public Formula formula ( final FormulaFactory f ) { if ( this . operator != FType . AND && this . operator != FType . OR ) throw new IllegalStateException ( "Illegal operator for formula list formula construction: " + this . operator ) ; if ( this . formula == null ) { if ( this . operator == FType . AND ) this . formula = f . and ( this . formulas ) ; else this . formula = f . or ( this . formulas ) ; } return this . formula ; }
Returns this formula list as a formula if there is an operator .