public function normalizeKey($key)
	{
		// Built-in/custom filter, normalized to lowercase
		if (preg_match('/^#[a-z_0-9]+$/Di', $key))
		{
			return strtolower($key);
		}

		// Valid callback
		if (is_string($key) && is_callable($key))
		{
			return $key;
		}

		throw new InvalidArgumentException("Invalid filter name '" . $key . "'");
	}
public function normalizeKey($key)
	{
		// Built-in/custom filter, normalized to lowercase
		if (preg_match('/^#[a-z_0-9]+$/Di', $key))
		{
			return strtolower($key);
		}

		// Valid callback
		if (is_string($key) && is_callable($key))
		{
			return $key;
		}

		throw new InvalidArgumentException("Invalid filter name '" . $key . "'");
	}
public function normalizeKey ( $ key ) { // Built-in/custom filter, normalized to lowercase if ( preg_match ( '/^#[a-z_0-9]+$/Di' , $ key ) ) { return strtolower ( $ key ) ; } // Valid callback if ( is_string ( $ key ) && is_callable ( $ key ) ) { return $ key ; } throw new InvalidArgumentException ( "Invalid filter name '" . $ key . "'" ) ; }
Normalize the name of an attribute filter

@param  string $key
@return string
Normalize the name of an attribute filter