[&onDouble] >> *(',' >> double_[&onDouble]),
        space
    );
    if (first != last) {
        return false;
    }
    return r;
}

int main() {
    std::string data("21.2, 34,5, 58.4, 56");
    if (parse_numbers(data.begin(), data.end())) {
        std::cout << "It works" << std::endl;
    } else {
        std::cout << "It failed" << std::endl;
    }
    return 0;
}