added filesystem

Main.cpp

@@ -1,9 +1,37 @@
 #include "code_writer.hpp"
 #include <iostream>
+#include <filesystem>
+namespace fs = std::filesystem;
 
 int main(int argc, char const *argv[])
 {
-    code_writer toassembly(argv[1]);
+    lots_of_files files;
+    std::string input(argv[1]);
+    if (fs::is_directory(input))
+    {
+        files.push_back(input);
+        for (auto &entry : fs::directory_iterator(input))
+        {
+            if (entry.path().extension() == ".vm")
+            {
+                std::string vmfile = entry.path().string();
+                if (entry.path().filename() == "Sys.vm")
+                {
+                    files.insert(files.begin() + 1, vmfile);
+                }
+                else
+                {
+                    files.push_back(vmfile);
+                }
+            }
+        }
+    }
+    else
+    {
+        files.push_back(input);
+    }
+
+    code_writer toassembly(files);
     toassembly.write_assembly();
     return 0;
 }