split ( p : like first_place;
	  before, after : BOX [ like Current ] ) is
    require
      nonvoid : p /= Void and before /= Void and after /= Void
    local
      q, r, s : like first_place
      rnk, next_rnk : INTEGER
      low, high, subtree : like Current
      left, right : like first_place
      p_less, next_p_less : BOOLEAN
    do

	-- Not all these local veriables are used.  They
	-- should suggest what's needed for the correct version.

	-- Caution: in the proper version, the red-black ranks
	-- of various nodes need to be calculated `on the fly.'
	-- This is where one needs to be careful.

      from
	!! low.make
		-- create an empty tree to contain
		-- all nodes left of p (in inorder)
	!! high.make
	q := first_place
		-- the leftmost node in the tree
	remove_first
		-- removes the leftmost node from the tree
	q.unlink
		-- resets fields in q to Void to avoid
		-- `dangling pointers.'  Otherwise it
		-- will violate the requirements for the attach
		-- feature.
      until
	q = p
      loop
		-- transfer node q from Current tree to low
	low.attach_last (q)
	q := first_place
	remove_first
	q.unlink
      end

		-- At this point, all nodes to the left of
		-- p have been transferred to the tree low.
		-- Note that p itself has been removed from
		-- the front of the list, so the remaining nodes
		-- are those to the right of p in the original tree.

      !! high . make_with_root ( root, protecting, rb_rank )
		-- It is necessary to remove all connection to
		-- this tree in the Current tree -- a node
		-- can belong to only one tree. Therefore
      wipe_out
		-- Put the low and high trees in the boxes
		-- before and after respectively.

      before.put ( low )
      after.put ( high )
    end