Log Line Parser

#define BOOST_SPIRIT_DEBUG 1
// ============================================================================
#include <boost/spirit/include/qi.hpp>
#include <boost/fusion/include/adapt_struct.hpp>
// ============================================================================
namespace qi = boost::spirit::qi;
// ============================================================================
struct log_entry_t
{
    std::string element_0;
    std::string element_1;
    int32_t element_2;
    int32_t element_3;
    int32_t element_4;
    int32_t element_5;
    std::string element_6;
    std::string element_7;
    std::string element_8;
};
// ============================================================================
BOOST_FUSION_ADAPT_STRUCT(
    log_entry_t
    , (std::string, element_0)
    , (std::string, element_1)
    , (int32_t, element_2)
    , (int32_t, element_3)
    , (int32_t, element_4)
    , (int32_t, element_5)
    , (std::string, element_6)
    , (std::string, element_7)
    , (std::string, element_8)
)
// ============================================================================
// Sample log entry:
// ^+ line-17532.dyn.kponet.fi      2   7   377     1   +1503us[+9103us] +/-   55ms
//
template <typename Iterator>
struct log_line_parser
    : qi::grammar<Iterator, log_entry_t(), boost::spirit::ascii::space_type>
{
    typedef boost::spirit::ascii::space_type skipper_t;

    log_line_parser()
        : log_line_parser::base_type(log_line)
    {
        element_0 %= qi::string("^+");
        element_1 %= +qi::char_("-.a-zA-Z0-9");
        element_2 %= qi::int_;
        element_3 %= qi::int_;
        element_4 %= qi::int_;
        element_5 %= qi::int_;
        element_6 %= qi::raw[qi::char_('+') >> qi::int_ >> time_unit];
        element_7 %= qi::raw[qi::char_('+') >> qi::int_ >> time_unit];
        element_8 %= qi::raw[qi::int_ >> time_unit];

        time_unit %= -qi::char_("nmu") >> qi::char_('s');

        log_line
            %=  element_0
            >>  element_1
            >>  element_2
            >>  element_3
            >>  element_4
            >>  element_5
            >>  element_6
            >>  qi::lit('[') >> element_7 >> qi::lit(']')
            >>  qi::lit("+/-")
            >>  element_8
            ;

        init_debug();
    }

    void init_debug()
    {
        BOOST_SPIRIT_DEBUG_NODE(element_0);
        BOOST_SPIRIT_DEBUG_NODE(element_1);
        BOOST_SPIRIT_DEBUG_NODE(element_2);
        BOOST_SPIRIT_DEBUG_NODE(element_3);
        BOOST_SPIRIT_DEBUG_NODE(element_4);
        BOOST_SPIRIT_DEBUG_NODE(element_5);
        BOOST_SPIRIT_DEBUG_NODE(element_6);
        BOOST_SPIRIT_DEBUG_NODE(element_7);
        BOOST_SPIRIT_DEBUG_NODE(element_8);

        BOOST_SPIRIT_DEBUG_NODE(time_unit);

        BOOST_SPIRIT_DEBUG_NODE(log_line);
    }

private:
    qi::rule<Iterator, std::string()> element_0;
    qi::rule<Iterator, std::string()> element_1;
    qi::rule<Iterator, int32_t()> element_2;
    qi::rule<Iterator, int32_t()> element_3;
    qi::rule<Iterator, int32_t()> element_4;
    qi::rule<Iterator, int32_t()> element_5;
    qi::rule<Iterator, std::string()> element_6;
    qi::rule<Iterator, std::string()> element_7;
    qi::rule<Iterator, std::string()> element_8;

    qi::rule<Iterator, std::string()> time_unit;

    qi::rule<Iterator, log_entry_t(), skipper_t> log_line;
};
// ============================================================================
int main()
{
    std::string log("^+ line-17532.dyn.kponet.fi      2   7   377     1   +1503us[+9103us] +/-   55ms");


    std::string::const_iterator iter(log.begin());
    std::string::const_iterator end(log.end());

    log_line_parser<std::string::const_iterator> g;

    log_entry_t entry;

    using boost::spirit::ascii::space;
    bool r(qi::phrase_parse(iter, end, g, space, entry));

    std::cout << "-------------------------\n";

    if (r && (iter == end)) {
        std::cout << "Parsing succeeded\n";
        std::cout << entry.element_0 << "\n"
            << entry.element_1 << "\n"
            << entry.element_2 << "\n"
            << entry.element_3 << "\n"
            << entry.element_4 << "\n"
            << entry.element_5 << "\n"
            << entry.element_6 << "\n"
            << entry.element_7 << "\n"
            << entry.element_8 << "\n";
        return 0;
    } else {
        std::string::const_iterator some = iter + 30;
        std::string context(iter, (some > end) ? end : some);
        std::cout << "Parsing failed\n";
        std::cout << "stopped at: \": " << context << "...\"\n";
        return 1;
    }
}
// ============================================================================