Commandline args --help

main.cpp

@@ -4,11 +4,28 @@
 #include <sys/types.h>
 #include <unistd.h>
 #include <sys/wait.h>
+#include <getopt.h>
+#include <string>
 
 using namespace std;
 const int MAX_PROCESSES = 4;
 const char* const COMPILER = "g++";
 
+const string help_header = "\
+KTPuild\n\
+    An application that makes the compiling of large projects easier. The\n\
+    intended use for EECS 280 students attending the University of \n\
+    Michigan. Built and maintained by Kappa Theta Pi Alpha Chapter. For reporting\n\
+    bugs or requesting features please visit: https://github.com/ktp-dev/KTPuild\n";
+
+const string help_msg = "\n\
+Usages:\n\
+    KTPuild\n\
+    KTPuild -h | --help\n\
+    \n\
+Options:\n\
+    -h | --help: display help information\n\n";
+
 
 void run_command(const vector<string>& command) {
     //To run a command, we have to call execvp. execvp expects a char** (C style array) that is null terminated. Thus, convert our nice C++ array of strings to a C array of C strings. Also, print them out so the user knows what we are running.
@@ -92,29 +109,93 @@ void link_executable(const Buildfile& buildfile, const vector<string>& cpp_files
     }
 }
 
-int main() {
+bool is_created(const string &filename){
+
+    // tests for the existence of the file with success being a 0
+    if(access(filename.c_str(), F_OK) == 0)
+    {
+        return true;
+    }
+    return false;
+}
+
+bool parse_commandline_args(int argc, char** &argv)
+{
+    struct option longOpts[] = {
+            { "help", no_argument, nullptr, 'h' },
+            { nullptr, 0, nullptr, '\0' }
+        };
+
+    int option;
+
+    while((option = getopt_long(argc, argv, "h", longOpts, nullptr))!= -1)
+    {
+        switch(option)
+        {
+            case 'h':
+            {
+                std::cout<<(help_header + help_msg);
+                return false;
+            }
+            default:
+            {
+                throw std::runtime_error(help_msg);
+            }
+        }
+    }
+    return true;
+}
+
+int main(int argc, char ** argv) {
     /*
-     * 1) get the cpp files
-     * 2) determine what cpp files to recompile
+     * 1) parse for commandline arguments
+     * 2) get the cpp files
+     * 3) determine what cpp files to recompile
      *      - need to recompile if no obj file we have to create it, or if there is an obj file,
      *      but the cpp file has been modified more recently than the obj file
-     * 3) if none, we are done
-     * 4) else, recompile them (done!)
-     * 5) relink everything
-     * 6) done!
+     *      - need to check to see if there is an executable created
+     * 4) if none, we are done
+     * 5) else, recompile them (done!)
+     * 6) relink everything
+     * 7) done!
      */
     try {
+
+        /*
+        parse command line arguments, if we get false back we encountered either a help or invalid
+        option and should exit the program while displaying the help message.
+        */
+        if(!parse_commandline_args(argc, argv))
+        {
+           return 1;
+        } 
+
         Buildfile buildfile;
         vector<string> cpp_filename = buildfile.get_cpp_files(); //1
         vector<string> changed;
         for (string &file : cpp_filename) { //2
             if (has_changed(file))
                 changed.push_back(file);
         }
-        //now we know what cpp files have changed
-        if (changed.empty()) //TODO: also ensure exe exists
+        // if there is nothing to recompile and the executable has been created we are done
+        if (changed.empty() && is_created(buildfile.get_executable_name()))
             return 0; //3
 
+int main()
+{
+
+}
+
+int main()
+{
+
+}
+
+int main()
+{
+
+}
+
         compile_object_files(buildfile, changed); //4
         link_executable(buildfile, cpp_filename); //4