Depth function

[harshey1103]

Initial implementation of depth function.
The function returns 0 for an empty tree and 1 for a tree whose root is a leaf.

[AryanGodara]

Also, it'll be a good idea to write a test for this new function. What do you say @harshey1103 :)

[patricoferris]

Awesome thanks @harshey1103 ! This looks good to me, I agree that a test or two would be great. The OMT loading algorithm that we support should produce a balanced tree so that can be used for the tests.

Also running dune build @fmt --auto will format the code :))

[patricoferris]

Just as an additional thing, your depth' function isn't tail-recursive. I'm totally fine with this but it might be a nice exercise to see if you can make it tail-recursive. Some extra info on that: https://www.cs.cornell.edu/courses/cs3110/2014fa/recitations/5/rec05.html

[harshey1103]

Hi @patricoferris, I looked into the test directory but I am not able to figure out how to write a test for the depth function. There aren't any tests for the Rtree module. :'(

[patricoferris]

Yes the tests are a little disorganised, apologies! There are tests of the Rtree module though. For example

ocaml-rtree/test/basic.ml

Lines 88 to 120 in ee12c37

	let test_lines () =
	let module R =
	Rtree.Make
	(Rtree.Rectangle)
	(struct
	type t = line
	let t = lint_t
	type envelope = Rtree.Rectangle.t
	let envelope { p1 = x1, y1; p2 = x2, y2 } =
	let x0 = Float.min x1 x2 in
	let x1 = Float.max x1 x2 in
	let y0 = Float.min y1 y2 in
	let y1 = Float.max y1 y2 in
	Rtree.Rectangle.v ~x0 ~y0 ~x1 ~y1
	end)
	in
	let l1 = { p1 = (1., 2.); p2 = (2., 3.) } in
	let index = R.insert (R.empty 8) l1 in
	let l1' = R.find index (Rtree.Rectangle.v ~x0:0. ~y0:0. ~x1:3. ~y1:3.) in
	assert (List.length l1' = 1);
	assert (l1 = List.hd l1');
	let l2 = { p1 = (3., 4.); p2 = (5., 5.) } in
	let index = R.insert index l2 in
	let l1' = R.find index (Rtree.Rectangle.v ~x0:0. ~y0:0. ~x1:3. ~y1:3.) in
	assert (List.length l1' = 1);
	assert (l1 = List.hd l1');
	let l1' = R.find index (Rtree.Rectangle.v ~x0:0. ~y0:0. ~x1:5. ~y1:5.) in
	assert (List.length l1' = 2);
	let vs = R.values index in
	assert (List.length vs = 2)

Here we test the OMT loader for an instantiation of the Rtree module using rectangles and lines. This should help write a test to check the depth function :))

[harshey1103]

I tried to make the function tail recursive and have written the tests can you please have a look @patricoferris @AryanGodara .

[patricoferris]

The changes are looking good to me. Our CI system seems a bit broken, so I've opened an issue for them: ocurrent/solver-service#74. I ran this locally and I'm happing with the changes, thank you @harshey1103 :))

[patricoferris]

One thing I would add is that the depth function is not quite tail-recursive here (the function call is not in the tail position) but that's okay, I think something else might break before we get depths that cause us trouble... I think