PCC/Start: histogram.cc

#include <iostream>
#include <ext/hash_map>
#include <boost/regex.hpp>

using namespace std;
using namespace __gnu_cxx;
using namespace boost;

namespace __gnu_cxx {
    template<> struct hash< std::string > {
        size_t operator()( const std::string& x ) const {
            return hash< const char* >()( x.c_str() );
        }
    };
}

int main (int argc, char **argv) {
    char *pattern = "(?:R|SP|AP)\\|SensorName=(.*?)\\|[lDBS]";
    regex re(pattern);

    hash_map<string,int> hist;

    string line;
    while (!cin.eof()) {
        getline(cin, line);
        smatch mat;
        if (regex_search(line, mat, re)) {
            ++hist[mat.str(1)];
        }
    }

    for (hash_map<string,int>::const_iterator p = hist.begin(); p != hist.end();  p++) {
        cout << p->first << "\t" << p->second << endl;
    }

    return 0;
}