# Reads `self` from pos `from` to pos `to` and store result in `buffer`.
	private fun read_until_pos(from, to: Int, buffer: Buffer): Int do
		if from < 0 or from >= length or
		   to < 0 or to >= length or
	       from >= to then return -1
		var pos = from
		while pos < to do
			buffer.add self[pos]
			pos += 1
		end
		return pos
	end