This assignment is not for credit, but if you’re interested enough in garbage collection to try it, the instructor will be happy to provide feedback.

Add garbage collection to your msdscript implementation as shown in the videos and slides.

Some notes and tips:

• Further conditionalize the macros in “pointer.h” through something like #define USE_GARBAGE_COLLECTOR 1 so you can switch between plain pointers (leaks), shared_ptr (crashes when trying to free a long data chain), or garbage collection.
• Note that running with --interp will leak with garbage collection, and that's ok. Let’s just say that --step is the right way to run.
• You’ll likely find it helpful to have a GCable::reset function as below to use for testing, because your non-stepping tests will send the collector into out_of_memory = true mode. You’ll need to reset the allocator just before stepping tests that cooperating with the collector.

void GCable::reset() {
  heap_size = (8*1024);
  to_space = nullptr;
  from_space = nullptr;
  allocation_offset = 0;
  out_of_memory = false;

  Env::empty = NEW(EmptyEnv)();
  Cont::done = NEW(DoneCont)();
}