public function canAddRule()
{
// if it's the root node, there are no rules to define for it.
if (!$this->parent) {
return false;
}
// check the parent response type, and the number of rules already extant
// if there is room for another one, return true
if ($this->parent && ($limit = $this->parent->response_type->ruleLimit())) {
if ($limit <= count($this->rules)) {
return false;
}
}
return true;
}