private class TemplateStringIterator
	super MapIterator[String, nullable Writable]

	var subject: TemplateString
	var key_it: Iterator[String] is noinit

	init do
		self.key_it = subject.macro_names.iterator
	end

	redef fun is_ok do return key_it.is_ok
	redef fun next do key_it.next
	redef fun key do return key_it.item
	redef fun item do return subject.macros[key].first.replacement
end