Reference a layer with index

I have a working project that I'm revisiting. It is a simple box (shape layer) that adjusts its position and size to a text layer. I’m thinking about ways to make it more efficient. In the expression I reference the layers by name, which is a hassle if I want to duplicate the layers. What I want is the shape layer to reference the layer above it, i.e. the text layer. But I despite my efforts I can't seem to get it to work. If anyone could please take a look at this, it would be very much appreciated. 

1. 
   //TextLayer.transform.Anchor point
   s=thisLayer;
   a=s.sourceRectAtTime(time-s.inPoint);
2. Height=s.sourceRectAtTime(outPoint).height;
   Width=s.sourceRectAtTime(time-s.inPoint).width;
3. Top=s.sourceRectAtTime(outPoint).top;
   Left=s.sourceRectAtTime(time-s.inPoint).left;
4. x=Left+Width/2;
   y=Top+Height/2;
   [x,y]

//ShapeLayer.transform.Anchor Point;
s=thisComp.layer("Text"); 
a=s.sourceRectAtTime(time-s.inPoint);

Height=s.sourceRectAtTime(outPoint).height;
Width=s.sourceRectAtTime(time-s.inPoint).width;

Top=s.sourceRectAtTime(outPoint).top;
Left=s.sourceRectAtTime(time-s.inPoint).left;

pCheck=s.sourceRectAtTime(time-s.inPoint).width;
if (pCheck>0){
p=50;
}else{
p=0;
}

x=Width/-2-Left;
y=Height/-2-Top;
[x,y]

//ShapeLayer.contents.Rectangle1.Rectangle Path1.size
s=thisComp.layer("Text");

Height=s.sourceRectAtTime(outPoint).height;
Width=s.sourceRectAtTime(time-s.inPoint).width;

pCheck=s.sourceRectAtTime(time-s.inPoint).width;
if (pCheck>0){
p=50;
}else{
p=0;
}

x=Width+p;
y=Height+p;
[x,y]