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#include <iostream> #include <optional> #include <experimental/meta> #include <experimental/compiler> using namespace std::experimental; namespace opts_util { namespace details { template<typename T> void parse_value(T& value, const std::string_view arg) { if constexpr (std::is_same_v<T, std::string>) { value = arg; } else if constexpr (std::is_same_v<T, int>) { value = std::atoi(arg.data()); } else if constexpr (std::is_same_v<T, double>) { value = std::atof(arg.data()); } else if constexpr (std::is_same_v<T, bool>) { value = (arg == "true" || arg == "1"); } else { []<bool flag = false>(){ static_assert(flag, "met an unmatched type"); }(); } } std::optional<std::string_view> try_parse_arg_value(const std::string_view member_name, std::string_view arg) { const std::string long_arg_pattern = "--" + std::string{member_name} + "="; const std::string short_arg_pattern = "-" + std::string{member_name[0]} + "="; for (const auto& pattern : {long_arg_pattern, short_arg_pattern}) { if (arg.starts_with(pattern)) { arg.remove_prefix(pattern.size()); return arg; } } return {}; } template<typename Opts> void parse_opt(Opts& opts, const std::string_view arg) { template for (constexpr meta::info e : meta::members_of(^Opts)) { if constexpr (meta::is_nonstatic_data_member([:^e:])) { constexpr std::string_view member_name = meta::name_of(e); if (const auto arg_value = try_parse_arg_value(member_name, arg)) { parse_value(opts.[:e:], *arg_value); break; } } } } } // namespace details template<typename Opts> requires std::is_class_v<Opts> Opts parse(int argc, char** argv) { Opts opts{}; for (int i = 0; i < argc; ++i) { details::parse_opt(opts, argv[i]); } return opts; } } // namespace opts_util struct program_opts { std::string folder; // --folder or -f int level = 10; // --level or -l bool help = false; // --help or -h double leverage = 100.0; // --leverage }; // example arguments: // ./bin -ar -l=23 f --leverage=228 df -fd levels -f=fdf -h=true int main(int argc, char** argv) { std::cout << "arguments count: " << argc << std::endl; for (int i = 0; i < argc; ++i) { std::cout << "arg #" << i << ": " << argv[i] << std::endl; } std::cout << std::endl; const auto opts = opts_util::parse<program_opts>(argc, argv); std::cout << "options are:" << std::endl; std::cout << "folder: " << opts.folder << std::endl; std::cout << "level: " << opts.level << std::endl; std::cout << "help: " << opts.help << std::endl; std::cout << "leverage: " << opts.leverage << std::endl; }
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