[boost] [xpressive] How can I get nested match_results?

From: shiwei xu (xushiweizh_at_[hidden])
Date: 2008-05-20 15:16:56

My program is the following.
And my question is:

I can get match_result such as item[time], item[count]. But, how can I get
nested match_results, eg. item[time][year], item[time][month]?

Best Regards,

ShiWei Xu

----
#include <iostream>
#include <boost/xpressive/xpressive.hpp>
using namespace boost::xpressive;
typedef std::string::const_iterator iterator_;
typedef basic_regex<iterator_> regex_;
typedef regex_iterator<iterator_> regex_iterator_;
typedef regex_iterator_::value_type match_results_;
typedef match_results_::value_type sub_match_;
boost::proto::terminal<char>::type const _dot = {'.'};
boost::proto::terminal<char>::type const _gt = {'>'};
boost::proto::terminal<char>::type const _quot = {'\"'};
inline void example()
{
    std::string str = "<tr><td>2008-05-20</td><td>70</td></tr>";
    // define some custom mark_tags with names more meaningful than s1, s2,
etc.
    mark_tag day(1), month(2), year(3), delim(4);
    regex_ rTime = // DateTime value
        (year = repeat<4>(_d)) >>        // year
        (delim = (set='/','-')) >>        // followed by a delimiter ...
        (month = repeat<1,2>(_d)) >> delim >>    // month
        (day = repeat<1,2>(_d))            // day
        ;
    regex_ rInteger = +_d; // Integer value
    regex_ rHtmlProperties =
        +(+_w >> *_s >> '=' >> *_s >> _quot >> *~_quot >> _quot >> *_s);
    mark_tag time(1), count(2);
    regex_ rTrade =
        (("<tr" >> +_s >> rHtmlProperties >> _gt) | "<tr>") >> *_s >>
        "<td>" >> (time = rTime) >> "</td>" >> *_s >>
        "<td>" >> (count = rInteger) >> "</td>" >> *_s >>
        "</tr>"
        ;
    iterator_ first = str.begin();
    iterator_ last = str.end();
    regex_iterator_ cur(first, last, rTrade);
    regex_iterator_ end;
    for( ; cur != end; ++cur )
    {
        match_results_ item = *cur;
        sub_match_ matched = item[0];
        std::cout << matched << '\n';
        std::cout << item[time] << ' ' << item[count] << '\n';
    }
}
///////////////////////////////////////////////////////////////////////////////
// main
int main()
{
    example();
    return 0;
}
///////////////////////////////////////////////////////////////////////////////