cebe\markdown\inline\LinkTrait::parseLinkOrImage PHP Method

    protected function parseLinkOrImage($markdown)
    {
        if (strpos($markdown, ']') !== false && preg_match('/\\[((?>[^\\]\\[]+|(?R))*)\\]/', $markdown, $textMatches)) {
            // TODO improve bracket regex
            $text = $textMatches[1];
            $offset = strlen($textMatches[0]);
            $markdown = substr($markdown, $offset);
            $pattern = <<<REGEXP
\t\t\t\t/(?(R) # in case of recursion match parentheses
\t\t\t\t\t \\(((?>[^\\s()]+)|(?R))*\\)
\t\t\t\t|      # else match a link with title
\t\t\t\t\t^\\(\\s*(((?>[^\\s()]+)|(?R))*)(\\s+"(.*?)")?\\s*\\)
\t\t\t\t)/x
REGEXP;
            if (preg_match($pattern, $markdown, $refMatches)) {
                // inline link
                return [$text, isset($refMatches[2]) ? $this->replaceEscape($refMatches[2]) : '', empty($refMatches[5]) ? null : $refMatches[5], $offset + strlen($refMatches[0]), null];
            } elseif (preg_match('/^([ \\n]?\\[(.*?)\\])?/s', $markdown, $refMatches)) {
                // reference style link
                if (empty($refMatches[2])) {
                    $key = strtolower($text);
                } else {
                    $key = strtolower($refMatches[2]);
                }
                return [$text, null, null, $offset + strlen($refMatches[0]), $key];
            }
        }
        return false;
    }