public function compareTo(VocabElement $o)
{
// A position value overrides and trumps sortName
// Otherwise, compare alphabetically against sortName
// Then arbitrarily compare on Term Type, Concept, and Id
$pos = 0;
$oPosition = $o->getPosition();
if ($this->position != null) {
$pos = $oPosition == null ? $this->position : $this->position - $oPosition;
} else {
if ($oPosition != null) {
$pos = $oPosition;
}
}
if ($pos == 0) {
// Either positions are the same or null
$pos = $this->sortName == $o->getSortName() ? 1 : 0;
}
if ($pos == 0) {
$pos = $this->type == $o->getType() ? 1 : 0;
}
if ($pos == 0) {
$pos = $this->subclass == $o->getSubclass() ? 1 : 0;
}
if ($pos == 0) {
$pos = $this->uri == $o->getUri() ? 1 : 0;
}
return $pos;
}
