# A reverse iterator capable of working with `Rope` objects
private class RopeCharReverseIterator
	super IndexedIterator[Char]

	# Current CString
	var ns: String is noautoinit
	# Current position in CString
	var pns: Int is noautoinit
	# Position in the Rope (0-indexed)
	var pos: Int is noautoinit
	# Iterator on the substrings, does the Postfix part of
	# the Rope traversal.
	var subs: IndexedIterator[String] is noautoinit

	init from(root: Concat, pos: Int) do
		self.pos = pos
		subs = new ReverseRopeSubstrings.from(root, pos)
		ns = subs.item
		pns = pos - subs.index
	end

	redef fun index do return pos

	redef fun is_ok do return pos >= 0

	redef fun item do return ns[pns]

	redef fun next do
		pns -= 1
		pos -= 1
		if pns >= 0 then return
		if not subs.is_ok then return
		subs.next
		if not subs.is_ok then return
		ns = subs.item
		pns = ns.length - 1
	end
end