New approach, new lexer

os_win32.c

@@ -1,36 +1,16 @@
 function S32 os_main();
 const SizeU page_size = 4096;
 
-LRESULT CALLBACK 
-WindowProc(HWND hwnd, UINT uMsg, WPARAM wParam, LPARAM lParam){
-  return DefWindowProcW(hwnd, uMsg, wParam, lParam);;
-}
-
-int
-WinMain(HINSTANCE hInstance, HINSTANCE a, LPSTR b, int nShowCmd){
-  wchar_t *CLASS_NAME  = L"Cool window class";
-  wchar_t *WINDOW_NAME = L"Have a good day!";
-  
-  WNDCLASSW wc = { };
-  wc.lpfnWndProc   = WindowProc;
-  wc.hInstance     = hInstance;
-  wc.lpszClassName = CLASS_NAME;
-  RegisterClassW(&wc);
-  
-  HWND window_handle = CreateWindowExW(0, CLASS_NAME, WINDOW_NAME, WS_OVERLAPPEDWINDOW, CW_USEDEFAULT, CW_USEDEFAULT, CW_USEDEFAULT, CW_USEDEFAULT, 0, 0, hInstance, 0);
-  ShowWindow(window_handle, nShowCmd);
-  return os_main();
-}
-
 function String
-os_read_file(String name){
-  String result = {};
+os_read_file(Arena *arena, String name){
+  String result = {0};
   FILE *f = fopen((char *)name.str, "rb");
+  assert(f);
   fseek(f, 0, SEEK_END);
   result.len = ftell(f);
   fseek(f, 0, SEEK_SET);  /* same as rewind(f); */
   
-  result.str = malloc(result.len + 1);
+  result.str = arena_push_size(arena, result.len + 1);
   fread(result.str, result.len, 1, f);
   fclose(f);