feat: add help command to linux and macos parsers.

src/headers/parser/platform_headers/linux_parser.hpp

@@ -17,6 +17,7 @@ namespace argument_parser {
 		class linux_parser : public v2::base_parser {
 		public:
 			linux_parser();
+			using base_parser::display_help;
 		};
 	} // namespace v2
 } // namespace argument_parser

src/headers/parser/platform_headers/macos_parser.hpp

@@ -18,6 +18,7 @@ namespace argument_parser {
 		class macos_parser : public v2::base_parser {
 		public:
 			macos_parser();
+			using base_parser::display_help;
 		};
 	} // namespace v2
 } // namespace argument_parser

src/source/parser/platform_parsers/linux_parser.cpp

@@ -24,6 +24,14 @@ namespace argument_parser {
 			for (std::string line; std::getline(command_line_file, line, '\0');) {
 				parsed_arguments.emplace_back(line);
 			}
+
+			add_argument({{flags::ShortArgument, "h"},
+						  {flags::LongArgument, "help"},
+						  {flags::Action, helpers::make_non_parametered_action([this]() {
+							   this->display_help(this->current_conventions());
+							   std::exit(0);
+						   })},
+						  {flags::HelpText, "Prints this help text."}});
 		}
 	} // namespace v2
 } // namespace argument_parser

src/source/parser/platform_parsers/macos_parser.cpp

@@ -24,6 +24,14 @@ namespace argument_parser {
 						ref_parsed_args().emplace_back(argv[i]);
 				}
 			}
+
+			add_argument({{flags::ShortArgument, "h"},
+						  {flags::LongArgument, "help"},
+						  {flags::Action, helpers::make_non_parametered_action([this]() {
+							   this->display_help(this->current_conventions());
+							   std::exit(0);
+						   })},
+						  {flags::HelpText, "Prints this help text."}});
 		}
 	} // namespace v2
 } // namespace argument_parser