cmd_line_args_manager.cpp

#include <string>
#include <algorithm>
#include <vector>
#include <tuple>
#include <iostream>
#include <optional>


void usage(const std::string& progName) {
  std::cout << progName << " -X FILE -P FILE -O DIRECTORY " << std::endl
            << "Options:"                        << std::endl
            << "-h  | --help    Print this help" << std::endl
            << "-X              Path to X file"  << std::endl
            << "-P              Path to P file"  << std::endl
            << "-O              Path to output directory." << std::endl;
}

class cmdline_args_parser{
    public:
        cmdline_args_parser (const int argc, char **argv){
            for (int i=0; i < argc; ++i)
                tokens.push_back(std::string(argv[i]));          
        }

        const std::optional<std::string> getCmdOption(const std::string &option) const{
            auto  itr =  std::find(tokens.begin(), tokens.end(), option);
            if (itr != tokens.end() && ++itr != tokens.end())
                return std::optional(*(itr));           
           return std::nullopt;
        }
    
        template<typename... Options>
        const auto get_all_options(const Options... ops) const{
            std::vector<std::optional<std::string>> v;
            (v.push_back(getCmdOption(ops)), ...);
            return v;
        }

        bool cmdOptionExists(const std::string &option) const{
            return 
                std::find(tokens.begin(), tokens.end(), option) != tokens.end();
        }
 
        template<typename... Options>
        bool all_options_exists(const Options... opts) const{
            return (... && cmdOptionExists(opts)); 
        }
        template<typename... Options>
        bool any_options_exists(const Options... opts) const{
            return (... || cmdOptionExists(opts)); 
        }
    
        const std::string& get_program_name() const{ return tokens[0]; }
    
    private:
        std::vector<std::string> tokens;
};


auto process_args(const cmdline_args_parser& p){
    auto opts = p.get_all_options("-X","-O","-P");
    if(p.any_options_exists("-h", "--help") || 
       !all_of(begin(opts), end(opts), [](const  auto& x ){return x;}) )
    {
        usage(p.get_program_name());
        return;
    }
    for(const auto opt : opts){
        std::cout<<opt.value()<<std::endl;
    }
}

int main(int argc, char** argv){
cmdline_args_parser p (argc, argv);
process_args(p);    

  return 0;
}