INTERFACE RefListUtils;

IMPORT RefList;

PROCEDURE Push (VAR list: RefList.T; item: REFANY);
PROCEDURE Pop (VAR list: RefList.T): REFANY;

PROCEDURE Equal (x, y: REFANY): BOOLEAN;

Compare x and y. If they are both RefList.T's, do a recursive comparison.

PROCEDURE Assoc (alist: RefList.T; item: REFANY): RefList.T;

An association list is a list of sublists. Return the first sublist s for which Equal(item, s.head) is TRUE, or NIL otherwise.

PROCEDURE AssocQ (alist: RefList.T; item: REFANY): RefList.T;

Return the first sublist s for which item = s.head is TRUE, or NIL otherwise.

PROCEDURE SetNth (list: RefList.T; n: CARDINAL; item: REFANY);

Store item as the nth element of list. If n >= RefList.Length(list), this is a no-op.

PROCEDURE NthTail (list: RefList.T; n: CARDINAL): RefList.T;

Return the nth tail of list. If n >= RefList.Length(list), this is a no-op.

PROCEDURE Delete (VAR list: RefList.T; item: REFANY);

Destructively remove all elements e of list for which Equal (item, e) is TRUE, and set list to the result.

PROCEDURE DeleteQ (VAR list: RefList.T; item: REFANY);

Destructively remove all elements e of list for which item = e is TRUE, and set list to the result.

END RefListUtils.