protected function process_regexp_separator_e(PHP_CodeSniffer_File $phpcsFile, $stackPtr) {
        $tokens = $phpcsFile->getTokens();
        $token = $tokens[$stackPtr];
        $text = trim($token['content'], " '\"\t\n");
        if (@preg_match($text, '') !== false) {
            // Regular expression found. Look for used separator (1st char).
            $separator = substr($text, 0, 1);
            // Get rid of separator.
            $text = trim($text, $separator);
            $parts = preg_split('~' . preg_quote($separator, '~') . '~', $text);
            // Need exactly 2 parts.
            if (isset($parts[1]) && !isset($parts[2])) {
                $modifiers = $parts[1];
                if (preg_match('~^[imsxeADSUXJu]+$~', $modifiers)) { // Only when modifiers are valid.
                    if (strpos($modifiers, 'e') !== false) {
                        $error = 'The use of the /e modifier in regular expressions is forbidden';
                        $phpcsFile->addError($error, $stackPtr, 'Found');
                    }
                }
            }
        }
    }