$re = '`(?s)(?:new\sMyClass\([^;]*?new\sAnotherClass\(\).*?\))|(new\sMyClass\([^;]*?\))`m';
$str = '# case 0
return new MyClass(constructor, options, ...);
# case 1
var mc = new MyClass();
# case 2
var mc = new MyClass(new AnotherClass());
# case 3
var amc = new MyClass(options, new AnotherClass(), ...);
# case 4
MyClass mc = new MyClass(
something
);
# case 5
MyClass mc = new MyClass(
new AnotherClass()
);
# case 6
MyClass mc = new MyClass(
options, new AnotherClass()
);
# case 7
var amc = new MyClass(new AnotherClass(), options, ...);';
preg_match_all($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