protected function set_path($ipath) {
		static $cache;
		if (!$cache) {
			$cache = array();
		}

		$ipath = (string) $ipath;

		if (isset($cache[$ipath])) {
			$this->ipath = $cache[$ipath][(int) ($this->scheme !== null)];
		}
		else {
			$valid = $this->replace_invalid_with_pct_encoding($ipath, '!$&\'()*+,;=@:/');
			$removed = $this->remove_dot_segments($valid);

			$cache[$ipath] = array($valid, $removed);
			$this->ipath = ($this->scheme !== null) ? $removed : $valid;
		}
		$this->scheme_normalization();
		return true;
	}