ruberon/source/COLLECTIONS.ob07

MODULE COLLECTIONS;


TYPE

    ITEM* = POINTER TO RECORD

        link: ITEM

    END;

    COLLECTION* = POINTER TO RECORD

        last: ITEM

    END;


PROCEDURE push* (collection: COLLECTION; item: ITEM);
    BEGIN
        item.link := collection.last;
        collection.last := item
    END push;


PROCEDURE pop* (collection: COLLECTION): ITEM;
    VAR
        item: ITEM;

    BEGIN
        item := collection.last;
        IF item # NIL THEN
            collection.last := item.link
        END

        RETURN item
    END pop;


PROCEDURE create* (): COLLECTION;
    VAR
        collection: COLLECTION;

    BEGIN
        NEW(collection);
        collection.last := NIL

        RETURN collection
    END create;


END COLLECTIONS.