public function parse( $str, $file_uri = null ){

		if( !$file_uri ){
			$uri_root = '';
			$filename = 'anonymous-file-'.Less_Parser::$next_id++.'.less';
		}else{
			$file_uri = self::WinPath($file_uri);
			$filename = $file_uri;
			$uri_root = dirname($file_uri);
		}

		$previousFileInfo = $this->env->currentFileInfo;
		$uri_root = self::WinPath($uri_root);
		$this->SetFileInfo($filename, $uri_root);

		$this->input = $str;
		$this->_parse();

		if( $previousFileInfo ){
			$this->env->currentFileInfo = $previousFileInfo;
		}

		return $this;
	}