# Reads `self` until `to` is encountered and store result in `buffer`.
	#
	# Returns `to` position or `-1` if not found.
	private fun read_until_char(from: Int, char: Char, buffer: Buffer): Int do
		if from < 0 or from >= length then return -1
		var pos = from
		while pos > -1 and pos < length do
			var c = self[pos]
			if c == char then return pos
			buffer.add c
			pos += 1
		end
		return -1
	end