Curve Switch

I was trying to make a Curve Switch.
It may sound a very simple thing, but I have no experience in scripting and my switch is not working well.

So....
If I start from a switch for map inputs, as the one below :

function prepare()
end;

function get_sample(x, y)
local r, g, b, a
local value = math.floor(get_sample_grayscale(x, y, SELECTOR)*5+.001)
if value == 0 then r, g, b, a = get_sample_map(x, y, INPUT01) end
if value == 1 then r, g, b, a = get_sample_map(x, y, INPUT02) end
if value == 2 then r, g, b, a = get_sample_map(x, y, INPUT03) end
if value == 3 then r, g, b, a = get_sample_map(x, y, INPUT04) end
if value >= 4 then r, g, b, a = get_sample_map(x, y, INPUT05) end
return r, g, b, a
end;

How would this change in case of curve inputs?

Thanks Indigo Ray. I already know almost nothing. I'm simply trying to understand how it works.

What I would like to do is a Curve Switch with more than the 12 inputs of the standard one.

Possibly, I would prefer not to go much far away from the structure of the previous simple switch, otherwise I may not be able to easily change it later.

Then......
As first, a curve doesn't use r,g,b,a. I should change it with c.
Could it be something like :
if value == 0 then c = get_sample_curve(x, y, INPUT01) end
?

The grayscale input can be ok for the selector of the switch?
Should I also add t, or x and y are enough?
As return values, I saw that in other scripts are used c, c, c, 1.
But I'm not sure.