$re = '/(\s+\w+\.(\w+(\.\w+)*))|(\=\>)(\w+(\.\w+)*)/m';
$str = 'x=>x.ab
x=> x.ab
x => x.ab
x =>x.ab
x =>{return x.ab}
x => {return x.ab;}';
preg_match_all($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