SMTP::iterateLines( $s )

773    private function iterateLines($s)774    {775        $start = 0;776        $length = strlen($s);777 778        for ($i = 0; $i < $length; $i++) {779            $c = $s[$i];780            if ($c === "\n" || $c === "\r") {781                yield substr($s, $start, $i - $start);782                if ($c === "\r" && $i + 1 < $length && $s[$i + 1] === "\n") {783                    $i++;784                }785                $start = $i + 1;786            }787        }788 789        yield substr($s, $start);790    }