private function createPolicy()
{
$preferStable = null;
$preferLowest = null;
if (!$this->update && $this->locker->isLocked()) {
$preferStable = $this->locker->getPreferStable();
$preferLowest = $this->locker->getPreferLowest();
}
// old lock file without prefer stable/lowest will return null
// so in this case we use the composer.json info
if (null === $preferStable) {
$preferStable = $this->preferStable || $this->package->getPreferStable();
}
if (null === $preferLowest) {
$preferLowest = $this->preferLowest;
}
return new DefaultPolicy($preferStable, $preferLowest);
}