anchor.diff:  interpolatedExpressionStart
       : '(' 
       | '{'
  -    | '#' 
       | LIDENTIFIER 
       | UIDENTIFIER 
       | selfReference 
       | nonstringLiteral
       | prefixOperator
  +    ;
  +
  +prefixOperator
  +    : '$' | '-' |'++' | '--' | '~'
       ;
   
   expression
  
positive.code:     FOR_CONTAINMENT;
      ENUM_LIST;
      SUPERCLASS;
      PREFIX_EXPR;
      POSTFIX_EXPR;
      EXISTS_EXPR;
      NONEMPTY_EXPR;
  
negative.code: //'..' a higher precedence than '->'
  rangeIntervalEntryExpression
      : additiveExpression
        (('..'^ | '->'^) additiveExpression)?
      ;
  
  additiveExpression
  