anchor.diff:  | regex
   ;
   
  -/*	
  -andGroup
  -: 	(((LRB exprGroup RRB)|expr) AND)+ ((LRB exprGroup RRB)|expr)
  -;
  -
  -orGroup
  -: 	(((LRB exprGroup RRB)|expr) OR)+ ((LRB exprGroup RRB)|expr)
  -;
  -*/
   
   relation
   :	(expr|exprGroup) conj (expr|exprGroup|relation)
  +//|	LRB relation RRB
   ; 
   
   exprGroup
  
positive.code: 
  start
  :	( expr 
  	| exprGroup EOF 
  	| relation EOF ) 
  ;
negative.code: 
  expr
  :	(value operator)? field operator value
  //|	LRB expr RRB
  ;
  	
  field
  