protected function parse()
    {
        $parseOptions = true;
        $this->parsed = $this->tokenPairs;
        while (null !== $tokenPair = \array_shift($this->parsed)) {
            // token is what you'd expect. rest is the remainder of the input
            // string, including token, and will be used if this is a code arg.
            list($token, $rest) = $tokenPair;

            if ($parseOptions && '' === $token) {
                $this->parseShellArgument($token, $rest);
            } elseif ($parseOptions && '--' === $token) {
                $parseOptions = false;
            } elseif ($parseOptions && 0 === \strpos($token, '--')) {
                $this->parseLongOption($token);
            } elseif ($parseOptions && '-' === $token[0] && '-' !== $token) {
                $this->parseShortOption($token);
            } else {
                $this->parseShellArgument($token, $rest);
            }
        }
    }