通过boost :: spirit读取为int的向量失败

Question

我在Fedora 19上的编译器gcc 4.8.1

我的代码是这样的：

#include <iostream>
#include <vector>
#include <string>
#include <boost/spirit/include/qi.hpp>
#include <boost/fusion/adapted.hpp>

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

struct expr {
    std::vector<int> prots;
};

BOOST_FUSION_ADAPT_STRUCT(
    struct expr,
    (std::vector<int>, prots)
)

template <class Iterator>
struct protocol : qi::grammar<Iterator, expr(), ascii::space_type> {
    protocol() : protocol::base_type(start) {
        using namespace qi;

        start %= int_ % ',';
    }

    qi::rule<Iterator, expr(), ascii::space_type> start;
};

int main(int argc, char* argv[]) {
    if (argc < 2)
        return -1;

    std::string str(argv[1]);
    std::string::const_iterator beg = str.begin();
    std::string::const_iterator end = str.end();
    protocol<std::string::const_iterator> g;
    expr e;
    bool r = qi::phrase_parse(beg, end, g, ascii::space, e);
    if (!r || beg != end) {
        std::cout << "parse failed!" << std::endl;
        return -1;
    } else
        std::cout << "parse success!" << std::endl;

    return 0;
}

编译失败，有很多编译器消息。

讯息

/usr/local/include/boost/spirit/home/support/container.hpp:116:12: error: no type named 'value_type' in 'struct expr'
/usr/local/include/boost/spirit/home/qi/detail/pass_container.hpp:296:66: error: no type named 'type' in 'struct boost::spirit::traits::container_value<expr, void>'
/usr/local/include/boost/spirit/home/qi/detail/pass_container.hpp:309:15: error: no type named 'type' in 'struct boost::spirit::traits::container_value<expr, void>'

但是当我把它改成下面时，就编译了。

    std::vector<int> e;
    bool r = qi::phrase_parse(beg, end, (*qi::int_), ascii::space, e);

有人帮忙吗？