protected final void add ( QueryExpression expr ) throws NullPointerException , IllegalArgumentException { if ( expr == null ) throw new NullPointerException ( "expr is null" ) ; // check for cycles if ( expr instanceof CompositeQueryExpression ) { ( ( CompositeQueryExpression ) expr ) . checkForCycles ( this ) ; } else if ( expr instanceof Not ) { ( ( Not ) expr ) . checkForCycles ( this ) ; } // no cycles, so add the expression to the list exprs . add ( expr ) ; }
Add a query expression to this composite expression .