question: public void addPosition ( int offset , int length , String ... ids ) { TextAttribute highlighting = ids . length == 1 ? attributeProvider . getAttribute ( ids [ 0 ] ) : attributeProvider . getMergedAttributes ( ids ) ; boolean isExisting = false ; for ( int i = 0 , n = removedPositions . size ( ) ; i < n ; i ++ ) { AttributedPosition position = removedPositions . get ( i ) ; if ( position == null ) continue ; if ( position . isEqual ( offset , length , highlighting ) ) { isExisting = true ; removedPositions . set ( i , null ) ; removedPositionCount -- ; break ; } } if ( ! isExisting ) { AttributedPosition position = presenter . createHighlightedPosition ( offset , length , highlighting ) ; addedPositions . add ( position ) ; } }
target:  Add a position with the given range and highlighting if it does not exist already.