public function lookup($itemName)
{
if (!$this->has($itemName)) {
throw new Swift_DependencyException('Cannot lookup dependency "' . $itemName . '" since it is not registered.');
}
switch ($this->_store[$itemName]['lookupType']) {
case self::TYPE_ALIAS:
return $this->_createAlias($itemName);
case self::TYPE_VALUE:
return $this->_getValue($itemName);
case self::TYPE_INSTANCE:
return $this->_createNewInstance($itemName);
case self::TYPE_SHARED:
return $this->_createSharedInstance($itemName);
}
}