std::map using string keys compared backwards

output.txt

map contents in order:
 - three: 3
 - one: 1
 - two: 2
 - four: 4
map["three"]: 3

reverse_map.cpp

#include <algorithm>
#include <map>
#include <string>

template <typename T> struct reverse_compare {
    bool operator()(T const & a, T const & b) const {
        return std::lexicographical_compare(a.rbegin(), a.rend(),
                                            b.rbegin(), b.rend());
    }
};

int main() {
    typedef std::map<std::string, int,
                     reverse_compare<std::string> > reverse_map;
    reverse_map map;
    map["one"] = 1;
    map["two"] = 2;
    map["three"] = 3;
    map["four"] = 4;
    std::cout << "map contents in order:" << std::endl;
    for (reverse_map::const_iterator i = map.begin(), e = map.end(); i != e; ++i)
        std::cout << " - " << i->first << ": " << i->second << std::endl;
    std::cout << "map[\"three\"]: " << map["three"] << std::endl;
}