.. _program_listing_file_gui_ArgsParser.cpp:

Program Listing for File ArgsParser.cpp
=======================================

|exhale_lsh| :ref:`Return to documentation for file <file_gui_ArgsParser.cpp>` (``gui/ArgsParser.cpp``)

.. |exhale_lsh| unicode:: U+021B0 .. UPWARDS ARROW WITH TIP LEFTWARDS

.. code-block:: cpp

   #include <cstdio>
   #include <getopt.h>
   
   #include <array>
   #include <cstdint>
   #include <iostream>
   #include <sstream>
   
   #include "ArgsParser.hpp"
   
   #define HELP_OPT 1000
   
   // Structure to hold the command line parameters, to be used by getopt_long
   static const std::array<struct option, 4> long_options = {
     {{"help", no_argument, nullptr, HELP_OPT},
      {"port", required_argument, nullptr, 'p'},
      {"host", required_argument, nullptr, 'h'},
      {nullptr, 0, nullptr, 0}}};
   
   uint16_t Args::ParseNumber(
     const std::string &arg,
     const char *name,
     uint16_t min,
     uint16_t max)
   {
     std::stringstream ss(arg);
     long value;
     if (!(ss >> value)) {
   
       std::cerr
         << "Invalid value for " << name << ": " << arg << " (not a number)\n";
     }
     if (!ss.eof()) {
       std::cerr
         << "Invalid value for " << name << ": " << arg
         << " (extra characters after number)\n";
       return 0;
     }
     if (value < min || value > max) {
       std::cerr
         << "Invalid value for " << name << ": " << arg << " (must be between "
         << min << " and " << max << ")\n";
       return 0;
     }
     return value;
   }
   
   bool Args::Dispatcher(char **argv, int opt)
   {
     (void)argv;
     switch (opt) {
       case HELP_OPT:
         help = true;
         break;
       case 'h':
         host = optarg;
         break;
       case 'p':
         port = ParseNumber(optarg, "p", 1024, UINT16_MAX);
         break;
       case '?':
       default:
         std::cerr << "Invalid option or missing argument\n" << GUI_USAGE << "\n";
         return false;
     }
     return true;
   }
   
   std::string Args::ToString() const
   {
     return
       "====================Zappy GUI====================\n"
       "port = " + std::to_string(port) + "\n"
       "host = " + host + "\n"
       "=================================================\n";
   }
   
   bool Args::Parse(int argc, char **argv)
   {
     for (int opt;;) {
       opt = getopt_long(argc, argv, "p:h:", long_options.data(), nullptr);
       if (opt < 0)
         break;
       if (!Dispatcher(argv, opt))
         return false;
     }
     if (help)
       return true;
     if (port == 0 || host.empty()) {
       std::cerr << GUI_USAGE;
       return false;
     }
     return true;
   }