private function parseExpression (){
		$entities = array();

		do{
			$e = $this->MatchFuncs(array('parseAddition','parseEntity'));
			if( $e ){
				$entities[] = $e;
				// operations do not allow keyword "/" dimension (e.g. small/20px) so we support that here
				if( !$this->PeekReg('/\\G\/[\/*]/') ){
					$delim = $this->MatchChar('/');
					if( $delim ){
						$entities[] = $this->NewObj1('Less_Tree_Anonymous',$delim);
					}
				}
			}
		}while($e);

		if( $entities ){
			return $this->NewObj1('Less_Tree_Expression',$entities);
		}
	}