enums handling should use maps of enum value -> string

[zeule]

Maps are sorted containers, and enums are sorted too. When presenting users a set of choices, like verbosity level, for example, it makes sense to sort them by their value, while the library currently sorts them by their names.

[ljluestc]

#include <iostream>
#include <map>
#include <string>

// Define your enum type
enum class VerbosityLevel {
    Low = 1,
    Medium = 2,
    High = 3,
};

// Custom comparison function for sorting enum values by their underlying value
struct EnumValueComparator {
    template <typename T>
    bool operator()(const T& lhs, const T& rhs) const {
        return static_cast<int>(lhs) < static_cast<int>(rhs);
    }
};

int main() {
    // Create a map with custom comparison function
    std::map<VerbosityLevel, std::string, EnumValueComparator> verbosityMap;
    
    // Populate the map with enum values and their corresponding names
    verbosityMap[VerbosityLevel::High] = "High";
    verbosityMap[VerbosityLevel::Medium] = "Medium";
    verbosityMap[VerbosityLevel::Low] = "Low";
    
    // Iterate and print the sorted enum values and their names
    for (const auto& entry : verbosityMap) {
        std::cout << static_cast<int>(entry.first) << ": " << entry.second << std::endl;
    }

    return 0;
}