public function getName() {
		if ($this->_name === null) {
			$name = get_class($this);
			$pos = strrpos($name, '\\');
			if ($pos !== false) {
				$name = substr($name, $pos + 1);
			}
			if (preg_match('/^Twig([A-Za-z]+)Extension$/', $name, $matches)) {
				$name = $matches[1];
			}
			$this->_name = strtolower(preg_replace('/([a-z])([A-Z])/', '$1_$2', $name));
		}
		return $this->_name;
	}