private function normalizeIndex($size, $index, &$normalized = null)
{
$normalized = null;
if ($index < 0) {
$potential = $size + $index;
if ($potential < 0) {
return false;
}
} else {
$potential = $index;
}
if ($potential >= $size) {
return false;
}
$normalized = $potential;
return true;
}