/**
* The applies method is the only point where the rule can be validated.
*
* Internally each rule implements the _applies() method to do the actual
* validation.
*
* There are only two types of outcome for each rule.
* Either the rule applies (true) or doesn't (false).
* Any other outcome should always be thrown as an exception so no false
* assumptions can be made by the caller. For example when a rule returns a
* NULL value the caller may asume that false is meant. The rule cannot
* trust that the caller checks the boolean type so we will.
*
* @return boolean
* @throws Exception https://en.wikipedia.org/wiki/Template_method_pattern
*/
public final function applies()
{
try {
if ($this->shouldReturnCache()) {
return $this->getCache();
}
$this->clearResult();
$this->clearCache();
$result = $this->_applies();
if (is_bool($result)) {
$this->setCache($result);
return $result;
} else {
throw new Exception('A rule must return a boolean.', Exception::CODE_NONBOOLEAN);
}
} catch (Exception $e) {
$this->handleException($e);
throw $e;
} catch (\Exception $e) {
$e = new Exception($e->getMessage(), $e->getCode(), $e);
$this->handleException($e);
throw $e;
}
}
