locale-unaware solution to cpp test

cpptestsol-locale-unaware.cc

#include <algorithm>
#include <codecvt>
#include <fstream>
#include <iostream>
#include <locale>
#include <string>
#include <tuple>
#include <unordered_map>
#include <vector>
 
using namespace std;

struct delims : ctype<wchar_t> {
    delims(locale& ru) : ru(ru) {}
    bool do_is(mask m, char_type c) const {   
        return (m & space) ? !isalpha(c, ru) : ctype::do_is(m, c);
    }
    locale& ru;
};

int main(int argc, const char* argv[]) try {
	locale ru(locale(argc>3 ? argv[3] : ""), new std::codecvt_utf8<wchar_t>);
	ios_base::sync_with_stdio(false);
 
	wifstream inf;
	if (argc>1) inf.open(argv[1]), wcin.rdbuf(inf.rdbuf());
	wcin.imbue(locale(ru, new delims(ru)));
 
	wofstream outf;
	if (argc>2) outf.open(argv[2]), wcout.rdbuf(outf.rdbuf());
	wcout.imbue(ru);
 
	unordered_map<wstring, int> dict;
	for(wstring s; wcin >> s;) {
		transform(begin(s),end(s), begin(s),
			[&ru](auto c) { return tolower(c, ru);});
		++dict[s];
	}
 
	vector<pair<wstring,int>> result(begin(dict),end(dict));
	sort(begin(result),end(result),
		[&ru](auto& a, auto& b) {
                      return tie(b.second,a.first)<tie(a.second,b.first);
		});
 
	for(auto& i : result) wcout << i.second << " " << i.first << "\n";
	return 0;
} catch(exception& e) { cout << e.what() << endl; }