// Resets [fiber] back to an initial state where it is ready to invoke [fn].
private void ResetFiber(Obj fn)
{
Stack = new Obj[InitialStackSize];
Capacity = InitialStackSize;
Frames = new List<CallFrame>();
// Push the stack frame for the function.
StackTop = 0;
NumFrames = 1;
OpenUpvalues = null;
Caller = null;
Error = null;
CallerIsTrying = false;
CallFrame frame = new CallFrame { Fn = fn, StackStart = 0, Ip = 0 };
Frames.Add(frame);
}
// Captures the local variable [local] into an [Upvalue]. If that local is
// already in an upvalue, the existing one will be used. (This is important to
// ensure that multiple closures closing over the same variable actually see
// the same variable.) Otherwise, it will create a new open upvalue and add it
// the fiber's list of upvalues.
public ObjUpvalue CaptureUpvalue(int index)
{
// If there are no open upvalues at all, we must need a new one.
if (OpenUpvalues == null)
{
OpenUpvalues = new ObjUpvalue(Stack[index], index);
return OpenUpvalues;
}
ObjUpvalue prevUpvalue = null;
ObjUpvalue upvalue = OpenUpvalues;
// Walk towards the bottom of the stack until we find a previously existing
// upvalue or pass where it should be.
while (upvalue != null && upvalue.Index > index)
{
prevUpvalue = upvalue;
upvalue = upvalue.Next;
}
// Found an existing upvalue for this local.
if (upvalue != null && upvalue.Index == index) return upvalue;
// We've walked past this local on the stack, so there must not be an
// upvalue for it already. Make a new one and link it in in the right
// place to keep the list sorted.
ObjUpvalue createdUpvalue = new ObjUpvalue(Stack[index], index);
if (prevUpvalue == null)
{
// The new one is the first one in the list.
OpenUpvalues = createdUpvalue;
}
else
{
prevUpvalue.Next = createdUpvalue;
}
createdUpvalue.Next = upvalue;
return createdUpvalue;
}
public void CloseUpvalue()
{
if (OpenUpvalues == null)
return;
// Push the value back into the stack
Stack[OpenUpvalues.Index] = OpenUpvalues.Container;
// Remove it from the open upvalue list.
OpenUpvalues = OpenUpvalues.Next;
}
