back(value: Any output): Boolean;
The back method of the SetMergeIterator class accesses entries in reverse order one at a time in the sets comprising the merged iterator view.
This method returns true when a prior entry is found, and the entry is assigned to the value parameter. It returns false when a prior entry is not found because the iterator is positioned before the first entry in the merged view, and the value parameter becomes a null reference.
When the back method is used with an iterator where that iterator has been passed to a method as a method parameter, the iterator must be defined as a usage input; that is, the iterator cannot be modified by the called method.
The following example shows the use of the back method.
getReversedPosition(pObj: Object; pIter: SetMergeIterator input): Integer;
vars
pos : Integer;
obj : Object;
begin
while pIter.back(obj) do
pos := pos - 1;
if obj = pObj then
return pos;
endif;
endwhile;
return 0;
end;