Here's something you can try:
$string = 'namespace Something;
use Foo\Bar\Baz as Name1, Foo\Bar\Qux as Name2;
use Foo\Bar\Grault,
Foo\Bar\Quux;
use Foo\Bar\Corge as Name3;';
$array_of_patterns = array('Name1', 'Name2', 'Name3');
foreach ($array_of_patterns AS $pattern) {
preg_match('~\b([A-Z\\\]+)(?= as '.$pattern.')~i', $string, $matches);
print "\n".$pattern.": ".$matches[0];
}
This outputs:
Name1: Foo\Bar\Baz
Name2: Foo\Bar\Qux
Name3: Foo\Bar\Corge