working cli prototype

Makefile

@@ -1,5 +1,5 @@
 main:
-	g++ -I lib/ src/setopt.cpp -o setopt
+	g++ -I lib/ src/setopt.cpp -o setopt -g
 
 test: test_template test_compile
 

src/setopt.cpp

@@ -1,7 +1,68 @@
 #include <stdio.h>
+#include <getopt.h>
 #include <json.hpp>
 #include "setopt.hpp"
 
-signed main(){
-	return 0;
+#define EXECUTABLE_NAME "setopt"
+
+const char HELP_MSG[] = "\
+%s <options>  : \n\
+\t-s <str>  : specify optstring\n\
+\t-j <json> : read arguments from JSON string\n\
+\t-h        : print help message and quit\n\
+";
+
+
+
+using json = nlohmann::json;
+using namespace std;
+
+
+
+void usage(){
+	printf(HELP_MSG, EXECUTABLE_NAME);
+}
+
+[[ noreturn ]] inline void die(){
+	usage();
+	exit(1);
+}
+
+char* json_str = nullptr;
+bool done_something = false;
+unordered_map<char, std::string> g_argv;
+const char* g_optstring = nullptr;
+
+void parse_args(int argc, char** argv){
+	char opt;
+	while((opt = getopt(argc, argv, "j:s:h")) != -1){
+		switch(opt){
+			case 'j':
+				json_str = strdup(optarg);
+				break;
+			case 's':
+				g_optstring = strdup(optarg);
+				break;
+			case 'h':
+				usage();
+				exit(0);
+		}
+		done_something = true;
+	}
+	if(not done_something){ die(); }
+}
+
+signed main(int argc, char** argv){
+	parse_args(argc, argv);
+
+	if(json_str){
+		json j = json::parse(json_str);
+		for(const auto &i : j.items()){
+			g_argv[i.key()[0]] = i.value();
+		}
+	}
+
+	if(not g_optstring){ die(); }
+
+	puts(setopt(g_optstring, g_argv));
 }