Replace Regex class by std::regex

[d3m3t3r]

C++11 introduced a standard implementation for regular expressions std::regex which can easily replace Regex class.

[i-ky]

Hi @d3m3t3r!

Thank you for the suggestion. Looks very neat! Throwing away 50 lines of code must feel nice. 😃

However, there are rumors that std::regex is unbelievably slow, see:

1. https://stackoverflow.com/questions/70583395/why-is-stdregex-notoriously-much-slower-than-other-regular-expression-librarie
2. https://stackoverflow.com/questions/20942450/why-c11-regex-libc-implementation-is-so-slow
3. https://www.reddit.com/r/cpp_questions/comments/yzqgm6/regex_is_comically_slow_high_performance/
4. include-what-you-use/include-what-you-use@cf53880

I haven't done my own research, but I don't have reasons to believe that the above benchmarks are wrong. That's why I went with good old <regex.h>.

Do you have hands on experience with std::regex? Can you say any good words about its performance?