Fix a lot of things and implement gc

src/ops.rs

@@ -74,6 +74,7 @@ lazy_static! {
             m[0xD1] = Operation::Op("NEWARRAY", newarray, vec![]);
             m[0xD2] = Operation::Op("IALOAD", iaload, vec![]);
             m[0xD3] = Operation::Op("IASTORE", iastore, vec![]);
+            m[0xD4] = Operation::Op("GC", gc, vec![]);
         }
 
         m
@@ -110,7 +111,7 @@ fn out(machine: &mut Machine) -> Result<()> {
     let mut out = machine.stream_out.lock().unwrap();
     out.write_all(&buffer).unwrap();
     out.flush().unwrap();
-    return Ok(());
+    Ok(())
 }
 
 fn pop(machine: &mut Machine) -> Result<()> {
@@ -266,14 +267,20 @@ fn invokevirtual(machine: &mut Machine) -> Result<()> {
 }
 
 fn ireturn(machine: &mut Machine) -> Result<()> {
-    let mut prev_frame: Frame = match machine.frame.pop() {
-        Some(a) => a,
-        None => return Err("Got no frame... somehow..."),
-    };
-    let result = prev_frame.stack.pop()?;
-    let return_addr: i32 = prev_frame.get(0)?.try_into()?;
-    machine.cur_stack().push(result);
-    machine.block.seek(return_addr as usize)
+    // Lifetime for prev frame, allows gc to reap into the frame
+    {
+        let mut prev_frame: Frame = match machine.frame.pop() {
+            Some(a) => a,
+            None => return Err("Got no frame... somehow..."),
+        };
+        let result = prev_frame.stack.pop()?;
+        let return_addr: i32 = prev_frame.get(0)?.try_into()?;
+        machine.cur_stack().push(result);
+        machine.block.seek(return_addr as usize)?;
+    }
+
+    machine.heap.gc();
+    Ok(())
 }
 
 #[cfg(feature = "extra:sleep")]
@@ -323,40 +330,46 @@ fn netclose(machine: &mut Machine) -> Result<()> {
 #[cfg(feature = "bonus:heap")]
 fn newarray(machine: &mut Machine) -> Result<()> {
     let size: i32 = machine.cur_stack().pop()?.try_into()?;
-    let heapref = machine.heap.alloc(size as usize);
-    machine.cur_stack().push(Value::HeapRef(heapref));
+    let heap = machine.heap.alloc(size as usize);
+    machine.cur_stack().push(Value::HeapRef(heap));
     Ok(())
 }
 
 #[cfg(feature = "bonus:heap")]
 fn iastore(machine: &mut Machine) -> Result<()> {
-    let heapref = match machine.cur_stack().pop()? {
+    use std::cell::RefCell;
+
+    let heap = match machine.cur_stack().pop()? {
         Value::HeapRef(a) => a,
         _ => return Err("Cannot use int as heapref"),
     };
     let index: i32 = machine.cur_stack().pop()?.try_into()?;
-    let value: i32 = machine.cur_stack().pop()?.try_into()?;
+    let value = machine.cur_stack().pop()?.clone();
 
-    let heap = machine.heap.get(heapref);
-    heap[index as usize] = value;
+    RefCell::borrow_mut(&heap)[index as usize] = value;
 
     Ok(())
 }
 
 #[cfg(feature = "bonus:heap")]
 fn iaload(machine: &mut Machine) -> Result<()> {
-    let heapref = match machine.cur_stack().pop()? {
+    let heap = match machine.cur_stack().pop()? {
         Value::HeapRef(a) => a,
         _ => return Err("Cannot use int as heapref"),
     };
     let index: i32 = machine.cur_stack().pop()?.try_into()?;
 
-    let value: i32;
+    let value: Value;
     {
-        let heap = machine.heap.get(heapref);
-        value = heap[index as usize];
+        value = heap.borrow()[index as usize].clone();
     }
-    machine.cur_stack().push(Value::Int(value));
+    machine.cur_stack().push(value);
 
     Ok(())
 }
+
+#[cfg(feature = "bonus:heap")]
+fn gc(machine: &mut Machine) -> Result<()> {
+    machine.heap.gc();
+    Ok(())
+}