# Expect a `SystemLiteral` production.
	#
	# Also used to parse productions that do not have references.
	# Append the parsed value to `buffer`.
	private fun expect_literal(buffer: Buffer): Bool do
		var delimiter = lexer.expect_delimiter

		if delimiter < 0 then return false
		loop
			if lexer.accept_int(delimiter) then
				return true
			else if not lexer.expect_xml_char(buffer) then
				return false
			end
		end
	end