$re = '/^(?=\w+\()\w+?\(([\s\'!\\\\\)",\w]+)+\);/m';
$str = '_("hello"); // should grab "hello"
_(\'foo"!\\\'bar\'); // should grab "foo"!\\\'bar"
_t("hello\\"!)\' you"); // should grab "hello\\"!)\' you"
_n("foo", "bar", 4); // should grab "foo" and "bar"
_n(\'foo\', \'bar\', 4);
{{_ "hello" }}
{{_t "hello" }}
{{_n "hello {{ count }}" "{{ count }} bar" count="4" }}
gettext("foo"); // should grab "foo"
ngettext("bar", "baz", 42); // should grab "bar" and "baz"
dgettext(domain, "bux"); // should grab "bux"
_( "bar" );
_n( "baz", "bux", 42);';
preg_match_all($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