$re = '/<a.*?href="(.*?)".*?>(.*)<\/a>/';
$str = '<a href="testing.html" data-id="1" data-popup-text="take me to <a href=\\"http://www.google.com\\">a search engine</a>">Testing</a>';
preg_match_all($re, $str, $matches, PREG_SET_ORDER, 0);
// Print the entire match result
var_dump($matches);
Please keep in mind that these code samples are automatically generated and are not guaranteed to work. If you find any syntax errors, feel free to submit a bug report. For a full regex reference for PHP, please visit: http://php.net/manual/en/ref.pcre.php